16S rRNA sequence-based phylogeny of a novel propionibacterium for enhanced fermentation of high moisture corn

A propionibacterium named DH42 was previously isolated from fermented, high moisture corn and evaluated as a starter culture to enhance bunk stability of high moisture corn. To determine phylogenetic relationships between DH42 and other representatives of the phylum Actinobacteria, a 1529-bp fragment of its 16S rRNA was PCR-amplified and sequenced. Out of 1,900 BLAST hits on the query sequence, the most probable similarity of the DH42 sequence to 16S rRNA sequences of Propionibacterium microaerophilus, Eubacterium combesii, and P. acidipropionici was found. Subsequently, the multiple alignment of 16S rRNA sequences of DH42 with 25 Propionibacterineae species, 23 other Actinobacteria species and Escherichia coli (as a non-related organism) was performed using the Clustal V method, Neighbor-Joining technique being employed to reconstruct phylogeny for the putative alignment. The propionibacterium DH42 formed a cluster of the closely related species including E. combesii, P. acidipropionici and P. microaerophilus. Judging from the metabolic profile, DH42 closely matched P. acidipropionici that confirms its 16S rRNA sequence-based affinity to this species. These comparative studies based on 16S rRNA sequences may shed light on the phylogenetic relationships between organisms inside the suborder Propionibacterineae and make its classification more precise.