6th World Congress on Biotechnology
New Delhi, India
Yerevan State University, Armenia
Title: Application of mixture of carbon sources to enhance H2 production by Escherichia coli
Biography: Karen Trchounian
The future substantial reduction in use of fossil fuels means that the identification of suitable ecologically clean, alternative renewable energy sources needs to be explored. One of these sources is molecular hydrogen (H2) which can be generated by diverse microbial or other biomasses. Escherichia coli are able to encode four membrane-bound [Ni-Fe] hydrogenases (Hyd). All Hyd enzymes are reversible depending on pH and carbon source. During glucose or glycerol fermentation Hyd-1 and Hyd-2 operate in H2 oxidizing or producing mode respectively. H2 production by E. coli wild type strain whole cells during utilization of glucose, glycerol and formate at pH 7.5 and pH 6.5 was investigated. In the mixture of 2 g/l glucose, 10 g/l glycerol and 0.68 g/l formate H2 production rate (VH2) in glucose assays was ~3 fold and ~5 folds more at pH 7.5 and pH 6.5 respectively, compared to the cells grown on glucose only. Interestingly, in glycerol assays at both pH VH2 ~2 fold lower, compared to the cells grown on glycerol only. In formate supplemented assays VH2 was the same as in glucose assays at both pH tested. Taken together, it can be concluded that glycerol in the presence of glucose and formate can be utilized anaerobically by E. coli and H2 can be produced. Moreover, E. coli grown in the presence of mixed carbon sources can be applied for enhanced H2 production from different wastes where glycerol and formate are present. Moreover, regulation and optimization of various substrates concentrations might be developed in enhancing H2 production.