ADNTs

Formation of the two monoamino transformation products, 2ADNT and 4ADNT from TNT is favored (Bruns-Nagel et al. 1999 Spain et al. 2000) and they are typically observed in TNT-contaminated sites (soil and ground water). 2ADNT and 4ADNT are more stable in the environment and more mobile, posing a potential threat to human health, and the environment (Harter 1985). Also, in earthworms, the toxicity of 4ADNT was higher than that of TNT and 2ADNT. Since, 2ADNT was bioaccumulated more than other ones...

Aerobic 10211 Bacteria

Bacteria are able to utilize PAHs as the sole source of carbon and energy (Reineke 2001). They exist as gram-positive and gram-negative bacteria with the ability to metabolize some PAHs (Cerniglia 1993). According to Johnsen et al. (2005), bacteria growing in suspended, shaken cultures with crystalline PAHs in concentrations exceeding the aqueous solubility as the sole source of energy and carbon exhibit characteristic growth curves. These curves can be divided into three phases exponential...

Aerobic Degradation of Alkanes

Aerobic alkane degraders activate alkane molecules using O2 as a reactant. The alkane-activating monooxygenase overcomes the low reactivity of the hydrocarbon by producing reactive oxygen species. Oxidation of methane leads to formation of CH4 CHjOH H2C 0 HCOOH CO Serine pathway Ribulose-P pathway Serine pathway Ribulose-P pathway Fig. 17.2 Aerobic pathways of methane oxidation (after Rojo 2009) methanol which is subsequently transformed to formaldehyde and then to formic acid (Fig. 17.2). This...

Aerobic Degradation of Dyes

Most common aerobic process is activated sludge process. Activated sludge is a process dealing with the treatment of sewage and dyes containing wastewaters (Beun et al. 1999). The combination of raw sewage (or industrial wastewater) and biological mass is commonly known as mixed liquor. In all activated sludge plants, once the sewage (or industrial wastewater) has received sufficient treatment, excess mixed liquor is discharged into settling tanks and the treated supernatant is run off to...

Aerobic Treatment

Conventional activated sludge treatment of wastes is often an effective and highly economic system for reducing organic pollutants in wastewater. A fair amount of research has been conducted assessing the viability of using activated sludge to treat textile effluents (Zissi et al. 1997). However, aerobic treatment of azo dye wastes has been proven ineffective in most cases, hence, a typical method of treatment is used today. Because aerobic microbes cannot reduce azo linkages, their ability to...

Aliphatic Aromatic Copolyester

Polyesters are classified into three groups aliphatic, aromatic, and aliphatic-co-aromatic. There are many reports of enzymatic and microbial attack on aliphatic polyesters. The polyesters are gradually hydrolyzable in water and are susceptible to enzymatic attack by lipases in general, but their degradation rate is dependent on their chemical structure or the melting point. Aromatic polyesters, such as polyethylene terephthalate (PET), are practically non-biodegradable, although two papers...

Anaerobic and Anoxic Conditions

During past two decades, anaerobic biodegradation of aromatic pollutants has been a subject of extensive research (Cao et al. 2009). According to them, some bacteria which are involved in PAHs anaerobic degradation are Acidovorax sp., Bordetella sp., Pseudomonas sp., Sphingomonas sp., Variovorax sp., P. stutzeri and Vivrio pelagiusrelated. Anaerobic degradation is a slower process than aerobic limited by several other factors and present in natural environments and so it cannot be overlooked....

Anaerobic Degradation of nAlkanes

Apart from aerobic oxidation, anaerobic degradation also plays an important role in the recycling of hydrocarbons in the environment. Alkanes are also degraded through anaerobic process as reported by various workers (Callaghan et al. 2009 Higashioka et al. 2009). There are two known pathways of anaerobic n-alkanes degradation (Fig. 17.5). First pathway is the alkane addition to fumarate, and second is through putative pathways (So et al. 2003). Fumarate addition proceeds via terminal or...

Anaerobic Treatment

Anaerobic reduction of dyes using microbial sludges can be an effective and economic treatment process for removing color from dye house effluents. Previous studies have demonstrated the ability of anaerobic bacteria to reductively cleave Fig. 12.2 A schematic diagram (a) and photo (b) of a laboratory scale upflow anaerobic sludge blanket reactor (UASB) Fig. 12.2 A schematic diagram (a) and photo (b) of a laboratory scale upflow anaerobic sludge blanket reactor (UASB) the azo linkages in...

Application of Biological Bacterial Methods for Azo Dye Containing Wastewaters

A wide range of structurally diverse dyes is used in the textile industry in the same unit. Although there are many reports available on dye decolorization under aerobic conditions in the presence of either glucose and or yeast extract, most of these are limited to few specific dyes. On the other hand, decolorization in the absence of oxygen is non-specific. As compared to methanogenic consortia, anoxic decolorization requires high concentrations of co-substrates, such as yeast extract or...

Azo Dye Decolorization Under Anoxic Microaerophylic Conditions

By definition, anoxic condition refers to the absence of oxygen, where as micro-aerophylic environments require very low level of dissolved oxygen (DO), but not completely oxygen-free. Azo dye decolorization under anoxic conditions has been reported by mixed, defined microbial consortia as well as pure bacterial cultures (Nigam et al. 1996 Kapdan et al. 2000 Padmavathy et al. 2003 Moosvi et al. 2005). Several pure bacterial strains belonging to Pseudomonas, Aeromonas, Bacillus, Enterococcus,...

Azo Dye Decolorization Under Methanogenic Conditions

Anaerobic methanogenesis, from complex organic compounds, requires the coordinated participation of many different trophic groups of bacteria, which include acidogenic, acetogenic and methanogenic bacteria (Kasper and Wuhrmann 1978). It has been widely reported that azo dyes are gratuitously reduced by anaerobic sludges, anaerobic sediments and anaerobic enrichment cultures (Brown and Hamburger 1987 Weber and Wolfe 1987 Chung et al. 1992 Manu and Choudhary 2003). Dye decolorization, under...

B

Fig. 2.3 Mechanisms of trichloroethylene (TCE) degradation by white rot fungi. a Proposed reductive dechlorination of TCE by LiP of P. chrysosporium using oxalate as the electron donor (Khindaria et al. 1995). b Oxidation of TCE catalyzed by cytochrome P450 system in T. versicolor (Marco-Urrea et al. 2008b) further indicated that TCE degradation by T. versicolor involves cytochrome P450 system, as suggested by inhibition of TCE degradation in the presence of 1-aminobenzotriazole (a known...

Bacterial Biodegradation

In a large-scale test of bacterial activity against PUs, Kay et al. (1991) investigated the ability of 16 bacterial isolates to degrade polyester PU. Seven of the isolates tested degraded PU when the media was supplemented with yeast extract. Two isolates, Corynebacterium sp. and Pseudomonas aeruginosa, could degrade PU in the presence of basal media. However, none of the isolates grew on PU alone. Physical tests of the degraded polyester PU revealed different but significant decreases in...

Biochemical Pathway

PAH degradation by microbial transformation mainly initiates with the action of intracellular dioxygenases after the toxic compound is taken up by the cells. Bacteria most often oxidize PAHs to cis-dihydrodiols by incorporation of both atoms of an oxygen molecule. The cis-dihydrodiols are further oxidized, first to the aromatic dihydroxy compounds (catechols) and then channeled through the ortho-or meta-cleavage pathways (Cerniglia 1984 Karthikeyan and Bhandari 2001). The aerobic...

Biodegradation of Polychlorinated Biphenyls

Polychlorinated biphenyls belong to persistent organic pollutants. Although their production was stopped long time ago, they still persist in the environment and represent a serious environmental problem. The aromatic ''doublering'' structure may be substituted with one to ten chlorine atoms. Although there are 209 individual compounds designated as congeners, but only 130 could be found in commercial PCB mixtures. The toxicity of such molecules is directly correlated to both number and...

Biodegradation of RDX and HMX by Fungi

Fungi have potential application in the degradation of cyclic nitramines owing to their widespread distribution in the environment, particularly in soil, and their capability to produce several extracellular enzymes. Fungi can degrade chemicals using several enzymes, such as peroxidases that are known to catalyze a number of free radical reactions (Stahl and Aust 1995). The electronegative -NO2 group in RDX readily accepts a free electron to form an anion radical. The elimination of nitrite...

Biodegradation of RDX and HMX under Aerobic Conditions

Several groups have studied aerobic metabolism of RDX and HMX and have demonstrated the potential for these energetic chemicals to be mineralized (Binks et al. 1995 Jones et al. 1995a, b Greer et al. 1997 Coleman et al. 1998 Tekoah and Abeliovich 1999 Sheremata and Hawari 2000). Binks et al. (1995) showed that Stenotrophomonas maltophilia can degrade RDX, but not HMX when the cyclic nitramine is used as a nitrogen source. Harkins et al. (1999) reported the formation of five nitroso derivatives...

Biodegradation of RDX and HMX under Anaerobic Conditions

Biod gradation of RDX and HMX under anaerobic condition has been extensively studied (McCormick et al. 1981 Hawari et al. 2000a Adrian and Arnett 2004 Bhatt et al. 2005). Anaerobic reduction of RDX and HMX can be achieved in several different ways. RDX biodegradation under anaerobic conditions was first reported by McCormick et al. (1981), who proposed RDX biodegradation by reduction of the RDX nitro (-NO2) groups to nitroso (-NO) groups to produce (MNX) hexahydro-...

Biodgradation of RDX and HMX

The non-aromatic cyclic nitramine explosives hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and (HMX) have weak C-N bonds. Initial enzymatic attack able to change N-NO2 or C-H bonds of the cyclic nitramine can readily destabilize the cyclic structure and cause further molecular fragmentation. Several chemical studies (Zhao et al. 1988 Brill 1990 Sewell and Thompson 1991 Wight and Botcher 1992) have shown that once the non-aromatic cyclic nitramine RDX or HMX undergoes a change in its molecular...

Biotransformation Pathways of RDX

Metabolic pathways involved in the biodegradation of the cyclic nitramines RDX and HMX have been reviewed (Hawari et al. 2000a Crocker et al. 2006). The potential degradation routes known for RDX are presented in Fig. 9.2. Three mechanisms for the transformation of RDX have been proposed two-electron reduction, single-electron reduction denitration, and direct enzymatic cleavage. Path A Reduction of RDX to nitroso derivatives before ring cleavage (McCormick et al, 1981) Path B Reduction of RDX...

Chemistry of TNT

Unlike toluene which is metabolized through oxidation pathway for its methyl group, 2,4,6-TNT is more resistant to oxidative reaction, because p electrons from the aromatic ring of TNT are removed by the electronegative nitro groups. Therefore, the aromatic ring of TNT has electrophilic property. The detail explanation has been schemed in Fig. 8.1. Basically, methyl group is an electron-releasing substituent, therefore, p electrons from the aromatic ring of toluene increase. The carbon atom of...

Chlorinated Insecticides

Lindane (y isomer of hexachlorocyclohexane) was a widely used pesticide in the past and an estimated 600,000 tons of lindane were produced globally between 1950 and 2000. There is a global ban on the use of lindane now because of its environmental persistence as a pollutant. P. chrysosporium, cultured under ligninolytic conditions, was reported to partially mineralize lindane in liquid cultures and in a corncob-amended soils inoculated with P. chrysosporium (Bumpus et al. 1985 Kennedy et al....

Co

Atrazine is a commonly used triazine herbicide and is degraded by a number of white rot fungi (Masaphy et al. 1993 Mougin et al. 1994 Entry et al. 1996 Bending et al. 2002 Nwachukwu and Osuji 2007). Degradation of atrazine by Pleurotus pulmonarius and P. chrysosporium leads to the accumulation of the N-dealkylated products deethylatrazine, deisopropylatrazine, deethyl-deisopropy-latrazine and hydroxyisopropylatrazine (the latter produced only by P. pulmonarius). Atrazine oxidation by these two...

CoMetabolism and Inhibition

Biodegradation is defined as the biologically catalyzed redox reaction in complexity of chemical compounds (Alexander 1994). It is based on two processes, growth and co-metabolism. In case of growth, organic pollutants are used as sole carbon and energy source. This process results in complete degradation (mineralization) whereas in co-metabolism, the metabolism of an organic compound occurred in presence of a growth substrate which is used as the primary carbon and energy source (Alexander...

Conclusion

The degradation of polymers was at first expected to be catalyzed solely by extracellular enzymes, given the assumption that macromolecules are never incorporated into cells, but this was disproved by the periplasmic degradation of PEG and PVA, as described above. These are surely incorporated into the periplasm through the outer membranes of Sphingomonads and are metabolized by periplasmic enzymes, although the mechanism of macromolecule uptake has not been well characterized. Many enzymes...

Conclusions

Despite of an extensive industrial usage of styrene which brings about significant anthropogenic releases in the environment, the ecological threat of this hydrocarbon is considerably limited due to its high volatility, its distinct chemical reactivity, and a pronounced susceptibility against biological transformations. In mammals and human, these transformations involve an initial cytochrome P450-mediated oxygenation yielding a mutagenic epoxide which, as a proven carcinogen, causes the most...

Control of Biodegradation of Fuels 13711 Physical Control

Apart from maintaining fuels at temperatures unsuitable for microbiological growth which is often very difficult, the more obvious method of control is to eliminate water by good house keeping techniques, but this is often very difficult to achieve for the following reasons Many fuels contain a degree of dissolved or chemically bound water which can later condense out during temperature changes and form free microbiologically available water. Atmospheric moisture may often enter the storage...

Cytochrome P450 Monooxygenase

These enzymes are heme proteins and catalyze the hydrocarbons using NAD(P)H as cofactor. They usually consist of two components hydroxylase and reductase (Sono et al. 1996). These enzymes are usually membrane-bound and have a multi-component nature (Ayala and Torres 2004). The molecular mechanisms of oxygen activation for some metalloenzymes are well investigated. Heme-oxygenases, such as CYP, hydroxylate inert hydrocarbon substrates by using a high-valent oxoiron(IV) porphyrin p-cation-radical...

Degradation of Chloroorganic Pollutants by White Rot Fungi

Ligno-cellulosic plant biomass is the most abundant renewable organic resource on earth and contains cellulose, hemicellulose, and lignin polymers as its key components. Lignin, the most abundant aromatic polymer in the biosphere, is a highly complex, three dimensional, branched, recalcitrant polymer. Because of its recalcitrance, biodegradation of lignin is the rate-limiting step in the degradation of lignocellulosic biomass and thus lignin plays a pivotal role in global carbon cycling....

Degradation of Four Ring PAHs

Of the four ring PAHs, degradation of fluoranthene, pyrene, chrysene, and benzo(a)anthracene has been investigated to varying degree. Fluoranthene, a non-alternant PAH containing a five carbon aromatic ring, is observed to be metabolized by a variety of bacteria, and pathways describing its biodegradation have been proposed. 7.2.1.1 Degradation of Fluoranthene by Bacteria In 1990, two independent groups of researcher reported the isolation of a single organism capable of utilizing fluoranthene...

Degradation of Hmw Pahs and Substrate Interaction Effects

In the environment, PAHs exist as complex mixtures along with a multitude of other compounds, such as, in creosote and coal tar. In this scenario, one compound may affect the rate and extent of degradation of another compound, e.g., through increasing the biomass growth, competitive inhibition and co metabolism. These effects are referred as substrate interaction effects. As observed by various researchers, the net result could be an increase in the rate of biodegradation as a result of...

Denitration

A variety of strains have been found capable of aerobic growth on TNT as sole nitrogen source. This unique phenomenon is coupled to their ability to denitrate the molecule with the subsequent release of nitrite to the medium (Table 5.3). A number of studies show that under aerobic conditions, the denitration pathway proceeds via the nucleophilic addition of a hydride ion to the aromatic ring in the presence of NAD(P)H and the formation of a hydride-Meisenheimer complex, which can be further...

Direct Interfacial Uptake

In direct interfacial uptake, bacteria attach itself to the surface of the NAPL droplets which are larger in size compared to the bacterial cell. Substrate uptake takes place at the point of contact through diffusion. CSH plays an important role in direct uptake. Microorganisms capable of direct uptake can modify their cell surface outer membrane to enhance CSH. In this case, substrate uptake does not depend on the dissolution rate. Some microorganisms have surface structures such as, fimbriae...

Environmental Science and Engineering Environmental Engineering

For further volumes http www.springer.com series 7487 Microbial Degradation of Xenobiotics National Botanical Research Institute ISBN 978-3-642-23788-1 e-ISBN 978-3-642-23789-8 Springer Heidelberg Dordrecht London New York Library of Congress Control Number 2011938665 Springer-Verlag Berlin Heidelberg 2012 This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations,...

Fate of Aromatic Amines Under Aerobic Conditions

General degradation pathways for benzene and naphthyl amines under aerobic conditions involve the participation of either mono or dioxygenases (specific hydroxylases) leading to the formation of dihydroxyaromatic compounds (Bayley and Barbour 1984). The dihydroxylated compounds are subsequently dearoma-tized by the cleavage of aromatic ring, which is catalysed by specific dioxygen-ases. Ring cleavage can occur either at ortho or meta position to the hydroxyl groups, leading to the formation of...

Freshwater

Levels of different PAHs in freshwater are very heterogeneous. For example, Wang et al. (2009) found in the Three Gorges Reservoir (Yangtze River) levels of total PAHs between 13.8 and 97.2 ng L-1. Fernandes et al. (1997) found PAH level in the Seine River and its estuary, ranging from 4 to 36 ng L-1. Countway et al. (2003) carried out a study in the York River and its estuary, and obtained levels of PAHs between 2.09 and 122.85 ng L-1 (with the salinity in these points around 13). Smith et al....

Fungal Biodegradation of Aliphatic Compounds

Fungal biodegradation of aliphatic compounds has been studied and reported in the literature for several decades and will, therefore, not be reviewed here extensively. Many different fungal species have been described for their growth on aliphatic substrates including alcohols, alkanes, and aldehydes, among others. Some examples are given in Table 6.1. Often these substrates can be used as sole carbon and energy source, although there are some exceptions, such as, the co-metabolic degradation...

Fungal Biodegradation of Endocrine Disrupting Compounds

Endocrine-disrupting compounds (EDCs) are a group of environmental pollutants known for their negative influence, particularly on aquatic organisms. EDCs tend to accumulate in aquatic organisms and also get adsorbed by sediments and on particles in the aquatic environment. These compounds mimic or antagonize the effects of endogenous hormones and hence, alter the synthesis and metabolism of natural hormones, or modify hormone receptor levels, disrupting endocrine and reproductive functions...

Fungal Decolorization and Degradation of Synthetic Dyes

Inefficiencies in industrial dyeing processes result in large amounts of synthetic dyes being directly lost to the wastewaters and consequently to the water environment. The amount of dye lost is dependent on the chemical structure of the dye and varies from 2 loss (basic dyes) to 50 loss (reactive dyes). Synthetic dyes represent a group of structurally different chemicals and are normally divided into azo, nitro, nitroso, diarylmethane, triarylsmethane, xanthene, anthraquinoid, acridine,...

Genes Involved in Alkane Degradation

The organization of the genes involved in alkane oxidation differs significantly among alkane degrading bacteria (van Beilen et al. 2003). The alkane degradation genes encoded by the OCT plasmid of P. putida GPo1 are clustered in two operons, and this pathway has clearly been transferred horizontally to many bacteria (van Beilen et al. 2001). When several alkane hydroxylases coexist in a single strain, they are normally located at different sites in the chromosome. Moreover, the regulators that...

Identifying and Quantifying In situ Biodegradation of Explosives

While identifying the potential of indigenous bacteria to biodegrade a compound is relatively simple, gaining evidence that biodegradation is actually occurring and further, quantifying its extent in complex environments is intrinsically difficult. Thus, studies on degradation potential, pathway identification, and rate quantification of explosives biodegradation under controlled laboratory conditions are frequently carried out. A few studies have been also aimed at characterizing the microbial...

Influence of Chemical and Physical Properties on Biodegradation Rate

Looking at the reductive transformation of the nitro group from a purely energetic compounds, one would expect the decrease in reduction rate from TNT to RDX, and finally to HMX (Uchimiya et al. 2010). On the other hand, in complex biotic systems such as the sub-surface, factors other than energetic yield will dictate the rate at which explosives degrade. Nutrient availability is one important factor that plays a significant role in the rate of explosives biodegradation. Compared to other...

Influence of Environmental Conditions on the Fungal Biodegradation of Non Oxygenated Mono Aromatic Compounds

For most microorganisms, environmental conditions, such as pH, temperature, relative humidity, moisture content of the ecosystem, play a key role on the activity of fungal species degrading mono-aromatic compounds. Interestingly, all fungi isolated so far on alkylbenzenes and other related non-oxygenated benzene-compounds are mesophilic organisms. Their optimal temperature is generally around 30 C. Toluene biodegradation by Exophiala oligospermia and Paecilomyces variotii at different...

Initial Denitration Followed by Ring Cleavage

Anaerobic denitration of HMX as a result of a single-electron transfer, followed by ring cleavage and MEDINA formation, was detected by resting cells of C. bifermentans strains HAW-1 and HAW-EB21 (Zhao et al. 2004a, b). NDAB was not detected in this study. Bhushan et al. (2003 a) studied the transformation pathway of HMX with the metallo-flavo enzyme xanthine oxidase. Based on the detected products, they proposed that HMX undergoes a single denitration step. They observed this step under...

Introduction

Styrene, the simplest representative of alkenylbenzenes, is one of the most important monomers produced by the chemical industry today. The compound shows a distinct toxicological behavior and is classified as a possible carcinogen due to its metabolism in human via a highly mutagenic epoxide. Considerable amounts of styrene are released by emissions and effluents during production and usage in polymer manufacture and by deposition of industrial wastes. A high chemical reactivity as well as its...

Limitations in Degradation of PAHs in Soil

Many microorganisms are metabolically capable of mineralizing or partially transforming PAHs in the environment. Some fungi can produce extracellular enzymes, but for most of the bacteria, the pollutants must cross the cell membrane to get direct access to the enzymes or at least attach to the membrane bound enzymes. With the exception of some bacterial species that can attach directly to the interface between the organic and aqueous phase, in general for degradation to Table 7.2 Rate and...

Mechanism of Azo Dye Reduction

The azo bond (-N N-) cleavage involves a transfer of four-electrons which proceeds through two stages at the azo linkage. Two electrons are transferred to the azo dye in each stage, which acts as final electron acceptor. The reduction may involve different mechanisms, such as enzymatic (Zimmermann et al. 1982, 1984 Rafii et al. 1990 Haug et al. 1991 Suzuki et al. 2001 Maier et al. 2004), involvement of low molecular weight redox mediators (Van der zee and Cervantes 2009), chemical reduction by...

Metabolism of PAH Compounds

PAHs with two to three fused aromatic rings are considered as low molecular weight (LMWPAHs) such as, naphthalene, anthracene and phenanthrene, whereas those with four and more fused rings are high molecular weight (HMWPAHs) that include chrysene, fluoranthene and pyrene, etc. (Igwo-Ezikpe et al. 2010). Isolation of highly efficient PAHs (containing four aromatic rings), degrading bacterium is the pioneering study that opened the possibility of PAH biodegradation (Heitkamp and Cerniglia 1988)....

Microbial Degradation of Polychlorophenols

Polychlorophenols are major environmental pollutants, and their degradation by microorganisms has been extensively studied for the purpose of bioremediation. Three different metabolic pathways for aerobic degradation of polychlorophenols have been completely worked out, revealing the metabolic diversity for these structurally similar compounds. Substituted quinols, rather than catechols, are key metabolic intermediates of polychlorophenol biodegradation. Substituted quinols and quinones are...

Nitrogen and phosphorus

There is an ambiguity regarding the limitation of petroleum biodegradation by available concentrations of nitrogen and phosphorus. Lepetit and Barthelemy (1968) reported that the concentration of available nitrogen and phosphorus in water are severe limiting factors for microbial hydrocarbon degradation. However, Kinney (1968) is of the opinion that nitrogen and phosphorus are not the limiting factors, since microorganisms require nitrogen and phosphorus for their incorporation into biomass and...

Nutrients

Van Hamme et al. (2003) reported that nitrogen and phosphorus contents greatly affect the microbial degradation of hydrocarbons. They further stated that adjustment of the ratios of N and P by their addition in the form of slow releasing fertilizers stimulated the biodegradation of hydrocarbons. Osteberg et al. (2006) found accelerated biodegradation of n-alkanes in aqueous solution by the addition of fermented whey. Bulking agents, such as compost, will enhance metabolism of organic...

PH

PH is not of much significance in marine environments since it is well buffered at about pH 8.5, but soil pH varies widely and pH between 7 and 8 has been found to support optimum degradation of alkanes in soils sediments. Surfactants are amphiphilic compounds, that reduce surface and interfacial tensions by accumulating at the interface of immiscible fluids or of a fluid and a solid, increase the contact surface areas of insoluble compounds, leading to increased mobility, bioavailability and...

Phenanthrene Degradation

Phenanthrene, a PAH with three condensed rings fused in angular fashion, has a 'bay-region' and a 'K-region' and is often used as a model substrate for studies on the metabolism of carcinogenic PAHs (Igwo-Ezikpe et al. 2010). For last few decades, a number of studies on phenanthrene degradation by several Gram-negative and Gram-positive bacteria revealed metabolic diversity involved in phenanthrene degradation (Kim et al. 2005a). Universally, the metabolic pathway is initiated by the double...

Physical and Chemical Properties of PAHs

PAHs are a group of compounds composed of two or more fused aromatic rings in linear, angular, and cluster arrangements as shown in Fig. 7.1. Based on structural diversity, PAHs can be broadly categorized into alternant and non-alternant classes. Alternant PAHs contain only fused benzenoid rings (e.g., anthracene, phenanthrene and pyrene), whereas non-alternant PAHs contain four or five carbon aromatic rings in addition to benzene ring (e.g., fluorene and fluoranthene) (Harvey 1991). PAHs can...

Polyamino acids and Polyamides

The degradation of poly(amino acid)s and polyamides was reviewed by Obst and Steinb chel (2004). In nature, proteins and poly(amino acid)s exist as two different types of amino acid polymers. The most critical differences are (i) that the former is a random polymerization of 20 amino acids and the latter a polymer of a single amino acid, and (ii) the synthesis of proteins is ribosome-dependent and forms an a-amino-a-carboxyl peptide linkage while that of poly(amino acid)s is...

Polyurethane Degradation

Research has been initiated to elucidate whether additives to the chemical structure of PU could decrease biodegradation. Kanavel et al. (1966) observed that sulfur-cured polyester and polyether PU had some fungal inertness. However, they noted that even with fungicides added to the sulfur- and peroxide-cured PU, fungal growth still occurred on the polyester PU and most fungicides had adverse effects on the formulations. Kanavel et al. (1966) also recognized the need for physical testing of the...

Polyurethane Degradation by Pseudomonas

Three Pseuomonads have been isolated for their ability to utilize a polyester PU as the sole carbon and energy source. Interestingly, three species of bacteria produce different PUase activities that are inhibited by serine hydrolase inhibitors. These data suggest that either esterase and or protease activities are involved in the degradation of Impranil (Fig. 14.4). Growth of Comamonas acidovorans on colloidal polyester-polyurethane resulted in the growth parameters for Ks and imax of 0.3 mg...

Polyvinyl Alcohol

Historically, PVA has been produced on an industrial scale by the hydrolysis of poly(vinyl acetate), since a vinyl alcohol monomer cannot exist due to tautomerization into acetoaldehyde. PVA are widely used due to its excellent physico-chemical properties, especially for fabric and paper sizing, fiber coating, adhesives, emulsion polymerization, films for packing and farming, and the production of poly(vinyl butyral). Maximum production of PVA amounted to about 1,250 kt in 2007 the top volume...

Production of Biosurfactants and PAH Uptake

Production of biosurfactant is another mechanism adopted by certain bacterial species to degrade complex petroleum hydrocarbons. Like chemical surfactants, biosurfactants are amphiphilic molecules having both hydrophilic and hydropho-bic regions which help them in attachment to different surfaces. Biosurfactants are categorized into groups based on their MW (Ron and Rosenberg 2002). LMW surfactants are typically glycolipids where the carbohydrate group is attached to long chain alkyl acids or...

Recombinant Bacteria for Alkane Degradation

Due to multi-component nature, recombinant production of CYP450 is difficult, but CYP BM-3 is readily expressed in E. coli (Peter et al. 2003). Rothen et al. (1998) constructed a plasmid with gene coding for the three enzymes alkane hydroxylase, alcohol dehydrogenase and aldehyde dehydrogenase simultaneously. The plasmid was inserted into an E. coli strain unable to Table 17.1 Different enzymes involved in alkane degradation (van Beilen et al. 2003) Cytochrome P450 (CYP153) monooxygenase...

Reduction of the Nitro Group

The most common degradation pathway for TNT proceeds along the sequential reduction of the nitro groups. Following sequential steps of two-electron transfers, the corresponding mononitroso, monohydroxylamino and monoamino derivatives 2-aminodinitrotoluene 4-aminodinitrotoluene (2-ADNT) (4-ADNT) Deaminationand formation of nitrogen free metabolites 2-aminodinitrotoluene 4-aminodinitrotoluene (2-ADNT) (4-ADNT) Bamberger rearrangement and formation nhoh of phenolic amine derivate Fig. 5.2...

Reductive Pathway of Nitro Groups

TNT is commonly biotransformed by converting nitro groups into nitroso, hydroxylamino and amino groups (Hawari et al. 2000 Esteve-NUnez et al. 2001 Snellinx et al. 2002), as shown in Fig. 8.2. Thus, because of its high electron deficiency, initial microbial transformations of TNT are characterized by reductive rather than by oxidative reactions (Barrows et al. 1996). In several bacterial species, the major reduction metabolites from TNT are hydroxylamino-dinitrotoluenes HADNTs...

References

Alexander M (1990) The environmental fate of styrene. SIRC Rev 1 33-42 Alexandrino M, Knief C, Lipski A (2001) Stable-isotope-based labeling of styrene-degrading microorganisms in biofilters. Appl Environ Microbiol 67 4796-4804 Alonso S, Bartolom -Mart n D, del Alamo M, D az E, Garc a JL, Perera J (2003a) Genetic characterization of the styrene lower catabolic pathway of Pseudomonas sp. strain Y2. Gene 319 71-83 Alonso S, Navarro-Llorens JM, Tormo A, Perera J (2003b) Construction of a bacterial...

Role of Microbes

Microbial diversity, the richness of species in environmental sites, provides a huge reservoir of resources that can be utilized for our benefit. However, the major bottleneck is our knowledge about the true diversity of bacterial life (Jain et al. 2005). Moreover, they have evolved the ability to utilize such highly reduced and recalcitrant compounds as potential source of carbon and energy (Phale et al. 2007). Therefore, mining out the array of microbial diversity would play a key role to...

Sequential Reduction Pathway

In contrast to TNT, sequential reduction of RDX occurs mostly under anaerobic conditions, as initially presented by McCormick et al. (1981). This pathway proceeds through reduction of the nitro groups to nitroso derivatives by subsequent two-electron transfer steps, followed by accumulation of (MNX), (DNX), and (TNX) derivatives. Again in contrast to TNT, the nitroso derivatives do not tend to undergo further reduction to stable detectable product. Although this degradation pathway leads to the...

Structure and Properties of RDX and HMX

(RDX) and (HMX) are two widely used cyclic nitramine explosives. The nitramines are the most recently introduced class of organic nitrate explosives. RDX (Research Department Explosive) and HMX (High Melting Explosive) are the most prominent members of this class. RDX and HMX are considered to be oligomers, (CH2NNO2)n n 3 or 4, respectively of the same repeating structural moiety, CH2NNO2. HMX is a big ring molecule, same as RDX but with an extra CH2NNO2 unit (Fig. 9.1). Research Department...

Structure of PAHs

The polynuclear aromatic hydrocarbons are composed of two or more aromatic (benzene) rings which are fused together in a linear, angular or cluster arrangement when a pair of carbon atoms is shared between them (Dhote et al. 2010). PAHs toxicity is quite structurally dependent, with isomers (PAHs with the same formula and number of rings) varying from non-toxic to extremely toxic. Thus, highly carcinogenic PAHs may be small or large. The PAH compound, benzo a pyrene (BAP), was notable as the...

Styrene Monooxygenases

Perhaps, the most prominent application derived from styrene-degrading bacteria is the production of enantiopure epoxides by means of highly stereoselective styrene monooxygenases (SMOs) (Fig. 3.5). Optically active oxiranes are high-value building blocks for pharmaceutical and agrochemical industry as well as for fine chemistry (Rao et al. 1992 Badone and Guzzi 1994 Besse and Veschambre 1994 Hattori et al. 1995 Schulze and Wubbolts 1999 Breuer et al. 2004). All styrene monooxygenases...

Styrene Oxide Hydrolases and Styrene Oxide Isomerases

As mentioned before, epoxide hydrolases (EHs) can be involved in styrene metabolism (Fig. 3.1). More frequently, these enzymes play a role in the detoxification process of xenobiotics with epoxide-like structures, especially in mammalians. EHs are enantioselective and show a broad substrate spectrum. Styrene oxide is a model substrate for this enzyme class and most representatives convert solely one enantiomer of racemic styrene oxide into a chiral phenylethan-1,2-diol. Thus, EHs can be used to...

Surfactant Enhanced Biodegradation of Hmw Pahs

Contradictory and inconclusive results have been observed regarding the effects of surfactants on the biodegradation of PAHs at surfactant concentration below and above the critical micelle concentration (CMC) (Margesin and Schinner 1999). Some studies showed an enhanced effect in which not only LMW PAHs were degraded successfully, but even compounds containing four and more than four rings were also degraded effectively. In contrast, in other studies, degradation was found to be inhibited....

The Autoxidation of Aromatic Amines

A few aromatic amines, formed during the anaerobic reduction of the azo dyes, are unstable under aerobic conditions and undergo auto-oxidation reactions. Examples are 5-ASA, phenylenediamine, o-amino hydroxy and o-dihydroxy naphthalenes Fig. 4.3 Proposed pathways for the degradation of substituted naphthalene-sulfonates. NSDO naphthalenesulfonate dioxygenease DHNDO 1,2-dihydroxynaphthalene dioxygenase HCCAI 2-hydroxychromene-2-carboxylate isomersae HBPA 2'-hydroxybenzal-pyruvate aldolase SADH...

The Gene Cluster styABCDE of the Upper Styrene Degradation Pathway

The number and arrangement of genes within the styABCD(E) clusters of pseudomonads reflect the necessity and sequence of encoded enzymes, respectively, Fig. 3.3 Comparison of the organization of a the styABCDE-operon from Pseudomonas sp. Y2, b other (incomplete) styrene-catabolic gene clusters from pseudomonads, and c the genetic location of flavin monooxygenases with ( hypothetical) function as styrene monooxygenases. The upper pathway of styrene degradation by side-chain oxygenation is shown...

The Regulatory System of the Sty Operon

The two-component regulatory system StyS StyR of the sty-operon from the strains Pseudomonas putida CA-3, Pseudomonas sp. Y2, and Pseudomonas fluo-rescens ST was investigated in detail (Velasco et al. 1998 Santos et al. 2000 O'Leary et al. 2001, 2002a Leoni et al. 2003). With respect to the conserved operon organization among pseudomonads (Fig. 3.3a, b), the described features of this regulatory system are supposed to occur and interact similarly in all functional sty-operons of pseudomonads....

Toxicity Assessment of Azo Dyes and their Degradation Products

The main aim of the azo dye containing wastewater treatment is the reduction of associated toxicity. Many reports cite textile wastewater as a significant contributor to toxic load on aquatic ecosystems (Rajaguru et al. 2002 Umbuzeiro et al. 2005 Puvaneshwari et al. 2006). Many in vivo and in vitro tests are available for toxicity assessment (Farre and Barcelo 2003). They include (1) Animal assays fish, rat, mice and Daphnia are generally used test organisms in the animal assays (2) The Comet...

Toxicity of TNT and its Metabolites 841 TNT

TNT is the most toxic substance and is mutagenic in Salmonella typhimurium strains TA98 and TA100 with or without exogenous metabolic activity (Berthe-Corti et al. 1998). An unpublished 2-year study was reported in 1984 by the IIT Research Institute, Chicago, IL. Fisher 344 rats were fed diets containing 0.4, 2, 10, or 50 mg-TNT kg-weight per day. In the urinary bladder, hyperplasia (12 of 47 animals) and carcinoma (11 of 47 animals) were observed at significant levels in high-dose (50 mg kg)...

Water Contamination in Fuel Storage Tanks Transporting Pipeline

Microorganisms may enter the fuel from the soil, air, polluted wash water, contaminated pipelines, or from the biofilm present on the tank walls, if the latter have not been sufficiently well cleaned (Rajasekar et al. 2010). Even in the best-kept tanks, microbial contamination is an occasional problem. Microorganisms are usually present in the fuel, but good housekeeping (removal of water and use of biocides) minimizes their growth. Nevertheless, reports of microbial growth in fuel tanks have...

Biodegradation of Petroleum Hydrocarbons in Petroleum Transporting Storage Tanks

Biodegradation of diesel hydrocarbon by B. cereus ACE4 and S. marcescens ACE2 was confirmed by GC-MS, NMR and FT-IR analyses in petroleum transporting pipeline, India (Rajasekar et al. 2007b, e). From GC-MS analysis, it was observed that the control system consisted of n-alkanes (Ci0-C20), branched alkanes, naphthalene derivatives, substituted naphthalenes and iso preniod alkanes (pristane, phytane) (Fig. 13.8a). The inoculated S. marcescens ACE2 degraded almost all the n-alkanes (C10-C20) and...

Microbial Degradation of Xenobiotic Polymers

What does ''biodegradability of polymers'' mean The first criterion for biodegradation is enzymatic processing. In particular, hydrolyzable polymers such as polyesters and polyamides are enzymatically degraded into monomers (depoly-merization process) that can easily enter central metabolic processes unless they are xenobiotic compounds. Most monomers are naturally occurring compounds, such as organic acids, alcohols glycols, and amide compounds. Proteases, lipases, and esterases originating...

Biodegradation of Non Oxygenated Mono Aromatic Compounds

Until the end of the past century, the biodegradation of non-oxygenated mono-aromatic compounds seemed to be an unusual capability of fungi (Kennes and Veiga 2004). The first isolated report suggesting minimal growth of a fungal strain on benzene compounds appeared in 1973 (Cofone et al. 1973). However, not enough evidence was obtained at that time to conclude that growth of the Cladosporium resinae strain was possible on benzene. Another report appeared several years later (Fedorak and...

Chlorinated Pharmaceutical and Personal Care Products

An expanding array of substances called 'Endocrine-disrupting compounds' (EDC) include chemicals of natural and anthropogenic origin. EDCs are widely distributed in the environment. They constitute a potential health risk to humans and aquatic life. Only a couple of EDCs are covered here. Triclosan is one such synthetic antimicrobial compound that is present in a wide range of health care products, such as tooth-paste, deodorant sticks and soaps. It has been detected in various environmental...

Microbial Degradation of Alkanes

Due to lack of functional groups as well as very low water solubility, aliphatic hydrocarbons exhibit both, low chemical reactivity and bioavailability for microorganisms. However, some microorganisms possess the metabolic capacity to use these compounds as carbon and energy sources for their growth (Berthe-Corti and Fetzner 2002). A number of microbes including bacteria, fungi and yeasts have been reported to degrade alkanes using them as the source of carbon and energy (van Beilen et al. 2003...

Role of Microbes in Petroleum Hydrocarbon Degradation

Xenobiotics

Twenty-one years after ZoBell's (1946) classic review, the super tanker Torrey Canyon sank in the English Channel. With this incident, attention of the scientific community was dramatically focused on problems of oil pollution. After this event, several studies were initiated to study the fate of oil pollution. Several studies were also initiated on the fate of petroleum in varied ecosystems. Biodegradation of petroleum products in natural ecosystem is no doubt a complex issue. The degradation...

Polyethers

Poly(alkylene glycol)s have a common structural formula HO R-O nH R CH2CH2 for PEG, CH3CHCH2 for polypropylene glycol (PPG), a polymer of 1,2-propylene oxide, (CH2)4 for polytetramethylene glycol (PTMG), and C2H5(CHCH2) for polybutylene oxide (PBO), a polymer of 1,2-butylene oxide , where n represents the average range of units. The physical properties of PEGs vary from viscous liquids to waxy solids based on their molecular sizes, although every PEG from oligomers up to polymers with a...

PAHs Degrading Organisms

The PAH-degrading microorganisms could be algae, bacteria and fungi. It involves breakdown of organic compounds through biotransformation into less complex metabolites, and through mineralization into inorganic minerals, H2O, CO2 (aerobic) or CH4 (anaerobic) (Haritash and Kaushik 2009) Schematic metabolic pathways to degrade PAHs of these microorganisms are shown in the Fig. 10.1. In aerobic pathways, the main strategy of microorganisms to degrade aromatic pollutants is to use a range of...