Microbiological Studies Towards Optimization of Methane from Plant Biomass

The conversion of marine biomass was studied with kelp-degrading methane-producing enrichment cultures. Mannitol and alginate are used concurrently. Hydrogen ranged I from 50nM to 1.2 pM. The appearance of ethanol correlates with increased hydrogen. A method was developed for measurement of intermediates in the sea water medium used for the enrichments. Acetate and propionate were found in the greatest concentrations. Several methylotrophic methanogens were isolated including a new genus, Methanococcoides. New strains of hydrogen and formate-utilizing methanogens were isolated. Formate dehydrogenase from Methanobacterium formicicum was purified and characterized. The isolated enzyme contains a cofactor not previously reported in methanogens. It was shown that formate can be an important substrate for methanogens in anaerobic habitats. For the production of acetate and hydrogen gas in high yield, mannitolfermenting bacteria can be found in strains of Clostridium sphenoides and C. sartagoformum. Alginatefermenting bacteria can be found -ifrainseroidzs ovatus, Cytophaga, Citrobacter and Klebsiella. Hydrogen partial pressure does not affect the fermentation pattern of B. ovatus, but heme does. The low potential electron carrier of - B. ovatus is a ferredoxin.