Genetics of Microbial Biodegradation

Adenine (A) & thymine (T), Guanine (G) & cytosine (C) Double helix DNA combined with protein Purine Purine Adenine (A) & thymine (T), Guanine (G) & cytosine (C)

Contaminants Microbial bioremediation depends on Genetics of Microbial Biodegradation Contaminants Microbial bioremediation depends on Existing microbial genome MO’s change to modify existing genome Contaminants + MO’s  Metabolite

Microbial genetic plasticity 소성 (change the structure) Evolution 진화 Mutation 돌연 변이 Insertion or deletion or substitution of nucleotide New metabolic potential to degrade xenobiotic depends on alteration or exchange of genetic information

DNA replication or repair error Mutation 돌연 변이 DNA replication or repair error Conversion, duplication & transposition important role in rearrangement of DNA fragments and activation and inactivation of cryptic gene. Cryptic genes: Silent DNA sequences, not normally expressed during life cycle

Deletions Duplications Translocations Inserted additional copy of chromosome Broken portion of chromosome attaches itself to second chromosome Lost the portion of chromosome

Microbes receive or lose genetic materials during Conjugation Transformation Transduction Conjugation

Plasmid 플라스미드 important role To transform information from host to recipients Gene study in field is difficult Plasmid  small, circular, double-stranded DNA molecule - distinct from cell's chromosomal DNA 

Microbial community adopt to contaminants Natural selection of mutants to possessing degradative enzymes New metabolic activities Protein sequence analysis give information about genetic mechanisms of adaptation

Role of plasmids in bioremediation Species identified Pseudomonas Development of new degradative enzyme Biodegradation augmented by surfactants with nutrients & inoculation biomass Fixed by environmental condition Degradative enzyme in plasmid transferred variety of bacterial species in many genera Plasmid important mechanisms for genetic adaptation Bacteria in various waste Available in contaminated free environment Plasmid containing bacteria Transfer plasmid by conjugation

Evolution barriers for new microbes New microbes unable to evolve for degradation of various chemicals due to Low contaminant concentration insufficient for growth Not enough time for microbes to evolve for newly introduced chemicals Low selective pressure to enrich microbes Before mutation toxicity kills microbes Fluctuation level of contaminants

Enhancement of novel microbial degradative abilities Primary mechanism for Degradation Random mutation & Environmental Selection After adaptation Interaction difficult to stop in field condition Degradative character continue to next generation High growth & dense microbial population Due to Genetic fitness Rapid reproductive rate

Genetics & Gene manipulation Genetic mechanisms of adoptation Gene transfer, Genetic mutation (DNA rearrangement, Gene duplication, transposition & activation by insertion)

3 Main mechanisms of genetic transfer & recombination Lead to new combinations of alleles among bacteria Transduction (bacteriophage mediated transfer DNA) Transformation (DNA uptake process) Conjugation (Donor & recipient direct contact)

Practically modify microbes In vivo In vitro Usual genetic transfer mechanisms Time consuming & unpredictable Resulting microbes genetically altered Expand the natural limit of gene alteration Fast, efficient & predictable

Metagenomics in Bioremediation Isolation Of DNA Manipulation of DNA Metagenomic process starts by extracting DNA from different types of environments from microbial community DNA fragment then merged with bacteria vector to become a cloned metagenomic DNA fragment