Mimura Haruo, Yagi Masahiro, Yoshida Kazutoshi
Graduate School of Maritime Sciences, Kobe University.
Department of Environmental Chemistry, Kobe Institute of Health.
Biocontrol Sci. 2017;22(2):89-96. doi: 10.4265/bio.22.89.
We compared the TBT-resistant ability of resting cells prepared from isolates that formed colonies on nutrient agar plates containing 100 µM tributyltin (TBT) chloride, such as Photobacterium sp. TKY1, Halomonas sp. TKY2, and Photobacterium sp. NGY1, with those from taxonomically similar type strains. Photobacterium sp. TKY1 showed the highest ability among those three isolates. The number of surviving Photobacterium sp. TKY1 cells was hardly decreased after 1 h of exposure to 100 µM TBTCl, regardless of the number of resting cells in the range from 10 to 10 CFU mL. In such an experimental condition, the maximum number of TBT molecules available to associate with a single cell was estimated to be approximately 6.0 x 10. Resting cells prepared from type strains Photobacterium ganghwense JCM 12487 and P. halotolerans LMG 22194, which have 16S rDNA sequences highly homologous with those of Photobacterium sp. TKY1, showed sensitivity to TBT, indicating that TBT-resistant marine bacterial species are not closely related in spite of their taxonomic similarity. We also estimated the impact of TBT-resistant bacterial species to indigenous microbial populations of TBT-polluted surface sediments. The number of surviving TBT-sensitive Vibrio natriegens ATCC 14048 cells, 10 CFU mL, was reduced to 10 CFU mL when TBT-resistant Photobacterium sp. TKY1 cells, 10 CFU mL, coexisted with 10 CFU mL of V. natriegens ATCC 14048 cells in the presence of 100 µM TBTCl. These results indicate that the toxicity of TBT to TBT-sensitive marine bacterial populations might be enhanced when a TBT-resistant marine bacterial species inhabits TBT-polluted surface sediments.
我们比较了从在含有100µM氯化三丁基锡（TBT）的营养琼脂平板上形成菌落的分离物（如发光杆菌属TKY1、嗜盐单胞菌属TKY2和发光杆菌属NGY1）制备的静息细胞与分类学上相似的模式菌株制备的静息细胞的抗TBT能力。发光杆菌属TKY1在这三种分离物中表现出最高的能力。在10至10 CFU/mL范围内，无论静息细胞数量如何，发光杆菌属TKY1细胞在暴露于100µM TBTCl 1小时后存活数量几乎没有减少。在这种实验条件下，与单个细胞结合的TBT分子的最大数量估计约为6.0×10。从与发光杆菌属TKY1的16S rDNA序列高度同源的模式菌株江华发光杆菌JCM 12487和耐盐发光杆菌LMG 22194制备的静息细胞对TBT敏感，这表明尽管分类学相似，但抗TBT的海洋细菌物种之间关系并不密切。我们还估计了抗TBT细菌物种对TBT污染的表层沉积物中本地微生物种群的影响。当10 CFU/mL的抗TBT发光杆菌属TKY1细胞与10 CFU/mL的创伤弧菌ATCC 14048细胞在100µM TBTCl存在下共存时，10 CFU/mL的对TBT敏感的创伤弧菌ATCC 14048细胞存活数量减少到10 CFU/mL。这些结果表明，当抗TBT的海洋细菌物种栖息在TBT污染的表层沉积物中时，TBT对TBT敏感的海洋细菌种群的毒性可能会增强。
