RESUMEN
Folate is a B-vitamin required for DNA synthesis, methylation, and cellular division, whose deficiencies are associated with various disorders and diseases. Currently, most folic acid used for fortification is synthesized chemically, causing undesirable side effects. However, using folate-producing probiotics is a viable option, which fortify folate in situ and regulate intestinal microbiota. In this study, the folate production potential of newly isolated strains from raw milk was analyzed by microbiological assay. Latilactobacillus sakei LZ217 showed the highest folate production in Folic Acid Assay Broth, 239.70 ± 0.03 ng/µL. The folate produced by LZ217 was identified as 5-methyltetrahydrofolate. LZ217 was tolerant to environmental stresses (temperature, pH, NaCl, and ethanol), and was resistant to gastrointestinal juices. Additionally, the in vitro effects of LZ217 on human gut microbiota were investigated by fecal slurry cultures. 16S rDNA gene sequencing indicated that fermented samples containing LZ217 significantly increased the abundance of phylum Firmicutes and genus Lactobacillus, Faecalibacterium, Ruminococcus 2, Butyricicoccus compared to not containing. Short-chain fatty acids (SCFAs) analysis revealed that LZ217 also increased the production of butyric acid by fermentation. Together, L. sakei LZ217 could be considered as a probiotic candidate to fortify folate and regulate intestinal microecology.
RESUMEN
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.