Biodegradation 11-19-07

Biodegradation 11-19-07 - Terms in Biodegradation ESM 219...

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1 ESM 219 Introduction to Biodegradation Terms in Biodegradation Biotransformation = biological modification of parent compound Biodegradation = biological destruction Biomineralization = biological transformation with CO 2 and H 2 O as end products Terms in Biodegradation catabolic transformations yield energy cometabolic transformations don’t yield energy to the catalysts; primary substrate required. example: oxidation of TCE by methanotrophs Biodegradation: what do you want to know? • What is the compound? – Name(s), forumula, properties? • Does it biodegrade? • What are the requirements for biodegradation? – Nutrients? Environmental conditions? • Who does it? – Single strain? Consortia? • What’s the pathway? – Intermediates? End products? • What gene(s) are involved? • How fast does it occur? – Under what conditions? Biodegradation/ Biocatalysis Database http://umbbd.msi.umn.edu/ • Examples – Atrazine: very-well studied, described • What’s known / not known? – Osmium: metal • Other attributes of the database What about chemicals not in BBD? • Example: APEOs: alkylphenol polyethoxylates (Science, 1984, v225). – Detergents, widely used – Being phased out (see JohnsonDiversey, 2006) – Biodegrades to endocrine disrupters (See Science, above) in WWTPs
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2 Related Research • Chen et al. (2006): kinetics for one isolated bacterial strain, sole carbon source OPEOn – enriched from rice paddy (recycle drainage, rice field) μ vs. S (Fig. 2) – Form & amount of N (Fig. 3) –pH (F ig . 4 ) – Models of growth, degradation (Fig. 5) – End products not quite identified…. (Fig. 7) Related Research (cont.) • Porter and Hay (AEM, 2007).: finding the responsible gene (monoxygenation) in OP degradation – Enrichment, C&E = octyphenol (OP), activated sludge—the polyethoxylate is gone – i.d. by 16S rRNA = Sphingomonas – What can you do with the result? (i.e. identification of the opd A gene and its activity, Fig. 3) Toxicity • Pollutant substrates are also toxic , with effects observable in – Lag period – Slow growth rate – Low yield / Low growth efficiency metabolites can affect other community members • effects on other processes : e.g., Ni inhibits nitrification, carbon mineralization and activities of specific enzymes Acclimation • delay that precedes onset of biodegradation • concentration dependent • reduced after exposure • explanations: – small starting population – toxins: slow growth, are removed, selective pressure, intermediates – predation – genetic change + gene transfer + growth – diauxie (preferential substrate) – enzyme induction (minor), lag phase (minor)
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Biodegradation 11-19-07 - Terms in Biodegradation ESM 219...

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