Short Communication: Enterotoxin Genes and Antibiotic Susceptibility of Bacillus cereus Isolated from Garlic Chives and Agricultural Environment

Antibiotic Resistance of Bacillus cereus in Plant Foods and Edible Wild Mushrooms in a Province

Bacillus cereus is a common pathogen causing foodborne diseases, secreting and producing a large number of toxins that can cause a variety of diseases and pose many threats to human health. In this study, 73 strains of Bacillus cereus were isolated and identified from six types of foods from seven different cities in a province, and the antibiotic-resistant phenotype was detected by using the Bauer-Kirby method. Results showed that the 73 isolates were completely sensitive to gentamicin and 100% resistant to chloramphenicol, in addition to which all strains showed varying degrees of resistance to 13 other common antibiotics, and a large number of strains resistant to multiple antibiotics were found. A bioinformatic analysis of the expression of resistance genes in Bacillus cereus showed three classes of antibiotic-resistant genes, which were three of the six classes of antibiotics identified according to the resistance phenotype. The presence of other classes of antibiotic-resistant genes was identified from genome-wide information. Antibiotic-resistant phenotypes were analyzed for correlations with genotype, and remarkable differences were found among the phenotypes. The spread of antibiotic-resistant strains is a serious public health problem that requires the long-term monitoring of antimicrobial resistance in Bacillus cereus, and the present study provides important information for monitoring antibiotic resistance in bacteria from different types of food.

Probiotic Potential of Bacillus sp. 62A Isolated from a Marine Extreme Environment

Antimicrobial resistance is an important health concern globally, and probiotics are considered an alternative to minimize it. The present study examined the in vitro probiotic characteristics and in vivo immunomodulatory potential of Bacillus sp. 62A - an extremophile bacterium. Bacillus sp. 62A was evaluated in vitro for its cytotoxicity, hemolytic activity, antibiotic susceptibility, and resistance to gastrointestinal conditions (bile salts, low pH, and intestinal adherence). Additionally, the immunomodulatory effect of Bacillus sp. 62A was studied in mice. The animals were supplemented daily with phosphate-buffered saline (control) and Bacillus sp. 62A at 1 × 108 colony forming units (CFU). Samples were taken on days 5 and 10. Isolated splenocytes were challenged with Escherichia coli for immunological analyses and immune-related gene expression. Serum and feces were collected for IgA and IgG determination. Bacillus sp. 62A did not show cytotoxicity, hemolytic activity, or resistance to antibiotics. Furthermore, the bacterium has autoaggregation and intestinal adhesion capacities and grows in the presence of bile salts and low pH. Bacillus supplementation in mice improved respiratory burst activity, nitric oxide production, and IL-1β and IL-6 gene expressions, mainly at 10 days. After E. coli challenge, Bacillus supplementation in mice induced an anti-inflammatory response through a decrease in immunological parameters and an increase in IL-10 gene expression. Moreover, serum IgA and IgG and fecal IgG augmented in supplemented mice. In conclusion, Bacillus sp. 62A has biosafe and immunomodulatory probiotic potential.