Sporobacterium olearium gen. nov., sp. nov., a new methanethiol- producing bacterium that degrades aromatic compounds, isolated from an olive mill wastewater treatment digester

Abstract

A strictly chemo-organotrophic, anaerobic bacterium was isolated from an olive mill wastewater treatment digester on syringate and designated strain SR1(T). The cells were slightly curved rods, stained Gram-positive and possessed terminal spores. Strain SR1(T) utilized crotonate, methanol and a wide range of aromatic compounds including 3,4,5-trimethoxybenzoate (TMB), 3,4,5-trimethoxycinnamate (TMC), syringate, 3,4,5-trimethoxyphenylacetate (TMPA), 3,4,5-trimethoxyphenylpropionate (TMPP), ferulate, sinapate, vanillate, 3,4-dimethoxybenzoate, 2,3-dimethoxybenzoate, gallate, 2,4,6- trihydroxybenzoate (THB), pyrogallol, phloroglucinol and quercetin as carbon and energy sources. Acetate and butyrate were produced from aromatic compounds, methanol and crotonate whereas methanethiol (MT) was produced from methoxylated aromatic compounds and methanol. Strain SR1(T) had a G+C content of 38 mol% and grew optimally between 37 and 40 °C at pH 7.2 on a crotonate- containing medium. Phylogenetically, strain SR1(T) was a member of cluster XIVa of the Clostridiales group and shared a sequence similarity of 90% with Clostridium aminovalericum and Eubacterium fissicatena. Consequently, its precise neighbourliness to any one of them depended on the selection of strains of the cluster. On the basis of the phylogenetic and phenotypic evidence presented in this paper, the designation of strain SR1(T) as Sporobacterium olearium gen. nov., sp. nov. is proposed. The type strain is SR1(T) (= DSM 12304(T)).