Obligately and facultatively autotrophic,sulfur- and hydrogen-oxidizing thermophilic bacteria isolated from hot composts |
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Authors: | T Beffa Michel Blanc Michel Aragno |
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Institution: | (1) Laboratoire de Microbiologie, Université de Neuchatel, Rue Emile-Argand 11, CH-2007 Neuchatel, Switzerland Tel. +41-38-232-261; Fax +41-38-232-231, CH |
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Abstract: | A variety of autotrophic, sulfur- and hydrogen-oxidizing thermophilic bacteria were isolated from thermogenic composts at
temperatures of 60–80° C. All were penicillin G sensitive, which proves that they belong to the Bacteria domain. The obligately
autotrophic, non-spore-forming strains were gram-negative rods growing at 60–80°C, with an optimum at 70–75°C, but only under
microaerophilic conditions (5 kPa oxygen). These strains had similar DNA G+C content (34.7–37.6 mol%) and showed a high DNA:DNA
homology (70–87%) with Hydrogenobacter strains isolated from geothermal areas. The facultatively autotrophic strains isolated from hot composts were gram-variable
rods that formed spherical and terminal endospores, except for one strain. The strains grew at 55–75° C, with an optimum at
65–70° C. These bacteria were able to grow heterotrophically, or autotrophically with hydrogen; however, they oxidized thiosulfate
under mixotrophic growth conditions (e.g. pyruvate or hydrogen plus thiosulfate). These strains had similar DNA G+C content
(60–64 mol%) to and high DNA:DNA homology (> 75%) with the reference strain of Bacillus schlegelii. This is the first report of thermogenic composts as habitats of thermophilic sulfur- and hydrogen-oxidizing bacteria, which
to date have been known only from geothermal manifestations. This contrasts with the generally held belief that thermogenic
composts at temperatures above 60° C support only a very low diversity of obligatory heterotrophic thermophiles related to
Bacillus stearothermophilus.
Received: 20 July 1995 / Accepted: 25 September 1995 |
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Keywords: | Compost Thermophilic bacteria Hydrogenobacter Bacillus schlegelii Sulfur- and hydrogen-oxidizing bacteria |
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