Differences in the bacterial profiles and physicochemical between natural and inoculated fermentation of vegetables from Shanxi Province

Abstract

Purpose Fermented vegetables can be divided into two types, natural fermented and artificially inoculated fermented. By detecting and identifying the changes of bacterial diversity using physical and chemical indicators during natural and inoculation fermentation, we analyzed and determined the dominant bacteria in the fermentation process and revealed the relationship between bacteria and volatile substances. Methods We used the Illumina Miseq to sequence the bacteria in fermented vegetable samples at different fermentation periods, and calculated the total number of mesophilic microorganisms and lactic acid bacteria. We used the pH and nitrite to monitor the acidification process. GC-MS was used to determine volatile flavor compounds. Finally, we analyzed the correlation between volatile flavor compounds and bacteria. Results Total mesophilic microorganisms and the number of lactic acid bacteria in the inoculated fermentation were higher than the natural fermentation. The bacterial diversity Shannon and Simpson indexes of the natural fermentation, higher than those of inoculated fermentation in 0~7 days, were between 55~71% and 36~45%, respectively. On the 7th day, the proportion of Lactobacillus in the natural fermentation and inoculated fermentation were 53.4% and 90.2%, respectively, which were significantly different. Lactobacillus was the dominant genus in the fermented vegetables and an important genus to promote the formation of volatile flavors. Lactobacillus was negatively correlated with two volatile substances (4-[2,2,6-trimethyl-7-oxabicyclo [4.1.0] hept-1-yl]-3-Buten-2-one (K4) and a-Phellandrene (X1)) and played a leading role in the fermentation process. Conclusions Results demonstrated that the total number of mesophilic microorganisms and lactic acid bacteria in inoculated fermentation were more than those in natural fermentation. Inoculated fermentation can shorten the fermentation cycle and reduce the content of nitrite. Lactic acid bacteria were the dominant bacteria in fermented vegetables.

The safety and potential probiotic properties analysis of Streptococcus alactolyticus strain FGM isolated from the chicken cecum

“…S. alactolyticus strain FGM isolated from the chicken cecum has a good ability to ferment A. membranaceus, which improves the concentration of polysaccharides, and the fermented products are more beneficial to the health of broilers. It is reported that the health benefits of fermented food is very associated with the probiotic lactic acid bacteria (Chen et al 2020). To indicate the safety and benefits of application in animal feed in future, this study sequenced the genome of S. alactolyticus strain FGM and subjected it to genomic analyses and probiotic properties analysis.…”

Comparison of Fermentation Behaviors and Characteristics of Tomato Sour Soup between Natural Fermentation and Dominant Bacteria-Enhanced Fermentation

“…After that, it stabilized. Lacticaseibacillus can decompose nitrite and reduce nitrite content in tomato sour soup [ 18 ]. Therefore, the inoculation of cultures with pure starters was more effective than spontaneous fermentation in controlling the nitrite concentration of fermented tomato sour soup.…”

“…In recent years, high-throughput sequencing (HTS) and gas chromatography–ion mobility spectroscopy (GC–IMS) technologies have been widely used in the detection of food microorganisms and VFCs [ 17 ], such as in fermented vegetables [ 18 ], Ma Milk wine [ 19 ], natural fermented bean curd [ 20 ], etc. Recently, HTS was used to analyze bacteria in tomato sour soup, in which Lacticaseibacillus spp.…”

Comparative Metagenomics Reveals Microbial Communities and Their Associated Functions in Two Types of Fuzhuan Brick Tea

“…Based on the above results, it is possible that greater abundances of tea polysaccharides may be produced in FBT_S type teas that contribute to reducing the risk of type 2 diabetes and obesity ( Chen et al, 2019 ). In addition, some abundant microbial populations participated in amino acid metabolism activity (e.g., with glycine, serine, threonine, arginine, proline, cysteine, and methionine substrates) that can improve the taste of tea ( Chen et al, 2020 ). The metabolic pathway of ethylbenzene degradation in FBT_H samples contributed to the regulation of fermented tea aroma ( Zhu et al, 2018 ).…”