Lactobacillus acidophilus is a common kind of lactic acid bacteria usually found in the human gastrointestinal tract, oral cavity, vagina, and various fermented foods. At present, many studies have focused on the probiotic function and industrial application of L. acidophilus. Additionally, dozens of L. acidophilus strains have been genome sequenced, but there has been no research to compare them at the genomic level. In this study, 46 strains of L. acidophilus were performed comparative analyses to explore their genetic diversity. The results showed that all the L. acidophilus strains were divided into two clusters based on ANI values, phylogenetic analysis and whole genome comparison, due to the difference of their predicted gene composition of bacteriocin operon, CRISPR-Cas systems and prophages mainly. Additionally, L. acidophilus was a pan-genome open species with a difference in carbohydrates utilization, antibiotic resistance, EPS operon, surface layer protein operon and other functional gene composition. This work provides a better understanding of L. acidophilus from a genetic perspective, and offers a frame for the biotechnological potentiality of this species.

Inflammatory bowel disease (IBD) is a worldwide chronic intestinal inflammatory immune-related disease. In this study, mice with dextran sulfate sodium (DSS)-induced colitis were used to evaluate the effect of Lactobacillus acidophilus on colitis. The results revealed that L. acidophilus CCFM137 and FAHWH11L56 show potential for relieving colitis symptoms, while L. acidophilus FGSYC48L79 did not show a protective effect. Moreover, L. acidophilus NCFM and FAHWH11L56 showed similar effects on various indicators of DSS-induced colitis, increasing the IL-10 and IL-17 in the colon, and modifying the CCL2/CCR2 axis and CCL3/CCR1 axis. For L. acidophilus CCFM137, its effects on colitis were different from the above two strains. Moreover, L. acidophilus FGSYC48L79 had negative effects on colitis by increasing the abundance of harmful bacteria in the gut microbiota and may promote the signaling of chemokines and their receptors. This may be related to its special genome compared to the other strains.

The application of nucleic acid detection methods improves the ability of laboratories to detect diarrheal pathogens, but it also poses new challenges for the interpretation of results. It is often difficult to attribute a diarrhea episode to the detected pathogens. Here we investigated the prevalence of 19 enteropathogens among diarrheal and nondiarrheal children and provided support for understanding the clinical significance of the pathogens. A total of 710 fecal samples were collected from children under 5 years old in 2 different regions of China from May 2017 to March 2018, comprising 383 mild to moderate diarrheal cases and 327 nondiarrheal controls. The enteropathogens were detected using real-time polymerase chain reaction (PCR) or real-time reverse transcription PCR (RT-PCR). Enteropathogens were detected in 68.9% of cases and 41.3% of controls. Rotavirus A (adjusted OR [aOR], 9.91; 95% CI, 4.99–19.67), norovirus GI and GII (aOR, 3.82; 95% CI, 2.12–6.89), and Campylobacter jejuni (aOR, 20.12; 95% CI, 2.57–157.38) were significantly associated with diarrhea (P < .05). Adenovirus, norovirus GII, rotavirus A, and enteroaggregative Escherichia coli (pCVD432) gave lower cycle threshold (Ct) values in cases than in controls (P < .05). Rotavirus A and norovirus GII were associated with diarrhea when the Ct values were ≤30 and ≤25, respectively. The types and loads of enteropathogens are likely to influence the interpretation of the clinical significance of positive results.