Degrading microorganisms

The rate and extent of pesticide metaboHsm can vary dramatically, depending on chemical stmcture, the number of specific pesticide-degrading microorganisms present and their affinity for the pesticide, and environmental parameters. The extent of metaboHsm can vary from relatively minor transformations which do not significantly alter the chemical or toxicological properties of the pesticide, to mineralisation, ie, degradation to CO2, H2O, NH" 4, Cf, etc. The rate of metaboHsm can vary from extremely slow (half-life of years) to rapid (half-life of days). 

For those pesticides that are cometabolized, ie, not utilized as a growth substrate, the assumption of first-order kinetics is appropriate. The more accurate kinetic expression is actually pseudo-first-order kinetics, where the rate is dependent on both the pesticide concentration and the numbers of pesticide-degrading microorganisms. However, because of the difficulties in enumerating pesticide-transforming microorganisms, first-order rate constants, or half-hves, are typically reported. Based on kinetic constants, it is possible to rank the relative persistence of pesticides. Pesticides with half-hves of <10 days are considered to be relatively nonpersistent pesticides with half-hves of >100 days are considered to be relatively persistent. 

U.S. Environmental Protection Agency, "EPA Signs License Agreement for TCE-Degrading Microorganisms," in Bioremediation in the Field, Center for Environmental Research Information, EPA/540/N-93/001, Cincinnati, Ohio, no. 8, 1993. 

Lohmeier-Vogel EM, KT Leung, H Lee, JT Trevors HJ Vogel (2001) Phosphorus-31 nuclear magnetic resonance study of the effect of pentachlorophenol on the physiologies of PCP-degrading microorganisms. Appl Environ Microbiol 67 3549-3556. 

Alexandrine M, C Knief, A Lipski (2001) Stable-isotope based labeling of styrene-degrading microorganisms in biofilters. Appl Environ Microbiol 67 4796-4804. 

Sassanella TM, F Fukumori, M Bagdasarian, RP Hausinger (1997) Use of 4-nitrophenoxyacetic acid for detection and quantification of 2,4-dichlorophenoxyacetic acid 2,4-D/a-ketoglutarate dioxygenase activity in 2,4- D-degrading microorganisms. Appl Environ Microbiol 63 1189-1191. 

Oxygenate-degrading microorganisms are typically slow growing and may not be present natively at all sites pilot or treatability studies may be needed to confirm the applicability of bioremediation at a specific site. 

Identification and Isolation of Extracellular Poly(HA)-Degrading Microorganisms... 

Table 1. Overview on poly(HA)-degrading microorganisms and biochemical characterization of purified poly(HA)-depolymerases... 

As it has been pointed out above, poly(HA)-degrading microorganisms, in particular the poly(HA)-hydrolyzing enzymes, differ highly in their substrate specificities for various poly(HA). Furthermore the physico-chemistry of the polymer itself also has a strong impact on its biodegradability. The most important... 

Poly(caprolactone) [poly(6-hydroxyhexanoate) (PCL)] is a synthetic unbranched polyester and has been used by man for a several decades. The biodegradability of PCL is well-known, and many PCL-degrading microorganisms have been described [26,38,112-115]. 

The taxonomy of aerobic dibenzothiophene (DBT)-degrading microorganisms acting as biocatalysts, include the Nocardiaceae [27,126,197,277,291,292], inclusive of genera Rhodococcus and Nocardia, Mycobacteriaceae [30,31], and Bacillaceae [87,293], At first, R. rhodochrous ATCC 53968 was the main biocatalyst, but several other... 

Sugiura W, Miyashita T, Yokoyama T, Arai M (1999) Isolation of azo-dye degrading microorganisms and their application to white discharge printing of fabric. J Biosci Bioeng... 

The available information about surfactant degradation under anaerobic conditions is restricted to anionic and non-ionic surfactants. Anaerobic biodegradation is strongly dependent on the chemical structure of the compound, the presence of a sufficient amount of anaerobically degrading microorganisms and a fulfilment of their growth requirements. 

Hydrocarbon-degrading microorganisms are ubiquitous in most ecosystems [32,117] however, it is often very difficult to prove that transformation, degradation, and mineralization actually occur in the environment because it is difficult to distinguish contributions from biotic and abiotic processes under uncontrolled conditions in the natural environment [338]. In contrast, laboratory assays can provide definitive evidence for microbial degradation, and sterilized samples can be used to determine abiotic losses. Thus, contributions from microbial degradation can be differentiated from abiotic loss by a mass balance... 

If PAH-degrading microorganisms use broad-specificity enzymes or common pathways to transform multiple PAHs, then inducers for the metabolism of one PAH substrate might co-induce the transformation of a range of PAHs. Preliminary evidence indicated that the transformation of naphthalene, phenanthrene, fluoranthene, and pyrene by Pseudomonas saccharophila P15 was stimulated by salicylate [132], a known inducer of naphthalene metabolism in pseudomonads [43]. However, Chen and Aitken [181] reported in more detail the inducing effects of salicylate on the transformation of various HMW PAHs by Pseudomonas saccharophila P15 isolated from contaminated soil, including... 

Lee, A. EPTC (5-ethyl lV,lV-dipropylthiocarbamate)-degrading microorganisms isolated from a soil previously exposed to EPTC, Soil Biol Blochem., 16 529-531, 1984. 

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