Download Screening for bacteria capable of biodegradation of toxic sulfur

Research Programme
Screening for bacteria capable of biodegradation of toxic sulfur compounds and
their application in treatment of contaminated soils/water/sludge
Sulfur is one of the most common and dominant elements present on the Earth crust and
plays an important role in essential life processes. Microorganisms play an important part in
sulfur transformations. Sulfur conversions involve the metabolism of several different specific
groups of bacteria, like, SRB, phototrophic sulfur bacteria and thiobacilli specialized to use these
sulfur compounds in various redox states. As many of these microorganisms possess many
unique metabolic and ecophysiological features with respect to microbial conversions of sulfur
cycle, they can be successfully implemented in pollution control technologies.
The almost ubiquitous distribution of bacteria and the vast information on their wide
applicability in aerobic and anaerobic transformations emphasizes their use in treatment of
environmental pollutants. As many environments are anaerobic or become anaerobic rapidly due
to contamination with pollutants, and as they will also harbor sulfate or other sulfur rich
compounds, these environments become ideal niches for the growth and activity of SRB and
other anaerobic sulfur dwelling microorganisms.
Aromatic compounds form the second largest group of organic compounds in nature after
carbohydrates. Hazardous aromatic compounds get into the environment in the form of diverse
detergents with oil spills, sewage from petroleum refineries and chemical plants, and with
municipal waste waters. Aerobic processes in waste treatments plants may not completely
remove aromatic compounds from waste waters, turning researchers' interest to the study of the
anaerobic metabolism of these compounds. Various kinds of compounds like lignin monomers,
quinones, amino acids, flavonoids which are released into the environment serve as good
substrates for many microorganisms.
The present project aims to explore the diversity of aerobic and anaerobic bacteria
particularly with respect to those capable of utilizing and degrading toxic aromatic sulfur
compounds. Also in applying the already isolated and preserved potential degraders of toxic
sulfur compounds in bioremediation of contaminated sites.
Objectives:
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To study the cultured and genetic diversity of aerobic and anaerobic bacteria capable of
degrading toxic aromatic compounds.
To describe novel taxa if any, based on polyphasic taxonomic analysis.
To evaluate the novel pathways if any of biodegradation of toxic sulfur compounds.
To analyze the biodegradative capability of potential strains in soil/water/sludge
To conduct microcosm studies followed by field studies for biodegradation
/bioremediation of contaminated sites.
Methodology:
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Selective enrichment of bacteria capable of degrading toxic sulfur compounds will be
done by inoculating environmental samples collected from various habitats in medium
with toxic sulfur compound as sole carbon/sulfur source.
Isolation, purification and characterization of bacteria will be done using standard
methods.
The degradation of toxic compounds by bacteria will be confirmed and quantified using
spectrophotometic and various chromatographic techniques.
Novel pathway (if any would be elucidated using HPLC, NMR, LC-MS methods
Potential isolates would be applied in soil/sludge/water microcosms and degradation
studies at regular intervaks.
Finally field studies would be conducted with the most promising isolate/s.
Work done so far:
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A novel Sulfate reducing bacterium Desulfovibrio psychrotolerans, train JS1T was
identified as a potential bacterium in degradation of three aromatic sulfur compounds
namely para-toluene sulfonic acid, Thiophene-2-acetic acid and Sulfanilic acid.
A few other aerobic bacteria capable of growth in toxic sulfur compounds were isolated
and have to be identified.
The strain JS1T was capable of degrading the sulfur compounds in soil and sludge
microcosms.