Evaluation of Bacillus subtilis P5-6 as Protective Culture in Traditional Back-slopped Fermented Milk

Abstract

Back slopping is referred to as the small inoculation of a previous successful fermentation product to the raw material, as the starter culture. One example of the traditional fermented product that utilizes the back-slopping methods is dadih. As it is an artisanal product that is made using traditional methods that involve humans and is prone to contamination, such as Staphylococcus aureus. These pathogens are able to produce toxins and cause intoxication in humans. In this study, the evaluation of protective culture was conducted to inhibit the growth of the Staphylococcus aureus. The specific strain used as the protective culture is Bacillus subtilis P5-6. The results of this study showed that the Bacillus subtilis P5-6 was able to inhibit the growth of Staphylococcus aureus by 1 log CFU/mL in the back-slopped fermented milk, without interfering with the growth of LAB as the main fermenter. However, this study only showed the bacteriostatic activity of the Bacillus subtilis P5-6. To obtain a bactericidal activity of Bacillus subtilis P5-6 it is recommended to test and use the MBC value to be utilized in the fermented milk. Moreover, it was advised to re-added the Bacillus subtilis P5-6 after two times of back-slopping to obtain maximum protective action in the fermented milk.