Abstract
Population development of key groups of bacteria involved in municipal refuse conversion to methane was measured from the time of initial incubation through the onset of methane production. Hemicellulolytic bacteria, cellulolytic bacteria, hydrogen-producing acetogens, and acetate- and H2-plus-CO2-utilizing methanogens were enumerated by the most-probable-number technique with media containing oat spelt xylan, ball-milled cellulose, butyrate, acetate, and H2 plus CO2, respectively. Refuse decomposition was monitored in multiple replicate laboratory-scale sanitary landfills. A laboratory-scale landfill was dismantled weekly for microbial and chemical analysis. Leachate was neutralized and recycled to ensure methanogenesis. The methane concentration of the sampled containers increased to 64% by day 69, at which time the maximum methane production rate, 929 liters of CH4 per dry kg-year, was measured. Population increases of 2, 4, 5, 5, and 6 orders of magnitude were measured between fresh refuse and the methane production phase for the hemicellulolytic bacteria, cellulolytic bacteria, butyrate-catabolizing acetogens, and acetate- and H2-CO2-utilizing methanogens, respectively. The cellulolytic bacteria and acetogens increased more slowly than the methanogens and only after the onset of methane production. The initial decrease in the pH of the refuse ecosystem from 7.5 to 5.7 was attributed to the accumulation of acidic end products of sugar fermentation, to the low acid-consuming activity of the acetogenic and methanogenic bacteria, and to levels of oxygen and nitrate in the fresh refuse sufficient for oxidation of only 8% of the sugars to carbon dioxide and water. Cellulose and hemicellulose decomposition was most rapid after establishment of the methanogenic and acetogenic populations and a reduction in the initial accumulation of carboxylic acids. A total of 72% of these carbohydrates were degraded in the container sampled after 111 days. Initially acetate utilization, but ultimately polymer hydrolysis, limited the rate of refuse conversion to methane. Microbial and chemical composition data were combined to formulate an updated description of refuse decomposition in four phases: an aerobic phase, an anaerobic acid phase, an accelerated methane production phase, and a decelerated methane production phase.
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- Barlaz M. A., Schaefer D. M., Ham R. K. Effects of prechilling and sequential washing on enumeration of microorganisms from refuse. Appl Environ Microbiol. 1989 Jan;55(1):50–54. doi: 10.1128/aem.55.1.50-54.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Chartrain M., Zeikus J. G. Microbial ecophysiology of whey biomethanation: characterization of bacterial trophic populations and prevalent species in continuous culture. Appl Environ Microbiol. 1986 Jan;51(1):188–196. doi: 10.1128/aem.51.1.188-196.1986. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ehrlich G. G., Goerlitz D. F., Bourell J. H., Eisen G. V., Godsy E. M. Liquid chromatographic procedure for fermentation product analysis in the identification of anaerobic bacteria. Appl Environ Microbiol. 1981 Nov;42(5):878–885. doi: 10.1128/aem.42.5.878-885.1981. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hermann M., Noll K. M., Wolfe R. S. Improved agar bottle plate for isolation of methanogens or other anaerobes in a defined gas atmosphere. Appl Environ Microbiol. 1986 May;51(5):1124–1126. doi: 10.1128/aem.51.5.1124-1126.1986. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hungate R. E., Stack R. J. Phenylpropanoic Acid: Growth Factor for Ruminococcus albus. Appl Environ Microbiol. 1982 Jul;44(1):79–83. doi: 10.1128/aem.44.1.79-83.1982. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kenealy W., Zeikus J. G. Influence of corrinoid antagonists on methanogen metabolism. J Bacteriol. 1981 Apr;146(1):133–140. doi: 10.1128/jb.146.1.133-140.1981. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Khan A. W. Anaerobic degradation of cellulose by mixed culture. Can J Microbiol. 1977 Dec;23(12):1700–1705. doi: 10.1139/m77-245. [DOI] [PubMed] [Google Scholar]
- Leedle J. A., Hespell R. B. Differential carbohydrate media and anaerobic replica plating techniques in delineating carbohydrate-utilizing subgroups in rumen bacterial populations. Appl Environ Microbiol. 1980 Apr;39(4):709–719. doi: 10.1128/aem.39.4.709-719.1980. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Mackie R. I., Bryant M. P. Metabolic Activity of Fatty Acid-Oxidizing Bacteria and the Contribution of Acetate, Propionate, Butyrate, and CO(2) to Methanogenesis in Cattle Waste at 40 and 60 degrees C. Appl Environ Microbiol. 1981 Jun;41(6):1363–1373. doi: 10.1128/aem.41.6.1363-1373.1981. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Stack R. J., Hungate R. E., Opsahl W. P. Phenylacetic acid stimulation of cellulose digestion by Ruminococcus albus 8. Appl Environ Microbiol. 1983 Sep;46(3):539–544. doi: 10.1128/aem.46.3.539-544.1983. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Varel V. H., Fryda S. J., Robinson I. M. Cellulolytic bacteria from pig large intestine. Appl Environ Microbiol. 1984 Jan;47(1):219–221. doi: 10.1128/aem.47.1.219-221.1984. [DOI] [PMC free article] [PubMed] [Google Scholar]
- WOLIN E. A., WOLIN M. J., WOLFE R. S. FORMATION OF METHANE BY BACTERIAL EXTRACTS. J Biol Chem. 1963 Aug;238:2882–2886. [PubMed] [Google Scholar]
- Warshaw J. E., Leschine S. B., Canale-Parola E. Anaerobic cellulolytic bacteria from wetwood of living trees. Appl Environ Microbiol. 1985 Oct;50(4):807–811. doi: 10.1128/aem.50.4.807-811.1985. [DOI] [PMC free article] [PubMed] [Google Scholar]