Isolation and molecular characterization of chrome resistant bacteria from chrome contaminated tannery waste from disposal sites in kenya

Abstract

The leather industry is one of the key agricultural sub-sectors in Kenya with a high potential towards contributing to economic growth, creation of wealth and employment. Tanneries however, are known to pollute the environment with hexavalent chromium metal (Cr6+). Cr6+ is non-biodegradable and is listed as a Class A human carcinogen by the US Environmental Protection Agency (USEPA). The treatment of environmental pollution by bioremediation is an evolving and promising technology although the application of this technology is uncommon in Kenya and other developing countries. Physicochemical characteristics of tannery waste such as pH and fat content were analyzed. Bacteria DNA was extracted using CTAB protocol from bacteria isolated from tannery waste. Isolates CRB01, CRB02 and CRB03 showed the ability to reduce different concentrations of Cr6+ by different percentages and exhibited MIC levels of 60mg/l, 80mg/l and 80mg/l respectively. Morphological, biochemical and 16S rRNA sequence analysis of these isolates identified CRB01, CRB02 and CRB03 to be Lysinibacillus pakistanensis NCCP 54, Bacillus pumilus SAFR-032 and Bacillus safensis strain NBRC 100820 respectively from the NCBI database. These three bacterial species can be exploited commercially for bioremediation of Cr6+. This study therefore demonstrates that waste matter from tanneries in Kenya harbor microorganisms that can biodegrade Cr6+. Different optimum conditions for the reduction of hexavalent Chromium and mechanisms of reduction should be investigated and the three isolates used to improvise bioremediation technology.