Effect of Oxygen Radicals and Peroxide on Survival After Ultraviolet Irradiation and Liquid Holding Recovery of Bacteroides fragilis

Abstract

The survival of Bacteroides fragilis cells after far-ultraviolet irradiation under anaerobic and aerobic conditions and the liquid holding recovery under aerobic conditions were not affected by peroxide or quenchers of toxic oxygen derivatives.

Effect of Oxygen on Host Cell Reactivation in Bacteroides fragilis

“…No studies on HCR in obligate anaerobes have been reported. Bacteroides fragilis is a convenient obligate anaerobe for investigating the effect of oxygen on HCR since we have shown that it can be maintained in aerobic solutions for at least 6 h without loss in viability (7,9).…”

“…These investigations were carried out on B. fragilis strain Bf-2 (6)(7)(8)(9). Brain heart infusion broth and agar, supplemented with hemin, menadione, and cysteine (5) and a defined minimal medium (12), were used for bacterial propagation at 37°C.…”

Effect of oxygen and UV irradiation on nucleic acid and protein syntheses in Bacteroides fragilis

“…Bacteroides fragilis Bf-2 is more sensitive to far-UV irradiation (254 nm) under aerobic conditions than it is under anaerobic conditions, and it differs from other bacteria in that its inactivation by far-UV light depends on the presence of oxygen (3,8). This B. fragilis strain is also interesting in that although it is an obligate anaerobe, it can be maintained in various aerobic holding solutions for i-to 6 h without loss in viability (4,8), and there is some evidence that the cells are able to carry out DNA and protein syntheses for 60 min after exposure to oxygen (9). This behavior contrasts with that of the two other Bacteroides species whose macromolecular synthesis was shown to be inhibited by air (1,11).…”

“…These studies were carried out on a B. fragilis strain (Bf-2) which was used in previous studies on far-UV irradiation (3,4,6,8,9). Brain heart infusion broth and agar supplemented with hemin, menadione, and cysteine (2) were used for bacterial propagation at 37°C.…”

UV light induction of proteins in Bacteroides fragilis under anaerobic conditions

“…The survival of Bacteroides fragilis cells after far-UV radiation (254 nm) is interesting as this organism is more sensitive to UV radiation in the presence of oxygen (9,10,28). In other bacteria, it has been shown that inactivation by far-UV light is independent of the presence of oxygen (31,32).…”