Time-series observations and a phytoplankton manipulation experiment were combined to test the hypothesis that phytoplankton succession effects changes in bacterial community composition. Three humic lakes were sampled weekly May-August and correlations between relative abundances of specific phytoplankton and bacterial operational taxonomic units (OTUs) in each time series were determined. To experimentally characterize the influence of phytoplankton, bacteria from each lake were incubated with phytoplankton from one of the three lakes or no phytoplankton. Following incubation, variation in bacterial community composition explained by phytoplankton treatment increased 65%, while the variation explained by bacterial source decreased 64%. Free-living bacteria explained, on average, over 60% of the difference between phytoplankton and corresponding no-phytoplankton control treatments. Fourteen out of the 101 bacterial OTUs that exhibited positively correlated patterns of abundance with specific algal populations in time-series observations were enriched in mesocosms following incubation with phytoplankton, and one out of 59 negatively correlated bacterial OTUs was depleted in phytoplankton treatments. Bacterial genera enriched in mesocosms containing specific phytoplankton assemblages included Limnohabitans (clade betI-A), Bdellovibrio and Mitsuaria. These results suggest that effects of phytoplankton on certain bacterial populations, including bacteria tracking seasonal changes in algal-derived organic matter, result in correlations between algal and bacterial community dynamics.

Two hydroxyethylamine chroman derivatives, ammonificins A (1) and B (2), were isolated from the marine hydrothermal vent bacterium Thermovibrio ammonificans. The molecular structures of these compounds were determined using a combination of NMR, mass spectrometry, and CD analyses. Biological activities were determined using an antimicrobial assay and the patented ApopScreen cellbased screen for apoptosis induction and potential anticancer activity. To our knowledge, this is the first report of secondary metabolites from the marine hydrothermal vent bacterium T. ammonificans.The oceans are Earth's largest ecosystem and hold great, underexplored potential for drug discovery. Within this vast ecosystem, however, one area remains enigmatic: deep-sea hydrothermal vents, which are characterized by high concentrations of reduced sulfur compounds. 1 Life is supported by the growth of chemolithoautotrophic bacteria, capable of oxidizing hydrogen sulfide, hydrogen, and other reduced inorganic compounds to provide energy that is used to fuel carbon dioxide fixation into macromolecules.Chemoautotrophic organisms are known to produce chemical defenses against their consumers. Some chemically deterrent species are also known to harbor chemoautotropic endosymbiotic bacteria, and these microbial symbionts may produce metabolites that defend their host species. 2 In this study we investigated the ability of chemolithoautotrophic bacteria to produce novel secondary metabolites. Thermovibrio ammonificans, a thermophilic, anaerobic, chemolithoautotrophic bacterium, was isolated from the walls of an active deep-sea hydrothermal vent chimney on the East Pacific Rise at 9°50′ N. Cells of the organism were Gram-negative, motile rods that were about 1.0 μm in length and 0.6 μm in width. Growth occurred between 60 and 80 °C (optimum at 75 °C ), 0.5 and 4.5% (w/v) NaCl (optimum at 2%), and pH 5 and 7 (optimum at 5.5). The generation time under optimal conditions was 1.57 h. Growth occurred under chemolithoautotrophic conditions in the presence of H 2 and CO 2 , with nitrate or sulfur as the electron acceptor and with concomitant formation of ammonium or hydrogen sulfide, respectively. 3Forty grams wet weight of the organism was extracted in MeOH. One part of the MeOH soluble extract was dissolved in DMSO and was tested for apoptosis induction as assessed by the ApopScreen protocol. [4][5][6] Screening should identify compounds that possess proapoptotic, and potentially anticancer, activity.The extract induced apoptosis and therefore was fractionated, with subsequent purification by analytical RPHPLC. Using this strategy, two compounds were isolated. The chemical structures of these two compounds (1 and 2) were ascertained by standard spectroscopic techniques, as described below. 8, 116.1, 119.7, 137.8, 155.7, 156.9, 157.1, 157.9, and 158.9 correlations between H-6 and C-7 (δ C 126.8), C-5 (δ C 155.7), C-4a (δ C 116.1); H-7 and C-8 (δ C 119.7), C-8a (δ C 157.9); H-4 and C-4a (δ C 116.1); and H-2 and C-8a (δ C 157.9) strongly sugg...

An aerobic, alkane-oxidizing bacterium, designated strain EPR92 T , was isolated from hydrothermal fluids that had been collected from a deep-sea vent on the East Pacific Rise (at 96 509 N 1046 179 W). The cells of the novel strain were Gram-staining-negative rods that measured approximately 1.4 mm in length and 0.4 mm in width. Strain EPR92T grew at 20-40 6C(optimum 35 6C), with1.0-5.0 % (w/v) NaCl (optimum 2.5 %), and at pH 4.0-8.5 (optimum pH 7.5). The generation time under optimal conditions was 63 min. Strain EPR92 T grew aerobically in artificial seawater minimal medium with n-alkanes as sole carbon and energy sources, and also in artificial seawater medium supplemented with peptone and yeast extract. The predominant fatty acids were C 18 : 1 v7c, C 19 : 0 cyclo v8c, 11-methyl C 18 : 1 v7c and a putative C 12 : 0 aldehyde. The major polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and four unidentified aminolipids. The major respiratory quinone was Q-10 and the genomic DNA G+C content was 60.7 mol%. Phylogenetic analyses of the 16S rRNA gene showed that strain EPR92 T belongs in the class Alphaproteobacteria and the recognized species that were most closely related to the novel strain were identified as Parvibaculum indicum P-31 T (98.7 % sequence similarity) and Parvibaculum lavamentivorans DS-1 T (95.8 %). In DNA-DNA hybridizations, the level of DNA-DNA relatedness observed between strain EPR92 T and P. indicum P-31 T was 47.7 %, indicating that the two strains do not belong to the same species. Based on the phylogenetic, physiological, chemotaxonomic and genetic evidence, strain EPR92 T represents a novel species within the genus Parvibaculum, for which the name Parvibaculum hydrocarboniclasticum sp. nov. is proposed. The type strain is EPR92 T (5DSM 232095JCM 16666 T ).At deep-sea hydrothermal vents, natural hydrocarbons are largely formed by the thermal decomposition of organic matter (thermogenesis) or by microbial processes such as the reduction of fatty acyl-CoA. However, hydrocarbons can have an abiotic origin and, in hydrothermal systems, may form by water-rock interactions such as FisherTropsch reactions and the serpentinization of ultramafic rocks (Berndt et al., 1996;McCollom et al., 1999). Despite the observation that hydrocarbons, including n-alkanes, are enriched in deep-sea hydrothermal vents (Brault et al., 1988), our knowledge of the taxonomic and functional diversity of alkane-oxidizing bacteria from these environments remains very limited. In this study, we describe a novel, aerobic, alkane-oxidizing member of the class Alphaproteobacteria that was isolated from hydrothermal fluids collected at a deep-sea vent on the East Pacific Rise.In April 2004, during the 'AT 11-10' cruise of the research vessel 'Atlantis', hydrothermal fluids at a temperature of 15 u C were collected at a depth of 2513 m from the Tica vent (9 u 509 N 104 u 179 W) on the East Pacific Rise. The fluids were collected using titanium samplers operated by 3Th...

Chemical and biological investigation of the cultured marine hydrothermal vent bacterium, Thermovibrio ammonifican led to the isolation of two hydroxyethylamine chromene derivatives, ammonificins C and D. Their structures were elucidated using combination of NMR and mass spectrometry. Absolute stereochemistry was ascertained by comparison of experimental and calculated CD spectra. Biological evaluation and assessment were determined using the patented ApopScreen cell-based screen for apoptosis-induction. Ammonificins C and D induce apoptosis in micromolar concentrations. To our knowledge, this finding is the first report of chemical compounds that induce apoptosis from the cultured deep-sea marine organism, hydrothermal vent bacterium, Thermovibrio ammonificans.