Characteristics ofBacteroides fragilis bacteriophages and comparison of their DNAs

Genomic structure of phage B40-8 of Bacteroides fragilis

“…These structures were probably generated by the physical pressure of the microscopy tip on the sample, producing some degree of degradation at the distal section of the tails. The size and composition of phage DNA, double stranded, 51.7 kb in length and with a G + C content of 38.9 mol YO , are similar to the values calculated by Kory & Booth (1986) we suggest that this effect is an evolutionary response of these. phages to restriction-modification systems of their bacterial hosts.…”

“…The similarity found between the G + C content of phage DNA (38.9 moI%) and host DNA (41 mol%; Johnson, 1978) is further evidence o€ the evolutionary pressure acting on phage-bacteria systems. Similar restriction patterns were observed when the B40-8 genome was compared with other similar-sized B. fragilis phage DNA (Kory & Booth, 1986) The presence of phage DNA restriction digests of submolar quantities of overlapping fragments provides a strong indication that packaging of €340-8 DNA occurs on a precursor concatemeric molecule according to a headful mechanism (Jackson et al, 1978). This type of pattern has been previously described as a characteristic for genomes with terminal redundancies belonging to phages using this model of encapsidation (Jackson et Johnsen et a!., 1996).…”

“…There are more than 100 descriptions of Bacteroides phages in the literature but information on genome length, mol '/o G + C, hybridization patterns (Kory & Booth, 1986) and restriction profiles (Kai et al, 1985) is available for only seven phage isolates of B. fragilis. The group of phages that infect B. fragilis strain HSP40 have been proposed as a potential model for the study of viral contamination of faecal origin (Tartera & Jofre, 1987; IAWPRC Study Group on Health Related Water Microbiology, 1991 ;Havelaar, 1993).…”

“…B40-8 was selected as phage prototype for this study based on the following: (i) it is a Siphouiridae family member, like M. PUIG a n d R. G I R O N E S most B. fragilis phages reported in the literature (Keller &Traub, 1974;Booth et al, 1979;Kai et d., 1985;Kory & Booth, 1986); (ii) it also has the most frequently isolated morphology of B. fragilis phages present in natural waters (Tartera & Jofre, 1987;Lasobras et al, 1997); (iii) it has been isolated from an urban sewage sample on B. fragilis strain HSP40 (Tartera & Jofre, 1987); and (iv) it infects the collection strain B. fragilis ATCC 25285. This study describes the structure of the genome and the localization of the major proteins in the genomic restriction map of this phage.…”

The Medically Important Bacteroides spp. in Health and Disease

“…There have been numerous reports on the isolation of bacteriophage capable of growth on all of the Bacteroides spp. except B. vulgatus Booth et al, 1979;Cooper et al, 1984;Kory and Booth, 1986). These phage are easily isolated, usually from sewage effluent, and in one extensive survey, 68 bacteriophage representing four morphological types were isolated (Booth et al, 1979).…”