Genetic Characterization of Biohydrogen-producing Purple Non-sulfur Bacteria Rhodobacter johrii MAY2 Isolate via Whole Genome Analysis. MAY2 genome

Purple non-sulfur bacteria (PNSB) are a diverse group of bacteria studied for various possible applications. They are commonly surveyed in bioenergy research as they produce biohydrogen, a candidate for clean alternative energy. This study aimed to assess the biohydrogen production ability and genetically characterize a high biohydrogen-producing PNSB (MAY2) isolated from Los Baños, Laguna, Philippines via whole genome sequencing (WGS). MAY2, when grown in mixed volatile fatty acids, generated 38% of hydrogen from the total gas it can produce. WGS results revealed that the isolate is positively classified under the genus Rhodobacter johrii. Also, 82 genetic hallmarks for biohydrogen production were found in the isolated genome which are involved in the production of key enzymes and proteins relevant to the photofermentative and hydrogen regulation pathways. Its nitrogenase gene cluster is stringently regulated by two genes, nifA and rofN, whose function and expression are easily affected by several environmental factors.