对虾肠道中产毒镰孢菌抑制菌的筛选与鉴定

Isolation and Identification of Strains Inhibiting Toxigenic Fusarium Isolated from Intestinal Bacteria of Prawns

为了获得对产毒镰孢菌具有抑制效应的海洋细菌,从对虾肠道中分离细菌,并将分离得到的优势细菌与产T-2毒素的禾谷镰孢菌(Fusarium graminearum)(FG1207)进行固体对峙培养,具有抑菌圈的细菌菌落即为产毒镰孢菌的抑制菌。然后选取对FG1207具有抑制作用的细菌与FG1207进行液体共同培养,用LC-MS/MS技术检测菌悬液中T-2毒素含量,最后对具有抑制FG1207的生长和降解T-2毒素效果的细菌进行16s r RNA序列鉴定和VITEK2细菌生化鉴定。实验结果分离得到8株优势细菌,其中一株对FG1207的生长具有明显的抑制作用;LC-MS/MS检测发现该细菌与FG1207共同培养菌悬液中未检测到T-2毒素,说明该细菌不仅能够抑制产毒镰孢菌的生长,还能降解T-2毒素。经16s r RNA鉴定该细菌为海洋尼泊尔葡萄球菌(Nepal Staphylococcus Aureus),相似度为99.93%,VITEK2细菌生化鉴定的相似度为96.86%。

In order to identify marine bacteria with the ability to inhibit the toxigenic fungus Fusarium, beneficial bacteria were isolated from prawns intestines and cultured on a solid medium in antagonism with Fusarium graminearum(FG1207), which produces the T-2 toxin. Bacteria with inhibition zones were regarded as being able to inhibit toxigenic FG1207. These were isolated and grown with FG1207 in a liquid medium. Liquid chromatography-mass spectroscopy/ mass spectroscopy(LC-MS/MS) was used to estimate the T-2 toxin present in the liquid medium. Bacterial strains found to both inhibit FG1207 growth and degrade T-2 toxin were identified using 16 s r RNA sequencing and VITEK 2 biochemical identification methods. Thus, eight strains of beneficial bacteria were isolated. Of these, one strain(H5) showed a significant inhibitory effect on FG1207 growth, wherein LC-MS/MS did not detect T-2 toxin in the liquid medium containing H5 and FG1207. This result indicated that not only could this bacterial strain inhibit the growth of toxigenic Fusarium but it could also degrade T-2 toxin. The strain H5 was identified via 16 s r RNA sequencing as Nepal Staphylococcus aureus, with 99.93% similarity seen, while VITEK 2 biochemical identification showed 96.86% similarity.