Developing Microbial Fuel Cells for wastewater treatment and energy production

Microbial fuel cells hold great promise as a sustainable biotechnological solution to future energy needs and wastewater treatment process. A microbial fuel cell converts chemical energy into electricity through the catabolic activities of microorganisms. Current efforts to improve the efficiency of such fuel cells are limited by the lack of knowledge about the microbial ecology of these systems. The study aims to elucidate the exoelectrogenic bacterial community from different environment and their potential in wastewater treatment and energy production.

Metagenomics

Microorganisms dominate the biosphere. Current methods of culture reveal less than 1% of the microbial diversity. The new approach is the culture-independent analysis of a mixture of microbial genomes (metagenomics) based on expression or sequencing. The hidden microbial diversity is an inexhaustible source for new valuable products such as industrial enzymes, antimicrobials and therapeutic agents and also source for novel genes for biodegradation. New enzymes could potentially be useful to many industrial applications, and new antimicrobial drugs are becoming increasingly important.

1. Bioprospecting the mangrove and estuarine metagenomes

   The study envisages construction of metagenomic libraries from the estuarine and mangrove environment, using expression cloning. These libraries will be screened by functional assay for the presence of genes for important industrial enzymes, antimicrobial agents and therapeutic enzymes. The discovered genes will be sequenced and compare with currently known sequences, to identify novel genes. This approach will help in the isolation of novel genes for the production of new enzymes applicable in industries or that may give rise to new antimicrobial compounds, through mining the genomes of microorganisms of diverse environmental origin without culturing them.

2. Assessing bacterial diversity by generating 16SrRNA clone library

   Our knowledge on the bacterial diversity in different environments is limited, since many of them cannot be cultured by current culture-based traditional methods. Molecular approaches have greatly enhanced the knowledge of population structure in natural microbial communities. In our study, we try to analyze the complex genomes of microbial niches through culture-independent molecular techniques by generating 16S rRNA clone library along with RFLP, sequencing and phylogenetic analysis.

3. Metagenomic analysis of the soil resistome

   Soil is one of the potentially rich but largely unstudied environmental reservoirs for antibiotic resistance genes. The complexity of its microbial community coupled with high density of antibiotic-producing bacteria makes the soil a likely source for diverse antibiotic resistance determinants. Despite the threat posed by antibiotic resistance in infectious bacteria, little is known about the diversity, distribution and origins of resistance genes, particularly among the unculturable environmental bacteria. Therefore we have initiated investigations through functional metagenomic approach in order to get a clear understanding on antibiotic resistance genes among uncultured bacteria from diverse soil environments.

Microbial production of Polyhydroxybutyric acid (PHB)

PHB [Poly(3-hydroxybutyric acid)] is a biodegradable thermoplastic accumulated by several microorganisms as carbon and energy reservoir. They are immunologically compatible with human tissue and can be used as biodegradable carriers for controlled drug release and are currently used in industry and medicine. The main limitations for the bulk production of bioplastics are its high production and recovery costs. Generation of recombinant organisms for the biosynthesis of PHB will improve the yields of production and reduce the costs. We have isolated several bacteria producing PHB from various environments in Kerala. The PHB gene cluster from a bacterial strain which exhibited high efficiency in PHB production have been amplified. Presently we are focusing on cloning and expression of PHB genes.

Microbial production of Magnetic Nanoparticles

The magnetic nanoparticles produced from bacteria could be used for various applications including drug targeting and delivery as well as for developing potential diagnostic tools. The aim of the study is to isolate bacterial strains capable of synthesizing magnetite nanoparticles from natural populations, to prepare axenic culture of these strains and their molecular characterisation. We have isolated a few strains of bacteria showing magnetic properties from the estuarine environments and in the process developing their axenic cultures in the laboratory.