Novel Stenotrophomonas maltophilia temperate phage DLP4 is capable of lysogenic conversion

Abstract

Background Temperate bacteriophages are capable of lysogenic conversion of new bacterial hosts. This phenomenon is often ascribed to “moron” elements that are acquired horizontally and transcribed independently from the rest of the phage genes. Whereas some bacterial species exhibit relatively little prophage-dependent phenotypic changes, other bacterial species such as Stenotrophomonas maltophilia appear to commonly adopt prophage genetic contributions. Results The novel S. maltophilia bacteriophage DLP4 was isolated from soil using the highly antibiotic-resistant S. maltophilia strain D1585. Genome sequence analysis and functionality testing showed that DLP4 is a temperate phage capable of lysogenizing D1585. Two moron genes of interest, folA (BIT20_024) and ybiA (BIT20_065), were identified and investigated for their putative activities using complementation testing and phenotypic and transcriptomic changes between wild-type D1585 and the D1585::DLP4 lysogen. The gp24 / folA gene encodes dihydrofolate reductase (DHFR: FolA), an enzyme responsible for resistance to the antibiotic trimethoprim. I-TASSER analysis of DLP4 FolA predicted structural similarity to Bacillus anthracis DHFR and minimum inhibitory concentration experiments demonstrated that lysogenic conversion of D1585 by DLP4 provided the host cell with an increase in trimethoprim resistance. The gp65 / ybiA gene encodes N-glycosidase YbiA, which in E. coli BW25113 is required for its swarming motility phenotype. Expressing DLP4 ybiA in strain ybiA 770(del)::kan restored its swarming motility activity to wildtype levels. Reverse transcription-PCR confirmed the expression of both of these genes during DLP4 lysogeny. Conclusions S. maltophilia temperate phage DLP4 contributes to the antibiotic resistance exhibited by its lysogenized host strain. Genomic analyses can greatly assist in the identification of phage moron genes potentially involved in lysogenic conversion. Further research is required to fully understand the specific contributions temperate phage moron genes provide with respect to the antibiotic resistance and virulence of S. maltophilia host cells.

Isolation and Characterization of the Novel Bacteriophage AXL3 against Stenotrophomonas maltophilia

“…It is possible that the competitive advantage of type IV pili to aid in the colonization of plants [ 2 , 31 ] has selected for the use of these structures as phage receptors in soil microbes. It is unknown if the type IV pilus is a favoured receptor of S. maltophilia phages isolated from other environmental sources, such as water and sewage, as the receptors for these phages have not been examined [ 12 , 13 , 14 , 15 , 16 , 22 , 23 , 24 , 32 ]. However, the T4-like virulent phage Smp14 has been observed to bind to the poles of S. maltophilia cells by TEM [ 21 ] where type IV pili are normally expressed.…”

“…The use of phages for human therapy requires extensive phage characterization, including host range analysis, genomic characterization and identification of potential moron genes, lifestyle determination and identification of cell surface receptors. In the last two decades, numerous phages against S. maltophilia have been isolated and characterized to various extents for their therapeutic potential [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. Herein we describe the isolation and characterization of a novel S. maltophilia phage, AXL3, unrelated to any phages currently sequenced in the NCBI database.…”

Characterization of Novel Broad-Host-Range Bacteriophage DLP3 Specific to Stenotrophomonas maltophilia as a Potential Therapeutic Agent

“…Like DLP3, many of the S. maltophilia temperate phages characterized to date feature moron genes that encode virulence factors or antibiotic resistance proteins that could cause lysogenic conversion of their host (Hagemann et al, 2006;Garcia et al, 2008;Peters and Dennis, 2018;Peters et al, 2019). Genetically modifying these phages by removing adverse genes, such as those encoding virulence factors or lysogeny proteins, will enable the creation of safe and highly targeted therapeutic agents (Lynch et al, 2010;Dedrick et al, 2019).…”

“…The slurry was incubated overnight at 30°C with shaking at 225 RPM. The supernatant was filter-sterilized with a Millex-HA 0.45 μm syringe-driven filter (Millipore, Billerica, MA, United States) and stored at 4°C, as performed previously ( Peters et al, 2015 , 2017 , 2019 ). A single plaque was picked to propagate a working-stock solution for analysis using top-agar overlays.…”

Antibiotic Resistance Surveillance of Clinical Isolates of Stenotrophomonas maltophilia Strains in the Central South of China from 2016 to 2019

“…Stenotrophomonas maltophilia has developed into an international cosmopolitan hominid microorganism, which does not occasionally affect healthful entertainer but occurs with tremendous morbidity and mortality in immunocompromised and weakened human beings (4). ponents inclusive of DNase, RNase, hyaluronidase, fibrinolysin, protease, lipases, and elastase (5)(6)(7). These pathogens can live in medical sections and hold to the parenthetic equipment (8).…”