Ras Geoffrey, Zuliani Véronique, Derkx Patrick, Seibert Tim M, Leroy Sabine, Talon Régine
Université Clermont Auvergne - INRA, MEDISClermont-Ferrand, France.
CHR. HANSEN SASSaint Germain les Arpajon, France.
Front Microbiol. 2017 Apr 6;8:598. doi: 10.3389/fmicb.2017.00598. eCollection 2017.
is used as a starter culture in fermented meat products and contributes to color formation by the reduction of nitrate to nitrite. Nitrite is a food additive that is chemically turned to nitric oxide (NO) in meat but its safety has been questioned. The objective of this study was to determine the ability of NO synthase (NOS) of C2a to produce NO. For this purpose, a deletion mutant (Δ) in was constructed and NO production was evaluated in a test based on its ability to form nitrosomyoglobin and nitrosoheme. Production of NO was abrogated in the Δ mutant under aerobic conditions and reduced about 35-40% comparing to the wild type C2a under limited oxygenation. This mutant was sensitive to oxidative stress. The expression of genes encoding catalase was modulated in the mutant with an up-regulation of and a down-regulation of and . The Δ mutant displayed high colony pigmentation after prolonged growth on agar medium. Finally, the Δ mutant showed no growth in minimal medium. Growth was not restored in the minimal medium by complementation with , but was restored by either addition of phenylalanine or complementation with , a gene that encodes a prephenate dehydratase involved in phenylalanine biosynthesis and co-transcribed with . Our findings clearly demonstrate NOS-mediated NO production in , a meat-associated coagulase-negative .
被用作发酵肉制品的起始培养物，并通过将硝酸盐还原为亚硝酸盐来促进颜色形成。亚硝酸盐是一种食品添加剂，在肉类中会化学转化为一氧化氮（NO），但其安全性一直受到质疑。本研究的目的是确定C2a的一氧化氮合酶（NOS）产生NO的能力。为此，构建了一个缺失突变体（Δ），并基于其形成亚硝基肌红蛋白和亚硝基血红素的能力在一项测试中评估了NO的产生。在有氧条件下，Δ突变体中NO的产生被消除，与野生型C2a相比，在有限氧合条件下减少了约35 - 40%。该突变体对氧化应激敏感。编码过氧化氢酶的基因表达在突变体中受到调节，其中 上调， 和 下调。Δ突变体在琼脂培养基上长时间生长后显示出高菌落色素沉着。最后，Δ突变体在基本培养基中不生长。用 互补不能恢复基本培养基中的生长，但添加苯丙氨酸或用 互补可以恢复生长， 是一个编码参与苯丙氨酸生物合成的预苯酸脱水酶且与 共转录的基因。我们的研究结果清楚地证明了在一种与肉类相关的凝固酶阴性菌 中存在NOS介导的NO产生。
