Abstract
BackgroundProbiotics are being considered as valuable microorganisms related to human health. Hu sheep is referred as one of the important sheep breeds in China. Goat milk produced by Hu sheep is characterized with high nutritional value and hypoallergenic in nature. Particularly, this milk contains plenty of milk prebiotic and probiotic bacteria. This study was aimed to scrutinize more bacterial strains from Hu sheep milk with potential probiotic activity.ResultsBased on 16S rRNA sequence analysis, pool of forty bacterial strains were identified and evaluated their antimicrobial activities against Staphylococcus aureus, enterohemorrhagic Escherichia coli (EHEC), Salmonella typhimurium, Listeria monocytogenes enterotoxigenic E. coli (ETEC) and Aeromonas caviae. Four out of these isolated strains demonstrated their efficient bacteriostatic ability and potential healthy properties. We also examined the safety aspects of these bacterial candidates including three Lactococcus lactis strains (named as HSM-1, HSM-10, and HSM-18) and one Leuconostoc lactis strain (HSM-14), and were further evaluated via in vitro tests, including antimicrobial activity, cell surface characteristics (hydrophobicity, co-aggregation, and self-aggregation), heat treatment, antibiotic susceptibility, simulated transport tolerance in the gastrointestinal tract, and acid/bile tolerance. The obtained results revealed that HSM-1, HSM-10, HSM-14, and HSM-18 showed high survival rate at different conditions for example low pH, presence of bovine bile and demonstrated high hydrophobicity. Moreover, HSM-14 had an advantage over other strains in terms of gastrointestinal tract tolerance, antimicrobial activities against pathogens, and these results were significantly better than other bacterial candidates.ConclusionHu sheep milk as a source of exploration of potential lactic acid bacteria (LAB) probiotics open the new horizon of probiotics usage from unconventional milk sources. The selected LAB strains are excellent probiotic candidates which can be used for animal husbandry in the future. Rationale of the study was to utilize Hu sheep milk as a source of potential probiotic LABs. The study has contributed to the establishment of a complete bacterial resource pool by exploring the Hu sheep milk microflora.
Highlights
Probiotics are being considered as valuable microorganisms related to human health
Gut microorganisms are wildly reported to have a great influence on the growth performance of animals, and maternal milk microbes are the first colonizers in gut of mammalian offspring, which microbes were existed in Hu sheep milk? The aim of the present study was to evaluate potential traits of probiotic strains of three Lactococcus lactis strains (HSM-1, HSM-10, and HSM-18) and one Leuconostoc lactis strain (HSM-14) isolated from Hu sheep milk through using a series of in vitro tests
The results indicated that HSM-1, HSM-10, HSM-14, and HSM-18 were resistant to low pH and high bile acid concentrations
Summary
Probiotics are being considered as valuable microorganisms related to human health. Hu sheep is referred as one of the important sheep breeds in China. Goat milk produced by Hu sheep is characterized with high nutritional value and hypoallergenic in nature. This milk contains plenty of milk prebiotic and probiotic bacteria. Consumers increasingly needs natural probiotic foods to improve their health and well-being [3]. Lactic acid bacterial strains (LABs) are the members of the our intestinal microbiota and widely being used as probiotics [4]. The genus Leuconostoc is Gram-positive, catalase-negative and facultative anaerobes [9]. They can be present in natural food and can be used as food additives because of their nutritional properties and organoleptic characteristics [10]. Leuconostoc lactis is one of the most important species in the genus Leuconostoc, which plays an important role in the production of glucan and bacteriocin in the food industry [12, 13]
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