Summary auto-generated
This study reports the isolation and characterization of Sporobacterium olearium, a novel anaerobic bacterium from an olive mill wastewater treatment digester. Strain SRIT, a slightly curved, Gram-positive, spore-forming rod, was isolated on syringate medium and characterized through physiological and molecular analyses. The bacterium utilizes a diverse range of substrates including aromatic compounds (methoxylated and polyhydroxylated benzoates, ferulate, vanillate, quercetin), methanol, and crotonate, but cannot metabolize carbohydrates or common organic acids. Key metabolic features include the production of acetate and butyrate as fermentation end products, and notably, methanethiol (MT) production from methoxylated aromatic compounds and methanol. The organism grows optimally at 37-40°C and pH 7.2. Phylogenetic analysis based on 16S rRNA gene sequencing revealed the strain belongs to cluster XIVa of the Clostridiales group with 90% sequence similarity to Clostridium aminovalericum and Eubacterium fissicatena. The G+C content is 38 mol%. Based on unique physiological and phylogenetic characteristics, the authors propose this strain as the type species of a new genus, Sporobacterium olearium.
Key findings
- Sporobacterium olearium is a novel anaerobic bacterium capable of degrading diverse aromatic compounds including methoxylated and polyhydroxylated benzoates, ferulate, and quercetin
- The bacterium produces methanethiol from methoxylated aromatic compounds and methanol, distinguishing it from related species that produce dimethylsulfide
- Hydrogen presence accelerates degradation rates and shifts fermentation product ratios, though hydrogen is not required for growth on most substrates
- The organism belongs to Clostridiales cluster XIVa with 90% 16S rRNA sequence similarity to Clostridium aminovalericum and Eubacterium fissicatena, but differs substantially in substrate utilization and metabolism
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Abstract
T Mechichi, M Labat, JL Garcia, P Thomas and BKC Patel
Laboratoire ORSTOM de Microbiologie des Anaerobies, Universite de Provence, CESB-ESIL case 925, 163 Avenue de Luminy, 13288 Marseille Cedex 9, France
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 degrees 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 12504(T)).