Screening and evaluation of lactic acid bacteria with probiotic potential from local Holstein raw milk

Wenqing Zhang; Shiji Lai; Ziyao Zhou; Jinpeng Yang; Haifeng Liu; Zhijun Zhong; Hualin Fu; Zhihua Ren; Liuhong Shen; Suizhong Cao; Lei Deng; Guangneng Peng

doi:10.3389/fmicb.2022.918774

Screening and evaluation of lactic acid bacteria with probiotic potential from local Holstein raw milk

Front Microbiol. 2022 Aug 1:13:918774. doi: 10.3389/fmicb.2022.918774. eCollection 2022.

Authors

Wenqing Zhang¹, Shiji Lai¹, Ziyao Zhou¹, Jinpeng Yang¹, Haifeng Liu¹, Zhijun Zhong¹, Hualin Fu¹, Zhihua Ren¹, Liuhong Shen¹, Suizhong Cao¹, Lei Deng^{1

2}, Guangneng Peng¹

Affiliations

¹ Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, China.
² Laboratory of Molecular and Cellular Parasitology, Department of Microbiology and Immunology, Healthy Longevity Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.

Abstract

There are massive bacteria in the raw milk, especially the lactic acid bacteria (LABs), which have been considered probiotics in humans and animals for a long time. Novel probiotics are still urgently needed because of the rapid development of the probiotic industry. To obtain new LABs with high probiotic potential, we obtained 26 LAB isolates, named L1 ~ L26, from local Holstein raw milk collected from a farm whose milk had never been used for LAB isolation. We identified them at the species level by biochemical and 16S rDNA sequencing methods. Their antagonistic activities against four target pathogens (Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa PAO1, and Salmonella enterica H9812), co-aggregative ability with these target pathogens, survivability in the simulated gastrointestinal tract conditions and phenol, auto-aggregation and hydrophobicity, hemolytic activity, and antibiotic susceptibility, were evaluated in vitro. Five Lactiplantibacillus plantarum isolates (L5, L14, L17, L19, and L20) showed more promising probiotic potential than others. Specifically, these five isolates conglutinated with and inhibited all the target pathogens, and survived in the simulated gastric juice (92.55 ~ 99.69%), intestinal juice (76.18 ~ 83.39%), and 0.4% phenol (76.95 ~ 88.91%); possessed considerable auto-aggregation (83.91 ~ 90.33% at 24 h) and hydrophobicity (79.32 ~ 92.70%); and were non-hemolytic, sensitive to kinds of common antimicrobials. Our findings demonstrated that these five isolates could be preliminarily determined as probiotic candidates because they have better probiotic potential than those previously reported. Again, this study highlighted the potential of raw milk for probiotic isolating and screening and provided the probiotic industry with five new LAB candidates.

Keywords: LAB strains; Lactiplantibacillus plantarum; probiotic potential; probiotics; raw milk; safety assessment.