Complete Genome of the Starch-Degrading Myxobacteria Sandaracinus amylolyticus DSM 53668T

Abstract

Myxobacteria are members of δ-proteobacteria and are typified by large genomes, well-coordinated social behavior, gliding motility, and starvation-induced fruiting body formation. Here, we report the 10.33 Mb whole genome of a starch-degrading myxobacterium Sandaracinus amylolyticus DSM 53668(T) that encodes 8,962 proteins, 56 tRNA, and two rRNA operons. Phylogenetic analysis, in silico DNA-DNA hybridization and average nucleotide identity reveal its divergence from other myxobacterial species and support its taxonomic characterization into a separate family Sandaracinaceae, within the suborder Sorangiineae. Sequence similarity searches using the Carbohydrate-active enzymes (CAZyme) database help identify the enzyme repertoire of S. amylolyticus involved in starch, agar, chitin, and cellulose degradation. We identified 16 α-amylases and two γ-amylases in the S. amylolyticus genome that likely play a role in starch degradation. While many of the amylases are seen conserved in other δ-proteobacteria, we notice several novel amylases acquired via horizontal transfer from members belonging to phylum Deinococcus-Thermus, Acidobacteria, and Cyanobacteria. No agar degrading enzyme(s) were identified in the S. amylolyticus genome. Interestingly, several putative β-glucosidases and endoglucanases proteins involved in cellulose degradation were identified. However, the absence of cellobiohydrolases/exoglucanases corroborates with the lack of cellulose degradation by this bacteria.