Abstract
Bacillus sp. DU-106, a newly isolated member of Bacillus cereus group, exhibits the predominant ability to produce L-lactic acid. The probiotic potency of test strain revealed its survivability at acidic pH, bile salts and viability in simulated gastric juice in vitro. The acute oral toxicity test indicated its no toxicity to laboratory mice in vivo. We further determined the complete genome of strain DU-106 to understand genetic basis as a potential probiotic. It has a circular chromosome and three plasmids for a total genome 5,758,208 bp in size with a G + C content of 35.10%. Genes associated with lactate synthesis were found in the DU-106 genome. We also annotated various stress-related, bile salt resistance, and adhesion-related domains in this strain, which likely provide support in exerting probiotic action by enabling adhesion to host epithelial cells and survival under gastrointestinal tract. Moreover, strain DU-106 genome lacks the virulence genes encodes cereulide synthetase, enterotoxin FM, and cytotoxin K. These phenotypic and genomic probiotic potencies facilitate its potential candidate as probiotic starter in food industry.
Highlights
Lactic acid has been widely used as a valuable chemical in food industries
The phylogenetic tree indicated that the strain DU-106 formed a clade with the Bacillus cereus group (Figure 1c) with 16S rRNA gene sequence similarity levels of 97.05%-99.92%, whereas their similarity to other Bacillus species was below 95.7%
DU-106 in simulated gastric fluid, 0.3% bile salt, and simulated intestinal fluid after 2 h treatment were 74.29, 59.67, and 150.52% (Figure 3B), respectively. These results indicated that strain DU-106 might possess excellent potential probiotic properties
Summary
Lactic acid has been widely used as a valuable chemical in food industries. Nowadays, lactic acid bacteria including Lactobacillus rhamnosus and Lactococcus lactis are frequently used in industrial production of lactic acid (Okano et al, 2010). We reported a Bacillus isolates with predominant ability to produce L-lactic acid and evaluated its properties to use as a potential probiotic. The protein coding sequences were predicted with Glimmer 3.02 (Delcher et al, 2007), and annotations of gene functions were performed according to NCBI Prokaryotic Genome Annotation Pipeline.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
