浙东腌冬瓜产组胺微生物的分离及产组胺特性研究

Isolation and Characteristics of Histamine-producing Bacteria from Pickled Wax Gourd in East Zhejiang

为了解浙东地区传统腌冬瓜发酵体系中产组胺细菌及其组胺产生规律,本研究通过鉴别培养基结合HPLC筛选并确认了菌株的产组胺能力,并利用16S r DNA分子鉴定产组胺菌株;研究培养温度、p H和盐度对菌株生长和产组胺的影响。结果表明,从腌冬瓜发酵前、中期筛选出的5株菌属于2个菌种,命为M1和M3,均是肠杆菌属,且分别与Enterobacter aerogenes(产气肠杆菌)和Enterobacter xiangfangensis的亲缘关系最近。这两种菌的最适生长温度均为30℃,最适生长p H均为7,在小于5%盐度时生长均稳定;在组胺发酵培养基中,产组胺的最适p H均为4,在20~35℃的适宜生长温度内,最适产组胺温度均为35℃,随盐度的升高,产组胺量均降低。适宜的实验条件下,M1和M3的最大生长量分别为11.65 lg CFU/m L和14.30 lg CFU/m L,最大产组胺量分别为35.66mg/L和39.54 mg/L。研究结果可为浙东特色腌冬瓜的加工工艺及质量安全控制等提供参考依据。

Selective culture and high-performance liquid chromatography(HPLC) screening were performed to study histamine production by bacteria in the traditional fermentation system of pickled wax gourd from Eastern Zhejiang. Histamine-producing strains were identified by 16 S ribosomal DNA(r DNA), and histamine production capacity of each strain was determined. Additionally, the effects of temperature, p H, and salinity on bacterial growth and histamine production were investigated. The results showed that all five strains obtained from the early- and mid-fermentation stages belonged to two species, designated as M1 and M3, from the genus Enterobacter and showed close genetic relationships with E. aerogenes and E. xiangfangensis, respectively. The optimum growth temperature and p H for the two strains were 30 ℃and 7, respectively. The growth of the strains was stable at salinity below 5%. In the histamine fermentation medium, p H 4 was found to be optimum for histamine production by both strains. In the temperature range(20 ℃~35 ℃) suitable for bacterial growth, the optimum temperature for histamine production was 35 ℃. The yield of histamine decreased with increasing salinity. Under optimal conditions, values for maximum bacterial growth shown by M1 and M3 were 11.65 and 14.30 log CFU/m L, while values for maximum histamine production were 35.66 and 39.54 mg/L, respectively. Thus, these results provide a reference for processing and quality control of pickled wax gourd from Eastern Zhejiang.