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|Title:||Isolation and Characterization of Syntrophomonas Wolfeii, a New Anaerobic, Syntrophic, Fatty Acid-Oxidizing Bacterium|
|Author(s):||Mcinerney, Michael Joseph|
|Department / Program:||Microbiology|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||A new anaerobic bacterium that degraded fatty acids in the absence of light energy using protons as the electron acceptor was obtained in co-culture with non-fatty acid-degrading, hydrogen-utilizing Desulfovibrio species or methanogenic bacteria. Three strains of this new bacterium obtained from different environmental sources were characterized and are herein described as a new genus and species Syntrophomonas wolfeii.
Enrichment culture techniques were developed in order to facilitate the isolation of the organism. Butyrate-degrading enrichment cultures were readily initiated from samples from several anaerobic environments such as sewage digestor sludge and aquatic sediments of lagoons and a creek and could be easily maintained by weekly transfer of fifty percent of the volume. Co-cultures of S. wolfeii with the hydrogen-utilizing bacterium were isolated from the enrichment cultures by serial dilution and inoculation of butyrate agar roll tubes containing a large inoculum of a pure culture of the hydrogen-utilizing bacterium which was added to maintain a low partial pressure of hydrogen.
S. wolfeii is a gram-negative curved rod (0.5 to 1.0 by 2.0 to 7.0 (mu)m) with rounded ends. The cells possessed between 2 to 8 flagella with diameters of about 20 nm that are laterally inserted in a linear fashion along the concave side of the cell about 130 nm or more apart. Under most conditions, only a sluggish twitching motility was observed. The presence of muramic and diaminopimelic acids, inhibition of growth by penicillin and increased sensitivity of the cells to lysis after treatment with lysozyme indicated that peptidoglycan was present in the cell wall. S. wolfeii contained poly-(beta)-hydroxybutyrate granules.
Butyrate, caproate and caprylate were degraded to acetate and hydrogen; valerate and heptanoate were degraded to acetate, propionate and hydrogen; and isoheptanoate was degraded to acetate, isovalerate and hydrogen. This indicated that the organism (beta)-oxidized these fatty acids. Hydrogen was shown to be the major electron sink product by co-culturing S. wolfeii with a methanogenic bacterium that used only hydrogen and carbon dioxide for growth and methanogenesis. Carbohydrates, proteinaceous materials, alcohols, or other organic compounds other than those listed above did not support growth. Common electron acceptors were not utilized with butyrate as the electron acceptor. Growth and degradation of fatty acids occurred only in association with hydrogen-utilizing bacteria.
S. wolfeii grew with a generation time of 54 and 84 h in co-culture with the Desulfovibro species and Methanospirillum hungatei, respectively. The addition of casamino acids but not Trypticase, yeast extract, coenzyme A, hemin nor increased rumen fluid concentrations stimulated growth resulting in a slight decrease in the generation time of S. wolfeii co-cultured with M. hungatei. The presence of hydrogen in the gas phase inhibited growth of S. wolfeii and butyrate degradation. S. wolfeii was present in numbers of 5.7 x 10('6) g('-1) in samples of anaerobic sewage digestor sludge.
The culture of S. wolfeii in association with a hydrogen-utilizing bacterium provided the first direct evidence for the involvement of a third major metabolic group of bacteria called the hydrogen-producing (i.e., proton-reducing) acetogenic bacteria in the complete anaerobic degradation of organic matter to carbon dioxide and methane as it occurs in ecosystems such as sewage sludge digestors and aquatic sediments.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1980.
|Date Available in IDEALS:||2014-12-14|