In this study, 23 strains of Bifidobacterium longum subsp. infantis were isolated and identified from 150 infant fecal samples in Northwest China by a culture method combined with polymerase chain reaction, with an isolation rate of only 10.67%. The genomes and probiotic properties of these strains of B. infantis were compared and analyzed. Genomic analysis showed that the average GC content, genome size, and number of coding sequences of B. infantis were 59.81%, 2.61 Mb, and 2273, respectively. Phylogenetic analysis based on core genes and average nucleotide identity (ANI) analysis showed that strains from the same geographical origin had high genetic similarity and close phylogenic relationships. There were differences in gene families related to plant-derived carbohydrate metabolism among strains. Carbohydrate metabolism experiments showed that most B. infantis strains were able to metabolize prebiotics such as galactooligosaccharides, oligofructose, and inulin, corroborating the presence of the glycoside hydrolase (GH) 32 and GH43 gene families, and four strains (A47X1, A79X4, A79X3, and S19X4) were able to utilize xylose. B. infantis S8X8 and S5X8_2 most effectively inhibited diarrheagenic Escherichia coli CICC-10411, enterotoxigenic E. coli CICC-10421, Salmonella enterica subsp. enterica serovar Typhimurium CICC-10420, enterohaemorrhagic E. coli CICC-21530, S. enterica subsp. enterica serovar Enteritidi CGMCC1.10754-SM1, but did not inhibit Listeria monocytogenes CGMCC1.9136-LS1. Intrinsic resistance genes to antibiotics such as rifampicin, mupirocin, and aminoglycoside, but not pathogenic virulence factors, were detected in the genome of B. infantis. All B. infantis strains were susceptible to vancomycin, gentamicin and streptomycin. This study provides a reference for the development of personalized probiotic preparations for infants in different regions.

This study was focused on 16 strains of Ligilactobacillus ruminis isolated from fecal samples of healthy persons from different families in Kashi, Xinjiang. Genomic and phylogenetic analysis were conducted, and the in vitro probiotic characteristics of the strains were compared. Genomic analysis revealed that the average genome size, gene number, and GC content of the L. ruminis strains were 1.4 Mb, 1374, and 43.55%, respectively. Notably, there were significant differences in the number of strain-specific genes, ranging from 3 to 886 (strain K646-58L had a notably higher number of specific genes compared with all other strains). In phylogenetic analysis, strains from the same family did not cluster together as closely based on their hosts’ genetic relatedness. The carbon source utilization experiments showed that the L. ruminis strains could utilize soybean oligosaccharides, cottonseed xylose, and maltodextrin, but not sorbitol or xylitol. The carbohydrate-active enzyme database (CAZy) annotated a large number of genes involved in polysaccharide substrate metabolism, such as the glycoside hydrolase (GH)1 and GH13 gene families. The 16 strains showed resistance to aminoglycosides but susceptibility to tetracyclines and chloramphenicol, which was not completely consistent with resistance gene prediction. All L. ruminis strains had high self-aggregation ability (> 50%) and good hydrophobicity (> 20%). Based on the genetic and phenotypic characteristics, L. ruminis had excellent probiotic properties, especially strains K227-6L and K645-5L. This study lays the theoretical foundation for the development and application of potential probiotic strains.

Probiotics have been proven to play a positive role in the prevention and treatment of diabetes. The gut microbiota of different populations harbors an extremely rich diversity of species and strains. This study aimed to explore potential new probiotic resources from the intestine of Tajik children with the goal of discovering new strains that can be used for the prevention and treatment of diabetes. In this study, Bifidobacterium strains were isolated from the intestine of healthy Tajik children in Xinjiang and identified using groEL gene sequencing. These strains were then screened for their in vitro probiotic characteristics to identify potential anti-diabetic strains. The results showed that 1579 Bifidobacterium strains were isolated and purified from the intestine of 62 children, with Bifidobacterium longum subsp. longum being the dominant ones (591 isolates). A total of 76 sequenced strains of B. longum subsp. longum from 33 samples containing B. longum, at least one strain of which was from each sample, were analyzed for in vitro probiotic characteristics. The results showed that five B. longum subsp. longum strains (TXX165-6, TXX127-13, TXX13-17, TXX51-1, and TXY63-27) exhibited a survival rate exceeding 60% in simulated gastrointestinal fluid and demonstrated good carbon source utilization capabilities. All of their cell-free supernatants exhibited strong antioxidant activity and α-glucosidase inhibitory activity, scavenging over 82% of 2,2’-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) cation radical and over 68% of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. Strain TXX165-6 exhibited the highest surface hydrophobicity (78.46%) and surface self-aggregation ability (49.15%). Strain TXX51-1 displayed the second-highest surface hydrophobicity (67.30%) and inhibited 68.75% of α-glucosidase activity, which was significantly superior to the model probiotic Lacticaseibacillus rhamnosus GG (20.15%). Therefore, strains TXX165-6 and TXX51-1 are promising candidates for further animal experiments to assess their potential as potential anti-diabetic strains.