EFFECT OF TEMPERATURE AND SODIUM CHLORIDE CONCENTRATION ON GROWTH OF Staphylococcus aureus MUTANTS

Abstract

The study included the identification of Staphylococcus aureus (wild type and mutant) isolates. All these isolates were identified as coagulase and catalase positive and able to ferment mannitol.

Strain number 24 was chosen & undergone mutation with NTG to isolate temperature sensitive osmotically fragile (TOF) mutants. TOF mutants were successfully isolated by exposing the cell suspension to 200 Mg/ml of NTG for 75 minutes. The results of characterization of TOF mutants, showed that these mutants were identical to their mother strain morphologically and biochemically. The result of this mutation is to make the lysozyme able to lyse the cell wall of the TOF mutants in pattern similar to lysostaphin .

Antibiotic sensitivity pattern was demonstrated for all the isolates and multiple resistance of some isolates were detected. The obtained results showed that the two mutant isolates were resistant to Methicillin, Benzathin, Penicillin, Cloxacillin Sodium and Lincomycin, wherease these isolates were sensitive to Amoxicillin, Cefotaxine Sodium, Cephalexin Sodium and Tetracyclin but intermediate in resistance to Clindamycin.

The effect of different temperature showed that the growth of the mother strain (strain No.24) increased with the increase of temperature.The mutant strains (3M,10M) are not stable in the different temperature and their growth is very low at 40C.

The effect of different NaCl concentration showed that the growth of the mother strain (strain No.24) and the 2 mutant strain (3M,10M) would increase with the increase of the NaCl concentration but decrease at NaCl concentration = 1.5 M .