Capacity of Isolates of Six Genera of Filamentous Fungi to Remove Lead, Nickel and Cadmium from Refinery Effluent

Laboratory experiments were carried out to determine the capacity of isolates of six genera of filamentous fungi to remove Lead (Pb), Nickel (Ni), and Cadmium (Cd) from broth cultures charged with raw refinery effluents. The concentrations of the three metals in the raw refinery effluents and tissues of the test fungi were determined both before and after the mycoremediation studies using Atomic Absorption Spectrophotometer (AA240FS). Both the percentage removal as well as the potential of the test isolates to bioaccumulate the metals in their tissues were calculated following standard procedures. It was observed that, the six isolates tested could remove from 36 to 64% of Pb, 30 to 58% of Ni and 0 to 50% of Cd. Trichoderma sp proved to be the most efficient in the removal of the three metals while Nigrospora sp and Chaetophoma sp were consistently the least efficient . It was also noted that, Trichoderma sp and Microsporum sp had the highest potential to bioaccumulation the metals than the other fungal species tested. It was therefore concluded that, Trichoderma sp, and Microsporum sp could be employed in the removal of Pb, Ni and Cd from heavy metal polluted effluents generated by petroleum refineries and other petro-chemical industries. Keywords: Refinery effluents, Heavy metals, Pollution, Fungi, Mycoremediation, Biosorption, Bioaccumulatio

Resistance to some Heavy Metals among Fungal Flora of Raw Refinery Effluent

Investigations were carried out to assess the capacity of strains of fungi isolated from raw flowing effluent and effluent retention pond of Kaduna refinery plant to resist and grow in the presence of lead (Pb), nickel (Ni) and cadmium (Cd) in vitro. Fungi belonging to the genera including Aspergillus spp., Penicillium spp., Fusarium spp., Curvularia spp. and Nigrospora spp. were isolated from the study sites. The isolates were inoculated into duplicate 100ml flask containing 50ml of potato dextrose broth (PDB) supplemented with 5,10 and 15ppm of Pb, Ni, and Cd. 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 preweighed filter paper (No.1). The filters bearing the mycelial mats were dried in an oven at 70\u2103 for 18hours. It was observed that most of the isolates tested resisted and grew in the medium containing 5 to 15ppm of tested heavy metals. Yield of dry mycelia mats in the heavy metal supplemented medium were also comparable to those grown in heavy metal free PDB medium. It was concluded that, these genera of fungi could be playing an important role in the removal of these metals usually present in the raw effluent during the period of residency in the retention pond through bioaccumulation

Composition of Fungal Flora in Raw Refinery Effluent, Effluent Retention Pond and a Treated Effluent Recipient River

Investigations were carried out to determine the composition of fungal flora in the studied sites. Samples of the raw effluent were collected along the flow channel and the retention pond. Water samples were also collected at the discharge point and up and down stream of the river from the discharge point. The samples were spinned at a speed of 250rpm for 10minutes and spread inoculated the deposits on potato carrot agar (PCA) and potato agar supplemented with 7.5% Nacl. Inoculated plates were incubated aerobically at room temperature in dark cupboard for 7days. Fungal colonies that emerged on the primary culture plates were distinguished into types. The pure isolates were characterized into genera using standard taxonomic guides. Genera such as Aspergillus , Penicillium , Curvularia , Fusarium , Microsporum , Trichoderma , Rhizoctonia , Nigrospora and Chaetophoma species were detected in the raw effluent. However, Microsporum, Trichoderma, Rhizoctonia, Nigrospora and Chaetophoma species were conspicuously absent in the effluent retention pond. Only Trichoderma and Chaetophoma species were absent in water samples collected at the treated effluent discharge point into the recipient River. Samples of water collected up stream of the discharge point did not contain Geotrichum , Nigrospora and Chaetophoma species. Curvularia, Microsporum, Rhizoctonia and Nigrospora species were not detected in water samples collected downstream of the discharge point. 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

Characterization and phylogeny of fungi isolated from industrial wastewater using multiple genes

The aim of this study was the isolation and molecular characterization of fungi from untreated refinery effluent by using multiple conserved genes. The Fungi isolated were characterized based on PCR amplification and genomic sequencing of the internal transcribed spacer region (ITS), partial β-tubulin (BenA), calmodulin (CaM), and RNA polymerase second large subunit (RPB2) genes, along with morphological characterization. The obtained sequences were subjected to BLAST analysis and the corresponding fungal isolates were assigned species names after comparison with representative sequences available in GenBank. Fifteen (15) Fungi species belonging to four genera of Aspergillus, Penicillium, Fusarium, and Trichoderma with Aspergillus as the predominant genus were identified. Therefore these genes should be used as molecular markers for species level identification of fungi (especially Aspergillus and Penicillium as proven in this study