Genome Characterization of a Novel Wastewater Bacteroides fragilis Bacteriophage (vB_BfrS_23) and its Host GB124

Intestinal Dysbiosis: Microbial Imbalance Impacts on Colorectal Cancer Initiation, Progression and Disease Mitigation

The human gastrointestinal tract houses a diverse range of microbial species that play an integral part in many biological functions. Several preclinical studies using germ-free mice models have demonstrated that the gut microbiome profoundly influences carcinogenesis and progression. Colorectal cancer appears to be associated with microbial dysbiosis involving certain bacterial species, including F. nucleatum, pks+ E. coli, and B. fragilis, with virome commensals also disrupted in patients. A dysbiosis toward these pro-carcinogenic species increases significantly in CRC patients, with reduced numbers of the preventative species Clostridium butyicum, Roseburia, and Bifidobacterium evident. There is also a correlation between Clostridium infection and CRC. F. nucleatum, in particular, is strongly associated with CRC where it is associated with therapeutic resistance and poor outcomes in patients. The carcinogenic mode of action of pathogenic bacteria in CRC is a result of genotoxicity, epigenetic alterations, ROS generation, and pro-inflammatory activity. The aim of this review is to discuss the microbial species and their impact on colorectal cancer in terms of disease initiation, progression, and metastasis. The potential of anticancer peptides as anticancer agents or adjuvants is also discussed, as novel treatment options are required to combat the high levels of resistance to current pharmaceutical options.

Anaerobiosis, a neglected factor in phage-bacteria interactions

IMPORTANCE

Many parameters affect phage-bacteria interaction. Some of these parameters depend on the environment in which the bacteria are present. Anaerobiosis effect on phage infection in facultative anaerobic bacteria has not yet been studied. The absence of oxygen triggers metabolic changes in facultative bacteria and this affects phage infection and viral life cycle. Understanding how an anaerobic environment can alter the behavior of phages during infection is relevant for the phage therapy success.

Characterization of a Bacteriophage GEC_vB_Bfr_UZM3 Active against Bacteroides fragilis

Bacteroides fragilis is a commensal gut bacterium that is associated with a number of blood and tissue infections. It has not yet been recognized as one of the drug-resistant human pathogens, but cases of the refractory infections, caused by strains that are not susceptible to the common antibiotic regimes established for B. fragilis, have been more frequently reported. Bacteriophages (phages) were found to be a successful antibacterial alternative to antibiotic therapy in many cases of multidrug-resistant (MDR) bacterial infections. We have characterized the bacteriophage GEC_vB_Bfr_UZM3 (UZM3), which was used for the treatment of a patient with a chronic osteomyelitis caused by a B. fragilis mixed infection. Studied biological and morphological properties of UZM3 showed that it seems to represent a strictly lytic phage belonging to a siphovirus morphotype. It is characterized by high stability at body temperature and in pH environments for about 6 h. Whole genome sequencing analysis of the phage UZM3 showed that it does not harbor any known virulence genes and can be considered as a potential therapeutic phage to be used against B. fragilis infections.

Complete Genome Sequence of a Bacteroides fragilis Bacteriophage, vB_BfrS_NCTC

Bacteroides fragilis is an obligate anaerobe and a common gut commensal bacterium that is also an important opportunistic pathogen. Here, we present the complete genome sequence of the circularly permuted B. fragilis bacteriophage vB_BfrS_NCTC. It comprises 47,160 bp, with 69 open reading frames.