Summary auto-generated
Researchers isolated and characterized a new bacterial species, Clostridium peptidivorans strain TMC4T, from an olive mill wastewater treatment digester in Tunisia. This strictly anaerobic, rod-shaped, Gram-positive bacterium ferments peptides and amino acids but cannot utilize carbohydrates, distinguishing it from most Clostridium species. The organism grows optimally at 37°C and pH 7, producing fermentation end-products including acetate, butyrate, and hydrogen gas depending on the substrate. Phylogenetic analysis based on 16S rRNA sequencing showed that C. peptidivorans belongs to the low-GC-content Clostridium cluster I, with its closest relative being C. pascui at 96% sequence similarity. Despite this genetic similarity, the two species display considerable phenotypic differences in morphology, substrate utilization, and habitat. The DNA GC content of 31 mol% and comprehensive characterization of its metabolic capabilities support its designation as a novel species. This peptide-fermenting bacterium represents an important contributor to the anaerobic digestion process in olive mill wastewater treatment systems.
Key findings
- Clostridium peptidivorans is a new strictly anaerobic, peptide-fermenting bacterium isolated from olive mill wastewater digesters that cannot utilize carbohydrates or most organic acids
- The bacterium ferments various amino acids and protein substrates, producing acetate, butyrate, hydrogen, and carbon dioxide as major end-products
- Phylogenetic analysis indicates C. peptidivorans belongs to Clostridium cluster I with 96% 16S rRNA sequence similarity to C. pascui, though significant phenotypic differences distinguish them
- The species has a DNA GC content of 31 mol% and grows optimally at 37°C and pH 7
- C. peptidivorans is proteolytic and can utilize complex proteinaceous substrates like gelatin and peptone, unlike its closest relative C. pascui
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Abstract
T Mechichi, ML Fardeau, M Labat, JL Garcia, F Verhe and BKC Patel
Laboratoire IRD de Microbiologie, Universite de Provence, CESB/ESIL, Case 925, 163 Avenue de Luminy, 13288 Marseille cedex 9, France
A new peptide-degrading, strictly anaerobic bacterium, designated strain TMC4(T), was isolated from an olive mill wastewater treatment digester. Cells of strain TMC4(T) were motile, rod-shaped (5--10 x 0.6--1.2 microm), stained Gram-positive and formed terminal to subterminal spores that distended the cells. Optimal growth occurred at 37 degrees C and pH 7 in an anaerobic basal medium containing 0.5% Casamino acids. Arginine, lysine, cysteine, methionine, histidine, serine, isoleucine, yeast extract, peptone, Biotrypcase, gelatin and crotonate also supported growth, but not carbohydrates, organic acids or alcohols. The end-products of degradation were: acetate and butyrate from lysine and crotonate; acetate, butyrate, H(2) and CO(2) from Biotrypcase, gelatin and peptone; acetate, alanine, H(2) and CO(2) from cysteine; acetate, H(2) and CO(2) from serine, cysteine and yeast extract; acetate and formate from histidine; propionate from methionine; methyl 2-butyrate, H(2) and CO(2) from isoleucine; acetate and ethanol from arginine; and acetate, propionate, butyrate, methyl 2-butyrate, H(2) and CO(2) from Casamino acids. The DNA G+C content of strain TMC4(T) was 31 mol%. Phylogeny based on 16S rRNA sequence analysis showed that strain TMC4(T) was a member of the low-G+C-content Gram-positive genus Clostridium, with the closest relative being Clostridium pascui (sequence similarity of 96 %). Due to considerable differences in genomic and phenotypic properties between strain TMC4(T) and those of its nearest relative, strain TMC4(T) is proposed as a new species of the genus Clostridium, Clostridium peptidivorans sp. nov. Strain TMC4(T) has been deposited in the DSMZ as strain DSM 12505(T).