Whole genome sequencing of the novel polyvalent bacteriophage Malk1: A powerful biocontrol agent for water pollution

Abstract

In this study, a novel Malk1 phage, was isolated and characterized for its ability to target a broad range of multidrug-resistant (MDR) bacterial strains. Malk1, classified within the Siphoviridae family, showed lytic activity with a capsid diameter of 84 nm and a tail length of 205 nm. It demonstrated a short latent period of 18 min and a burst size of 102 virions per infected cell. The phage exhibited strong thermal stability up to 60 °C and maintained activity across a pH range of 6.0–10.0. However, exposure to hand soap and 70 % ethanol reduced its titers by over 94 % and 97 %, respectively. Malk1 lysed 92 % of the tested bacterial strains and had a genome of 44.3 kb, encoding 75 open reading frames (ORFs), with no genes for toxins, antibiotic resistance, or CRISPR elements, making it a virulent phage. A novel design utilizing immobilized polyvalent Malk1 phage on plastic sheets demonstrated superior efficacy in reducing multi-drug resistant (MDR) bacterial strains. The removal efficiencies for C.freundii (78–91 %), E.coli (74–85 %), S.enterica (60–76 %), and S.flexneri (63–72 %) were significantly higher compared to purified phage, which achieved removal efficiencies of 63–69 %, 58–66 %, 52–63 %, and 55–68 %, respectively, after 6 to 8 h. Furthermore, the immobilized phage treatment led to a 94.1 % improvement in the removal of physicochemical pollutants in wastewater, significantly surpassing the 65.3 % removal achieved with purified phage. The treatment process led to significant improvements in water quality, achieving an average removal efficiency of 71.1 % for electrical conductivity, 67.52 % for turbidity, 73.67 % for total dissolved solids (TDS), 88.02 % for biochemical oxygen demand (BOD), and 81.88 % for ammonia (NH₃). Additionally, the average dissolved oxygen (DO) levels increased by 79.17 % compared to untreated wastewater. These findings highlight the promising potential of Malk1 phage, particularly in its immobilized form, for pathogen control and enhancing water quality.

Originality-significance statement

We introduce the newly isolated polyvalent Malk1 phage, which has been thoroughly genome characterized and annotated. Immobilized Malk1 phage has proven effective in controlling drainage water pollution and addressing global concerns for irrigation water quality. Our experiments successfully reduced several multi-drug-resistant (MDR) bacterial strains in highly polluted drainage water, leading to significant improvements in water quality in a short time and at an affordable cost, facilitated by our innovative laboratory design.