title: Geobacillus sp., a thermophilic soil bacterium producing volatile antibiotics.
abstract: Geobacillus, a bacterial genus, is represented by over 25 species of Gram-positive isolates from various man-made and natural thermophilic areas around the world. An isolate of this genus (M-7) has been acquired from a thermal area near Yellowstone National Park, MT and partially characterized. The cells of this organism are globose (ca. 0.5 mu diameter), and they are covered in a matrix capsule which gives rise to elongate multicelled bacilliform structures (ranging from 3 to 12 mum) as seen by light and atomic force microscopy, respectively. The organism produces unique petal-shaped colonies (undulating margins) on nutrient agar, and it has an optimum pH of 7.0 and an optimum temperature range of 55-65 degrees C. The partial 16S rRNA sequence of this organism has 97% similarity with Geobacillus stearothermophilus, one of its closest relatives genetically. However, uniquely among all members of this genus, Geobacillus sp. (M-7) produces volatile organic substances (VOCs) that possess potent antibiotic activities. Some of the more notable components of the VOCs are benzaldehyde, acetic acid, butanal, 3-methyl-butanoic acid, 2-methyl-butanoic acid, propanoic acid, 2-methyl-, and benzeneacetaldehyde. An exposure of test organisms such as Aspergillus fumigatus, Botrytis cinerea, Verticillium dahliae, and Geotrichum candidum produced total inhibition of growth on a 48-h exposure to Geobacillus sp.(M-7) cells (ca.10(7)) and killing at a 72-h exposure at higher bacterial cell concentrations. A synthetic mixture of those available volatile compounds, at the ratios occurring in Geobacillus sp. (M-7), mimicked the bioactivity of this organism.
authors.affiliation: Department of Plant Sciences, Montana State University, Bozeman, MT 59717, USA.
authors.forename: Yuhao
authors.initials: Y
authors.lastname: Ren
authors.forename: Gary
authors.initials: G
authors.lastname: Strobel
authors.forename: Joe
authors.initials: J
authors.lastname: Sears
authors.forename: Melina
authors.initials: M
authors.lastname: Park
mesh_terms: D000890:Anti-Infective Agents / Q000378:metabolism*; D000898:Antibiosis; D004269:DNA, Bacterial / Q000235:genetics; D056506:Geobacillus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D006358:Hot Temperature; D009009:Montana; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012988:Soil Microbiology; D055549:Volatile Organic Compounds / Q000378:metabolism*
chemical_list: D000890:Anti-Infective Agents; D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D055549:Volatile Organic Compounds