ABSTRACT
The gut microbiota is engaged in multiple interactions affecting host health. Bacteriocins showed the ability of impeding the growth of intestinal pathogenic bacteria and modulating gut microbiota in animals. Few studies have also discovered their regulation on human intestinal flora using an in vitro simulated system. However, little is known about their effect on gut microbiota of different enterotypes of human. This work evaluated the modification of the gut microbiota of two enterotypes (ET B and ET P) by the class IIb bacteriocin plantaricin NC8 (PLNC8) by using an in vitro fermentation model of the intestine. Gas chromatography results revealed that PLNC8 had no influence on the gut microbiota's production of short-chain fatty acids in the subjects' samples. PLNC8 lowered the Shannon index of ET B' gut microbiota and the Simpson index of ET P' gut microbiota, according to 16S rDNA sequencing. In ET B, PLNC8 enhanced the abundance of Bacteroides, Bifidobacterium, Megamonas, Escherichia-Shigella, Parabacteroides, and Lactobacillus while decreasing the abundance of Streptococcus. Prevotella_9, Bifidobacterium, Escherichia-Shigella, Mitsuokella, and Collinsella were found more abundant in ET P. The current study adds to our understanding of the impact of PLNC8 on the human gut microbiota and lays the groundwork for future research into PLNC8's effects on human intestinal disease.
ABSTRACT
Microbial contamination and nitrite accumulation are the two major concerns in the quality control of fermented vegetables. In the present study, a lactic acid bacteria strain Lactobacillus plantarum ZJ316 (ZJ316) was inoculated during Stachys sieboldii Miq. (SSM) fermentation, and the effects of ZJ316 on the quality and bacterial community of SSM during fermentation were investigated. It was observed that ZJ316 could avoid the occurrence of the nitrite peak and maintain the nitrite content of fermented SSM at a low level. Gas chromatography-mass spectrometry (GC-MS) results suggested that ZJ316 gave good flavor to the fermented SSM. 16S rDNA sequencing showed that Firmicutes was the dominant flora after ZJ316 inoculation, and the abundance of Proteobacteria decreased at the same time. At the level of the genus, SSM fermented by ZJ316 had a more obvious inhibitory effect on Pseudomonas on the 7th day compared with the naturally fermented SSM. Additionally, the effect of ZJ316-fermented SSM on gut microbiota modulation was also evaluated using an in vitro fecal fermentation system. The results revealed that ZJ316 had a relatively subtle influence on intestinal communities with a potentially positive impact on probiotics such as Lactobacillus and Bifidobacterium and a negative impact on Enterobacteriaceae. Furthermore, SSM fermented by ZJ316 promoted the production of short-chain fatty acids (SCFAs) in the human intestine. These results demonstrate that L. plantarum ZJ316 can be used as a good starter in the fermentation process of pickles.