Mining activities can lead to the generation of large quantities of heavy metal laden wastes which are released in an uncontrolled manner, causing widespread contamination of the ecosystem. Though some heavy metals classified as essential are important for normal life physiological processes, higher concentrations above stipulated levels have deleterious effects on human health and biota. Bacteria able to withstand high concentrations of these heavy metals are found in the environment as a result of various inherent biochemical, physiological, and/or genetic mechanisms. These mechanisms can serve as potential tools for bioremediation of heavy metal polluted sites. This review focuses on the effects of heavy metal wastes generated from gold mining activities on the environment and the various mechanisms used by bacteria to counteract the effect of these heavy metals in their immediate environment.

Mine tailings are a potential source of heavy metals (HM) that can be toxic to microbes, plants, and animals in aquatic and terrestrial ecosystems. Bacteria have evolved several mechanisms to tolerate the uptake of HM ions. This study aimed to assess the physicochemical properties, concentrations of selected HM and metalloids [arsenic (As), nickel (Ni), lead (Pb), zinc (Zn), cadmium (Cd), and cobalt (Co)], and isolate potential metal-tolerant bacteria present at three abandoned gold mining sites with a view of understanding how tailings characteristics vary and the implications on microbial activities in tailings dumps. Heavy-metal-tolerant bacteria were isolated from the samples using minimum inhibitory and maximum tolerable concentrations of the Ni, Pb, Zn, Cd, and Co. The substrates of the studied sites were acidic and deficient in nutrients. High metals and metalloid concentrations in the order Zn > Ni > Co > As > Pb > Cd were recorded in some of the studied sites and its adjacent soil which exceeded South African recommended values for soil and sediments. Heavy-metal-tolerant bacteria that showed multiple tolerances to Ni, Pb, and Zn were isolated and putatively identified using biochemical tests as belonging to the phyla Proteobacteria, Actinobacteria, and Firmicutes. Gold mine tailings enriched the soil with HM and also affect soil physicochemical properties. Proper management of mine wastes must be ensured to prevent their adverse effects on the diversity, composition, and activity of soil microorganisms that help in maintenance of the ecosystem.

Background and Aims: Food is of paramount importance to the sustenance of human health, on that basis this study was initiated with a view to determining bacterial agents associated with the vended foods and to investigating antibacterial resistance of the isolates. Methods: Twelve food samples from vendors were randomly collected from ten locations within Lagos environs. The food samples were analyzed bacteriologically by standard methods. The isolates were identified and subjected to antimicrobial susceptibility testing using standard procedures. Results: The total plate counts of bacteria recorded was between 2.98 × 10³ cfu/g in Jollofrice and 4.09 × 10⁴ cfu/g in Salad. Seventy-six bacterial isolates made up of six genera; Escherichia coli, Salmonella Typhimurium, Alcaligenes spp., Klebsiella pneumoniae, Enterobacter spp., Serratia marcensens and Proteus spp. were identified. Most of the bacterial isolates were moderately sensitive to cotrimoxazole, nalidixic acid, amoxicillin and nitrofurantion except in S. Typhimurium with less than 50% susceptibility. Also over 60% of the pathogens isolated were inhibited by ceftazidime, cefpodoxime, and levofloxacin antibiotics and most strains of E. coli, S. Typhimurium and K. pneumoniae were resistant to ofloxacin, ciprofloxacin and ceftriazone. Conclusion: The study revealed gross contamination of various vended foods. It also indicated that vended foods are potential ...

No abstract