Production of polysaccharide and surfactin by Bacillus subtilis ATCC 6633 using rehydrated whey powder as the fermentation medium.

The aim of this research was to assess the amounts of polysaccharide and surfactin produced by Bacillus subtilis ATCC 6633 in rehydrated whey powder (RWP) as the growth medium. One-day-old cultures of B. subtilis (∼4.6 log cfu/mL) were inoculated into 100mL of 10, 15, or 20% (wt/vol) RWP and incubated at 30°C for 72 h. To analyze the effects of lactose and protein on polysaccharide and surfactin production, 6 RWP solutions containing different levels of lactose and protein were also used as media. The number of vegetative cells and spores, pH, viscosity, and the concentration of lactose were determined at 0, 24, 48, or 72 h of fermentation. The levels of polysaccharide and surfactin produced after 72 h of fermentation were measured using HPLC and the phenol-sulfuric acid method, respectively. During 72 h of fermentation, B. subtilis populations increased from 4.6 to 10.54, 9.82, and 9.67 log(10) cfu/mL in 10, 15, and 20% RWP, respectively. The number of B. subtilis spores in 10% RWP increased from 3.91 to 4.72 log(10) cfu/mL after 48 and 72 h of fermentation, respectively. The increased level of lactose or protein in RWP did not significantly change the vegetative growth. After 72h of fermentation, the pH of RWP decreased from 5.70 to 4.99 with a slight increase in viscosity. Polysaccharide levels in 10, 15, and 20% RWP after fermentation were 513.6, 613.5, and 768.3mg/L, respectively, with B. subtilis producing 0.18 to 0.29 g/L of surfactin after 72 h of fermentation. The polysaccharide or surfactin production was not changed significantly by addition of protein or lactose to RWP. These results indicate that RWP is a good fermentation substrate for surfactin and polysaccharide production.

Inhibition of Listeria monocytogenes and Salmonella enteritidis on chicken wings using scallop-shell powder.

The present study was designed to determine the inhibitory effect of scallop-shell powder (SSP) on Listeria monocytogenes and Salmonella enteritidis on chicken wings. Chicken wings artificially inoculated with L. monocytogenes (8.3 log(10) cfu/g) or S. enteritidis (8.8 log(10) cfu/g) were immersed in distilled water (0.10 or 0.50% wt/vol) of SSP slurries for 10 or 30 min, respectively. The amount of L. monocytogenes, S. enteritidis, mesophilic aerobic bacteria (MAB), and yeast or mold was determined for the chicken wings at d 0 or 7 of storage at 4°C. Results indicated that 0.5% SSP decreased the amount of L. monocytogenes and S. enteritidis on chicken wings by 3.7 and 5.0 log(10) cfu/g, respectively. The growth of L. monocytogenes, S. enteritidis, MAB, and yeast or mold was inhibited by SSP during the 7-d refrigerated storage. Color and odor of chicken wings were not significantly changed by SSP treatment (P > 0.05).