ASSESSMENT OF THE POTENTIAL OF FUNGAL SPECIES IN THE BIOACCUMULATION OF LEAD, NICKEL AND CADMIUM FROM REFINERY EFFLUENT
ASSESSMENT OF THE POTENTIAL OF FUNGAL SPECIES IN THE BIOACCUMULATION OF LEAD, NICKEL AND CADMIUM FROM REFINERY EFFLUENT
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Date
2015-04
Authors
EZEONUEGBU, Blessing Amaka
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Abstract
This study was carried out to assess the potential of fungal species in the
bioaccumulation of lead, nickel and cadmium by fungal species isolated from refinery
effluent and effluent impacted River. Physicochemical, heavy metal and mycological
analyses were carried out on untreated and treated effluent from Kaduna Refinery and
Petrochemical Company (KRPC) and water samples from Romi River, Kaduna State,
Nigeria, using standard procedures. A total of 133 fungal isolates belonging to 15
species (Aspergillus flavus, A. niger, A. fumigatus, A. carbonarius, A. glaucus,
Penicillium spp., Fusarium spp., Curvularia spp., Trichodermaspp., Nigrosporaspp.,
Microsporum spp., Rhizoctonia spp., Trichophytonspp., Geotrichum spp.and
Chaetophoma spp.) were isolated from the study site, identified and characterized on
the basis of their macroscopic and microscopic morphologies using standard taxonomic
guides. Aspergillus flavus had the highest percentage occurrence of 18.05% followed by
Penicillium spp. and Curvularia spp. which had equal occurrence of 12.78% each. A.
glaucus and Trychophytonspp. had the least and equal percentage occurrence of 0.75%
each. The isolates were inoculated into duplicate 100ml flask containing 50ml of potato
dextrose broth (PDB) supplemented with 5,10 and 15µg/ml of Pb, Ni, and Cd analytical
grade salts. Each test isolate was inoculated into duplicate flask containing the same
medium without the heavy metals to serve as control. All inoculated flasks were
incubated aerobically at room temperature on a rotator shaker for 7days. The mycelial
mats were harvested by filtering the cultures through pre weighed filter paper (No.1).
The filters bearing the mycelial mats were dried in an oven at 70oC for 18hours and
weighed. Yields of dry mycelial mats in the heavy metal supplemented medium were
also comparable to those grown in heavy metal free PDB medium. It was observed that
52 out of the 133 fungal isolates tested, resisted and grew in the medium containing 5,
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10 and 15ppm of the test heavy metals. pH and temperature optimization studies on
growth conditions of the resistant isolates were carried out at varying pH of 4, 5, 6 and 7
and varying temperatures of 25oC, 30oC and 35oC. The various test isolates grew
optimally at the varying pH and temperature levels except pH 7 and temperature of
35oC. Heavy metal uptake capacity and removal from refinery effluent by the test fungal
isolates were also determined. The genera Aspergillus, Penicillium, Trichoderma,
Curvularia, Fusarium and Nigrosporaaccumulated and removed substantial amount of
Pb, Ni and Cd from the effluent. Trichoderma sp. and Microsporumsp. had an uptake
capacity of 0.28mg/g of lead each. Nigrosporasp. and Fusarium sp. had an uptake
capacity of 0.14mg/g and 0.13mg/g of nickel respectively. The uptake capacity of
cadmium by Penicillium sp. was 0.02mg/g while A. flavusand A. niger removed 71.29%
each of lead. A. nigerwas able toremove 85.06% of nickel while 85% of cadmium was
removed by Penicillium sp. It was therefore concluded that, fungi constitute a
significant proportion of the microflora of sites contaminated with the refinery effluent
and could be playing an important role in the remediation of sites receiving the effluent.
Also, their tolerance to Pb, Ni and Cd indicates that these test fungal isolates, could be
employed in the treatment of refinery effluents and bioremediation of water bodies and
sites polluted with Pb, Ni and Cd.
Description
A THESIS SUBMITTED TOTHE SCHOOL OF POSTGRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA
IN PARTIALFULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OFMASTER OF SCIENCE DEGREE IN MICROBIOLOGY
DEPARTMENT OF MICROBIOLOGY FACULTY OF SCIENCE AHMADU BELLO UNIVERSITY, ZARIA NIGERIA
Keywords
FUNGAL SPECIES,, BIOACCUMULATION,, LEAD,, NICKEL,, CADMIUM,, REFINERY EFFLUENT