Draft Genome Sequence of Clostridium straminisolvens Strain JCM 21531T, Isolated from a Cellulose-Degrading Bacterial Community.

Here, we report the draft genome sequence of a fibrolytic bacterium, Clostridium straminisolvens JCM 21531(T), isolated from a cellulose-degrading bacterial community. The genome information of this strain will be useful for studies on the degradation enzymes and functional interactions with other members in the community.

GENOME ANNOUNCEMENT

Lignocellulosic biomass, which is a mixture of cellulose, hemicellulose, and lignin, is the most abundant biopolymer in the Earth. In nature, lignocellulosic biomass is degraded by a set of synergistically acting enzymes of various microorganisms. Strain CSK1T (deposited as IAM 15070 and now available from Japan Collection of Microorganisms as JCM 21531T) was isolated from a cellulose-degrading bacterial community and described as the type strain of a novel species, Clostridium straminisolvens (1, 2). The 16S rRNA gene sequence analysis indicated that C. straminisolvens is related to anaerobic cellulolytic bacteria Clostridium thermocellum and Clostridium aldrichii. C. straminisolvens JCM 21531T grows optimally at 50 to 55°C and shows aerotolerance for growth and an ability to ferment cellulose and cellobiose (1). The cellulose-degrading efficiency in pure culture of C. straminisolvens JCM 21531T is remarkably lower than that in coculture with aerobic noncellulolytic bacteria, suggesting their synergistic relationships (3, 4).

The genome of C. straminisolvens JCM 21531T was sequenced using the Ion Torrent PGM system. The 367,174 sequence reads were assembled using Newbler version 2.8 (Roche) into 195 contigs, with an N50 length of 48,174 bp. This assembly resulted in the draft genome sequence of 3,907,117 bp, with 18.7× redundancy and a G+C content of 38.3%. A total of 4,383 protein-coding genes and 53 RNA-coding sequences were identified using the RAST server (5) and with the manual inspections detailed below.

RAST annotations and the following CAZy database analyses (6) revealed that C. straminisolvens JCM 21531T has various genes encoding endoglucanases classified in the glycoside hydrolase 5 (GH5), GH8, GH9, GH48, GH74, and GH124 families, genes encoding GH5 and GH9 of cellobiohydrolases, which degrade crystalline cellulose, and genes encoding β-glucosidases of GH1 and GH3. In addition, C. straminisolvens JCM 21531T also has several genes encoding xylanases of GH10. The presence of genes encoding nitrogenase and enzymes for the reductive acetyl-coenzyme A (CoA) pathway indicated the potentials of this strain of a diazotrophic and homoacetogenic nature, respectively. Detailed analyses of the genome of this strain, including comparisons with published genome sequences of C. thermocellum strains (7–10), will facilitate studies on the nature of cellulose degradation of C. straminisolvens JCM 21531T and its synergistic relationships with other bacteria in the cellulose-degrading community.

Nucleotide sequence accession numbers.

The genome sequence of C. straminisolvens JCM 21531T has been deposited in the DDBJ/EMBL/GenBank database under the accession no. BAVR01000001 to BAVR01000195.