A Novel Freshwater Cyanophage Mae-Yong1326-1 Infecting Bloom-Forming Cyanobacterium Microcystis aeruginosa

Abstract

Microcystis aeruginosa is a major harmful cyanobacterium causing water bloom worldwide. Cyanophage has been proposed as a promising tool for cyanobacterial bloom. In this study, M. aeruginosa FACHB-1326 was used as an indicator host to isolate cyanophage from Lake Taihu. The isolated Microcystis cyanophage Mae-Yong1326-1 has an elliptical head of about 47 nm in diameter and a slender flexible tail of about 340 nm in length. Mae-Yong1326-1 could lyse cyanobacterial strains across three orders (Chroococcales, Nostocales, and Oscillatoriales) in the host range experiments. Mae-Yong1326-1 was stable in stability tests, maintaining high titers at 0–40 °C and at a wide pH range of 3–12. Mae-Yong 1326-1 has a burst size of 329 PFU/cell, which is much larger than the reported Microcystis cyanophages so far. The complete genome of Mae-Yong1326-1 is a double-stranded DNA of 48, 822 bp, with a G + C content of 71.80% and long direct terminal repeats (DTR) of 366 bp, containing 57 predicted ORFs. No Mae-Yong1326-1 ORF was found to be associated with virulence factor or antibiotic resistance. PASC scanning illustrated that the highest nucleotide sequence similarity between Mae-Yong1326-1 and all known phages in databases was only 17.75%, less than 70% (the threshold to define a genus), which indicates that Mae-Yong1326-1 belongs to an unknown new genus. In the proteomic tree based on genome-wide sequence similarities, Mae-Yong1326-1 distantly clusters with three unclassified Microcystis cyanophages (MinS1, Mwe-Yong1112-1, and Mwes-Yong2). These four Microcystis cyanophages form a monophyletic clade, which separates at a node from the other clade formed by two independent families (Zierdtviridae and Orlajensenviridae) of Caudoviricetes class. We propose to establish a new family to harbor the Microcystis cyanophages Mae-Yong1326-1, MinS1, Mwe-Yong1112-1, and Mwes-Yong2. This study enriched the understanding of freshwater cyanophages.

Ecological Dynamics of Broad- and Narrow-Host-Range Viruses Infecting the Bloom-Forming Toxic Cyanobacterium Microcystis aeruginosa

“…Microcystis CRISPRbased studies have revealed that blooms are composed of diverse populations with different CRISPR spacers acquired from foreign DNA fragments (12)(13)(14), suggesting that M. aeruginosa has frequently interacted with diverse viruses in the environment. Consistent with this observation, the number of Microcystis viral isolates has been gradually increasing since Ma-LMM01 was first isolated (e.g., MaMV-DC, PhiMa05, Mic1, Me-ZS1, UMHI42, Mwe-Yong1112-1, and Mae-Yong1326-1) (15)(16)(17)(18)(19)(20)(21)(22). In addition to these isolates, we recently revealed the existence of Microcystis viruses classified into groups I (including Ma-LMM01), II, and III through a metagenomic approach (23).…”

Current and Previous Green Technologies, Their Efficiency, Associated Problems, and Success Rates to Mitigate M. aeruginosa in Aquatic Environments

“…A novel, wide-ranging freshwater cyanophage called MinS1has the ability to infect multiple different cyanobacterial orders and could be used as a biological control measure against cyanobacterial blooms [184]. In host-range experiments, a novel freshwater cyanophage called Mae-Yong1326-1 was effective in lysing M. aeruginosa FACHB-1326 [181].…”