Development of detection method for algal-lytic bacteria in eutrophic lakes.

为应用荧光原位杂交（FISH）技术检测溶藻细菌，从富营养化湖泊中分离了溶藻细菌，并对其遗传特性进行了分析。从日本9个富营养化湖泊中分离到29株溶藻细菌。泰国和中国通过使用包括铜绿微囊藻（NIES-90）的琼脂平板作为细菌的底物。从分离的细菌。提取DNA并分析16 S rDNA序列，将细菌分为三组。属于A组的细菌的16 SrDNA序列与黄单胞菌非常相似，其细胞长度为2 μ m以上（5 μ m以上时为线状），鸟嘌呤-胞嘧啶含量很高，为68- 70%。在A组菌株中，泰国北部和曼谷分离的3株菌株16 SrDNA序列基本一致，日本和内蒙古分离的菌株16 SrDNA序列基本一致，但存在部分差异。另一类细菌（B）为短杆状，鸟嘌呤-胞嘧啶含量约为59- 62%，从16 SrDNA序列上看与假单胞菌属（Pseudomonasmendocina）相近。通过对溶藻细菌共有的特异DNA序列的研究，发现溶藻细菌的近缘种黄单胞菌（Xanthomonas）缺失的由21个碱基组成的DNA序列。表明基于这些DNA序列的荧光原位杂交方法能够从现场样品中特异性地检测出溶藻细菌。

For detection of algal-lyiic bacteria by FISH method, such bacterial strains were isolated from eutrophic lakes, and analysed genetic property. Total of 29 strains of algal-lyiic bacteria were isolated from 9 eutrophic lakes in Japan. Thailand and also China by using agar plates including Microcystis aeruginosa (NIES-90) as substrate for the bacteria. From the isolated bacte ria. DNA was extracted and the 16S rDNA sequence was analysed to classify the bacteria into three groups. The 16S rDN A sequence of the bacteria belonging to a group (A), of which cell length was 2 μ m over (the thread state of at times 5 p m over) and the guanine-cyiosine content was very high with 68-70%, was very similar to those of Xanthomonas. Amon g the bacterial strain of group (A), 16S rDNA sequences of 3 strains isolated from north Thailand and Bangkok agreed, an d although difference is partially seen on the sequences, the sequences of isolates from Japan and Inner Mongolia were simi lar. Bacteria belonging to another group (B), which were short rods, guanine-cytosine contents were about 59-62%, seemed to be near of Pseudomonas such as Pseudomonas mendocina from the sequence for 16S rDNA. As a result of research for the specific DNA sequence which are common to the algae decomposition bacteria, DNA sequence that consists of 21 base pairs was found out that absent to the bacteria belong Xanthomonas which is near to the algal-lyiic bacteria. The possibilit y that is able to detect the algal-lytic bacteria specifically from in situ samples by the FISH method on the basis of these DNA sequence was shown.