Effect of temperature on the lipolytic and proteolytic activity of Bacillus cereus isolated from dairy products.
Bacillus cereus is a bacterium with deteriorating potential for dairy products, by being a psychrotrophic organism producer of lipases and proteases. This study evaluated the psychrotrophic behavior, lipolytic and proteolytic activity at 30oC, 10oC and 7oC of 86 strains of B. cereus lato sensu isolated from dairy products, marketed in Southern Brazil. It was also evaluated the optimal temperature for protease production. No strain grew at 7oC; but at 10oC, 84.9% of strains have grown. Only one strain had lipolytic activity at 30oC, and none at 7oC. At 10oC, 16.3% of strains produced lipases. All the strains presented proteolytic activity at 30oC; and at 10oC, 72.1% had this activity, and at 7oC, only 4.6%, an amount significantly lower (p < 0.05). The temperature of 20oC promoted the highest proteolytic activity, and at 10oC, the lowest activity. B. cereus can produce lipases and proteases at room and marginal chilling temperatures, causing technological defects in dairy products stored under these conditions.