Potential bioremediation of heavy metal ions, polycyclic aromatic hydrocarbons and biofilms with South African hot spring bacteria

Abstract Hot spring bacteria, Bacillus and Bacillus-related spp. from South Africa were screened for biosorption and biosurfactant properties for bioremediation of toxic pollutants. Concentrations of heavy metal ions of copper, chromium, nickel and iron were determined spectrophotometrically. Biosorption resulted in reductions of chromium and copper with four isolates (7T, 9T, 30M, 83Li) but not for iron and nickel. The majority of 40 isolates were biosurfactant positive using paraffin oil. Twelve of which were further screened against petroleum and sunflower seed oil with only four showing positive in all assays tested (16S, 71T, 76S, 85Li). By LC-MS, two isolates (76S, 77S) were shown to produce biosurfactant, subtilisin. Nine biosurfactant-positive isolates were screened for their anti-biofilm properties. Brevibacillus sp. (16S) was able to disrupt a crystal violet stained biofilm of Bacillus subtilis (54T). Screening of bacterial isolates from hot springs reveals potential bacterial candidates with diverse biophysical properties that can be useful in bioremediation of hazardous polluted water.