Spores are resistant against many extreme conditions including the disinfection and sterilization methods used in the food industry. Selective prevention of sporulation of Bacillus species is an ongoing challenge for food scientists and fermentation technologists. This study was conducted to evaluate the effects of single and combined supplementation of calcium and manganese on sporulation of common pathogenic and food spoilage Bacillus species: B. cereus, B. licheniformis, B. subtilis and B. coagulans. Sporulation of Bacillus vegetative cells was induced on sporulation media supplemented with diverse concentrations of the minerals. Under the various mineral supplementation conditions, the degree of sporulation was quantified with colonies formed by the Bacillus spores. The results revealed that B. licheniformis and B. cereus displayed the weakest sporulation capabilities on media with minimal supplementation levels of calcium and manganese. The lowest sporulation of B. subtilis and B. coagulans was observed on media supplemented with the highest level of calcium and low levels of manganese. Depending on effect of supplementation on sporulation, the Bacillus species were divided into two distinct groups: B. licheniformis and B. cereus; and B. subtilis and B. coagulans. The information provides valuable insight to selectively reduce sporulation of Bacillus species undesirable in the food industry.
Keywords: Bacillus species; calcium; manganese; mineral; sporulation.