Effects of Arsenic on Laccase Enzyme Activity in Strains of Bacillus Subtilis in Vitro

One of the important environmental problems in the international community is contamination with heavy metals from industrial development. Not only do these elements threaten human health but they also make changes in the natural state of the ecosystem. The purpose of this study was to investigate the effect of the heavy arsenic element on lactate enzyme activity in the Bacillus subtilis bacteria.   Bacillus subtilis bacteria were isolated from the wastewater of paper and pasteboard industry of Hormozgan province from a depth of 51 cm below the surface of the soil and the strain was subjected to biochemical and morphological tests for screening. After determining the optimum growth conditions, the activity of the bacteria laccase enzyme in different concentrations of arsenic was measured from (5, 10, 15, and 20 mg.) was measured. The enzymatic activity of the strains was measured by the kinetic method at each concentration using a spectrophotometer at 634 nm using a 25 mM citrate buffer with pH 4.5 as a substrate.   Maximum laccase enzyme activity in Bacillus subtilis bacteria was not significantly different at concentration of 5 mg/L of arsenic from maximum growth of bacteria in control sample and maximum growth of bacteria at concentration of 20 mg/L. However, by increasing the concentration of arsenic in the culture medium, the growth of the bacteria in the control sample, with the exception of its maximum growth in concentration of 20 mg/L, showed a significant difference with other concentrations (P<0.05(.   Discussion & The results show that arsenic can decrease bacterial growth rate and lactate enzyme activity in Bacillus subtilis bacteria.