Complete genome analysis of Bacillus velezensis HF-14,109 with potential for broad-spectrum antimicrobial activity and high enzyme-producing ability from common carp (Cyprinus carpio L.).

Abstract

Bacillus velezensis (B. velezensis) HF-14,109 is an aerobic Gram-positive bacterium isolated from the gut of healthy carp (Cyprinus carpio L.). Here, we sequenced and annotated the genome of HF-14,109, identified and classified its enzyme-producing genes and secondary metabolite biosynthesis gene clusters (BGCs), and verified the inhibitory effects on pathogenic bacteria in vitro. Results suggested that HF-14,109 had a circular 4,214,172 bp genome that contains 4,392 predicted genes with an average length and GC content of 851.56 bp and 46.94%, respectively. A total of 210 non-coding RNAs, 8 CRISPR sequences, and 152 tandem repeats were predicted. Based on a CAZy database analysis, HF-14,109 contains 93 genes encoding enzymes for carbohydrate-related processes, 38 of which were glycoside hydrolase genes and divided into 20 families. Based on enzyme predictions, HF-14,109 had the capability to hydrolyze high molecular carbohydrates such as starch, disaccharides such as lactose and sucrose, and non-starch polysaccharides such as β-glucan, mannan, fructan and xylan. Twelve BGCs for producting secondary metabolites were identified by antiSMASH analysis, 5 of which were predicted to encode polyketide synthases (PKSs) and non-ribosomal peptide synthetases (NRPSs), indicating that HF-14,109 could produce multiple secondary metabolites. The genome of HF-14,109 contained numerous genes encoding glycoside hydrolases and BGCs for producting secondary metabolites. Besides, the HF-14,109 could inhibit pathogenic bacteria such as E. tarda, A. hydrophila, S. aurenus, and E. coli in vitro. In conclusion, our results demonstrate that HF-14,109 has the effects of hydrolyzing non-starch polysaccharides and inhibiting pathogenic bacteria, which lays a solid foundation for elucidating its antibacterial and enzyme-producing mechanisms, and is expected to be developed as a probiotic for aquaculture feed in the future.