Background: 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. 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. Results: Based 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.

Due to the inflow of meltwater from the Midre Lovénbreen glacier upstream of Kongsfjorden, the salinity of Kongsfjorden increases from the estuary to the interior of the fjord. Our goal was to determine which bacterial taxa and metabolism-related gene abundance were affected by changes in salinity, and whether salinity is correlated with genes related to nitrogen and sulfur cycling in fjord ecosystem using metagenomic analysis. Our data indicate that changes in salinity may affect some bacterial taxa, such as the relative abundance of Alphaproteobacteria and Deltaproteobacteria is higher at high salinity sites, while the relative abundance of Gammaproteobacteria and Betaproteobacteria is more dominant at low salinity sites. In addition, the relative abundance of some bacteria at the high and low salinity sites was different at the family level. For example, Rhodobacteraceae, Pseudoalteromonadaceae, Flavobacteriaceae, Vibrionaceae at the high salinity site Colwelliaceae, Chromatiaceae and Alteromonadaceae at the low salinity site are affected by salinity. In terms of functional gene diversity, our study proved that salinity could affect the relative abundance of related genes by affecting the metabolic mechanism of microorganisms. In addition to salinity, functional attributes of microorganisms themselves were also important factors affecting the relative abundance of metabolism-related genes. In addition, salinity has a certain effect on the relative abundance of genes related to nitrogen and sulfur cycling.