Increased sulfate-reducing bacteria can drive microbial dysbiosis in bleached corals.

This article focuses on the microbial community changes associated with coral bleaching in Porites lutea colonies from eastern Shenzhen, emphasizing shifts in Symbiodiniaceae and bacterial populations. Using internal transcribed spacer 2 (ITS2) and 16S rRNA amplicon sequencing, the study found that bleached corals exhibited significantly higher bacterial diversity and richness, particularly an increased abundance of sulfate-reducing bacteria (SRB) such as Desulfobulbus and Desulfobacter, while Symbiodiniaceae diversity remained relatively stable but with altered composition. The research highlights a negative correlation between SRB and the beneficial coral-associated bacterial genus Endozoicomonas, suggesting that increased SRB may disrupt microbial balance and contribute to bleaching by producing toxic hydrogen sulfide that impairs algal symbiont photosynthesis. These findings provide insights into the complex microbial interactions underlying coral bleaching and propose SRB as potential microbial indicators of coral health decline.