RESUMO
Blooms of cyanobacteria cause enormous losses in both the economy and environment. Cyanophages are of great potential for fighting blooming cyanobacteria. Research report on cyanophage of bloom-forming cyanobacterium, Microcystis elabens is deficient. vB_MelS-Me-ZS1 (abbreviated as Me-ZS1) was isolated from fresh water by double-layer agar plate method using M. elabens. TEM exhibited that cyanosiphovirus Me-ZS1 has an icosahedral head about 60 nm in diameter, and a noncontractile tail approximately 260 nm. Experimental infection against 15 cyanobacterial strains showed that Me-ZS1 can infect 12 strains across taxonomic orders (Chroococcales, Nostocales and Oscillatoriales). High-throughput sequencing and bioinformatics analysis revealed that Me-ZS1 has a double-stranded DNA genome of 49,665 bp, with a G + C content of 58.22%, and 73 predicted open reading frames (ORFs). BLASTn and ORF comparisons showed that Me-ZS1 shares very low homology with the public sequences, and the phylogenetic tree based on TerL indicated that Me-ZS1 may delegate a novel and genetically distinct clade of Siphoviridae phages. In microcosm experiment, Me-ZS1 represented apparent effect on reducing relative abundance of cyanobacteria, increasing relative abundance of Saprospiraceae and protecting brocade carp (Carassius auratus) in cyanobacterial bloom water. This study isolated and characterized a novel broad-host-range Microcystis phage Me-ZS1 presenting a genetically distinct clade of freshwater cyanophage. The features of cyanophage Me-ZS1 provide a potential solution to the loss caused by cyanobacterial bloom.