Pediococcus pentosaceus is important probiotics in Chinese Laomian. Its role in meat and fermented vegetable has been largely demonstrated, but few studies have investigated the role of P. pentosaceus in Chinese Laomian. For this purpose, we simulated Laomian fermentation using Saccharomyces cerevisiae and P. pentosaceus. Volatile aroma was detected by headspace solid‐phase microextraction gas–chromatography‐mass spectrometry. Real‐time fluorescent quantitative polymerase chain reaction was used to determine dynamic growth of S. cerevisiae and P. pentosaceus in fermentation. Extracellular proteins were analyzed by sodium dodecyl sulfate–polyacrylamide gel electrophoresis. Folin–Ciocalteu method was used to detect extracellular protease activity in different pH values. Owing to addition of P. pentosaceus, the types and contents of esters increase, the relative contents of acetic acid hexyl ester, formic acid octyl ester, and heptanoic acid ethyl ester rise obliviously; especially, the relative content of hexanoic acid ethyl ester was highly correlated with P. pentosaceus by increasing 20.61%. As the gel electrophoresis results display, due to mixed fermentation of S. cerevisiae and P. pentosaceus, the 25k Da and 51k Da proteins expression quantity of P. pentosaceus clearly increased. Under neutral and alkaline culture conditions, the extracellular protease activity of P. pentosaceus is higher. This research benefits to gain insight into the fermentation actions of P. pentosaceus in Chinese Laomian.

Aims In this study, Mrhst4, encoding a member of NAD+-dependent histone deacetylase (HDAC), was deleted to evaluate its regulation on the production of Monascus azaphilone pigments (MonAzPs) and mycotoxin as well as the developmental process in Monascus ruber. Methods and results Agrobacterium tumefaciens-mediated transformation was applied in this study to generate Mrhst4 null strain. Mrhst4-deleted strain did not display obvious differences in the sexual and asexual reproduction, colonial morphology and micro-morphology. UV-Vis scan and UPLC detection showed that disruption of Mrhst4 significantly increased the MonAzPs yields, and citrinin content was dramatically enhanced during the tested period. RT-qPCR results showed that the absence of Mrhst4 significantly increased the relative expression of citrinin biosynthetic pathway genes including pksCT, mrl1, mrl2, mrl4, mrl6 and mrl7. Western blot assay suggested that deletion of Mrhst4 could significantly elevate the acetylation levels of H3K4, H3K9, H3K18, H3K56 and H4K12, but attenuated the lysine acetylation modification of H4Pan, H4K8 and H4K16. Conclusion MrHst4 is an important regulator involved in secondary metabolism in Monascus ruber. In particular, MrHst4 plays a pivotal role in regulation of citrinin production.

SummaryThis study aimed to reveal different inoculation proportions starters (Lactobacillus bulgaricus and Streptococcus thermophilus) on the quality of Osmanthus glutinous rice fermented‐milk1/2/3 (GRFM1/2/3), which was a superior new variety of glutinous rice with rich nutrition, but its refined development was still lacking. The results showed during fermentation stages, pH of GRFM1 decreased faster (6.95 ± 0–4.67 ± 0.02), and acidity increased faster (25 ± 0–78.33 ± 2.89°T). In 21‐day preservation period, Day11 was an important turning point. At the begin of storage period, there were 7 main categories of volatile flavour compounds (VFCs): esters, alcohols, acids, ketones, aldehydes, hydrocarbons, and phenols, but the main different VFCs were hexanal. At the end, main VFCs differences were propane, 2‐chloro‐2‐nitro, etc. In brief, GRFM1 was the best inoculation proportions starter in superior new variety Osmanthus glutinous rice‐fermented milk for quality properties.

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