Diversity of microcystin genes within a population of the toxic cyanobacterium Microcystis spp. in Lake Wannsee (Berlin, Germany)
Diversity of microcystin genes within a population of the toxic cyanobacterium Microcystis spp. in Lake Wannsee (Berlin, Germany)
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DOI：
10.1007/s00248-001-0039-3
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发表时间：
2002-01-01
影响因子：
3.6
通讯作者：
Chorus, I
中科院分区：
文献类型：
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作者：
Kurmayer, R;Dittmann, E;Chorus, I
为了找出有多少种基因型决定了微囊藻属的微囊藻毒素的产生。在田间群体中，从万湖湖（德国柏林）采集单菌落（克隆），进行形态学表征，随后通过 PCR 分析 mcyB 基因内编码微囊藻毒素生物合成过程中一种氨基酸激活的区域。不同形态种产生微囊藻毒素的基因型的比例差异很大。大多数铜绿分枝杆菌菌落 (73%) 含有该基因，而只有 16% 属于鱼鳞分枝杆菌的菌落且没有威森氏分枝杆菌菌落提供 mcyB 基因的 PCR 产物。限制性片段长度多态性揭示了七种限制性图谱，显示每种限制性类型内核苷酸序列的低变异性(0.4-4%)以及限制性类型之间的低到高变异性(1.6-38%)。此外，还分析了 mcyB 基因内的氨基酸序列，以比较限制性类型之间微囊藻毒素生物合成过程中氨基酸激活的特异性，以及通过基质辅助激光解吸/电离飞行时间质谱法检测到的微囊藻毒素变体中氨基酸的出现情况。大多数产微囊藻毒素的菌落在氨基酸序列上表现出高度相似性，并含有微囊藻毒素-LR（LR指七肽可变位置的亮氨酸和精氨酸）、微囊藻毒素-RR和微囊藻毒素-YR，以及其他浓度较低的变体。结论是，湖中大多数产生微囊藻毒素的菌落发现的基因产物相当不具有特异性，湖中微囊藻毒素变体的多样性是由于相同基因型的微囊藻毒素生物合成过程中各种氨基酸的激活所致。
In order to find out how many genotypes determine microcystin production of Microcystis spp. in field populations, single colonies (clones) were sampled from Lake Wannsee (Berlin, Germany), characterized morphologically, and subsequently analyzed by PCR for a region within the mcyB gene encoding the activation of one amino acid during microcystin biosynthesis. The different morphospecies varied considerably in the proportion of microcystin-producing genotypes. Most colonies (73%) of M. aeruginosa contained this gene whereas only 16% of the colonies assigned to M. ichthyoblabe and no colonies of M. wesenbergii gave a PCR product of the mcyB gene. Restriction fragment length polymorphism revealed seven restriction profiles showing low variability in nucleotide sequence within each restriction type (0.4-4%) and a low to high variability (1.6-38%) between restriction types. In addition, the sequences of amino acids within the mcyB gene were analyzed to compare the specificity of the amino acid activation during microcystin biosynthesis between restriction types and with the occurrence of amino acids in microcystin variants as detected by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Most of the microcystin-producing colonies showed high similarity in the sequence of amino acids and contained microcystin-LR (LR refers to leucine and arginine in the variable positions of the heptapeptide), microcystin-RR, and microcystin-YR, as well as other variants in minor concentrations. It is concluded that the gene product found for most of the microcystin-producing colonies in the lake is rather unspecific and the diversity of microcystin variants in the lake results from activation of various amino acids during microcystin biosynthesis in the same genotypes.