Analysis of Key Genes Responsible for Low Urea Production in Saccharomyces cerevisiae JH301

Mitigation of microbial nitrogen-derived metabolic hazards as a driver for safer alcoholic beverage choices: An evidence-based review and future perspectives

Alcoholic beverages have been enjoyed worldwide as hedonistic commodities for thousands of years. The unique quality and flavor are attributed to the rich microbiota and nutritional materials involved in fermentation. However, the metabolism of these microbiota can also introduce toxic compounds into foods. Nitrogen-derived metabolic hazards (NMH) are toxic metabolic hazards produced by microorganisms metabolizing nitrogen sources that can contaminate alcoholic beverages during fermentation and processing. NMH contamination poses a risk to dietary safety and human health without effective preventive strategies. Existing literature has primarily focused on investigating the causes of NMH formation, detection methods, and abatement techniques for NMH in fermentation end-products. Devising effective process regulation strategies represents a major challenge for the alcoholic beverage industry considering our current lack of understanding regarding the processes whereby NMH are generated, real-time and online detection, and the high degradation rate after NMH formation. This review summarizes the types and mechanisms of nitrogenous hazard contamination, the potential risk points, and the analytical techniques to detect NMH contamination. We discussed the changing patterns of NMH contamination and effective strategies to prevent contamination at different stages in the production of alcoholic beverages. Moreover, we also discussed the advanced technologies and methods to control NMH contamination in alcoholic beverages based on intelligent monitoring, synthetic ecology, and computational assistance. Overall, this review highlights the risks of NMH contamination during alcoholic beverage production and proposes promising strategies that could be adopted to eliminate the risk of NMH contamination.

Synergistic Fermentation with Functional Microorganisms Improves Safety and Quality of Traditional Chinese Fermented Foods

Traditional fermented foods are favored by people around the world for their positive health and taste advantages. Many of the fermented foods, including Chinese traditional fermented foods, are produced through mixed-culture fermentation. Apart from reducing the formation of harmful compounds such as ethyl carbamate (EC) and biogenic amines (BAs) during food fermentation, it is also difficult to precisely control and regulate the fermentation process based on the control of environmental conditions alone, due to the complex microbiota and an unclarified fermentation mechanism. In this review, key microorganisms involved in Chinese fermented foods such as baijiu, soy sauce, and vinegar production are elaborated, and relations between microbial composition and the aroma or quality of food are discussed. This review focuses on the interpretation of functions and roles of beneficial (functional) microorganisms that participate in food fermentation and the discussion of the possibilities of the synergistic use of functional microorganisms to improve the safety and quality of Chinese fermented foods. Conducting work toward the isolation of beneficial microorganisms is a challenge for modern food fermentation technology. Thus, methods for the isolation and mutagenesis of functional microbial strains for synergistic food fermentation are summarized. Finally, the limitations and future prospects of the use of functional microorganisms in traditional Chinese fermented foods are reviewed. This review provides an overview of the applications of synergistic fermentation with functional microorganisms in the improvement of the safety or sensory qualities of fermented foods.

Complete genome sequence, metabolic model construction, and huangjiu application of Saccharopolyspora rosea A22, a thermophilic, high amylase and glucoamylase actinomycetes

Saccharopolyspora is an important microorganism in the fermentation process of wheat qu and huangjiu, yet the mechanisms by which it performs specific functions in huangjiu remain unclear. A strain with high amylase and glucoamylase activities was isolated from wheat qu and identified as Saccharopolyspora rosea (S. rosea) A22. We initially reported the whole genome sequence of S. rosea A22, which comprised a circular chromosome 6,562,638 bp in size with a GC content of 71.71%, and 6,118 protein-coding genes. A functional genomic analysis highlighted regulatory genes involved in adaptive mechanisms to harsh conditions, and in vitro experiments revealed that the growth of S. rosea A22 could be regulated in response to the stress condition. Based on whole-genome sequencing, the first genome-scale metabolic model of S. rosea A22 named iSR1310 was constructed to predict the growth ability on different media with 91% accuracy. Finally, S. rosea A22 was applied to huangjiu fermentation by inoculating raw wheat qu, and the results showed that the total higher alcohol content was reduced by 12.64% compared with the control group. This study has elucidated the tolerance mechanisms and enzyme-producing properties of S. rosea A22 at the genetic level, providing new insights into its application to huangjiu.