Methane fermentation utility

Some of the other research studies have addressed topics such as high soHds biomass digestion (154), utilization of superthermophilic organisms (155), advanced reactor designs (156), landfill gas enhancement (157), and microbiology of the mixed cultures involved in methane fermentation (158). 

The Marine Biotechnology Institute (MBI) was founded in 1987 for the study and applications of biodiversity in marine environments. Currently, and within the scope of the present book, the research area of relevance is industrial applications of microbiology . The institute also performs research in C02 fixation. The Applied Microbiology Laboratory is searching cost-effective utilization of microbes for environmental conservation and restoration. In particular, the decontamination of areas polluted with petroleum-related compounds has been addressed. Attention has been paid to removal of polycyclic hydrocarbons. They are also developing processing methods for the conversion of biomass and organic wastes by methane fermentation. 

There are several ways to produce energy by fermentation, such as methane fermentation, ethanol fermentation and hydrogen fermentation. Of these, methane fermentation is rather organic waste treatment than energy production, while ethanol fermentation is of practical importance under certain conditions as demonstration in Brazil. Hydrogen fermentation is still not in practical use because the energy conversion efficiency from substrates is fairly low (Table 1), and also is not estimated from a suitable point of view for utilization. 

The over-all reduction of CO2 to CH4 is expected to be a spontaneous process that goes through the reduction levels of formate, formaldehyde, and methanol with only a limited, perhaps early requirement for activation by ATP. At the lowest reduction stages, extra ATP may even be generated. In the fermentation of methanol by M. barkeri which utilizes only the last reduction step for methane formation (Reaction 12) somewhat more than 1 mole of ATP appears to be generated for each mole of CH3OH oxidized to CO2, judging from cell yields (14). 

The remainder of this paper discusses the nutritional requirements of three strains of methane bacteria grown with H2-CO2 as energy source —i.e., M. ruminantium strains isolated from sludge and the rumen and Methanobacterium strain MOH isolated from M. omelianskii 14). The latter is believed to be related closely to M. formicicum, except that it does not ferment formate (25). M. formicicum and M. ruminantium utilize... 

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