Effects of temperatures, pH-values, ultra-violet light, ethanol and chloroform on the growth of isolated thermophilic Bacillus phages.

Seven thermophilic Bacillus phages were characterized with reference to their host range, time of appearance, morphology of plaques, thermal inactivation, stability, lipid presence and inactivation by ultraviolet irradiation. Response surface methodology was adapted to describe the response of growth parameters to environmental changes. Most phages are susceptible to temperatures above 60 degrees C and inactivated immediately at 103 degrees C. Most phages are resistant to pH ranges 5 to 9 and almost all to pH 7 to 8. Both phages 46 and 80 were highly resistance to UV exposure for 13 minutes and 20 minutes, respectively. The presence of chloroform or 75% ethanol showed no effect on almost all isolated phages that indicate of possibility of the absence of lipids. The isolated phages were slow in their growth, possibly due to the lower gross growth efficiency.