The role of nitric oxide in the mechanism of lactic acid bacteria substituting for nitrite

This study aims to reveal the role of nitric oxide (NO) in substituting nitrite with lactic acid bacteria. Three lactic acid bacterial strains (<i>L. fermentum</i> JCM1173, <i>L. fermentum</i> IFO3956, <i>Weissella cibaria</i> X31) with nitrite substitution ability were inoculated into fermented sausages, respectively. Results indicated that the ratio of nitrosomyoglobin (NO-Mb) to total pigments was positively correlated with the substitution ability of the strain. UV-visible and resonance Raman spectroscopy suggested the NO-Mb was five-coordinated. In addition, the intracellular NO detected by fluorescent DAF-FM probe showed that <i>W. cibaria</i> X31 had the strongest NO-producing ability. Inhibitory experiments showed that both nitrate reductase and nitric oxide synthase-like protein participated in the NO production. These results indicated the vital role NO played in the substitution through the formation of NO-Mb and demonstrated the sources of NO in lactic acid bacteria preliminarily.

本研究旨在揭示一氧化氮（nitric oxide, NO）在乳酸菌替代亚硝酸盐过程中所发挥的作用。选取3株具备亚硝酸盐替代能力的乳酸菌菌株——发酵乳杆菌（L. fermentum）JCM1173、发酵乳杆菌（L. fermentum）IFO3956以及食片魏斯氏菌（Weissella cibaria）X31，分别接种至发酵香肠中。研究结果显示，亚硝基肌红蛋白（NO-Mb）占总色素的比值与菌株的亚硝酸盐替代能力呈正相关。紫外-可见光谱与共振拉曼光谱分析表明，该亚硝基肌红蛋白为五配位结构。此外，经荧光探针DAF-FM检测得到的胞内一氧化氮水平显示，食片魏斯氏菌X31的产一氧化氮能力最强。抑制实验证实，硝酸还原酶与类一氧化氮合酶蛋白均参与了一氧化氮的生成过程。上述结果揭示了一氧化氮通过形成亚硝基肌红蛋白在亚硝酸盐替代过程中所起到的关键作用，并初步阐明了乳酸菌中产一氧化氮的来源途径。