Molecular analysis of an inactive aflatoxin biosynthesis gene cluster in Aspergillus oryzae RIB strains
Molecular analysis of an inactive aflatoxin biosynthesis gene cluster in Aspergillus oryzae RIB strains
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DOI：
10.1128/aem.72.1.484-490.2006
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发表时间：
2006-01-01
影响因子：
4.4
通讯作者：
Akita, O
中科院分区：
文献类型：
--
作者：
Tominaga, M;Lee, YH;Akita, O
为了帮助评估米曲霉生产黄曲霉毒素的潜力，对米曲霉 RIB 40 中黄曲霉毒素生物合成基因同源簇的结构进行了分析。尽管相应簇中的大多数基因与黄曲霉的基因表现出 97% 至 99% 的相似性，但有 3 个基因的相似性为 93% 或更低。在米曲霉 RIB 40 中发现了 of 区域的 257 bp 缺失、norA 中的移码突变以及 verA 中的碱基对取代。在 aflR 启动子中，在三个推定的 AreA 结合位点之一和 FacB 结合位点中发现了两个取代。 PCR 引物设计用于扩增 aflT、nor-1、aflR、norA、avnA、verB 和 vbs 的同源物，并用于检测 210 种米曲霉菌株中的这些基因。根据PCR结果，米曲霉RIB菌株被分为三组，尽管大多数菌株属于其中两组。第 1 组确认了所有 7 个基因的扩增，包含 122 个 RIB 菌株（所检查菌株的 58.1%），其中包括 RIB 40。第 2 组有 77 个菌株（36.7%），其特征是簇中的一半仅含有 vbs、verB 和 avnA。尽管通过逆转录-PCR 在一些第 1 组菌株（包括 RIB 40）中检测到 aflR 的轻微表达，但未检测到与黄曲霉毒素产生相关的其他基因（avnA、vbs、verB 和 omtA）。 Southern 分析未在第 2 组菌株中检测到 aflR。
To help assess the potential for aflatoxin production by Aspergillus oryzae, the structure of an aflatoxin biosynthesis gene homolog cluster in A. oryzae RIB 40 was analyzed. Although most genes in the corresponding cluster exhibited from 97 to 99% similarity to those of Aspergillus flavus, three genes shared 93% similarity or less. A 257-bp deletion in the of region, a frameshift mutation in norA, and a base pair substitution in verA were found in A. oryzae RIB 40. In the aflR promoter, two substitutions were found in one of the three putative AreA binding sites and in the FacB binding site. PCR primers were designed to amplify homologs of aflT, nor-1, aflR, norA, avnA, verB, and vbs and were used to detect these genes in 210 A. oryzae strains. Based on the PCR results, the A. oryzae RIB strains were classified into three groups, although most of them fell into two of the groups. Group 1, in which amplification of all seven genes was confirmed, contained 122 RIB strains (58.1% of examined strains), including RIB 40. Seventy-seven strains (36.7%) belonged to group 2, characterized by having only vbs, verB, and avnA in half of the cluster. Although slight expression of aflR was detected by reverse transcription-PCR in some group 1 strains, including RIB 40, other genes (avnA, vbs, verB, and omtA) related to aflatoxin production were not detected. aflR was not detected in group 2 strains by Southern analysis.