Browsing by Author "Ren, Yuhao"
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Item Geobacillus sp., a Thermophilic Soil Bacterium Producing Volatile Antibiotics(2010-01) Ren, Yuhao; Strobel, Gary A.; Sears, Joe; Park, MelinaGeobacillus, 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 μ diameter), and they are covered in a matrix capsule which gives rise to elongate multicelled bacilliform structures (ranging from 3 to 12 μm) 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°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.107) 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.Item The production of myco-diesel hydrocarbons and their derivatives by the endophytic fungus Gliocladium roseum (NRRL 50072)(2010-12) Strobel, Gary A.; Knighton, W. Berk; Kluck, Katreena; Ren, Yuhao; Livinghouse, Tom; Griffin, Meghan; Spakowicz, Daniel; Sears, JoeAn endophytic fungus, Gliocladiun roseum (NRRL 50072), produced a series of volatile hydrocarbons and hydrocarbon derivatives on an oatmeal-based agar under microaerophilic conditions as analysed by solid-phase micro-extraction (SPME)-GC/MS. As an example, this organism produced an extensive series of the acetic acid esters of straight-chained alkanes including those of pentyl, hexyl, heptyl, octyl, sec-octyl and decyl alcohols. Other hydrocarbons were also produced by this organism, including undecane, 2,6-dimethyl; decane, 3,3,5-trimethyl; cyclohexene, 4-methyl; decane, 3,3,6-trimethyl; and undecane, 4,4-dimethyl. Volatile hydrocarbons were also produced on a cellulose-based medium, including heptane, octane, benzene, and some branched hydrocarbons. An extract of the host plant, Eucryphia cordifolia (ulmo), supported the growth and hydrocarbon production of this fungus. Quantification of volatile organic compounds, as measured by proton transfer mass spectrometry (PTR-MS), indicated a level of organic substances in the order of 80 p.p.m.v. (parts per million by volume) in the air space above the oatmeal agar medium in an 18 day old culture. Scaling the PTR-MS profile the acetic acid heptyl ester was quantified (at 500 p.p.b.v.) and subsequently the amount of each compound in the GC/MS profile could be estimated; all yielded a total value of about 4.0 p.p.m.v. The hydrocarbon profile of G. roseum contains a number of compounds normally associated with diesel fuel and so the volatiles of this fungus have been dubbed ‘myco-diesel’. Extraction of liquid cultures of the fungus revealed the presence of numerous fatty acids and other lipids. All of these findings have implications in energy production and utilization.