Researchers isolated and characterized a novel anaerobic bacterium, designated Acetoanaerobium noterae strain NOT-3T, from oil drilling site sediment in Israel. This gram-negative rod-shaped organism produces acetate from hydrogen and carbon dioxide through chemolithotrophic metabolism. The bacterium exhibits biphasic growth on yeast extract with H₂-CO₂ gas: rapid initial growth independent of hydrogen, followed by slower H₂-dependent acetate production. Acetate formation is stoichiometrically related to H₂ consumption, producing approximately one mole of acetate per four moles of H₂ consumed. The organism also ferments glucose and maltose, producing acetate as the sole fermentation product. Morphologically, cells are motile rods with peritrichous flagella and possess an atypical gram-negative cell wall with two distinct layers. The organism grows optimally at 37°C and pH 7.6-7.8, requires yeast extract for growth, and does not form endospores. DNA analysis shows 36.8 mol% guanine plus cytosine content. The strain differs significantly from previously described H₂-oxidizing acetogenic bacteria, warranting classification as a new genus and species in the family Bacteroidaceae.

Key findings

• Acetoanaerobium noterae is a novel anaerobic bacterium that produces acetate from H₂ and CO₂ with nearly 1:4 molar stoichiometry
• The organism exhibits biphasic growth on yeast extract with H₂-CO₂, combining rapid heterotrophic growth followed by slower H₂-dependent chemolithotrophic growth
• It possesses an atypical gram-negative cell wall with two distinct layers, not typical of known gram-negative bacteria
• The bacterium requires yeast extract for both heterotrophic and chemolithotrophic growth
• Distinctive characteristics including lack of endospores, peritrichous flagella, and unique growth kinetics warrant establishment of a new genus