Comparison of nutritional value, bioactivity, and volatile compounds of soybean meal-corn bran mixed substrates fermented by different microorganisms.

To evaluate the impact of fermentation with different microorganisms on the nutritional quality and bioactivity of soybean meal-corn bran mixed substrates (MS), five lactic acid bacteria (LAB) strains, two Bacillus, and two yeast strains with excellent probiotics were selected for solid-state fermentation of soybean meal and corn bran MS. The fermented mixed substrate (FMS) inoculated with Lacticaseibacillus casei, Lactobacillus fermentum, Lactiplantibacillus plantarum, and Lactobacillus acidophilus presents lower risk of infection with pathogenic bacteria, probably due to their low pH and high lactate content. Compared to the FMS with LAB and yeast, Bacillus subtilis and B. pumilus showed significant improvements in nutritional quality and bioactivity, including TCA-SP, small peptide, free amino acids, total phenol, and protein digestibility. More than 300 volatile compounds were identified in FMS, including alcohols, ketones, aldehydes, esters, acids, ethers, furans, pyrazines, benzene, phenols, amines, alkanes, and others. FMS with Bacillus was characterized as containing a greater number of compounds such as ketones, aldehydes, and pyrazines. This study showed that microbial fermented feeds differed with various microorganism, and fermentation was an effective way to improve the quality of soybean meal-corn bran mixed feeds. This study might be the basis for excellent strains screening for multi-microbial combined fermentation in the future.

Application of soy protein isolate-xylose conjugates for improving the viability and stability of probiotics microencapsulated by spray drying.

BACKGROUND: Production and consumption of probiotics need to meet many adverse stresses, which can reduce their health-promoting effects on humans. Microencapsulation is an effective technique to improve the biological activity of probiotics and wall materials are also required during encapsulation. Application of Maillard reaction products (MRPs) in probiotic delivery is increasing. RESULTS: This work aims to study the effects of soy protein isolate (SPI)-xylose conjugates heated at different times on the viability and stability of probiotics. SPI-xylose MRPs formed after heat treatment based on changes in the browning intensity, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Fourier transform infrared spectroscopy. After heat treatment, α-helix and ß-sheet contents of SPI-xylose mixture shifted from 11.3% and 31.3% to 6.4-11.0% and 31.0-36.9%, respectively, and the thermal stability slightly changed. During spray drying, except for MRP240@LAB, probiotic viability was higher in the MRP-based probiotic microcapsules (21.36-25.31%) than in Mix0@LAB (20.17%). MRP-based probiotic microcapsules had smaller particle sizes (431.1-1243.0 nm vs. 7165.0 nm) and greater intestinal digestion tolerance than Mix0@LAB. Moreover, the MRP-based probiotic microcapsules showed better storability than Mix0@LAB and adequate growth and metabolism capacity. CONCLUSION: SPI-xylose Maillard reaction products are a promising wall material for probiotics microencapsulation, which can improve bacterial survivability during spray drying and enhance bacterial gastrointestinal digestion resistance. This study sheds light on preparing probiotic microcapsules with superior properties by spray drying. © 2023 Society of Chemical Industry.

The lactic acid bacteria and yeast community of home-made sauerkraut from three provinces in Southwest China.

The aim of this study was to investigate the lactic acid bacteria (LAB) and yeast community from home-made sauerkraut collected from Southwest China through culture-dependent and culture-independent technology. Forty-eight samples of home-made sauerkraut were collected from households at three different locations in Southwest China. The pH, total acidity and salt contents among these fermented vegetables were 3.69 ± 0.42, 0.86 ± 0.43 g/100 ml, and 3.86 ± 2.55 g/100 ml, respectively. The number of lactic acid bacteria (LAB) and yeasts were 7.25 ± 1.05 log10 colony-forming units (CFU)/ml and 3.74 ± 1.01 log CFU/ml, respectively. A total of 182 LAB and 81 yeast isolates were identified. The dominant isolates were Lactobacillus plantarum, L. brevis, Pediococcus ethanolidurans, Pichia membranifaciens, P. fermentans and Kazachstania bulderi. Denaturing gradient gel electrophoresis (DGGE) showed that L. plantarum, uncultured Lactobacillus sp, P. ethanolidurans, and K. exigua were the predominant microflora. Our studies demonstrated that the DGGE technique combined with a culture-dependent method is very effective for studying the LAB and yeast community in Chinese traditional fermentation vegetables. The results will give us an understanding of LAB and yeast community of Chinese sauerkraut and improve the knowledge of LAB and yeast community of Chinese sauerkraut.

Composition and functional diversity of fecal bacterial community of wild boar, commercial pig and domestic native pig as revealed by 16S rRNA gene sequencing.

The bacterial community in mammalian gastrointestinal tract is abundant and complex. To date, little is known about the gut microbiota of wild boar. This study aimed to investigate the fecal bacterial diversity of wild boar and compare with commercial pig and domestic native pig. The diet composition showed that the diets of wild boar, commercial pig and domestic native pig were different from each other. More than 1,760,000 quality-filtered sequences were obtained, and the results revealed distinct compositions and diversity of fecal microbiota in three groups. PCoA and NMDS analyses showed that fecal bacterial communities of wild boar, commercial pig and domestic native pig formed distinctly different clusters. Although the three groups shared a large size of OTUs comprising a core microbiota community, a strong distinction existed at family and genus levels. Ruminococcaceae, Prevotellaceae and Christensenellaceae were more abundant in the feces of wild boar than in domestic native pig and commercial pig. At the genus level, the proportion of unidentified Christensenellaceae was remarkably higher in wild boar group, while commercial pig and domestic native pig group had a higher abundance of Streptococcus and Lactobacillus. Tax4Fun predictions of metagenome function showed statistically significant differences in the functions of fecal microbiota in three groups. There were more bacteria genes with amino acid metabolism, cell growth and death, cell motility, energy metabolism, immune system and environmental adaptation observed in wild boar feces, while commercial pig feces contained more bacteria genes with carbohydrate metabolism, drug resistance, aging, infectious diseases, lipid metabolism, endocrine and metabolic diseases. These results indicated that the fecal microbial ecosystem of the wild boar is significantly different from that of domestic native pig and commercial pig, suggesting that diet is an important factor leading to differences in bacterial abundance and diversity in feces.

Two-stage fermentation of corn and soybean meal mixture by Bacillus subtilis and Lactobacillus acidophilus to improve feeding value: optimization, physicochemical property, and microbial community.

Microbial treatment can reduce the antinutritional factors and allergenic proteins in corn-soybean meal mixture (CSMM), but the role of the microbial community in hypoallergenicity and digestibility during the fermentation process remains unclear. Therefore, the fermentation strains of Bacillus and LAB were determined, and the compatibility and fermentation process of two-stage solid fermentation composite bacteria were optimized, and the dynamic changes in physicochemical property and microbial community during two-stage fermentation were investigated. Results showed that Bacillus subtilis NCUBSL003 and Lactobacillus acidophilus NCUA065016 were the best fermentation combinations. The optimal fermentation conditions were inoculum 7.14%, solid-liquid ratio of 1:0.88 and fermentation time of 74.30 h. The contents of TI, ß-conglycinin and glycinin decreased significantly after fermentation. Besides, TCA-SP, small peptides and FAA increased. Bacillus and Lactobacillus were the main genera. Pathogenic bacteria genera were inhibited effectively. This study suggests the feasibility of two-stage fermentation in improving the nutrient values and safety of the CSMM. Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-023-01426-7.

Organic acids drove the microbiota succession and consequently altered the flavor quality of Laotan Suancai across fermentation rounds: Insights from the microbiome and metabolome.

Laotan Suancai, a popular traditional Chinese fermented vegetable, is manufactured in the industry via four fermentation rounds. However, the differences in flavor quality of Laotan Suancai from the four fermentation rounds and the causes of this variation remain unclear. Metabolome analysis indicated that the different content of five taste compounds and 31 aroma compounds caused the differences in flavor quality among the variated fermentation rounds of Laotan Suancai. Amplicon sequencing indicated that the microbial succession exhibited a certain pattern during four fermentation rounds and further analysis unveiled that organic acids drove the microbiota shift to more acid-resistant populations. Spearman correlation analysis highlighted that seven core microbes may be involved in the formation of differential flavor and the corresponding metabolic pathways were reconstructed by function prediction. Our findings offer a novel perspective on comprehending the deterioration of flavor quality across the fermentation rounds of Laotan Suancai.

Effects of fermentation with Lactiplantibacillus plantarum NCU116 on the antihypertensive activity and protein structure of black sesame seed.

Effects of fermentation by Lactobacillus Plantarum NCU116 on the antihypertensive potential of black sesame seed (BSS) and structure characteristics of fermented black sesame seed protein (FBSSP) were investigated. Angiotensin-I-converting enzyme (ACE) inhibition and zinc chelating ability of fermented black sesame seed hydrolysate (FBSSH) reached the highest of 60.78 ± 3.67 % and 2.93 ± 0.04 mg/mL at 48 h and 60 h of fermentation, respectively. Additionally, the antioxidant activities of FBSSH and surface hydrophobicity of FBSSP were increased noticeably by fermentation. The α-helix and ß-rotation of FBSSP tended to decrease and increase, respectively, during fermentation. Correlation analysis indicated strong positive relationships between ß-turn and ACE inhibition activity as well as zinc chelating ability with correlation coefficients r of 0.8976 and 0.8932. Importantly, novel ACE inhibitory peptides LLLPYY (IC50 = 12.20 µM) and ALIPSF (IC50 = 558.99 µM) were screened from FBSSH at 48 h using in silico method. Both peptides showed high antioxidant activities in vitro. Molecular docking analysis demonstrated that the hydrogen bond connected with zinc ions of ACE mainly attributed to the potent ACE inhibitory activity of LLLPYY. The findings indicated that fermentation by Lactobacillus Plantarum NCU116 is an effective method to enhance the antihypertensive potential of BSS.

Integrated metatranscriptomics and metabolomics reveal microbial succession and flavor formation mechanisms during the spontaneous fermentation of Laotan Suancai.

Laotan Suancai, a Chinese traditional fermented vegetable, possesses a unique flavor that depends on the fermentative microbiota. However, the drivers of microbial succession and the correlation between flavor and active microbiota remain unclear. A total of 21 characteristic flavor metabolites were identified in Laotan Suancai by metabolomics, including 8 sulfides, 6 terpenes, 3 organic acids, 2 isothiocyanates, 1 ester, and 1 pyrazine. Metatranscriptome analysis revealed variations in the active microbiota at different stages of fermentation, and further analysis indicated that organic acids were the primary drivers of microbial succession. Additionally, we reconstructed the metabolic network responsible for the formation of characteristic flavor compounds and identified Companilactobacillus alimentarius, Weissella cibaria, Lactiplantibacillus plantarum, and Loigolactobacillus coryniformis as the core functional microbes involved in flavor development. This study contributed to profoundly understanding the relationship between the active microbiota and flavor quality formation, as well as the targeted selection of starters with flavor regulation abilities.

Effects of enzyme treatment on the antihypertensive activity and protein structure of black sesame seed (Sesamum indicum L.) after fermentation pretreatment.

Effects of enzyme treatment on the hypertensive potential and protein structure of black sesame seed (BSS) were investigated. Compared with BSS, Angiotensin-converting enzyme (ACE) inhibition of fermented black sesame seed (FBSS) has significantly improved after acid protease processing and reached 75.39% at 2 U/g in 3 h. Meanwhile, the zinc chelating ability and antioxidant activity of FBSS hydrolysate as well as surface hydrophobicity, free sulfhydryl content, and peptide content of FBSS protein, were significantly increased. The results illustrated that this strategy promoted the protein unfolding and exposure of hydrophobic residues, thus contributing toward enzymatic hydrolysis. Secondary structure results indicated that the α-helix of FBSS protein and ß-sheet of BSS protein decreased after hydrolyzing. The differences in ACE inhibition may also result from the difference in peptide sequence except for peptide content. In conclusion, the combination of fermentation pretreatment and enzyme treatment is an effective method to enhance the antihypertensive potential of BSS.