基于宏基因组学技术解析工业发酵蔬菜中亚硝酸盐形成及降解机理

Metagenomic analysis of formation and degradation mechanism of nitrite in industrially fermented vegetables

蔬菜发酵过程中亚硝酸盐形成及降解机制对于控制亚硝酸盐含量,保证发酵蔬菜食用安全性至关重要。该研究利用宏基因组学方法分析了4种工业发酵蔬菜中的微生物群落分布以及功能基因。物种注释结果表明,发酵蔬菜以乳杆菌属(Lactobacillus)、盐单胞菌属(Halomonas)、枝芽孢杆菌属(Virgibacillus)为优势细菌属,以德巴利酵母属(Debaryomyces)、苏吉雅玛酵母属(Sugiyamaella)、毕赤酵母属(Pichia)和舍弗氏酵母属(Scheffersomyces)为优势真菌属。功能基因分析表明,4种工业发酵蔬菜中亚硝酸盐代谢途径包括反硝化作用、异化硝酸盐还原作用和同化硝酸盐还原作用,硝酸盐还原酶、硝基单加氧酶、亚硝酸盐还原酶、一氧化氮还原酶[细胞色素c]、一氧化二氮还原酶、亚硝酸盐还原酶[NADH]、铁氧还蛋白亚硝酸盐还原酶和亚硝酸盐还原酶[NAD(P)H]是亚硝酸盐代谢过程中起主导作用的酶。微生物与功能基因关联分析表明,费斯莫尔德乳杆菌(Lactobacillus versmoldensis)、咸海鲜盐单胞菌(Halomonas jeotgali)、橙色盐单胞菌(Halomonas lutea)、反硝化盐单胞菌(Halomonas halodenitrificans)、盐反硝化枝芽孢杆菌(Virgibacillus halodenitrificans)等细菌以及米曲霉(Aspergillus oryzae)、尖孢镰刀菌(Fusarium oxysporum)等真菌可能参与反硝化作用、异化硝酸盐还原作用,细菌解淀粉嗜盐碱球菌(Natronococcus amylolyticus)和真菌汉逊德巴利酵母(Debaryomyces hansenii)、食腺嘌呤芽生葡萄孢酵母(Blastobotrys adeninivoran)可能参与同化硝酸盐还原作用,从而促进发酵蔬菜中亚硝酸盐的形成与降解。该研究为探究蔬菜自然发酵过程中亚硝酸盐代谢途径、功能基因以及关联微生物信息提供了新的思路,为发酵蔬菜亚硝酸盐调控提供理论依据。

The high nitrite content in fermented vegetables could cause concerns about food safety.Understanding the process of nitrite formation and degradation during vegetable fermentation is crucial for controlling nitrite levels and ensuring the edibility of fermented vegetables.This study evaluated the microbial community structure and functional genes in four industrially fermented vegetables using metagenomics technology.According to the results of non-redundant protein sequences annotation,the predominant bacterial genera in fermented vegetables were Lactobacillus,Halomonas,and Virgibacillus,whereas the major fungal genera were Debaryomyces,Sugiyamaella,Pichia,and Scheffersomyces.The KEGG annotation results showed that the pathways for nitrite metabolism in four industrially fermented vegetables were denitrification,dissimilatory nitrate reduction,and assimilatory nitrate reduction.The enzymes nitrite reductase,nitric oxide reductase[cytochrome c],nitrous-oxide reductase,nitrite reductase[NADH],ferredoxin-nitrite reductase,and nitrite reductase[NAD(P)H]were the main players in nitrite metabolism.Certain bacteria,such as Lactobacillus versmoldensis,Halomonas jeotgali,Halomonas lutea,Halomonas halodenitrificans,Virgibacillus halodenitrificans,and fungi,such as Aspergillus oryzae and Fusarium oxysporum,may be involved in denitrification and dissimilatory nitrate reduction,according to association analysis of microorganisms and functional genes.The assimilatory nitrate reduction may be facilitated by the bacteria Natronococcus amylolyticus and the fungi Debaryomyces hansenii,Blastobotrys adeninivoran.This study provides new insight for investigating the functional genes,core microbial information,and nitrite metabolic pathways in fermented vegetables in the future.It also provides a theoretical framework for controlling nitrite in fermented vegetables.