Feasibility Evaluation of Methane Production from Rumen Fibrolytic Bacteria and Methanogen Coculturing on Agricultural Wastes
Date Issued
2015
Date
2015
Author(s)
Yang, Shuen-Yao
Abstract
Climate change, energy crisis and fossil fuel depletion are driving the development of renewable energy. Methane is one of the potential fuel and it has the highest hydrogen to carbon ratio in all hydrocarbons, is a relatively clean fuel and more eco-friendly than oil. Methane is produced by methanogens in the anaerobic environment such as, swamps, land fills and the intestinal tracts of animals. Rumen has a great ability to digest grass by its abundant microorganisms. It also produce considerable methane during fermenting. The aim of the present study is to coculture the rumen cellulolytic bacteria and methanogen on the agricultural wastes and produce methane as a way to make renewable energy. Ruminococcus albus 7 (ATCC 27210) is one of the main fibrolytic bacteria in rumen and produces acetic acid, hydrogen and carbon dioxide. Methanosarcina barkeri (BCRC 19175) presences in many anaerobic environment and it can use hydrogen, carbon dioxide and acetic acid as energy sources for growing. In this experiment we chose rice straw, corn stover and rice hull as the biomass for culturing R. albus 7 alone and its coculturing with M. barkeri. We measured the pH, gas production and collected the gases, broth and solids and analyzed the gas compositions, volatile fatty acids and fiber compositions at different time points. In our results, R. albus 7 was able to digest corn stover and rice stover but had a low ability to digest rice hull. Coculturing with M. barkeri could promote the cellulose digestibility and the concentration of acetic acid on rice straw significantly (P < 0.05), but not on corn stover. According to the gas product, the presence of M. barkeri decreased yield of hydrogen and carbon dioxide and produced methane. The methane yield of coculturing on rice straw, corn stover and rice hull were 0.4 mmol/g-DM, 0.3 mmol/g-DM and 0.13 mmol/g-DM, respectively. But the methane was only produced at the early stage of fermenting and the growth of M. barkeri wasn’t ideal. The current research demonstrated that the result of coculturing R. albus 7 and M. barkeri to turn the agricultural wastes to methane is not ideal.
Subjects
methane
agricultural waste
rumen fibrolytic bacteria
methanogen
coculture
Type
thesis
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