Evaluation of antimicrobial activity of Lactobacilli isolated from traditional sourdoughs against Bacillus cereus
Subject Areas : Food Microbial ContaminationAbolfazl Golshan Tafti 1 , Ghazal Yazdanpanah 2 , Mohammad Hassan Fooladi 3
1 - Agricultural Engineering Research Department, Kerman Agricultural and Natural Resources Research and Education Centre, AREEO, Kerman, Iran.
2 - Environmental Health Engineering Research Center, Kerman University of Medical Sciences, Kerman, Iran.
3 - Department of Food Science and Technology, College of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran
Keywords: Lactobacillus, Bacillus cereus, spotting method, well diffusion agar method, paper disk method,
Abstract :
In this study, the inhibitory effect of 71 Lactobacilli isolated from traditional sourdoughs against Bacillus cereus was evaluated and compared by using three methods (spot on lawn,well diffusion and disk diffusion). There was no inhibition zone around the discs and wells in the well diffusion and disk diffusion methods. The inhibitory effect of Lactobacillus isolates against Bacillus cereus in the Spot on lawn method was observed as a clear zone around the colonies. All Lactobacillus isolates were able to inhibit the growth of Bacillus cereus in the spot on lawn method, but there was a significant difference (p<0.01) among the isolates in terms of antimicrobial activity. Among the Lactobacillus isolates, 8 isolates had significantly stronger antimicrobial activity and the diameter of clear zone around the colonies was reported in the range of 2.67-7.83 mm. The diameter of clear zone around the Lactobacillusisolates 70, 46, 21, 55, 59 and 11 was 7.83, 7.67, 7.33, 7.16, 7 and 7 mm, respectively. Therefore, they were reported as Lactobacillus isolates with strong antimicrobial activity in the spot on lawn method. These isolates can have potential to be used as starter cultures in production of sourdough and bread.