Alkalibaculum bacchi gen. nov., sp. nov., a CO-oxidizing, ethanol-producing acetogen isolated from livestock-impacted soil

Abstract

Phenotypic and phylogenetic studies were performed on three strains of an acetogenic bacterium isolated from livestock-impacted soil. The bacterium stained Gram-negative and was a non-spore-forming rod that was motile by peritrichous flagella. The novel strains had an optimum pH for growth of 8.0–8.5 and utilized H2 : CO2, CO : CO2, glucose, fructose, mannose, turanose, ribose, trimethylamine, pyruvate, methanol, ethanol, n-propanol and n-butanol as growth substrates. Acetate was produced from glucose. Acetate, CO2 and ethanol were produced from CO : CO2. 16S rRNA gene sequence analysis indicated that the novel strains formed a new subline in the family Eubacteriaceae (rRNA cluster XV) of the low G+C-containing Gram-positive bacteria of the class Clostridia. The DNA G+C base composition was 34 mol%. Cell wall analysis revealed the existence of a novel B-type peptidoglycan similar to the B2α-type (B4) configuration with a variation containing aspartic acid. Based on phylogenetic and phenotypic evidence, it is proposed that the new isolates represent a novel genus and species, for which the name Alkalibaculum bacchi gen. nov., sp. nov. is proposed. The type strain of the type species is CP11T (=ATCC BAA-1772T=DSM 22112T).