Characterization and safety assessment of promising probiotic lactic acid bacteria from naturally fermented goat milk for use as functional yogurt starters

This study aimed to isolate and characterize promising probiotic lactic acid bacteria (LAB) from naturally fermented goat milk using acidified and unacidified raw goat milk incubated under two temperatures of 37 °C and 42 °C. Microbial community analysis revealed that acidified goat milk promoted the growth of beneficial LAB and reduced potentially harmful genera. The fermentation temperature has a notable impact on microbial composition, with 37 °C favoring the growth of mesophilic LAB such as Lactobacillus plantarum , whereas 42 °C enhanced the proliferation of thermotolerant species like Pediococcus pentosaceus and Enterococcus faecium . Ultimately, a total of thirteen newly isolated LAB strains were screened based on their morphological, physicochemical, and technological characteristics. Among them, Lactiplantibacillus plantarum R-03 and Enterococcus faecium APH-03 were selected due to their strong acidification capacity, notable antimicrobial activity against pathogenic microbes, good tolerance to acidic and bile salt conditions, non-hemolytic, and acceptable antibiotic susceptibility profiles. Their use in goat milk yogurt production enhanced fermentation efficiency, improved physicochemical properties, and increased microbial safety by inhibiting spoilage and pathogenic bacteria, thereby highlighting their potential as functional starter cultures. Additionally, the study on goat milk yogurt production revealed that the newly isolated LAB strains and their synergistic co-cultures could serve as promising functional starters with enhanced technological features.