Evaluation of probiotic characteristics of newly isolated lactic acid bacteria from dry-aged Hanwoo beef
Received: Jan 13, 2021 ; Revised: Feb 26, 2021 ; Accepted: Mar 06, 2021
Published Online: Mar 17, 2021
Dry aging is a traditional method that improves meat quality, and diverse microbial communities are changed during the process. Lactobacillus is widely present in fermented foods and has many beneficial effects, such as immune enhancement and maintenance of intestinal homeostasis. In this study, we conducted metagenomic analysis to evaluate the changes in the microbial composition of dry-aged beef. We found that the Lactobacillus genus was the most abundant genus in dry-aged beef and subsequently isolated lactic acid bacteria, including Lactobacillus sakei and Enterococcus faecalis. We investigated their capabilities in acid and bile tolerance, adhesion to the host, antibiotic resistance, and antimicrobial activity as potential probiotics, confirming that L. sakei and E. faecalis strains had remarkable capability as probiotics. The isolates from dry-aged beef showed at least 70% survival under acidic conditions in addition to an increase in the survival level under bile conditions. Antibiotic susceptibility and antibacterial activity assays further verified their effectiveness in inhibiting all pathogenic bacteria tested, and most of them had low resistance to antibiotics. Finally, we used the Caenorhabditis elegans model to confirm their life extension and influence on host resistance. In the model system, 12D26 and 20D48 strains had great abilities to extend the nematode life span and to improve host resistance, respectively. These results suggest the potential use of newly isolated strains from dry-aged beef as probiotic candidates for production of fermented meat.