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PubMed2025

Characterization of the novel Cutibacterium acnes phage KIT08 and its associated pseudolysogenic bacterial isolate.

Cutibacterium acnes, formerly Propionibacterium acnes, is a Gram-positive bacterium commonly recognized as an important factor in acne vulgaris and infections associated with prosthetic medical devices. With the rise in antibiotic resistance, phage therapy has gained renewed attention as a promising alternative to antibiotics. In addition to a strict lytic cycle, some virulent phages may enter a pseudolysogenic state and exclude superinfections, thereby significantly limiting the applicability of these potential antimicrobial agents. However, the trade-off induced by phage infection of bacterial cells during this state and its molecular mechanism are yet to be confirmed, especially for C. acnes phages. In this study, a novel Cutibacterium acnes phage, KIT08, was isolated and characterized. It demonstrated rapid infectivity and moderately strong bacteriolysis. After infection of C. acnes NBRC 107,605, pseudolysogenic bacteria were collected and examined for physiological tradeoffs. The pseudolysogenic isolate exhibited slower growth and downregulation of the transcriptional levels of biofilm-producing genes, such as lipase 2 and hyaluronate lyase, leading to a decrease in biofilm formation. Additionally, a genomic study of phage KIT08 revealed that open reading frames 23 and 34 encode putative proteins homologous to repressor C and LTP proteins, which may play an important role in the induction of pseudolysogeny and superinfection exclusion in C. acnes.

Propionibacterium acnes↗
PubMed1976

Phage and defective phage of strains of Myxococcus.

1. Phage-like particles were found in the supernatants of cultures of strains of Myxococcus xanthus, M. virescens and M. fulvus. The largest number of such particles was associated with M. virescens V2. Most of the particles were similar in morphology to the virulent Myxococcus phage, MX-1. 2. Several new phages were isolated from soil and animal droppings. A new phage was isolated from cultures of M. virescens V2. All resembled phage MX-1 in morphology and were related to phage MX-1 serologically. One of these phage, om, was characterized by fractionation of its proteins by SDS-polyacrylamide gel electrophoresis and by analysis of restriction fragments of its DNA. The very close relatedness with MX-1 was confirmed by these techniques. Phage om, was found to exist in a state of pseudolysogeny with strains of M. virescens and M. fulvus. 3. Two types of bacteriocin-like activity were found associated with Myxococcus strains. In one case, the activity was extracted from chloroformkilled or from sonicated cells. In the second case it was associated with extracellular material. Strains of Salmonella and Cytophaga were found to be good indicators for this latter activity. These strains were found to be killed by phage MX-1. 4. The significance of these data for origin of the phages of myxococci are discussed and it is proposed that MX-1 and the newly isolated phages may be virulent mutants of a family of lysogenic phages.

Bacteriocins↗
PubMedDate not supplied

Bacteriophages of Bacteroides.

Sixty-eight bacteriophages specific for nine species (DNA homology groups) of Bacteroides were isolated from sewage. Four distinct morphological types were isolated, three of which had not previously been described. Attempts to use these phages to transduce Bacteroides fragilis were unsuccessful. A total of 91 phage-susceptible strains of Bacteroides were used with these phages in a study of the feasibility of developing a scheme for identification of Bacteroides species. Blind trials were performed with 10 B. fragilis-specific phages and a collection of over 200 bacterial strains, including 144 strains of B. fragilis. Of the strains of B. fragilis, 78% were identified correctly within 24 hr. A phage-carrier state, or pseudolysogeny, was observed with most of the phage-host systems, and this state was studied in detail with B. fragilis phage Bf-1. The presence of a thick capsule around some cells in a pure culture of a host strain appears to render these cells resistant to phage infection, thus perpetuating the carrier state. It is suggested that such capsules may play a role in the virulence of strains of Bacteroides.

Bacteriophages↗