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This study aimed to investigate the presence and diversity of AmpC β-lactamase and integrase genes among DNA (genomic and plasmid) from bacterial populations in selected aquatic systems. Following an enrichment step, DNA was isolated and subjected to polymerase chain reaction (PCR) and digital droplet PCR. The intI1 gene and AmpC β-lactamase genes were present in genomic and plasmid DNA from all sites in the Mooi, Crocodile and Marico Rivers, with the exception of intI1 in the Marico River. Digital droplet PCR demonstrated that copy numbers varied considerably (0.0 to 29.38 copies per picogram of DNA). Some samples in which ampC was not detected, intI1 was present. Amplicons of ampC genes were subjected to restriction digest using HindIII. Samples where the restriction markers were absent were purified by cloning followed by plasmid extraction, PCR amplification, and sequencing of individual AmpC gene fragments. Phylogenetic analysis identified all positive AmpC genes as Class C β-lactamases, comprising of ampC, CMY- and ACT-families. Detecting AmpC and intl1 genes on plasmids suggests a high risk of horizontal gene transfer and potential dissemination of these and other antibiotic resistance genes surrounding immediate aquatic environments. Consequences of β-lactamase diversity in aquatic ecosystems are relatively unexplored in South African aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Virulence factors in Enterococcus may be indicative of potential pathogenicity. The aim of this study was to determine the relationship between the presence of clinically relevant virulence genes, in Enterococcus spp. from environmental water, and their in vitro expression. One hundred and twenty-four Enterococcus isolates (seven species), from five surface water systems in the North West Province, South Africa, were screened for the presence of asa1, cylA, esp, gelE and hyl using polymerase chain reaction. The expression of cylA, hyl and gelE was determined by phenotypic assessments. Sixty-five percent of the isolates were positive for one virulence gene and 13% for two or more. Most frequently detected genes were gelE (32%) and cylA (28%). Enterococcal surface protein was absent in all isolates screened. The presence of virulence genes was correlated with their extracellular enzyme production. The results show that a large percentage of these environmental Enterococcus spp. possess virulence factors that could be expressed in vitro. This is a cause for concern and could have implications for individuals using this water for recreational and cultural purposes. Further investigation is required into the sources of these potential pathogenic Enterococcus isolates and measures to minimize their presence in water sources. [ABSTRACT FROM AUTHOR]

This study aimed to identify bacterial community structures in the Vaal River using PCR-DGGE (polymerase chain reaction denaturing gradient gel electrophoresis) and high-throughput sequencing. The impact of physico-chemical characteristics on bacterial structures was investigated through multivariate analysis. Samples were collected from 4 sampling stations along the Upper Vaal River during winter (June 2009) and summer (December 2010). Physico-chemical analysis was conducted on-site. Additional physico-chemical data were obtained from statutory bodies. DNA was directly isolated from water samples and PCR amplified using universal bacterial primer pairs. PCR products were subjected to DGGE fingerprinting and high-throughput sequencing, followed by Shannon-Weaver diversity calculations, cluster analysis and multivariate analysis. Physico-chemical parameters did not exceed the prescribed South African water quality standards for domestic use, aquatic ecosystems, livestock watering and irrigation. DGGE banding patterns revealed similar bacterial community structures for 3 of the 4 sampling stations. PCA and RDA indicated that pH, water temperature and inorganic nutrient concentrations could be used to explain changes in bacterial community structures. High-throughput sequencing data showed that bacterial assemblages were dominated by common freshwater groups: Cyanobacteria, Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Bacteroidetes and Actinobacteria. Other freshwater phyla such as Deltaproteobacteria, Epsilonbacteria, Acidobacteria, Verrucomicrobia, Firmicutes, Fusobacteria, Flavobacteria and Fibrobacteres were found in low proportions. This study provides an overview of the dominant bacterial groups in the Upper Vaal River and the impact of environmental changes on bacterial diversity. [ABSTRACT FROM AUTHOR]

Atypical enteropathogenic E. coli (aEPEC) strains are emerging pathogens responsible for fatal diarrhoea in humans worldwide. The purpose of this study was to investigate genetic diversity, virulence and antimicrobial resistance profiles of aEPEC O177 strains isolated from faeces of cattle reared in intensive and extensive production systems in South Africa. A total of 96 multidrug resistant (MDR) aEPEC O177 isolates were typed using enterobacterial repetitive intergenic consensus (ERIC) and random amplified polymorphism DNA (RAPD) typing. The resistome, virulome and mobilome of two aEPEC O177 isolates were investigated using WGS analysis. The ERIC typing was efficient and reproducible with a discriminatory index of 0.95. RAPD typing had poor reproducibility with satisfactory discriminatory power of 0.859. The dendrograms constructed based on ERIC and RAPD banding patterns produced 9 and 8 clusters, respectively, which indicate genetic variation among E. coli O177 isolates. WGS analysis revealed that CF-154-A and CF-335-B) isolates belonged to the O177 serotype with H7 and H21, respectively. Both isolates harboured several virulome genes such as intimin (eaeA), haemolysin (hlyA and hlyE), translocated iron receptor (tir), Type III secretion system (eprH , gspL and prgH), bssR and bssS. However, genes encoding shiga toxins were not found in either isolate. Antibiotic resistance genes such as ampC , tet , ermB , sul2 , strB AcrD , aph (6)- Ic , aph (6)- Ib , aph (3″) - I , ant (3″) - 1a AcrA and acrE were found in the E. coli O177 strains. Furthermore, genome annotation results indicated that both isolates carried plasmids, insertion sequences, prophages and cluster of regularly interspaced short palindromic repeats (CRISPR) type I. Based on in silico multi locus typing (MLST) analysis, the two isolates were assigned to different sequence types (CF-154-A, ST-1308 and CF-335-B, ST-58). Whole genome multi locus typing tree showed that our isolates clustered with E. coli O177:H21 (reference), suggesting the close genomic relatedness among the strains. Overall, these findings showed that cattle carry genetically diverse E. coli O177 strains, which harbour a repertoire of virulome, resistome and mobilome genes. This highlights a need for multidrug resistant E. coli O177 strain surveillance in cattle. • Cattle harbour genetically diverse atypical enteropathogenic E. coli O177 strains • Complete genome sequence analysis of two E. coli O177 strains revealed a high number of virulence and antimicrobial resistance profiles. • The two E. coli O177 strains were ascribed to different MLST sequence types (ST-1308 and ST-58) • WgMLST analysis confirmed genomic relatedness of the two E. coli O177 strains and the reference strain (E. coli O177:H21) [ABSTRACT FROM AUTHOR]

Abstract: Escherichia coli O157 strains cause diseases in humans that result from the consumption of food and water contaminated with faeces of infected animals and/or individuals. The objectives of this study were to isolate and characterise E. coli O157 strains from humans, cattle and pigs and to determine their antibiotic resistant profiles as well as detection of virulence genes by PCR. Eight hundred faecal samples were analysed for typical E. coli O157 and 76 isolates were positively identified as E. coli O157 strains. 16S rRNA sequence data were used to confirm the identity of the isolates. Susceptibility profiles to 9 antibiotics were determined and the multiple antibiotic resistant (MAR) patterns were compiled. A large proportion (52.6%–92.1%) of the isolates from pigs, cattle and humans were resistant to tetracycline, sulphamethoxazole and erythromycin. Thus the phenotype Smx–T–E (sulphamethozaxole–tetracycline–erythromycin) was present in most of the predominant MAR phenotypes obtained. Cluster analysis of antibiotic resistances revealed a closer relationship between isolates from pig and human faeces than cattle and humans. PCR were performed to amplify STEC virulence and tetracycline resistance gene fragments. A tetB gene fragment was amplified among the isolates. Eighteen (60%) of the isolates possessed the hlyA gene and 7(23.3%) the eae gene while only 5(16.7%) possessed both genes. Although shiga toxin genes were detected in the E. coli O157:H7 positive control strain none of the isolates that were screened possessed these genes. In a related study we reported that the prevalence of E. coli O157 was higher in pigs than cattle and humans. A high market demand for pork and beef in South Africa amplifies the risk that diseased animals pose to human health. This highlighted the need for proper hygiene management to reduce the prevalence of E. coli O157 in farm animals and prevent the spread from animals to humans. [Copyright &y& Elsevier]

Sceletium tortuosum (L.) N.E.Br. (Mesembryanthemaceae), commonly known as kanna or kougoed, is an effective indigenous medicinal plant in South Africa, specifically to the native San and Khoikhoi tribes. Today, the plant has gained strong global attraction and reputation due to its capabilities to promote a sense of well-being by relieving stress with calming effects. Historically, the plant was used by native San hunter-gatherers and Khoi people to quench their thirst, fight fatigue and for healing, social, and spiritual purposes. Various studies have revealed that extracts of the plant have numerous biological properties and isolated alkaloids of Sceletium tortuosum are currently being used as dietary supplements for medicinal purposes and food. Furthermore, current research has focused on the commercialization of the plant because of its treatment in clinical anxiety and depression, psychological and psychiatric disorders, improving mood, promoting relaxation and happiness. In addition, several studies have focused on the isolation and characterization of various beneficial bioactive compounds including alkaloids from the Sceletium tortuosum plant. Sceletium was reviewed more than a decade ago and new evidence has been published since 2008, substantiating an update on this South African botanical asset. Thus, this review provides an extensive overview of the biological and pharmaceutical properties of Sceletium tortuosum as well as the bioactive compounds with an emphasis on antimicrobial, anti-inflammatory, anti-oxidant, antidepressant, anxiolytic, and other significant biological effects. There is a need to critically evaluate the bioactivities and responsible bioactive compounds, which might assist in reinforcing and confirming the significant role of kanna in the promotion of healthy well-being in these stressful times. [ABSTRACT FROM AUTHOR]

It is important that environmental parameters that may affect the prevalence of AmpC beta-lactamase genes are investigated to devise frameworks for their surveillance, management and prevention. The aim of this study was thus to determine which environmental parameters are associated with the prevalence of clinically relevant AmpC beta-lactamase genes in aquatic systems. River water was sampled from seven sites in the Crocodile West River, South Africa. Physical-chemical parameters, metal levels and beta-lactam levels were measured. Environmental DNA was extracted from the water samples and six AmpC beta-lactamase gene groups (ACC, ACT/MIR, BIL/LAT/CMY, DHA, FOX, MOX/CMY) were quantified using quantitative PCR. Additionally, 16S rRNA gene metabarcoding analyses were performed on eDNA for each site and metabolic pathways were predicted using PICRUST2. Network analysis was performed to establish co-occurrences of AmpC genes with environmental factors. Quantification results indicated that AmpC gene copy numbers were significantly high (Kruskal Wallis H Test, p < 0.05) at Sites 1–3 of the Crocodile West River. In contrast, no significant changes regarding environmental factors were observed across the seven sites. Results of network analysis indicated that the AmpC gene groups had limited associations with all the environmental parameters, except for some key bacterial families, specifically Pseudomonadaceae , Aeromonadaceae and Enterobacteriaceae. A significant positive correlation between population density and AmpC genes suggested that in more densely populated areas more faecal pollution will be prevalent which is associated with high AmpC gene levels. Areas such as these are also likely to be linked with more antibiotic use which supports the notion that pre-selection of AmpC genes occurs before entering the aquatic environment. Moreover, it was demonstrated that prevalent selectors of AmpC genes do not ensure that continuous selection occurs in an aquatic environment. This information could be vital in future detection and management of AmpC genes in aquatic systems. Unlabelled Image • Physical-chemical environmental parameters are not correlated with AmpC genes. • A correlation was observed between population density and AmpC gene prevalence. • Pathogenic bacterial families are associated with the prevalence of AmpC genes. • Possible selective pressures of AmpC genes do not ensure continuous selection. • AmpC genes are likely pre-selected before environmental exposure and detection. [ABSTRACT FROM AUTHOR]

There is a rapid spread of antibiotic resistance in the environment. However, the impact of antibiotic resistance in drinking water is relatively underexplored. Thus, this study aimed to quantify antibiotic resistance genes (ARGs) and antibiotic residues in two drinking water production facilities (NW-E and NW-C) in North West Province, South Africa and link these parameters to bacterial communities. Physicochemical and ARG levels were determined using standard procedures. Residues (antibiotics and fluconazole) and ARGs were quantified using ultra-high performance liquid chromatography (UHPLC) chemical analysis and real-time PCR, respectively. Bacterial community compositions were determined by high-throughput 16S rRNA sequencing. Data were analysed using redundancy analysis and pairwise correlation. Although some physicochemical levels were higher in treated than in raw water, drinking water in NW-E and NW-C was safe for human consumption using the South African Water Quality Guideline (SAWQG). ARGs were detected in raw and treated water. In NW-E, the concentrations of ARGs (sul1, intl1, EBC, FOX, ACC and DHA) were higher in treated water than in raw water. Regarding antimicrobial agents, antibiotic and fluconazole concentrations were higher in raw than in treated water. However, in NW-C, trimethoprim concentrations were higher in raw than in treated water. Redundancy analysis showed that bacterial communities were not significantly correlated (Monte Carlo simulations, p-value >0.05) with environmental factors. However, pairwise correlation showed significant differences (p-value <0.05) for Armatimonas, CL500-29 marine group, Clade III, Dickeya and Zymomonas genera with environmental factors. The presence of ARGs and antibiotic residues in the current study indicated that antibiotic resistance is not only a clinical phenomenon but also in environmental settings, particularly in drinking water niches. Consumption of NW-E and NW-C treated water may facilitate the spread of antibiotic resistance among consumers. Thus, regulating and monitoring ARGs and antibiotic residues in drinking water production facilities should be regarded as paramount. [ABSTRACT FROM AUTHOR]

Background: Escherichia coli, a ubiquitous inhabitant of the gut microbiota, has been recognized as an indicator of fecal contamination and a potential reservoir for antibiotic resistance genes. Its prevalence in drinking water sources raises concerns about the potential dissemination of antibiotic resistance within aquatic ecosystems and the subsequent impact on public health. The ability of E. coli to acquire and transfer resistance genes, coupled with the constant exposure to low levels of antibiotics in the environment, underscores the need for comprehensive surveillance and rigorous antimicrobial stewardship strategies to safeguard the quality and safety of drinking water supplies, ultimately mitigating the escalation of antibiotic resistance and its implications for human well-being. Methods: WG5D strain, isolated from a drinking water distribution source in North-West Province, South Africa, underwent genomic analysis following isolation on nutrient agar, anaerobic cultivation, and DNA extraction. Paired-end Illumina sequencing with a Nextera XT Library Preparation kit was performed. The assembly, annotation, and subsequent genomic analyses, including phylogenetic analysis using TYGS, pairwise comparisons, and determination of genes related to antimicrobial resistance and virulence, were carried out following standard protocols and tools, ensuring comprehensive insights into the strain's genomic features. Results: This study explores the notable characteristics of E. coli strain WG5D. This strain stands out because it possesses multiple antibiotic resistance genes, encompassing tetracycline, cephalosporin, vancomycin, and aminoglycoside resistances. Additionally, virulence-associated genes indicate potential heightened pathogenicity, complemented by the identification of mobile genetic elements that underscore its adaptability. The intriguing possibility of bacteriophage involvement and factors contributing to pathogenicity further enriches our understanding. We identified E. coli WG5D as a potential human pathogen associated with a drinking water source in South Africa. The analysis provided several antibiotic resistance-associated genes/mutations and mobile genetic elements. It further identified WG5D as a potential human pathogen. The occurrence of E. coli WG5D raised the awareness of the potential pathogens and the carrying of antibiotic resistance in drinking water. Conclusions: The findings of this study have highlighted the advantages of the genomic approach in identifying the bacterial species and antibiotic resistance genes of E. coli and its potential as a human pathogen. [ABSTRACT FROM AUTHOR]

Busseola fusca (Fuller) (Lepidoptera: Noctuidae), a major insect pest of maize in sub-Saharan Africa, has developed high levels of non-recessive resistance to Cry1Ab toxin expressed in genetically modified Bt maize. Multiple resistance mechanisms to various Cry toxins have been identified in Lepidoptera, but no study has yet been done to determine the mechanism of Cry1Ab resistance in B. fusca. Therefore, the larval transcriptome of B. fusca was sequenced, de novo assembled and characterized. Differential expression analysis was performed to compare gene expression profiles of Cry toxin challenged and unchallenged neonate larvae to assess the molecular basis of the defence mechanism employed by this insect. Several genes associated with Cry toxin resistance in other lepidopteran pests were detected in B. fusca. Results suggest that differential expression of metabolic and immune-related genes might explain Cry1Ab toxin defence in this pest (supplemental file). Transcript expression profiles of neonates demonstrated that 33.59% and 60.31% of the 131 differentially expressed genes were upregulated and downregulated in the toxin-challenged neonate larvae, respectively. Transcripts were grouped into two subclusters according to the similarity of their expression patterns. Transcripts in subcluster 1 were moderately upregulated in the toxin-challenged neonate larvae, and, conversely, downregulated in the unchallenged neonate larvae. The solute carrier organic anion transporter, which is involved in insecticide detoxification, was upregulated in the toxin-challenged neonate larvae. Conversely, most of the transcripts in subcluster 2 were moderately downregulated in the toxin-challenged neonate larvae, and upregulated for neonates feeding on non-challenged maize. Four unidentified transcripts were extremely down-regulated in the toxin-challenged neonate larvae, and upregulated in the unchallenged neonate larvae. Further studies are recommended to establish if there is a direct correlation between these differentially expressed genes and the observed resistance. Elucidation of such defence mechanisms is crucial for developing insect resistance management strategies to ensure sustainable use of genetically modified maize in Africa. Nevertheless, this is the first study on gene expression profiles of B. fusca strains challenged with Cry toxin. The transcriptome characterized in this study provides a significant resource base for future studies on B. fusca and contributes to understanding some of the gene regulation and signalling networks involved in the defence of B. fusca against Cry1Ab toxin. • First whole transcriptome analysis of Busseola fusca • Busseola fusca defence against Cry1Ab toxin. • Differential expression of immune genes in response to toxin challenge. • Identification of potential Bt resistance genes • Signal transduction and immune system pathways identified for Busseola fusca. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the spatial and temporal variation of microbiological parameters of the Lower Vaal River, with emphasis on the Staphylococci population. River water concentrations of Staphylococci, heterotrophic, total coliforms, fecal coliforms and Streptococci groups of sanitary indicator bacteria were monitored. Results indicated significant contamination from agricultural land use inputs and municipal waste applications. Significant temporal and spatial variation was observed in response to the varying river discharge. Higher microbial concentrations were detected during high river discharge whereas during low river discharge both low and high microbial concentrations were detected. The varying responses associated with river discharge helped to identify the importance of different sources of contamination in the catchment and the mechanisms transferring them. The overall impact of contamination on the water quality of the Vaal River could have potentially serious public health risks but also provide valuable data for integrated water resource management. [ABSTRACT FROM AUTHOR]

Priestia is a genus that was renamed from the genus Bacillus based on the conserved signature indels (CSIs) in protein sequences that separate Priestia species from Bacillus , with the latter only including species closely related to B. subtilis and B. cereus. Diagnosis of anthrax, a zoonotic disease, is implicated by tripartite anthrax virulence genes (lef, pagA , and cya) and poly-γ-D-glutamic acid capsular genes cap-ABCDE of Bacillus anthracis. Due to the amplification of anthrax virulence genes in Priestia isolates, the search for homologous anthrax virulence genes within the Priestia genomes (n = 9) isolated from animal blood smears was embarked upon through whole genome sequencing. In silico taxonomic identification of the isolates was conducted using genome taxonomy database (GTDB), average nucleotide identity (ANI), and multi-locus sequence typing (MLST), which identified the genomes as P. aryabhattai (n = 5), P. endophytica (n = 2) and P. megaterium (n = 2). A pan-genome analysis was further conducted on the Priestia genomes, including the screening of virulence, antibiotic resistance genes and mobile genetic elements on the sequenced genomes. The oligoribonuclease NrnB protein sequences showed that Priestia spp. possess a unique CSI that is absent in other Bacillus species. Furthermore, the CSI in P. endophytica is unique from other Priestia spp. Pan-genomic analysis indicates that P. endophytica clusters separately from P. aryabhattai and P. megaterium. In silico BLASTn genome analysis using the SYBR primers, Taqman probes and primers that target the chromosomal marker (Ba-1), protective antigen (pagA), and lethal factor (lef) on B. anthracis , showed partial binding to Priestia regions encoding for hypothetical proteins, pyridoxine biosynthesis, hydrolase, and inhibitory proteins. The antibiotic resistance genes (ARG) profile of Priestia spp. showed that the genomes contained no more than two ARGs. This included genes conferring resistance to rifamycin and fosfomycin on P. endophytica , as well as clindamycin on P. aryabhattai and P. megaterium. Priestia genomes lacked B. anthracis plasmids and consisted of plasmid replicon types with unknown functions. Furthermore, the amplification of Priestia strains may result in false positives when qPCR is used to detect the virulence genes of B. anthracis in soil, blood smears, and/or environmental samples. • Occurrence of false-positives by Priestia spp. during insilico screening of anthrax may create misdiagnosis. • Genome analysis indicates non-specific alignment of anthrax virulence genes to Priestia genomes. • Conserved signature indels and pan-genomics revealed differences among closely related Priestia species. [ABSTRACT FROM AUTHOR]

Endophytic fungi have the ability to live inside the host plant tissues without causing neither symptoms of diseases/or harm. Opportunistic infections are accountable for majority of the outbreaks, thereby putting a burden on the health system. To investigate and characterize the bioactive compounds for the control of bacteria of clinical importance, extracts from endophytic fungi were isolated from indigenous South African medicinal plants. Extracts from endophytic fungi were isolated from 133 fungal strains and screened against Gram positive and negative bacteria namely Bacillus cereus, Escherichia coli, Enterococcus faecium, and E. gallinarum using disk diffusion. Furthermore, gas chromatography–mass spectrometry was performed to identify the bioactive compounds. Sixteen out of one hundred and thirty-three (12%) fungi extracts exhibited antibacterial properties against some of the selected bacteria. E. coli was found to be the most susceptible in contrast to E. faecium and E. gallinarum which were the most resistant. The isolate MHE 68, identified as Alternaria sp. displayed the greater spectrum of antibacterial activities by controlling selected clinical bacteria strains including resistant E. faecium and E. gallinarum. The chemical analysis of the extract from MHE 68 indicated that linoleic acid (9,12-octadecadienoic acid (Z,Z)) and cyclodecasiloxane could be accountable for the antibacterial activity. This is the first study conducted on the secondary metabolites produced by endophytic fungal strains isolated from the Pelargonium sidoides DC. possessing antibacterial properties. [ABSTRACT FROM AUTHOR]

Response and growth kinetics of microbes in contaminated medium are useful indices for the screening and selection of tolerant species for eco-friendly bio-augmentative remediation of polluted environments. In this study, the heavy metal (HM) tolerance, bioaccumulation and growth kinetics of seven bacterial strains isolated from mining sites to 10 HMs (Cd, Hg, Ni, Al, Cr, Pb, Cu, Fe, Mn and Zn) at varied concentrations (25–600 mgL −1 ) were investigated. The isolates were phylogenetically (16S rRNA gene) related to Lysinibacillus macroides , Achromobacter spanius , Bacillus kochii , B . cereus , Klebsiella pneumoniae , Pseudomonas mosselii and P . nitroreducens . Metal tolerance, effects on lag phase duration and growth rates were assessed using the 96-well micro-titre method. Furthermore, metal bioaccumulation and quantities within cells were determined by transmission electron microscopy and electron dispersive x-ray analyses. Tolerance to Ni, Pb, Fe and Mn occurred at highest concentrations tested. Growth rates increased with increasing Fe concentrations, but reduced significantly ( p  < .05) with increasing Zn, Cu, Hg, Cd and Al. Significantly higher ( p  < .05) growth rates (compared to controls) was found with some isolates in Hg (25 mgL −1 ), Ni (100 mgL −1 ), Cr (150 mgL −1 ), Mn (600 mgL −1 ), Pb (100 mgL −1 ), Fe (600 mgL −1 ) and Al (50 mgL −1 ). Lag phase urations were isolate- and heavy metal-specific, in direct proportion to concentrations. A . spanius accumulated the most Mn and Zn, while B . cereus accumulated the most Cu. Metals accumulated intra-cellularly without cell morphology distortions. The isolates' multi-metal tolerance, intra-cellular metal bioaccumulation and growth kinetics suggest potentials for application in the synergetic biodegradation and bioremediation of polluted environments, especially HM-rich sites. [ABSTRACT FROM AUTHOR]

Increased heavy metal pollution generated through anthropogenic activities into the environment has necessitated the need for eco-friendly remediation strategies such as mycoremediation. With a view to prospecting for fungi with heavy metal remediation potentials, the tolerance of fiveAspergillusspecies isolated from soils of three active gold and gemstone mining sites in southwestern Nigeria to varied heavy metal concentrations was investigated. IsolatedAspergillusstrains were identified based on the internal transcribed spacer 1 and 2 (ITS 1 and ITS 2) regions. Growth ofAspergillusstrains were challenged with a range of varied concentrations of heavy metals: cadmium (Cd) (0–100), copper (Cu) (0–1000), lead (Pb) (0–400), arsenic (As) (0–500), and iron (Fe) (0–800) concentrations (ppm) incorporated into Malt Extract Agar (MEA) in triplicates. Mycelial radial growths were recorded at intervals of 3 days during a 13-day incubation period.Aspergillusstrains were identified asA. tubingensis, A. fumigatus, A. terreus, A. nidulans, andA. nomius. A. tubingensistolerated Cd, Cu, Pb, As, and Fe at all test concentrations (100–1000 ppm), showing no significant (p> .05) difference compared with the control. Similarly,A. nomiustolerated all concentrations of Cu, Pb, As, and Fe and only 50 ppm Cd concentrations.A. nidulans, A. terreus, andA. fumigatus, on the other hand, tolerated all concentrations of Cu, Pb, and Fe with no statistical significance (p> .05) difference from the controls. Overall, theAspergillusspecies showed tolerance to heavy metal concentrations above permissible limits for contaminated soils globally. These heavy metal tolerance traits exhibited by theAspergillusisolates may suggest that they are potential candidates for bioremediation of heavy metal–polluted environments. [ABSTRACT FROM AUTHOR]