Keywords: anaerobic digestion, bioremediation, brewery sludge, detoxification, global warming, heavy metals, sulphate reducing bacteria, SRB, cadmium, copper, zinc, heavy metal resistant bacteria
Heavy metal resistant anaerobic bacterial strains from brewery digester sludge
This work focused on the study of the types of heavy–metal–resistant anaerobic bacteria from the sludge of a brewery wastewater treatment plant exposed to high concentrations of dissolved Cd (II), Cu (II) and Zn (II). Characterisations were carried out by polymerase chain reaction of the 16S rRNA gene of bacterial strain. Using special culture media, two types of strong heavy metal–resistant bacterial strains were isolated. The first was a sulphate–reducing bacterium identified as Clostridium ganghwense strain HY–42–06. This strain of sulphate–reducing bacteria tolerated Cd (II), Cu (II) and Zn (II) at the tested concentrations. The other type was identified as consisting of a mixture of Micrococcus luteus, Wolinella succinogenes, Sporosarscina sp. PIC–C28 and Alicycliphilus sp. R–24604. The results found that these four dominant strains tolerated Cd (II) at 20 mg/l, only Wolinella succinogenes cannot tolerate Cu (II) at 2 mg/l while none of them tolerated Zn (II) at 30 mg/l.