The potential of indigenous fungi in bioremediation of heavy metals in the Chemu Lagoon, Ghana

dc.contributor.authorDoku, Emmanuel Tetteh
dc.descriptionA thesis submitted to the Department of Theoretical and Applied Biology, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirement for the Degree of Master of Philosophy in Microbiology, 2015en_US
dc.description.abstractThe release of industrial effluents laden with heavy metals has polluted the quality of aquatic ecosystems. The Chemu lagoon located in Tema has served as a sink for both untreated and semi-treated industrial and municipal effluents. This study was conducted on the Chemu lagoon and selected nearby industries from November, 2011 to October, 2012. Physicochemical parameters and heavy metal concentrations of selected industrial point sources, lagoon water and sediments at three selected sites (upstream, midstream and downstream) were determined. Fungi were also isolated, sub cultured and grown on lagoon water-agar medium to determine their heavy metal bioaccumulation potential. The mean BOD, pH, conductivity, temperature, nitrate, sulphate and phosphate ranged from 149.67-4765mg/l, 5.67-11.47, 9.3-261.53 μS/cm and 36.3-38.97˚C, 0.127-3.633mg/l, 1.04-88.69mg/l and 0.014-237.98mg/l respectively. Majority of observed physicochemical parameters were above stipulated WHO standards. The Dry season (V1 and V2) recorded higher concentrations of heavy metals compared to Wet (V2 and V3) season. Mean range of Iron (Fe), Zinc (Zn), Lead (Pb), Arsenic (As) and Cadmium (Cd) concentrations in lagoon and industrial effluents were 0.036-2.854mg/l, 0.043-0.202mg/l, 0.0013-0.08mg/l, 0.0017-0.027mg/l and 0.003-0.055mg/l respectively. The observed concentrations of these heavy metals in the effluents varied significantly and were mostly above WHO (2004) drinking water quality limits. Mean range of Iron (Fe), Zinc (Zn), Lead (Pb), Cadmium (Cd) and Arsenic (As) concentrations in lagoon sediments were 55.57-179.97mg/l, 0.154-5.09mg/l, 0.163-4.267mg/l, 0.013-1.38mg/l and 0.067-1.51mg/l respectively. With the exception of Cadmium (Cd) all observed ranges of heavy metal concentrations in sediments were within Canadian Sediment Quality Guideline (CSQG) limits. Total Viable Counts (TVC) (expressed in as mean logarithm) in lagoon effluents and sediments ranged from log 4.49-5.98 CFU/100ml and log 6.72-8.97 CFU/100ml respectively. The population of total coliforms recorded indicated significant pollution of lagoon effluents and sediments. Aspergillus candidus, Aspergillus fumigatus, Aspergillus niger, Aspergillus tamarii, Mucor rouxii, Penicillium notatum and Rhizopus spp were isolated from lagoon sediments. The potential of A. niger and A. fumigatus in bioaccumulation of heavy metals were highest in 1:1 and 1:5 media respectively. The bioaccumulation potential of Aspergillus niger was in decreasing order; Iron (Fe) 130.9% >Arsenic (As) 53.7% >Zinc (Zn) 44.3% > Lead (Pb) 36.9% > Cadmium (Cd) 18.1%. Iron (Fe) had the highest bioaccumulation potential for Aspergillus fumigatus followed by Zinc (Zn), Arsenic (As), Lead (Pb) and Cadmium (Cd) in decreasing order 128.3% > 71.5% > 62.8% > 40% > 6.4% respectively. Selected fungi showed excellent bioaccumulation potential and thus their molecular and physiological mechanisms of bioaccumulation could be studied to improve their levels of heavy metals removal on the large industrial scale.en_US
dc.titleThe potential of indigenous fungi in bioremediation of heavy metals in the Chemu Lagoon, Ghanaen_US