This study evaluated the production of antihypertensive and antidiabetic peptides through the fermentation of amaranth grain proteins with Weizmannia coagulans. After 15 h of fermentation with W. coagulans, the initial protein content decreased by 21.57% for albumin (ALB) and 28.43% for globulin (GLOB). The electrophoretic profiles revealed progressive degradation of ALB and GLOB with increasing fermentation time. Consequently, the fermentation process generated peptides with inhibitory activity against both angiotensin I-converting enzyme (ACE) and dipeptidyl peptidase IV (DPP-IV). Gel filtration chromatography identified peptide fractions ranging from 0.95 to 5.15 kDa, notably the 0.95 kDa peptide fraction derived from GLOB, which exhibited the highest inhibitory activity against ACE and DPP-IV, with IC50 values of 0.12 and 0.27 mg/mL, respectively. Therefore, our findings show that fermentation with W. coagulans promotes the proteolysis of ALB and GLOB in amaranth grain, producing high-value peptides that can serve as bioactive ingredients in the development of nutraceuticals and/or functional foods.
Lactobacillus sp. from fermented cassava was investigated for rhodanese production. Purified rhodanese from Lactobacillus sp. exhibited a specific activity of 2.15 U/mg protein, a recovery of 12.5%, and a purification fold of 2.8. The subunit molecular weight of the enzyme was approximately 35 kDa. The apparent Km values for Na2S2O3 and KCN were 0.05 and 0.06 mM, respectively, while the corresponding Vmax values were 0.74 and 2.25 mu mol/min. The enzyme demonstrated a high binding affinity for thiosulfate as a substrate. The optimum pH and temperature were 6.0 and 40 degrees C, respectively. The enzyme exhibited thermal stability within 40-50 degrees C, with reduced activity at higher temperatures. Compounds such as EDTA, 2-mercaptoethanol, urea, and chloride salts (1-10 mM) inhibited the enzyme activity. The study concluded that the isolate from fermented cassava exhibited significant rhodanese activity, highlighting the crucial role of Lactobacillus sp. rhodanese in cyanide detoxification during cassava fermentation.
Rice-flavor baijiu xiaoqu is an essential raw material in the brewing process of rice-flavor baijiu, as its microbial composition and volatile flavor compounds (VFCs) influence the flavor of final product. Using high-throughput sequencing (HTS), physicochemical assays, and HS-SPME-GC-MS, a total of 53 volatile flavor substances were detected, including 15 alcohols, 16 esters, 5 acids, 5 ketones, 3 phenols, 3 aldehydes, and 6 other compounds. HTS revealed Saccharomycopsis, Saccharomyces, and Rhizopus as the dominant fungi, and Pediococcus, Acetobacter, and Weissella as the primary bacteria in rice-flavor baijiu xiaoqu. PICRUSt2 predicted predominant bacterial functions in carbohydrate, cofactor/vitamin, and amino acid metabolism. Correlation analysis revealed 179 significant associations (45 positive, 134 negative) between microbial genera and VFCs. Co-occurrence network analysis highlighted Fusarium, Aspergillus, Cladosporium, Lactococcus, and Botryotinia as dominant, highly connected genera crucial to the xiaoqu-making process. These findings provide direction for future efforts in the targeted breeding of functional strains.
