gvpA-C间隔区在微囊藻株系分型中的应用

从暴发水华的水体分离微囊藻(Microcystis)株，并依据gvpA-C间隔区和16S rDNA序列对其分型和比较。在gvpA-C间隔区序列中，有的类型具有一段172—176 bp的额外序列。以不包括额外序列的0.27 kb序列相比较，不同类型之间差异碱基位点达50余个。在16S rDNA碱基变异集中的0.69 kb序列中，不同类型之间有差异的碱基位点共有8个。与16S rDNA序列相比，微囊藻gvpA-C间隔区序列具有高度变异性，并且其PCR扩增可一步完成，不受其他细菌污染，因而可用于微囊藻株系分型。由于横向转移，2种分型存在交叉关系。此外，原本含有或不含有额外序列的微囊藻gvpA-C间隔区序列在系统进化树中分别聚成一簇。

APPLICATION OF THE GVPA-C INTERGENIC SEQUENCE IN TYPING OF MICROCYSTIS

Microcystis strains isolated from bloom-forming ponds were analyzed based on gvpA-C intergenic sequence and 16S rDNA. Several gvpA-C intergenic sequences shared an 172—176 bp extra sequence. An alignment of different types of 0.27 kb sequences, exclusive of the extra sequence, showed over 50 substitutions, whereas in a 0.69 kb hot spot region of 16S rDNA only 8 substitutions were identified. Compared to 16S rDNA, the gvpA-C intergenic sequence was generated by one-step PCR without contamination from co-existing bacteria and showed much higher variability, therefore should be useful in typing of Microcystis. Due to horizontal gene transfer, the two sets of types demonstrated an intersecting relationship. In addition, Microcystis gvpA-C intergenic sequences with or without the extra sequence formed two distinct clusters in a phylogenetic tree.