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. © JASEM http://dx.doi.org/10.4314/jasem.v18i4.5

Several items containing residual antimicrobial agents are disposed of in dumpsites, placing a pressure on the microbial flora and a potential for development of resistance in these microorganisms. Multidrug resistance patterns and multiple antibiotic resistance index of Salmonella spp. isolated from waste dumps in Zaria Metropolis were thus assayed in this study using one hundred and twelve (112) soil samples collected from four waste dumpsites located in Sabon-Gari, Samaru, Tudun-Wada and Zaria City. Salmonella spp. were isolated by culture methods on selective media and characterized using a series of biochemical tests. The isolates were confirmed using microgen identification kits. Results were statistically analysed using percentages. The antibiotic resistance patterns were determined, using the disc-diffusion method. Ten antibiotics belonging to eight different classes, namely B-lactams, aminoglycosides, tetracycline, cephalosporins, fluoroquinolone, Nitrofurantoins, sulphonamides, and phenicols were tested. The result of the study revealed that 57.2% of the isolates exhibited multidrug resistance (MDR) taken as resistance to four or more antibiotics tested. On the other hand, all the isolates showed 100% susceptibility to Chloramphenicol (30µg) and Gentamicin (30µg) while 76.2% had Multiple Antibiotic Resistance (MAR) Index of 0.2 and above. The isolates showing resistance to the highest number of antibiotics were obtained from refuse dumpsites in Zaria City while an isolate from Sabon-Gari was found to be resistant to six antibiotics. These results could be indicative of possible disposal of these drug residues in the waste dump locations making them hot spots for development of resistance.

Biofilm producing bacteria are associated with many recalcitrant infections and are highly resistant to antimicrobial agents, hence notoriously difficult to eradicate. This study aimed at determining the biofilm forming capacities of bacterial isolates recovered in the raw wastewater and treated effluent from Wastewater Treatment Plants of Ahmadu Bello University Zaria using Tube Method (TM) and Congo Red Agar (CRA) method; and from the results, among the isolates recovered from the raw wastewater, TM detected 62.5% isolates as positive and 37.5% as negative for biofilm production, CRA detected 37.5% isolates as positive and 62.5% as negative for biofilm production. TM also demonstrated to be more suitable in detecting biofilm producing bacterial isolates from the treated effluent were it detected 50% isolates as positive and 50% as negative. However, CRA detected only 12.5% isolates as positive and 87.5% as negative for biofilm production. We therefore, conclude that the TM is more efficient and reliable for detection of biofilm producing bacteria in the laboratory when compared to CRA method and can be recommended as one of the suitable standard screening method for the detection of biofilm producing bacteria in laboratories.Keywords: Biofilm; Bacteria; Congo red agar and Tube method

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) invitro. 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 o C 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. ©JASEM

Wastewater from three functional tanneries within sokoto metropolis, Nigeria, was investigated to determine the physicochemical properties as well as the distribution of fungal species in the untreated wastewater samples. Samples collected were designated (a-c) representing three sampling points. The isolated fungal species were; Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus, Aspergillus terreus, Aspergillus tamarii and Aspergillus oryzae. Of the fungal species, Aspergillus flavus was the most prevalent (17%) of the total count on the isolation plate, followed by Aspergillus niger (12%) and the least was Aspergillus oryzae. High levels of pH (9.6±1.7-9.9±1.2); electrical conductivity (4656 µs/cm ±886-5933µs/cm± 228); total dissolved solids (2024 mg/l±514-2934 mg/l±113) and nitrate (88.7 mg/l±2.2-94.7 mg/l±4.5) was observed in all the sampling points. The fungal species were screened for their ability to resist and grow in the presence of different concentrations of Pb (lead), Cr (chromium) and Cd (cadmium) in the laboratory. The result revealed that the majority of the isolates were resistant to Pb and Cr, whereas to Cd, only a few were able to resist and grow. A. niger, A. flavus and A. terreus had the highest level of resistance and tolerance to all the heavy metals, with a strong growth often exceeding the control (PDB without test heavy metals). Therefore, it was concluded that these species of Aspergillus could be performing an essential role in the mycoremediation of these metals present in the tannery wastewater during their period of acclimatization through bioaccumulation.