Genomic characteristics and probiotic properties of Latilactobacillus curvatus HFS9

Abstract:

[Background] In recent years, the health benefits of Latilactobacillus curvatus have received much attention and genome analysis combined with phenotypic test provides a new approach for the development of probiotics. [Objective] To explore the genomic characteristics and probiotic properties of L. curvatus HFS9 isolated from healthy human feces. [Methods] The genome of L. curvatus HFS9 was characterized by pan-genome analysis and genomic annotation was performed to identify the probiotic genes. The probiotic properties of L. curvatus HFS9 in vitro were assessed based on survivability in low pH and 0.3% bile salt, self-aggregation capacity, hydrophobicity and cell adhesion, susceptibility tests, radical scavenging activities, and antibacterial experiments. The mouse model of colitis was established to evaluate the anti-inflammatory effect of HFS9 in vivo. [Results] L. curvatus had an open pan-genome and a conserved core genome. The genome of L. curvatus HFS9 was 1.97 Mb, with the GC content of 41.86% and 2 050 coding sequences. It carried Lactobacillus phage PLE3 genes and possessed the probiotic genes related to cell adhesion, acid tolerance, bile salt tolerance, and antioxidation. The survival rates of L. curvatus HFS9 in acid and bile salt environments were 62.42% and 92.92%, respectively. The self-aggregation capacity and hydrophobicity of L. curvatus HFS9 were 63.33% and 75.00%, respectively. L. curvatus HFS9 showed the adhesion rate of 12.97% to human colon cancer cells (HT-29 cells), was sensitive to most of the antibiotics tested, had inhibitory effects on six common human pathogens, and possessed the abilities to scavenge 1,1-diphenyl-2-picrylhydrazyl radical 2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl (DPPH) and hydroxyl radicals. In addition, L. curvatus HFS9 relieved the symptoms and ameliorated colon shortening and histopathological changes in the mouse model of colitis. [Conclusion] L. curvatus HFS9 contains probiotic genes and has probiotic properties in vitro and in vivo, which can be further developed and utilized as a candidate probiotic strain.