Project description:Bathymodiolin mussels are a group of bivalves associated with deep-sea reducing habitats, such as hydrothermal vents and cold seeps. These mussels usually engage in an obligatory symbiosis with sulfur and/or methane oxidizing Gammaproteobacteria. In addition to these bacteria, Bathymodiolus heckerae that inhabit gas and oil seeps in Campeche Bay, the southern Gulf of Mexico, host bacteria phylogenetically with the Cycloclasticus genus. We recently discovered the capability for short-chain alkane degradation in draft genomes of symbiotic Cycloclasticus. With proteomics, we investigated whether the genes required for this process are expressed by the symbionts.
Project description:Acetic acid bacteria are obligately aerobic alphaproteobacteria that have a unique ability to incompletely oxidize various alcohols and sugars to organic acids. The ability of these bacteria to incompletely oxidize ethanol to acetate has been historically utilized for vinegar production. The mechanism of switching between incomplete oxidation and assimilatory oxidation and the control of energy and carbon metabolism in acetic acid bacteria are not fully understood. To understand the physiology and molecular biology of acetic acid bacteria better, we determined the draft genome sequence of Acetobacter aceti NBRC 14818, which is the type strain of the genus. Based on this draft genome sequence, the transcriptome profiles in A. aceti cells grown on ethanol, acetate, glucose, or mix of ethanol and glucose was determined by using NimbleGen Prokaryotic Expression array (4x72K).
Project description:Acetic acid bacteria are obligately aerobic alphaproteobacteria that have a unique ability to incompletely oxidize various alcohols and sugars to organic acids. The ability of these bacteria to incompletely oxidize ethanol to acetate has been historically utilized for vinegar production. The mechanism of switching between incomplete oxidation and assimilatory oxidation and the control of energy and carbon metabolism in acetic acid bacteria are not fully understood. To understand the physiology and molecular biology of acetic acid bacteria better, we determined the draft genome sequence of Acetobacter aceti NBRC 14818, which is the type strain of the genus. Based on this draft genome sequence, the transcriptome profiles in A. aceti cells grown on ethanol, acetate, glucose, or mix of ethanol and glucose was determined by using NimbleGen Prokaryotic Expression array (4x72K). Acetobacter aceti NBRC14818 was cultivated in the medium containing ethanol, acetate, glucose, or mix of ethanol and glucose as carbon sources in Erlenmeyer flask with rotary shaking. Total RNA was extracted when optical density at 600 nm was 0.3-0.4. The experiment was performed in duplicate independent cultures.
Project description:Cable bacteria of the family Desulfobulbaceae form centimeter-long filaments comprising thousands of cells. They occur worldwide in the surface of aquatic sediments, where they connect sulfide oxidation with oxygen or nitrate reduction via long-distance electron transport. In the absence of pure cultures, we used single-filament genome amplification and metagenomics to retrieve draft genomes of three marine Candidatus Electrothrix and one freshwater Ca. Electronema species. These genomes contain >50% of unknown genes but still largely share their core genomic makeup with sulfate-reducing and sulfur-disproportionating Desulfobulbaceae, with few genes lost and 212 unique genes conserved among cable bacteria. Last common ancestor analysis indicated gene divergence and lateral gene transfer as equally important origins of these unique genes. With support from metaproteomic data of Ca. Electronema, the genomes suggest that cable bacteria oxidize sulfide by inversing the canonical sulfate reduction pathway and fix CO2 using the Wood-Ljungdahl pathway. Cable bacteria show limited organotrophic potential, may assimilate smaller organic acids and alcohols, fix N2, and synthesize polyphosphates and polyglucose as storage compounds; several of these traits were confirmed by cell-level experimental analyses. We propose a model for electron flow from sulfide to oxygen that involves periplasmic cytochromes, type IV pili as integral components of conductive periplasmic fibers, and periplasmic oxygen reduction. This model proposes that an active cable bacterium gains energy in the anodic, sulfide-oxidizing cells, while cells in the oxic zone flare off electrons through intense cathodic oxygen respiration without energy conservation; this peculiar form of multicellularity seems unparalleled in the microbial world.