16S rRNA gene high-throughput sequencing of two algicidal bacteria strains treated with phytoplankton

Algicidal bacteria exhibit considerable promise for mitigating harmful algal blooms (HABs) through their capacities to inhibit or lyse algal cells in aquatic environments. Nevertheless, their practical effectiveness can be significantly limited by survival challenges and complex microbial interactions in natural conditions, which are conventionally less addressed with laboratory co-inoculation experiments. In this study, we assessed the algicidal efficacy of pre-isolated bacterial strains in a synthetic cyanobacterial culture primarily composed of Microcystis aeruginosa and native lake microorganisms. We found while most individual bacterial strains showed limited effects, certain bacterial combinations displayed strong algal-inhibiting abilities. Among them, the dual-strain inoculation of Chromobacterium sp. MERYL1-35 and Paucibacter aquatile MERXLGS1 yielded the highest algicidal efficiency. Both strains exhibited higher persistence of relative abundances in their dual-strain inoculations than in single-strain inoculations, which may contribute to the enhancement of algicidal ability. Substantial alterations in the aquatic microbial community structure were also detected in the algicidal bacteria treated samples. These results suggested that cyanobacterial control efficiency of algicidal bacteria within complex microbial ecosystems can be substantially enhanced through designed co-inoculation strategies. Our study may provide new insights into the complex microbial interactions among algicidal bacteria, cyanobacteria, and the indigenous microbial communities, and the further applications of algicidal bacteria in HAB control.