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Title:Syntrophic saturated fatty acid-oxidizing bacteria and their phylogeny: An extremely thermophilic, methanogenic bacterium and its plasmid
Author(s):Zhao, Hongxue
Doctoral Committee Chair(s):Bryant, Marvin P.
Department / Program:Microbiology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Biology, Microbiology
Abstract:Enriched from rural anaerobic digester sludge, anaerobic, sporing and nonsporing, curved and straight rod-shaped bacteria were isolated as cocultures with H$\sb2$- and formate-utilizing Methanospirillum hungatei or Desulfovibrio strain G-11. They oxidized four carbon to eight carbon saturated fatty acids, including isobutyrate and 2-methylbutyrate, with H$\sb2$ or formate as the electron sink product. The cocultures were adapted to grow on unsaturated acid crotonate, and pure subcultures of the syntrophs were then isolated. The crotonate-grown pure cultures alone did not grow on butyrate in either the presence or absence of some common electron acceptors. However, when they were reconstituted with M. hungatei, growth on butyrate again occurred. The pure isolates were subjected to 16S rRNA sequence analysis. Several previously documented mesophilic fatty acid-$\beta$-oxidizing syntrophs were also subjected to this comparative sequence analysis after adaptation to grow on crotonate and further purification. The sequence analyses revealed that our new sporeforming and nonsporing isolates and other syntrophs we sequenced, with either Gram-negative or Gram-positive cell wall ultrastructure, all belonged to the phylogenetically Gram-positive phylum of eubacteria. However, they were not closely related to any of the clusters of the Gram-positive phylum with which they were compared but they were all closely related to each other, forming a new cluster in the phylum. We recommended that this cluster be placed in the new family SYTROPHOMONADACEAE.
An extremely thermophilic methanogenic bacterium, strain AG86, was isolated from a deep sea hydrothermal vent mud sample. On the bases of its morphology, physiology, nutrition, DNA base composition and 16S rRNA partial sequence, the new isolate was the second strain of the species Methanococcus jannaschii. One plasmid was isolated from strain AG86 and two plasmids were isolated from the type strain of M. jannaschii. The three plasmids were different in DNA sequences. Membrane-bound ATPases of strain AG86 and other 4 strains of Methanococcus were studied in comparison to P-type and F-type ATPases at the levels of DNA homology, protein homology, inhibitor sensitivity, ion requirement and ion transport.
Issue Date:1991
Rights Information:Copyright 1991 Zhao, Hongxue
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9136780
OCLC Identifier:(UMI)AAI9136780

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