Isolation and characterization of dominant lactic acid bacteria from raw goat milk: Assessment of probiotic potential and technological properties

Abstract

The objective of this study was to isolate and characterize Lactic Acid Bacteria (LAB) from raw goat milk, and to evaluate their probiotic attributes, technological properties and safety profiles. A total of 50 LAB strains were isolated and identified from 18 goat milk samples based on their morphological, physiological, biochemical, and genotypic characteristics. We found the existence of 6 genera where Lactobacillus was found as dominant (50 %). The in-vitro experiment showed that more than 80 % of the representative LAB strains inhibited the growth of tested pathogenic microorganisms. Out of 11 tested LAB strains, most of them exhibited moderate to high survivability (80–100 %) under intestinal juice, pancreatic juice and bile salt, and which was 70–80 % at low pH conditions. All tested LAB strains produced diacetyl, and 73 % of the tested strains showed proteolytic activity whereas only 27 % strains exhibited weak lipolysis. In case of antibiotic susceptibility, most of the LAB strains exhibited resistance against the tested antibiotics. All LAB strains produced exopolysaccharide to a variable extent ranging from 20 to 93 mg/L where the Lactobacillus delbrueckii subsp. bulgaricus being the greatest producer. The in-vitro experiments regarding safety profile showed that all the isolated LAB strains were found as non-virulence. Furthermore, our lab-scale fermentation study demonstrated that most isolated LAB strains possess the starter culture properties for producing firm milk curd. In conclusion, this study revealed that the isolated LAB strains from raw goat milk retain the potential to be used in fermented foods because of their safety aspects, probiotic attributes, and technological characteristics.