Nitrate salts suppress sporulation and production of enterotoxin in Clostridium perfringens strain NCTC8239
Nitrate salts suppress sporulation and production of enterotoxin in Clostridium perfringens strain NCTC8239
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硝酸盐抑制产气荚膜梭菌菌株 NCTC8239 中的孢子形成和肠毒素的产生
DOI：
10.1111/1348-0421.12437
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发表时间：
2016
影响因子：
2.6
通讯作者：
Keisuke Otsuka and Masami Miyake
中科院分区：
文献类型：
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作者：
Mayo Yasugi;Keisuke Otsuka and Masami Miyake
A型产气荚膜梭菌是人类食源性疾病的常见来源。摄取的营养细胞在小肠中产生孢子，并在此过程中产生。perfringensenterotoxin (CPE)。尽管产孢在食源性疾病的发病机制中起着关键作用，但触发/抑制产孢的分子仍在很大程度上是未知的。本研究小组此前曾报道过在Dulbecco's Modified Eagle Medium （DMEM）中，将inC.产孢菌株NCTC8239与Caco - 2细胞共培养诱导产孢。相比之下，当细菌在罗斯威尔公园纪念研究所1640培养基（RPMI）中共同培养时，没有观察到等量的孢子。本研究发现，当这两种培养基混合时，RPMI抑制了DMEM诱导的孢子形成和CPE的产生。在DMEM中加入RPMI成分后，发现硝酸钙（Ca[NO3]2）显著抑制孢子形成和CPE的产生。当使用缺乏Ca(NO3)2‐的RPMI时，孢子数量增加。其他硝酸盐对孢子形成有显著抑制作用，而钙盐对孢子形成无明显抑制作用。qPCR结果显示，硝酸盐增加了细菌硝酸盐/亚硝酸盐还原酶的表达。此外，还发现亚硝酸盐和一氧化氮抑制孢子形成。在孢子形成阶段，Ca(NO3)2下调了孢子形成的主要调控因子Spo0A控制的基因，但对Spo0A本身不起作用。综上所述，这些结果表明硝酸盐通过下调Spo0A调控基因NCTC8239抑制产孢和CPE的产生。硝酸盐的减少可能与抑制孢子形成有关。
Clostridium perfringenstype A is a common source of food‐borne illness in humans. Ingested vegetative cells sporulate in the small intestinal tract and in the process produceC. perfringensenterotoxin (CPE). Although sporulation plays a critical role in the pathogenesis of food‐borne illness, the molecules triggering/inhibiting sporulation are still largely unknown. It has previously been reported by our group that sporulation is induced inC. perfringensstrain NCTC8239 co‐cultured with Caco‐2 cells in Dulbecco's Modified Eagle Medium (DMEM). In contrast, an equivalent amount of spores was not observed when bacteria were co‐cultured in Roswell Park Memorial Institute‐1640 medium (RPMI). In the present study it was found that, when these two media are mixed, RPMI inhibits sporulation and CPE production induced in DMEM. When a component of RPMI was added to DMEM, it was found that calcium nitrate (Ca[NO3]2) significantly inhibits sporulation and CPE production. The number of spores increased when Ca(NO3)2‐deficient RPMI was used. The other nitrate salts significantly suppressed sporulation, whereas the calcium salts used did not. qPCR revealed that nitrate salts increased expression of bacterial nitrate/nitrite reductase. Furthermore, it was found that nitrite and nitric oxide suppress sporulation. In the sporulation stages, Ca(NO3)2down‐regulated the genes controlled by Spo0A, a master regulator of sporulation, but notspo0Aitself. Collectively, these results indicate that nitrate salts suppress sporulation and CPE production by down‐regulating Spo0A‐regulated genes inC. perfringensstrain NCTC8239. Nitrate reduction may be associated with inhibition of sporulation.