Bioremediation - 5,000 8,000 new chemicals each year over...

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Why are xenobiotics degraded at all? Example: Some phenolic compounds related to plant compounds - e.g. lignin, flavonoids 1. Some enzymes have low specificity 2. Mutations occur to change specificity 5,000 – 8,000 new chemicals each year – over 200 made in large amounts
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Since synthetic chemicals are new to the environment microbes have not yet evolved efficient pathways for degradation “New pathways” do not suddenly appear - old pathways change - often modularly Current pathways almost certainly not optimal for novel chemicals
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Microbes evolve for ecological fitness - not biotechnological efficacy Selective use of compounds not required in nature Conditional use of compound with high K m is often the norm Process conditions can thus almost always be improved
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Strategies for pathway improvement or accelerated biodegradation in situ bioremediation Used when: Large contamination where impractical to remove materials Characteristics of site allow easy access of microbes to pollutant Pollutant can be degraded by indigenous microbes Simply speeds up naturally occurring biodegradation Improved microbes not necessarily helpful Process: Determine limiting factors for biodegradation - ie. N or P - usually not C Supply O 2 Increase dispersion of pollutant in water - surfactants
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Example: Oil bioremediation Natural sources of oil in environment (marine oil seeps) Plant waxes related to petroleum hydrocarbons
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N and P fertilizer added t 1/2 for natural degradation = ca. 10 years 1/2 to about 1.5 years Rate of petroleum degradation often limited by abundance of N and P
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A pit dug on a Prince William Sound beach in 2001 revealing oil in the sediments. (Source: NOAA) Long-chain and branched alkanes are slow to degrade relative to others in crude oil.
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In situ bioremediation often employed for subterranean aquatic pollutant cleanup
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ex situ bioremediation Remove pollutant and substrate to more accessible site
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This note was uploaded on 01/19/2011 for the course ESPM 192 taught by Professor Lindow during the Fall '10 term at University of California, Berkeley.

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Bioremediation - 5,000 8,000 new chemicals each year over...

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