Isolation and characterization of a new CO-utilizing strain, Thermoanaerobacter thermohydrosulfuricus subsp. carboxydovorans, isolated from a geothermal spring in Turkey

A novel anaerobic, thermophilic, Gram-positive, spore-forming, and sugar-fermenting bacterium (strain TLO) was isolated from a geothermal spring in Ayaş, Turkey. The cells were straight to curved rods, 0.4–0.6 μm in diameter and 3.5–10 μm in length. Spores were terminal and round. The temperature range for growth was 40–80°C, with an optimum at 70°C. The pH optimum was between 6.3 and 6.8. Strain TLO has the capability to ferment a wide variety of mono-, di-, and polysaccharides and proteinaceous substrates, producing mainly lactate, next to acetate, ethanol, alanine, H2, and CO2. Remarkably, the bacterium was able to grow in an atmosphere of up to 25% of CO as sole electron donor. CO oxidation was coupled to H2 and CO2 formation. The G + C content of the genomic DNA was 35.1 mol%. Based on 16S rRNA gene sequence analysis and the DNA–DNA hybridization data, this bacterium is most closely related to Thermoanaerobacter thermohydrosulfuricus and Thermoanaerobacter siderophilus (99% similarity for both). However, strain TLO differs from Thermoanaerobacter thermohydrosulfuricus in important aspects, such as CO-utilization and lipid composition. These differences led us to propose that strain TLO represents a subspecies of Thermoanaerobacter thermohydrosulfuricus, and we therefore name it Thermoanaerobacter thermohydrosulfuricus subsp. carboxydovorans

Structural characterization of diabolic acid-based tetraester, tetraether and mixed ether/ester, membrane-spanning lipids of bacteria from the order Thermotogales

The distribution of core lipids in the membranes of nine different species of the order Thermotogales, one of the early and deep branching lineages in the Bacteria, were examined by HPLC/MS and demonstrated to consist of membrane-spanning diglycerol lipids comprised of diabolic acid-derived alkyl moieties. In the Thermotoga species the core membrane lipids are characterized by the presence of both ester and ether bonds, whereas in the phylogenetically more distinct Thermosipho and Fervidobacterium spp. only ester bonds occur. A tentative biosynthetic route for the biosynthesis of these membrane-spanning lipids is proposed. Since species of the order Thermotogales are assumed to have occurred early during the evolution of life on Earth, as suggested by its position in the phylogenetic tree of life, these data suggest that the ability to produce both ether and ester glycerol membrane lipids developed relatively early during microbial evolution

The deep-subsurface sulfate reducer Desulfotomaculum kuznetsovii employs two methanol-degrading pathways

Methanol is generally metabolized through a pathway initiated by a cobalamine-containing methanol methyltransferase by anaerobic methylotrophs (such as methanogens and acetogens), or through oxidation to formaldehyde using a methanol dehydrogenase by aerobes. Methanol is an important substrate in deep-subsurface environments, where thermophilic sulfate-reducing bacteria of the genus Desulfotomaculum have key roles. Here, we study the methanol metabolism of Desulfotomaculum kuznetsovii strain 17T, isolated from a 3000-m deep geothermal water reservoir. We use proteomics to analyze cells grown with methanol and sulfate in the presence and absence of cobalt and vitamin B12. The results indicate the presence of two methanol-degrading pathways in D. kuznetsovii, a cobalt-dependent methanol methyltransferase and a cobalt-independent methanol dehydrogenase, which is further confirmed by stable isotope fractionation. This is the first report of a microorganism utilizing two distinct methanol conversion pathways. We hypothesize that this gives D. kuznetsovii a competitive advantage in its natural environment.Research was funded by grants of the Division of Chemical Sciences (CW-TOP 700.55.343) and Earth and Life Sciences (ALW 819.02.014) of The Netherlands Organisation for Scientific Research (NWO), the European Research Council (ERC grant 323009), and the Gravitation grant (024.002.002) of the Netherlands Ministry of Education, Culture and Scienceinfo:eu-repo/semantics/publishedVersio

Thermosipho geolei sp nov., a thermophilic bacterium isolated from a continental petroleum reservoir in Western Siberia

The novel isolate reduced elemental sulfur ana cystine. but not thiosulfate sulfate, to hydrogen sulfide, The G+C content of the genomic DNA was 30.0 mol%, As determined by 16S rDNA sequence analysis, this organism Three strictly anaerobic, thermophilic bacteria (SL31(T), SL30 and MLM39636) were isolated from a deep continental oil reservoir in Western Siberia (Russia), Following the mid-exponential phase of growth, the non-motile rod-shaped organisms were surrounded by a sheath-like structure, As DNA-DNA hybridizations showed that these strains were highly related genomically, only strain SL31T was studied in detail, The temperature range for growth of strain SL31T was between 45 and 75 degreesC, with optimum growth at 70 degreesC, its optimum ph and NaCl concentration for growth were pH 7.5 and 20-30 g l(-1), respectively. The novel isolate reduced elemental sulfur and cystine, but not thiosulfate or belonged to the genus Thermosipho. DNA-DNA hybridization levels between strain SL31T and type strains of the previously described species of Thermosipho were less than 10%, On the basis of physiological and molecular properties, it is proposed that this organism should be placed in a new species, Thermosipho geolei sp, nov, The novel organism represents the first species of the genus Thermosipho that has been isolated from a petroleum reservoir, The type strain is SL31(T) (= DSM 13256(T) = JCM 10986(T))

Petrotoga olearia sp nov and Petrotoga sibirica sp nov., two thermophilic bacteria isolated from a continental petroleum reservoir in Western Siberia

Strictly anaerobic, thermophilic bacteria (strains SL24(T), SL25(T), SL27, SL29 and SL32) were isolated from a deep, continental oil reservoir in Western Siberia (Russia). These motile, rod-shaped organisms were surrounded by a sheath-like structure, a feature characteristic of the Thermotogales. On the basis of partial 16S rDNA sequences (500 nucleotides), strains SL25(T), SL27, SL29 and SL32 were identical. Therefore, only strains SL24(T) and SL25(T) were studied in detail. The optimum temperature for growth of both strains was 55degreesC. Their optimum pH for growth was 7.5 and their optimum NaCl concentration was between 20 and 30 g l(-1). The novel isolates reduced elemental sulfur and cystine, but not thiosulfate or sulfate, to hydrogen sulfide. The G+C contents of the genomic DNA of strains SL24(T) and SL25(T) were respectively 35 and 33 mol%. Phylogenetically, both strains are most closely related to Petrotoga miotherma, there being 98.9-99.4% similarity between their 16S rDNA sequences. Phenotypic properties and DNA-DNA hybridization experiments indicate that the strains belong to two novel species, for which the names Petrotoga olearia (type strain SL24(T)=DSM 13574(T)=JCM 11234(T)) and Petrotoga sibirica (type strain SL25(T)=DSM 13575(T)=JCM 11235(T)) are proposed

Biological control of grey mould in strawberry fruits by halophilic bacteria

Aims: Grey mould caused by Botrytis cinerea is an economically important disease of strawberries in Tunisia and worldwide. The aim of this study was to select effective halophilic bacteria from hypersaline ecosystems and evaluate the abilities of antifungal bacteria to secrete extracellular hydrolytic enzymes, anti- Botrytis metabolites and volatiles. Methods and Results: Grey mould was reduced in strawberry fruits treated with halophilic antagonists and artificially inoculated with B. cinerea. Thirty strains (20Æ2%) were active against the pathogen and reduced the percentage of fruits infected after 3 days of storage at 20 C, from 50% to 91Æ66%. The antagonists were characterized by phenotypic tests and 16S rDNA sequencing. They were identified as belonging to one of the species: Virgibacillus marismortui, B. subtilis, B. pumilus, B. licheniformis, Terribacillus halophilus, Halomonas elongata, Planococcus rifietoensis, Staphylococcus equorum and Staphylococcus sp. The effective isolates were tested for antifungal secondary metabolites. Conclusions: Moderately halophilic bacteria may be useful in biological control against this pathogen during postharvest storage of strawberries. Significance and Impact of the study: The use of such bacteria may constitute an important alternative to synthetic fungicides. These moderate halophiles can be exploited in commercial production and application of the effective strains under storage and greenhouse conditions