| Fermented vegetable is an important part of traditional fermented food in China.Fermented vegetables is loved by most people in our country due to its delicious taste,rich nutrition and benifial to digestion.In this paper,the microorganisms in these fermented vegetables(paocai,jiangshui,Nangfeng yancai,suancai,Chinese spicy cabbage,meigancai,zaocai)were systematically analyzed.At the same time,the physical and chemical properties of these fermented vegetables were also investigated and compared.Meanwhile,the fuctions of microorganisms in these fermented vegetables were also predicted and classified.This study could provide an important theoretical basis for the theoretical research level of traditional fermented vegetable products,standardization,quality improvement and the food safety of traditional fermented vegetable products in China and had a great significance for excavating and rescuing traditionally characteristic fermented vegetable foods of various nationalities in China and promoting the food culture of Chinese.The main conclusions are as follows:1.A total of 96 paocai samples,25 jiang-shui samples,10 Nanfeng salted yancai samples,8 Nanfeng saltfree yancai samples,60 suancai samples,42 Chi nese spicy cabbage samples,47 meigancai samples and 9 zaocai samples were collected in this study.The basic physicochemical properties of these fermente d vegetables are as follows: the average p H values in paocai,jiang-shui,Nanfe ng salted yancai,Nanfeng saltless pickles,suancai,Chinese spicy cabbage,meg ancai and zaocai were 3.98,3.73,4.04,4.68,4.19,3.89,4.65,4.10,respectivel y;the average acidity contents in paocai,jiang-shui,Nanfeng salted yancai,Na nfeng saltless pickles,suancai,Chinese spicy cabbage,megancai and zaocai we re 3.97 g/L,0.55 g/L,3.41 g/L,1.38 g/L,5.61 g/L,20.17 g/L,9.25 g/L,11.73 g/L,respectively;the average nitrite contents in paocai,jiang-shui,Nanfeng s alted yancai,Nanfeng saltless pickles,suancai,Chinese spicy cabbage,meganca i and zaocai were 9.27 mg/kg,15.87 mg/kg,13.45 mg/kg,13.12 mg/kg,8.63mg/kg,5.42 mg/kg,8.50 mg/kg and 13.31 mg/kg,respectively;the average sur cose contents in paocai,jiang-shui,Nanfeng salted yancai,Nanfeng saltless pic kles,suancai,Chinese spicy cabbage,megancai and zaocai were 9.37 g/L,0.16g/L,0.04 g/L,0.13 g/L,0 g/L,0.01 g/L,13.20 g/kg and 10.32 g/kg,respecti vely;the average glucose contents in paocai,jiang-shui,Nanfeng salted yancai,Nanfeng saltless pickles,suancai,Chinese spicy cabbage,megancai and zaocai were 0.56 g/L,0.14 g/L,0.02 g/L,0.08 g/L,0.16 g/L,0.66 g/L,0.36 g/kg an d 0.26g/L,respectively;the average contents of frucose in paocai,jiang-shui,N anfeng salted yancai,Nanfeng saltless pickles,suancai,Chinese spicy cabbage,megancai and zaocai were 0.92 g/L,0.35 g/L,0.1 g/L,0.02 g/L,0.81 g/L,4.37 g/L,1.46 g/kg and 0.48 g/kg,respectively;the average contents of oxalate i n paocai,jiang-shui,Nanfeng salted yancai,Nanfeng saltless pickles,suancai,C hinese spicy cabbage,megancai and zaocai were 4.40 g/L,0.98 g/L,8.30 g/L,3.67 g/L,3.57 g/L,6.12 g/L,10.05 g/kg and 7.11 g/kg resepctively;the aver age contents of acetic acid in paocai,jiang-shui,Nanfeng salted yancai,Nanfen g saltless pickles,suancai,Chinese spicy cabbage,megancai and zaocai were 8.12 g/L,2.55 g/L,9.43 g/L,3.26 g/L,7.54 g/L,22.19 g/L,1.70 g/kg and 1.34g/kg,respectively;the average contents of acetic acid in paocai,jiang-shui,N anfeng salted yancai,Nanfeng saltless pickles,suancai,Chinese spicy cabbage,megancai and zaocai were 2.16 g/L,2.85 g/L,1.54 g/L,1.12 g/L,2.18 g/L,11.61 g/L,1.11 g/kg and 0.20 g/kg,respectively.2.A total of 267 strains(33 species)were isolated in Paocai.Lactobacillus,Pediococcus and Weissella were the main genera and Lactobacillus plantarum and Lactobacillus brevis were the main species in paocai.A total of 138 strains(3 genera and 18 species)were isolated in Jiangshui.Lactobacillus was the main genus and Lactobacillus fermentans,Lactobacillus plantarum and Lactobacillus subspecies were the main species in Jiang shui.A total of 105 strains(10 species)were isolated in Nangfeng yancai.Among them,55 strains are salted yancai and 50 strains were saltfree yancai.Lactobacillus plantarum and Pediococcu pentosaceus were the main species in Nanfeng salted yancai.Lactobacillus fermentans and Lactobacillus subspecies were the main isolates in Nanfeng saltfree yancai.A total of 337 strains(28 species)of lactic acid bacteria were isolated in Suancai.Lactobacillus,Pediococcus and Weissella were the main genera and Lactobacillus plantarum,Lactobacillus brevis,Lactobacillus coryniformis and Pediococcu parvulus were the main species in Suancai.A total of 197 strains(27 species)were isolated in Chinese spciy cabbage.Lacobacillus,Pediococcus,Leuconostoc,and Weissella were the genera and Lactobacillus plantarum,Leuconostoc mesenteroides,Lactobacillus brevis,Lactobacillus sakei,Lactobacillus curvatus and Lactobacillus sp were the main species in Chinese spicy cabbage.The Lactobacillus and Pediococcus were the main genera and the Lactobacillus brevis and Lactobacillus plantarum were the species in meigancai.37 strains(9 species)of lactic acid bacteria were isolated in zaocai and Lactobacillus plantarum were the major species zaocai.3.High-throughput sequencing analysis showed that the abundance and diversity of microbial communities in these fermented vegetables changed with the regions and samples.Meanwhile,the sequencing depth index and species accumulation curve showed that the sequencing samples and sequencing data of fermented vegetabls were reasonable in our study.Alpla diversity showed that the number of observed species,Shannon-Weiner index,Simpson index,Chao1 index,ACE index,Good coverage index and phylogenetic diversity index in paocai were 252.88,3.28,0.77,328.44,339.35,0.998 and 51.26,respectively.The Alpha diversity showed that the number of observed species,Shannon-Weiner index,Simpson index,Chao1 index,ACE index,Good coverage index and phylogenetic diversity index in jiangshui were433.05,2.70,0.69,640.20,677.33,0.9934 and 46.84,respectively.The Alpha diversity showed that the number of observed species,Shannon-Weiner index,Simpson index,Chao1 index,ACE index,Good coverage index and phylogenetic diversity index in Nanfeng yancai were 187.22,2.34,0.62,206.54,209.51,0.9993 and 19.78,respectively.The Alpha diversity showed that the number of observed species,Shannon-Weiner index,Simpson index,Chao1 index,ACE index,Good coverage index and phylogenetic diversity index in suancai were 265.94,4.22,0.88,335.30,347.15,0.9973 and 47.71,respectively.The Alpha diversity showed that the number of observed species,Shannon-Weiner index,Simpson index,Chao1 index,ACE index,Good coverage index and phylogenetic diversity index in Chinese spicycabbage were 234.14,3.77,0.85,304.67,312.41,0.9976 and 48.01,respectively.The Alpha diversity showed that the number of observed species,Shannon-Weiner index,Simpson index,Chao1 index,ACE index,Good coverage index and phylogenetic diversity index in meigancai were 299.56,3.24,0.72,399.37,425.51,0.9974 and28.12,respectively.The Alpha diversity showed that the number of observed species,Shannon-Weiner index,Simpson index,Chao1 index,ACE index,Good coverage index and phylogenetic diversity index in zaocai were 401.66,3.77,0.81,560.41,571.65,0.9962 and 33.99,respectively.4.High-throughput sequencing(HTS)showed that 28 phyla,47 classes,109 orders,218 families,606 genera,529 species and 2367 OTUs were detected in paocai.A total of 31 phyla,79 classes,107 orders,197 families,284 genera,143 species and138 OTUs were observed by HTS in jiangshui.A total of 19 phyla,36 classes,75 orders,139 families,339 genera,204 species and 713 OTUs were observed by HTS in Nanfeng yancai.A total of 17 phyla,35 classes,77 orders,145 families,362 genera,248 species and1414 OUT were observed by HTS in suancai.A total of 18 phyla,33 classes,75 orders,143 families,362 genera,248 species and 1214 OTUs were observed by HTS in Chinese spicy cabbage.A total of 31 phyla,46 classes,112 orders,225 families,556 genera,422 species and 2007 OTUs were observed by HTS in meigancai.A total of 23 phyla,39 classes,102 orders,210 families,517 genera,397 species and 1711 OTUs were observed by HTS in zaocai.5.High-throughput sequencing showed that at the phylum level,Firmicutes and Proteoobacteria were the most dominant bacteria in paocai(>95%),jiang-s hui(>96%),Nanfeng yancai(>97%),suancai(>89%),Chinese spciy cabbage(>97%),meigancai(>97%)and zaocai(>96%).At the family level,the relative abunda nce of Lactobacillaceae in jiangshui,salt-free yancai and Chinese spicy cabbage were higher than that in other five fermented vegetables,while that of Entero bacteriaceae in paocai,salted yancai,meigancai and zaocai were were higher th an that in other four fermented vegetables.At the genus level,Lactobacillus is the highest abundance in all fermented vegetables,the relative abundance of S erratia in paocai,meigancai and zaocai was higher than that in other five fer mented vegetables.The relative abundance of Oligotrophomonas in paocai andsuancai was higher than that in other six fermented vegetables.The relative abu ndance of Pediococcus in salted yancai,suancai and Chinese spicy cabbage w as higher than that in other five fermented vegetables.At the species level,dif ferent dominant strains were observed in different fermented vegetables,Lactob acillus pentosae was the dominant strain in most vegetables.Lactobacillus acet otolerans had the highest relative content in paocai.The relative abundance of Lactobacillus fermentum in jiangshui and salt-free yancai was higher than that i n other fermented vegetables.The relative abundance of Lactobacillus parabrevi s and Pediococcus parvulus in suancai and Chinese spicy cabbage were higher than those in other fermented vegetables.The relative abundance of Lactobaci llus amylolyticus was the highest content in jiangshui.The relative abundance of Lactobacillus delbrueckii in salt-free yancai and jiangshui was higher than t hat other fermented vegetables.The relative abundance of Pediococcus pentosac eus was the highest in salted yancai and the relative abundance of Lactobacillu s coryniformis was the highest in suancai.6.By comparing the physicochemical properties,microbial analysis and using the functional prediction analysis of bacterial communitis in different fermented vegetables,the physicochemical properties and microorganisms of different fermented vegetables have similarities and differences.The results showed that the contents of lactic acid and acetic acid in Chinese spciy cabbage were the highest;compared with other six fermented vegetables,meigancai and zaocai had higher salinity,oxalic acid,acidity and sucrose;the average level of nitrite in these fermented vegetables was lower than the national standard of pickled food(20mg/kg),and the contents of glucose and fructose in fermented vegetables were very low;the oxalic acid content in Chinese spciy cabbage,meigancai and zaocai showed was higher than that of other fermented vegetables.The main lactic acid bacteria isolated from different fermented vegetables were different.The Alpha diversity in different fermented vegetables was different.The sample sequencing data is reasonable and the sample is sufficient.The high-throughput sequencing showed that Firmicutes and Proteoobacteria were the main bacteria of fermented vegetables,but their relative contents were different among fermented vegetables.Lactobacillaceae and Enterobacteriaceae were thedominant families in fermented vegetables;Lactobacillus was the main genus in fermented vegetables,at species level,the species in different fermented vegetables were different and their relative contents were different in different fermentd vegebaltes.Lefse analysis showed that the strains infermented vegetables were different.NMDS showed that the microflora of zaocai and meigancai were similar;the microorganisms in jiangshui and Nanfeng salt-free pickles were similar,and those in Chinese spicy cabbage and suancai were similar.The effects of environmental factors on microorganisms in different fermented vegetable were different by CCA.Spearman analysis showed that different microorganisms had different positive and negative correlations with environmental factors,which included positive correlations,negative correlations,significant and significant differences.Picrust results showed that the relative abundance of microorganisms in different fermented vegetables was different.Metabolism,genetic information processing and environmental information processing were the main functions of microorganisms in fermented vegetables by Picrust.Secondary predictive function showed that membrane transport,carbohydrate metabolism,amino acid metabolism and microbial replication and repair function were the most important functions of microorganisms in fermented vegetable by Picrust.The three-level prediction function indicated that the transport function was the most important function of microorganisms in fermented vegetables.The results of Faprotax showed that the chemotrophic microorganisms and fermenting microorganisms were the main microorganisms in fermented vegetables. |
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