Metagenomic analysis of wastewater phageome from a University Hospital in Turkey

Unveiling the genomic diversity and ecological impact of phage communities in hospital wastewater

Phages are pivotal in shaping microbial communities and biogeochemical cycles, while our understanding of the diversity, functions potential, and resistance gene carriage of phages in hospital wastewater (HWW) remains limited. We collected influent and effluent samples from the 3 hospital wastewater treatment plants (HWTPs) to assess the diversity and fate of phages, the interactions between phages and hosts, and the presence of resistance genes and auxiliary metabolic genes (AMGs) encoded by phages. Compared to influent, effluent showed reduced phage abundance and altered composition, with decreases in Microviridae and Inoviridae. The gene-sharing network highlights that many phages in HWW are not classified in known viral genera, suggesting HWW as a rich source of new viruses. There was a significant association between phages and microorganisms, with approximately 32.57 % of phages expected to be capable of infecting microbial hosts, characterized primarily by lytic activity. A total of 8 unique antibiotic resistance genes, 13 unique metal resistance genes, and 5 mobile genetic elements were detected in 3 HWTPs phageomes. Phage AMGs have the potential to influence carbon, nitrogen, phosphorus, and sulfur metabolism, impacting biogeochemical cycles. This study reveals the genomic diversity and ecological role of phages in HWTPs, highlighting their environmental and ecosystem impact.

Virome Analysis of Paddy Floodwater in Two Cropping Seasons

Paddy fields include two interconnected ecosystems-soil and floodwater. Microbes and viruses are an integral component of these ecosystems, yet the viral communities have not been extensively studied. We present an analysis of the viromes of paddy floodwater collected during the two cropping seasons in India, the kharif and rabi seasons respectively. The overall taxonomic and functional characteristics appeared to be similar in both seasons, suggesting stability of the viral community. Taxonomically, the families of tailed bacteriophages dominated. The predominance of functional roles related to lytic phages further confirmed this. We reconstructed two complete and several partial viral genomes from the assembled data. The genomes did not align with any known sequences, thus representing novel viruses of the floodwater ecosystem.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-024-01292-9.

Environmental DNA transformation resulted in an active phage in Escherichia coli

The achievement of an active biological entity from environmental DNA is important in the field of phage. In this study, the environmental DNA extracted from hospital wastewater was transferred into Escherichia coli DH10B and Escherichia coli BL21 with chemical transformation and electroporation. After transformation, overnight cultures were filtered and used as phage source. The efficacies of the techniques were evaluated with spot test and double-layer agar assay. The emerged phage, named as ADUt, was purified and host-range analysis was performed. Phage DNA was isolated, sequenced and restriction profile was determined. The genome was assembled. The phylogenetic tree was constructed via VipTree. The extracted DNA resulted in active phage by the transformation of E. coli DH10B, but not E. coli BL21. The chemical transformation was found more successful than electroporation. ADUt phage was found to be polyvalent and effective against limited strains of Shigella and Escherichia genera. The phage genome size and GC ratio are 166904 bp and 35.67%, respectively. ADUt is a member of Straboviridae family and Tequatrovirus genus. This is the first study that uses environmental DNA for acquiring active phage, which may be an important source of new phage discovery. The result showed that DNA transformation yields active bacteriophage with both chemical transformation and electroporation.

Characterization, genome analysis and antibiofilm efficacy of lytic Proteus phages RP6 and RP7 isolated from university hospital sewage

The crystalline formation of biofilms by Proteus blocks the urine flow which often complicates the health care of catheterized patients. Bacteriophages has been highlighted as a promising tool to control biofilm-mediated bacterial infections. Here, we isolated and characterized two newly isolated lytic phages capable of infecting clinical isolates of P. mirabilis and P. vulgaris. Moreover, insights regarding the biological and molecular characterization were analysed. Both RP6 and RP7 phages showed a Proteus-genus-specific profile, administering no lytic activity against other family of Enterobacteriaceae. The optimal MOI value of the RP6 and RP7 phages were determined as 0.1 and 0.01, respectively. The one-step growth curve showed that RP6 and RP7 phages have a short latent period of 20 min and large burst size of 220-371 PFU/ML per infected host cell. Bacteria growth was reduced immediately after the phages were added, which is shown by the optical density (OD) measurement after 24 hr. Proteus phage RP6 and RP7 were found to eradicate both the planktonic and mature biofilms produced by the Proteus isolates tested. Genome sequence of Proteus phage RP6 was found to be 58,619 bp, and a G-C content of 47%. Also, Proteus phage RP7 genome size was 103,593 bp with G-C ratio of 38.45%. A total of 70 and 172 open reading frame (ORF) was encoded in RP6 and RP7 phage genomes, respectively. Interestingly, there were no tRNA encoded by Proteus phage RP6 genome even though there is a significant G-C content difference between the phage and its host. Additionally, the exhibition of highly lytic activity and absence of virulence and antibiotic-resistant genes in both Proteus RP6 and RP7 phages emphasized that this newly isolated phages are promising for potential therapeutic phages.

Isolation and characterization of Brochothrix phage ADU4

B. thermosphacta is a psychrotrophic bacterium that often forms the predominant part of the spoilage microflora of aerobically and anaerobically stored meats. Bacteriophages are natural enemies of bacteria and their potential for use in environmentally friendly biocontrol of specific pathogens in food is being intensively studied. In this study, we reported the isolation and characterization of the newly isolated lytic Brochothrix phage ADU4, which is capable of infecting the B. thermosphacta bacterium. For the characterization of Brochothrix phage ADU4; host range, multiplicity of infection values (MOI), phage growth parameters (latent period and burst size), stability at various temperatures and pH, reduction growth of bacteria, effect on biofilm, and molecular characterization were investigated. The spot-test analysis showed positivity with B. thermosphacta strains, while no infection was observed in any other species and genera of bacteria tested. The optimal MOI value of the phage was determined as 0.1. The phage latent period and burst sizes were 40-50 min and 311 PFU/ml per infected host cell, respectively by one-step growth curve analysis. Brochothrix phage ADU4 reduced bacteria immediately after infection, which is shown by optical density (OD) measurement and colony counting (<10 CFU/ml) for 3 days. The degradation of B. thermosphacta in biofilm by Brochothrix phage ADU4 was analyzed and it was found that high titer phage breakdown the existing biofilm and also persistently inhibited biofilm formation. Brochothrix phage ADU4 genome was found to be 127,819 bp, and GC content 41.65%. The genome contains 217 putative open reading frames (ORFs), 4 tRNAs, and additionally, no known virulence and antibiotic resistance genes (AMR) were identified. Brochothrix phage ADU4 showed a high identity (96.09%) to the A9 phage that belongs to the Herelleviridae family. Nevertheless, the assembly module and its around appeared less conserved, and some DNA fragments in Brochothrix phage ADU4 genome were not found in A9 genome and vice versa. A9 contains TnpB, a transposase accessory protein involved in lysogenicity which is absent in Brochothrix phage ADU4. In contrary Brochothrix phage ADU4 had auxiliary metabolic genes (AMG) mostly carried by lytic phages. All these results showed that the Brochothrix phage ADU4 has excellent properties such as strong antibacterial activity, short latent period, high burst size, stability in different conditions, inhibition of biofilms, and absence of virulence and AMR genes. Based on all these features, this newly isolated phage is promising to control B. thermosphacta contamination in meat and meat products, and has the potential to be used alone or in combination with phage cocktails.