Identification and Characterization of the First Virulent Phages, Including a Novel Jumbo Virus, Infecting Ochrobactrum spp.

Przemyslaw Decewicz,Mateusz Szymczak,Lukasz Dziewit,Piotr Golec,Monika Radlinska

doi:10.3390/ijms21062096

Przemyslaw Decewicz, Mateusz Szymczak + Show 3 more

Open Access

https://doi.org/10.3390/ijms21062096

Copy DOI

Abstract

The Ochrobactrum genus consists of an extensive repertoire of biotechnologically valuable bacterial strains but also opportunistic pathogens. In our previous study, a novel strain, Ochrobactrum sp. POC9, which enhances biogas production in wastewater treatment plants (WWTPs) was identified and thoroughly characterized. Despite an insightful analysis of that bacterium, its susceptibility to bacteriophages present in WWTPs has not been evaluated. Using raw sewage sample from WWTP and applying the enrichment method, two virulent phages, vB_OspM_OC and vB_OspP_OH, which infect the POC9 strain, were isolated. These are the first virulent phages infecting Ochrobactrum spp. identified so far. Both phages were subjected to thorough functional and genomic analyses, which allowed classification of the vB_OspM_OC virus as a novel jumbo phage, with a genome size of over 227 kb. This phage encodes DNA methyltransferase, which mimics the specificity of cell cycle regulated CcrM methylase, a component of the epigenetic regulatory circuits in Alphaproteobacteria. In this study, an analysis of the overall diversity of Ochrobactrum-specific (pro)phages retrieved from databases and extracted in silico from bacterial genomes was also performed. Complex genome mining allowed us to build similarity networks to compare 281 Ochrobactrum-specific viruses. Analyses of the obtained networks revealed a high diversity of Ochrobactrum phages and their dissimilarity to the viruses infecting other bacteria.

Highlights

Ochrobactrum spp. are non-fermenting, aerobic, Gram-negative bacteria of the Alphaproteobacteria class, which are frequently isolated from a variety of environmental and clinical samples [1,2,3,4,5,6,7,8]
This study initially aimed to determine whether there are viruses in wastewater treatment plants (WWTPs) that may act as natural bactericidal agents for the POC9 strain, which may limit its efficiency as a biogas production enhancer
POC9, the strain enhancing the reduction of organic biomass and biogas production in WWTPs, was characterized

Summary

Introduction

Ochrobactrum spp. are non-fermenting, aerobic, Gram-negative bacteria of the Alphaproteobacteria class, which are frequently isolated from a variety of environmental (water, soil, and plants) and clinical (animals and human) samples [1,2,3,4,5,6,7,8]. (e.g., representatives of O. anthropii and O. intermedium) are recognized as opportunistic pathogens. In these cases, bacteria are isolated mostly from immunocompromised patients, as pathogens colonizing respiratory tract and wounds. Bacteria are isolated mostly from immunocompromised patients, as pathogens colonizing respiratory tract and wounds These are mostly opportunistic infections, including central venous catheter-associated bloodstream infections, prosthetic valve endocarditis, septic arthritis, osteomyelitis, and peritonitis [16,17,18,19,20]. To prevent using pathogenic or multi-resistant strains, the application of Ochrobactrum spp. in bioremediation or industry ought to be preceded by a careful and insightful analysis of their metabolic properties and preferentially their genomic sequences

Objectives

Methods

Results

Conclusion