Optimization of heavy metals chlorides resistance by Staphylococcus aureus andits ability to remove them

Abstract

Three Staphylococcus aureus isolates were selected after screening on nutrient agar
media amended with 100μg/ml of five heavy metals chlorides (i.e: Aluminum Al+2, Iron
Fe+2, Lead Pb+2, Mercury Hg+2 and Zinc Zn+2) from those isolates one S. aureus (S3) isolate
was selected depending on its resistance to all heavy metals chloride. Minimum inhibitory
concentration (MIC) for this isolate was 1000μg/ml for all tested metals chlorides except
Hg+2 (300μg/ml). Growth of S. aureus (S3) was not affected in presence of pbCl2 and AlCl2
for 72hrs; however, it was affected by ZnCl2 and FeCl2 during incubation period while
mercury causes no bacterial growth. In response to various temperatures bacterial isolate
had clear growth in presence of heavy metals ZnCl2, FeCl2, AlCl2, PbCl2at 28 ºC and 37 ºC
and the growth was inhibited at 50 ºC in presence of FeCl2. At different pH values; 4, 7
and 9 the growth of S. aureus (S3) isolate was affected at pH4 in presence of the four
heavy metals chlorides Al+2, Fe+2, Pb+2and Zn+2. S. aureus (S3) isolate showed the highest
Zn+2 removal ratio 43% while Pb+2 has the lowest removal ratio 7%.