Study On The Effects Of 60Co Gamma-Rays, Ultraviolet Light (UV), And Hydrogen Peroxide On Haloferax IRU
E Asgarani, M Shirzad, M Soudi, H Shahmohammadi
gamma-rays, haloferax, hydrogen peroxide, ultraviolet light uv
E Asgarani, M Shirzad, M Soudi, H Shahmohammadi. Study On The Effects Of 60Co Gamma-Rays, Ultraviolet Light (UV), And Hydrogen Peroxide On Haloferax IRU. The Internet Journal of Microbiology. 2006 Volume 3 Number 1.
The capacity of
A highly radioresistant archaebacterium isolated from the water of a salt lake located near Uromia city, west-north of Iran. The organism is a gram-negative, pleomorphic coccoid, and was assigned to the genus
Very highly radioresistant bacterium,
In our previous work, it has been shown that
Materials and methods
Treatment with H2O2. Hydrogen peroxide (final concentration 5-30 mM) and (10-50 mM) was added to 5 ml freshly prepared cell suspension of
Fig. 1 shows survival curves of these three bacteria by irradiation with 60 Co gamma-rays
Their D37 values were 645 Gy, 400 Gy, and 99 Gy, respectively.
Fig. 2 shows survival curves of these three bacteria by irradiation with UV light. Their D37 values were 231 J/m 2 , 246 J/m 2 , and 9 J/m 2 , respectively.
Fig. 3 shows survival curves of these three bateria by exposure to hydrogen peroxide. Their D37 values were 22 mM, 43.5 mM, and 3 mM, respectively.
The results obtained in the present study are summarized in Table 1. It is apparent from the data that the withstand to the lethal effects of UV light, rays, and hydrogen peroxide of
To the lethal effects of γ rays, the resistibility factor of
To the lethal effects of UV light, the resistibility factor of
To the lethal effects of hydrogen peroxide, the resistibility factor of
Hydrogen peroxide as same as γ-irradiation generates hydroxyl radicals, the most toxic species of the reactive oxygen species. It has been shown that bacterioruberin (which contains 13 conjugated double bonds) scavenges hydroxyl radicals much more efficiently than β-carotene (which contains only 9 conjugated double bonds), and that the highly conjugated double bonds of bacterioruberin may act as a more effective oxidation protector (Saito
In addition to the characteristic carotenoids, Hfx. Radiotolerans contains highly concentrated potassium cations (K + ) and chloride anions (Cl - ) in the cell (unpublished data). In previous work, we showed that accumulated ions modulate the formation of DNA damage by ionizing radiation, since Cl - has an ability to scavenge hydroxyl radicals via electron transfer (Ward and Kuo 1968), thereby contributing to the resistance of
Therefore, high resistance of
According to these findings,
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