淡豆豉炮制中黄曲霉毒素产毒株的筛选鉴定和产毒能力测定

目的 对淡豆豉炮制过程中产黄曲霉毒素(aflatoxins,AFTs)的微生物(简称产毒菌)进行筛选鉴定、定量分析和产毒能力测定.方法 运用紫外荧光法初筛淡豆豉炮制中各样本的产毒菌并菌落计数;对初筛菌株的18S rDNA序列进行PCR扩增、测序,测序结果经NCBI同源性比对、MEGA7.0软件构建系统发育树进行分子生物...

Screening, identification and toxin-producing ability analysis of aflatoxin-producing strains in processing of Sojae Semen Preaparatum

Objective Aflatoxins (AFTs) producing strains (referred to as toxin-producing microorganism) during the processing of Sojae Semen Preaparatum (SSP) were screened, identified, quantitatively analyzed, and tested for their toxin-producing ability. Methods Preliminary screening of various toxin-producing microorganism in SSP processing by ultraviolet fluorescence method, then count the colonies; Analyse the 18S rDNA of those strains by PCR amplification and sequencing. The sequences are compared by NCBI homology, and the phylogenetic tree be constructed by MEGA 7.0 for molecular biology identification; Ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) were used to detect the AFTs content in the culture solution of each strain to determine their toxin-producing ability. Results Fifteen toxin-producing strains were screened and identified by ultraviolet fluorescence & molecular biology analyze, which were Aspergillus flavus or A. tamarii; During the processing of SSP, the toxin-producing microorganism gradually increased during the''yellow cladding'' stage, and it became the maximum at the 6th day, which was 1×10^6.30 CFU/g, then it gradually decreased in the''secondary fermentation'' stage, even no toxin-producing strains be found during day 9 to day 15; With UPLC-MS/MS, we found that five strains did not produce toxin, 10 strains produced toxin. Though they can make toxin, all the toxin the microorganism made below 5 ng/mL. It''s much lower than A. flavus standard strain (654.90 ng/mL). Conclusion In the processing of SSP, some A. flavus and A. tamarii with different toxin-producing ability were found, and these strains increased at first and decreased later. This study will lay the foundation for studying the law and mechanism of AFTs content changing in SSP processing. It also proved the importance of''secondary fermentation'' and the rationality of''secondary fermentation'' time, from the perspective of safety for the first time.