强光及高温诱发白化的中国绿水螅共生细菌多样性的特征.

Objective: To investigate the symbiotic bacterial diversity of Hydra sinensis undergoing bleaching induced by strong light and high temperature. Method(s): The bleaching of H. sinensis was induced under strong light (6000 Lux, 25℃), high temperature (2000 Lux, 33℃) and combined stresses of strong light and high temperature (6000 Lux, 33℃), respectively. After 21 days of bleaching experiment, the bleaching degree of H. sinensis was detected by counting symbiotic algae in single cells of H. sinensis, and the diversity and abundance of symbiotic bacteria in H. sinensis were studied by use of high-throughput sequencing of 16S rDNA. Result(s): The number of symbiotic algae was observably decreased under strong light, high temperature and combined stresses of strong light and high temperature (P<0.05). The abundance of Phylum Cyanobacteria in H. sinensis increased under strong light, while the abundances of Phylum Cyanobacteria and Chlorobi in H. sinensis increased significantly under the combined stresses of strong light and high temperature. In addition, KEGG enrichment analysis indicated that symbiotic bacteria in H. sinensis undergoing bleaching were related to the biosynthesis and metabolism of antioxidants such as linoleic acid, carotenoid and betalain. Conclusion(s): Cyanobacteria and chloracea may provide their photosynthetic products to the host of H. sinensis to make up for the nutritional deficiency caused by the decrease of symbiotic algae. Furthermore, the diversity of symbiotic bacteria in H. sinensis changed in the direction of improving the antioxidant capacity of the host under strong light and/or high temperature stress. [ABSTRACT FROM AUTHOR]