Microbial diversity analysis of thermophilic hydrogen-producing consortia from hot spring in the south of Thailand and evaluate cashew apple juice as a substrate

This study aims to develop thermophilic hydrogen-producing consortia from ten sediment samples of hot springs in southern Thailand by repeated batch cultivation at 60°C with fructose, glucose and combination of fructose and glucose. The promising hydrogen production potentials consortia were obtained from thermophilic enriched cultures and encoded as NST1 consortia. NST1 consortia exhibited the maximum hydrogen yields of 259 ml/g sugar consumed when fructose-glucose mixed was used as a substrate. PCR amplified 16S rDNA product was separated by using denaturing gradient gel electrophoresis (DGGE) to identify the diversity of bacteria in NST1 consortia. The phyologenetic profile of the NST1 consortia showed a significant diversity in the microbial community, where major nucleotide sequences were affiliated to class Clostridia, followed by Bacteroidetes, Deltaproteobacteria, and Flavobacteria. Time course of hydrogen production revealed that NST1 consortia gave the maximum hydrogen yield of 540 ml H2/g sugar consumed after 96 hrs of cultivation when 60% of cashew apple juice was used as a substrate. Keyword: biohydrogen, cashew apple juice, hot springs, microbial community analysis, thermophilic consortia Songklanakarin J. Sci. Technol. 39 (6), 803-812, Nov. Dec. 2017