Assessing the Fungal Simultaneous Removal Efficiency of Carbamazepine, Diclofenac and Ibuprofen in Aquatic Environment.

Unused pharmaceutical compounds (PhCs) discharged into the aquatic environment have been regarded as emerging pollutants due to potential harmful effects on humans and the environment. Microbial bioremediation is considered as a viable option for their removal from wastewater. The aim of this study was to assess the simultaneous removal of carbamazepine (CBZ), diclofenac (DCF) and ibuprofen (IBP) by previously isolated fungi (Aspergillus niger, Mucor circinelloides, Trichoderma longibrachiatum, Trametes polyzona, and Rhizopus microsporus). The tolerance to PhCs was conducted by tracking the fungal mycelium mat diameters in solid media and its dry biomass in liquid media, at the drug concentration range of 0.1 to 15 mg/L. The fungal enzymatic activities were determined for lignin peroxidase (LiP), manganese peroxidase (MnP) and laccase (Lac), respectively. The PhC removal efficiency of the fungi was assessed in aerated batch flasks and the drug concentrations and intermediate compounds formation were determined by using SPE-UPLC/MS. A tolerance over 70% was recorded for all the fungi at drug concentration of 0.1 mg/L. Manganese peroxidase was produced by all the fungi with very low amount of LiP, while all the enzymes were produced by T. polyzona. The pH of 4.3, temperature 37 ± 1.5°C and incubation time of 6 days were the optimum parameters for the fungal enzymatic activities. The best removal of CBZ (87%) was achieved by R. microsporus after 10 days. Between 78 and 100% removal of DCF was observed by all the fungi after 24 h, while 98% of IBP was removed after 2 days by M. circinelloides. Only a few intermediate compounds were identified after 3 days and disappeared after 10 days of incubation. This study demonstrated that apart from the basidiomycetes, the ascomycetes and zygomycetes are also producers of ligninolytic enzymes and have the ability to biodegrade emerging pollutants such as PhCs.

Comparing the effect of zinc oxide and titanium dioxide nanoparticles on the ability of moderately halophilic bacteria to treat wastewater.

This study evaluates the ability of moderately halophilic bacterial isolates (Serratia sp., Bacillus sp., Morganella sp., Citrobacter freundii and Lysinibacillus sp.) to treat polluted wastewater in the presence of nZnO and nTiO2 nanoparticles. In this study, bacteria isolates were able to take up nZnO and nTiO2 at concentrations ranging from 1 to 50 mg/L in the presence of higher DO uptake at up to 100% and 99%, respectively, while higher concentrations triggered a significant decrease. Individual halophilic bacteria exhibited a low COD removal efficiency in the presence of both metal oxide nanoparticles concentration ranged between 1 and 10 mg/L. At higher concentrations, they triggered COD release of up to - 60% concentration. Lastly, the test isolates also demonstrated significant nutrient removal efficiency in the following ranges: 23-65% for NO3- and 28-78% for PO43-. This study suggests that moderately halophilic bacteria are good candidates for the bioremediation of highly polluted wastewater containing low metal oxide nanoparticles.

Ultraviolet and solar photocatalytic ozonation of municipal wastewater: Catalyst reuse, energy requirements and toxicity assessment.

The present study evaluated the treatment of municipal wastewater containing phenol using solar and ultraviolet (UV) light photocatalytic ozonation processes to explore comparative performance. Important aspects such as catalyst reuse, mineralization of pollutants, energy requirements, and toxicity of treated wastewater which are crucial for practical implementation of the processes were explored. The activity of the photocatalysts did not change significantly even after three consecutive uses despite approximately 2% of the initial quantity of catalyst being lost in each run. Analysis of the change in average oxidation state (AOS) demonstrated the formation of more oxidized degradation products (ΔAOS values of 1.0-1.7) due to mineralization. The energy requirements were determined in terms of electrical energy per order (EEO) and the collector area per order (ACO). The EEO (kWh m-3 Order-1) values were 26.2 for ozonation, 38-47 for UV photocatalysis and 7-22 for UV photocatalytic ozonation processes. On the other hand, ACO (m2 m-3 order-1) values were 31-69 for solar photocatalysis and 8-13 for solar photocatalytic ozonation. Thus photocatalytic ozonation processes required less energy input compared to the individual processes. The cytotoxicity of the wastewater was analysed using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay with Vero cells. The cell viability increased from 28.7% in untreated wastewater to 80% in treated wastewater; thus showing that the treated wastewater was less toxic. The effectiveness of photocatalytic ozonation, recovery and reusability of the photocatalysts, as well as detoxification of the wastewater make this low energy consumption process attractive for wastewater remediation.

Evaluation of synergy and bacterial regrowth in photocatalytic ozonation disinfection of municipal wastewater.

The use of solar and ultraviolet titanium dioxide photocatalytic ozonation processes to inactivate waterborne pathogens (Escherichia coli, Salmonella species, Shigella species and Vibrio cholerae) in synthetic water and secondary municipal wastewater effluent is presented. The performance indicators were bacterial inactivation efficiency, post-disinfection regrowth and synergy effects (collaboration) between ozonation and photocatalysis (photocatalytic ozonation). Photocatalytic ozonation effectively inactivated the target bacteria and positive synergistic interactions were observed, leading to synergy indices (SI) of up to 1.86 indicating a performance much higher than that of ozonation and photocatalysis individually (SI≤1, no synergy; SI>1 shows synergy between the two processes). Furthermore, there was a substantial reduction in contact time required for complete bacterial inactivation by 50-75% compared to the individual unit processes of ozonation and photocatalysis. Moreover, no post-treatment bacterial regrowth after 24 and 48h in the dark was observed. Therefore, the combined processes overcame the limitations of the individual unit processes in terms of the suppression of bacterial reactivation and regrowth owing to the fact that bacterial cells were irreparably damaged. The treated wastewater satisfied the bacteriological requirements in treated wastewater for South Africa.

Impact of ozonation in removing organic micro-pollutants in primary and secondary municipal wastewater: effect of process parameters.

The study investigates the influence of process parameters on the effectiveness of ozonation in the removal of organic micro-pollutants from wastewater. Primary and secondary municipal wastewater containing phenol was treated. The effect of operating parameters such as initial pH, ozone dosage, and initial contaminant concentration was studied. An increase in contaminant decomposition with pH (3-11) was observed. The contaminant removal efficiencies increased with an increase in ozone dose rate (5.5-36.17 mg L(-1) min(-1)). Furthermore, the ultraviolet absorbance (UV 254 nm) of the wastewater decreased during ozonation indicating the breakdown of complex organic compounds into low molecular weight organics. Along the reaction, the pH of wastewater decreased from 11 to around 8.5 due to the formation of intermediate acidic species. Moreover, the biodegradability of wastewaters, measured as biological and chemical oxygen demand (BOD5/COD), increased from 0.22 to 0.53. High ozone utilization efficiencies of up to 95% were attained thereby increasing the process efficiency; and they were dependent on the ozone dosage and pH of solution. Ozonation of secondary wastewater attained the South African water standards in terms of COD required for wastewater discharge and dissolved organic carbon in drinking water and increased significantly the biodegradability of primary wastewater.

Effect of nickel on nutrient removal by selected indigenous protozoan species in wastewater systems.

Nutrient and heavy metal pollutions are major concern worldwide. This study aimed at comparing the effect of Ni(2+) on nutrient removal efficiency of four indigenous wastewater protozoan species (Aspidisca sp., Paramecium sp., Peranema sp., Trachelophyllum sp.). Specific physicochemical parameters and microbial growth/die-off were measured using standard methods. The results revealed that protozoan species were able to simultaneously remove phosphate, nitrate and Ni(2+) at concentrations ranging between 66.4-99.36%, 56.19-99.88% and 45.98-85.69%, respectively. Peranema sp. appeared to be the isolates with the highest removal of nutrients (Phosphate-99.36% and Nitrate-99.88%) while Paramecium sp. showed higher removal of Ni(2+) at 85.69% and low removal of nutrients. Aspidisca sp. was the most sensitive isolate to Ni(2+) but with significant nutrient removal (Phosphate-66.4% and Nitrate-56.19%) at 10 mg-N(2+)/L followed by an inhibition of nutrient removal at Ni(2+) concentration greater than 10 mg/L. Significant correlation between the growth rate and nutrient removal (r = 0.806/0.799, p < 0.05 for phosphate and nitrate, respectively) was noted. Except for Peranema sp. which revealed better nutrient removal ability at 10 mg-Ni(2+)/L, an increase in Ni(2+) concentration had a significant effect on nutrient removal efficiency of these indigenous protozoan species. This study suggests that although Ni(2+) appeared to be toxic to microbial isolates, its effect at a low concentration (10 mg-Ni(2+)/L) towards these isolates can be used to enhance the wastewater treatment process for the removal of nutrients. Peranema sp., which was able to remove both Ni(2+) and nutrients from wastewater mixed-liquor, can also be used for bioremediation of wastewater systems.

Profile of bacterial communities in South African mine-water samples using Illumina next-generation sequencing platform.

Mine water is an example of an extreme environment that contains a large number of diverse and specific bacteria. It is imperative to gain an understanding of these bacterial communities in order to develop effective strategies for the bioremediation of polluted aquatic systems. In this study, the high-throughput sequencing approach was used to characterize the bacterial communities in two different mine waters of South Africa: vanadium and gold mine water. Over 2629 operational taxonomic units (OTUs) were recovered from 15,802 reads of the 16S ribosomal RNA (rRNA) gene. They represented 8 phyla, 43 orders, 84 families and 105 genera. Proteobacteria and unclassified bacterial sequences were the most dominant. Apart from these, Firmicutes, Bacteroidetes, Actinobacteria, Candidate phylum OD1, Cyanobacteria, Verrucomicrobia and Deinococcus-Thermus were the recovered phyla, although their relative abundance differed between both the mine-water samples. Yet, diversity indices suggested that the bacterial communities inhabiting the vanadium mine water were more diverse than those in gold mine water. Interestingly, substantial percentages of the reads from either sample (58 % in vanadium and 17 % in gold mine water) could not be assigned to any phylum and remained unclassified, suggesting hitherto unidentified populations, and vast untapped microbial diversity. Overall, the results of this study exhibited bacterial community structures with high diversity in mine water, which can be explored further for their role in bioremediation and environmental management.

Bacterial profiling in brine samples of the Emalahleni Water Reclamation Plant, South Africa, using 454-pyrosequencing method.

A metagenomic approach was applied using 454-pyrosequencing data analysis for the profiling of bacterial communities in the brine samples of the water reclamation plant. Some physicochemical characteristics of brine samples were also determined using standard methods. Samples ranged from being lightly alkaline to highly alkaline (pH 7.40-10.91) throughout the various treatment stages, with the salinity ranging from 1.62 to 4.53 g L(-1) and dissolved oxygen concentrations ranging from 7.47 to 9.12 mg L(-1). Phenotypic switching was found to occur due to these physicochemical parameters. Microbial diversities increased from those present in Stage I reactor (six taxonomic groups) to those in Reverse Osmosis (RO) stage I (17 taxonomic groups), whereas in the second phase of the treatment, it increased in Stage II clarifier (14 taxonomic groups) followed by a decrease in RO stage II (seven taxonomic groups). Overall, seven phyla were detected, apart from many bacterial sequences that were unclassified at the phylum level. The most dominant phylum found was Proteobacteria accounting for 59% of the total sequences. A blastn sequence similarity search showed that the majority of the sequences (56%) were homologous to the uncultured bacterial species, underlining the vast untapped bacterial diversity.

Effect of vanadium toxicity at its different oxidation states on selected bacterial and protozoan isolates in wastewater systems.

This study assesses and compares vanadium toxicity in its different oxidation states towards bacterial isolates (Pseudomonas putida and Bacillus licheniformis) and protozoan isolates (Peranema sp. and Trachelophyllum sp.). The isolates were exposed to various concentrations of V in mixed liquors and their tolerance to V was assessed at 30 degrees C at a pH of 4. The results revealed that the increase in V oxidation state increased its toxicity to bacterial isolates, whereas its toxicity decreased for protozoan isolates. Among the bacterial isolates, P putida was found to be more tolerant to V3+(24h-median lethal concentration (LC50): 390mg/l), V4+(24h-LC50: 230-250mg/l) and V5+(24h-LC50: 180-200mg/l), whereas for the protozoan isolates, Peranema sp. appeared to be more tolerant to V3+(24 h-LC50: 110-120 mg/l), V4+(24 h-LC50: 160-170 mg/l) and V5+(24 h-LC50: 160-200 mg/l). A comparison of both groups of organisms revealed Trachelophyllum sp. as the most sensitive organism to V at its various oxidation states. The visual and spectrophotometric methods used to assess V reduction revealed that P. putida was the only isolate able to reduce V5+, V4+ and V3+ to V2+ in mixed liquor media. Vanadium (+2) in concentrations of approximately 46.46 mg/l, 29.57 m mg/l and 38.01 mg/l found in the media was treated with V3+, V4+ and V5+, respectively, and inoculated with P. putida. This study revealed that the ability of V reduction, adopted with P putida, can be an effective strategy to remove V from polluted environments. This study also showed that the toxicity of V, in terms of its oxidation states, differs from one species to another and in kingdoms.

Faecal pollution loads in the wastewater effluents and receiving water bodies: a potential threat to the health of Sedibeng and Soshanguve communities, South Africa.

The discharge of untreated or inadequately treated effluents has been identified among the activities responsible for the spread of a wide range of potentially infectious agents. The aim of this study was to determine whether inadequate treatment of wastewater and the faecal pollution load of effluents and receiving water bodies in Sedibeng District and Soshanguve peri-urban area of the Tshwane Metropolitan Municipality could be a potential threat to the health of the surrounding communities. Variations in the counts of faecal indicator bacteria and pathogenic microorganisms and compliance of the effluents and receiving water bodies with South African and World Health Organization standards were assessed between August 2011 and May 2012 using culture-based methods and molecular techniques. The overall quality of effluents did not comply with the South African special standard of no risk for unrestricted irrigation (zero Escherichia coli/100 ml). The quality of the receiving water bodies did not comply with South African regulatory limits set for domestic purposes (zero E. coli/100 ml, <30 faecal enterococci/100 ml and <1 somatic coliphages/100 ml), for full contact recreation (<20 somatic coliphages/100 ml) and aquaculture (<10 E. coli/100 ml) and WHO standards for full and intermediate contact recreational use (<1 E. coli/100 ml and <40 faecal enterococci/100 ml, respectively). The PCR results revealed the prevalence of pathogenic microorganisms; between 0 and 60 % of samples tested positive for Salmonella Typhimurium and Shigella dysenteriae, and between 20 and 60% of samples tested positive for Vibrio cholerae. These findings demonstrated that potential health risks might be associated with the use of the target river waters for domestic, recreational and irrigation purposes. This study calls for a prompt intervention to improve wastewater management.

The impact of microbial ecology and chemical profile on the enhanced biological phosphorus removal (EBPR) process: a case study of Northern Wastewater Treatment Works, Johannesburg.

The impact of polyphosphate-accumulating organism (PAO) and glycogen-accumulating organism (GAO) populations as well as of the chemical profile on the performance of Unit-3 (open elutriation tanks) and Unit-5 (covered elutriation tank) of the City of Johannesburg Northern Wastewater Treatment Works was determined. Physicochemical parameters of wastewater samples were measured using standard methods. Bacterial diversity was determined using 16S rRNA gene amplicon pyrosequencing of the variable region V1-3. Results showed soluble COD concentrations from settled sewage for Unit-3 at 192.8 mg COD/L and for Unit-5 at 214.6 mg COD/L, which increased to 301.8 mg COD/L and 411.6 mg COD/L in the overflow from elutriation tanks and decreased to 170.9 mg COD/L and 256.3 mg COD/L at the division boxes, respectively. Both long-chain volatile fatty acids (heptanoic acid, isobutyric acid, 3-methylbutanoic acid, pentanoic acid, 4-methylpentanoic acid, methylheptanoic acid) and short-chain volatile fatty acids (acetic acid, propionic acid, isobutyric acid) were present within concentration ranges of 17.19 mg/L to 54.98 mg/L and 13.64 mg/L to 87.6 mg/L for Unit 3 and 38.61 mg/L to58.85 mg/L and 21.63 mg/L to 92.39 mg/L for Unit 5, respectively. In the secondary settling tanks, the phosphate-removal efficiency in Unit-5 appeared to be slightly higher (0.08 mg P/L) compared to that of Unit-3 (0.11 mg P/L). The average DO concentrations (2.1 mg/L and 2.2 mg/L) as well as the pH values (pH 7 to pH 7.5) were found to be slightly higher in Unit-5 in the aerobic zones. The high presence of PAOs in the bioreactors (Unit-5: Dechloromonas (14.96%), Acinetobacter (6.3%), Zoogloea (4.72%) in the anaerobic zone and Dechloromonas (22.37 %) in the aerobic zone; Unit-3: Dechloromonas (37.25%) in the anaerobic zone and Dechloromonas (23.97%) in the aerobic zone) confirmed the phosphate-removal efficiencies of both units. Negligible GAOs were found in the aerobic zones (Defluviicoccus spp.: 0.33% for Unit-5 and 0.68% for Unit-3) and in the anaerobic zones (Defluviicoccus: 9.8% for Unit-3). The high microbial diversity and a negligible percentage of GAOs in Unit-5 could contribute to its high phosphate-removal efficiency, although results did not indicate statistically significant differences between the unit with a covered elutriation tank (Unit-5) and that with open elutriation tanks (Unit-3).

Assessing the resistance and bioremediation ability of selected bacterial and protozoan species to heavy metals in metal-rich industrial wastewater.

BACKGROUND: Heavy-metals exert considerable stress on the environment worldwide. This study assessed the resistance to and bioremediation of heavy-metals by selected protozoan and bacterial species in highly polluted industrial-wastewater. Specific variables (i.e. chemical oxygen demand, pH, dissolved oxygen) and the growth/die-off-rates of test organisms were measured using standard methods. Heavy-metal removals were determined in biomass and supernatant by the Inductively Couple Plasma Optical Emission Spectrometer. A parallel experiment was performed with dead microbial cells to assess the biosorption ability of test isolates. RESULTS: The results revealed that the industrial-wastewater samples were highly polluted with heavy-metal concentrations exceeding by far the maximum limits (in mg/l) of 0.05-Co, 0.2-Ni, 0.1-Mn, 0.1-V, 0.01-Pb, 0.01-Cu, 0.1-Zn and 0.005-Cd, prescribed by the UN-FAO. Industrial-wastewater had no major effects on Pseudomonas putida, Bacillus licheniformis and Peranema sp. (growth rates up to 1.81, 1.45 and 1.43 d-1, respectively) compared to other test isolates. This was also revealed with significant COD increases (p < 0.05) in culture media inoculated with living bacterial isolates (over 100%) compared to protozoan isolates (up to 24% increase). Living Pseudomonas putida demonstrated the highest removal rates of heavy metals (Co-71%, Ni-51%, Mn-45%, V-83%, Pb-96%, Ti-100% and Cu-49%) followed by Bacillus licheniformis (Al-23% and Zn-53%) and Peranema sp. (Cd-42%). None of the dead cells were able to remove more than 25% of the heavy metals. Bacterial isolates contained the genes copC, chrB, cnrA3 and nccA encoding the resistance to Cu, Cr, Co-Ni and Cd-Ni-Co, respectively. Protozoan isolates contained only the genes encoding Cu and Cr resistance (copC and chrB genes). Peranema sp. was the only protozoan isolate which had an additional resistant gene cnrA3 encoding Co-Ni resistance. CONCLUSION: Significant differences (p < 0.05) observed between dead and living microbial cells for metal-removal and the presence of certain metal-resistant genes indicated that the selected microbial isolates used both passive (biosorptive) and active (bioaccumulation) mechanisms to remove heavy metals from industrial wastewater. This study advocates the use of Peranema sp. as a potential candidate for the bioremediation of heavy-metals in wastewater treatment, in addition to Pseudomonas putida and Bacillus licheniformis.

Removal of Escherichia coli and faecal coliforms from surface water and groundwater by household water treatment devices/systems: a sustainable solution for improving water quality in rural communities of the Southern African development community region.

There is significant evidence that household water treatment devices/systems (HWTS) are capable of dramatically improving microbially contaminated water quality. The purpose of this study was to examine five filters [(biosand filter-standard (BSF-S); biosand filter-zeolite (BSF-Z); bucket filter (BF); ceramic candle filter (CCF); and silver-impregnated porous pot (SIPP)] and evaluate their ability to improve the quality of drinking water at the household level. These HWTS were manufactured in the workshop of the Tshwane University of Technology and evaluated for efficiency to remove turbidity, faecal coliforms and Escherichia coli from multiple water source samples, using standard methods. The flow rates ranged from 0.05 L/h to 2.49 L/h for SIPP, 1 L/h to 4 L/h for CCF, 0.81 L/h to 6.84 L/h for BSF-S, 1.74 L/h to 19.2 L/h and 106.5 L/h to 160.5 L/h for BF The turbidity of the raw water samples ranged between 2.17 and 40.4 NTU. The average turbidity obtained after filtration ranged from 0.6 to 8 NTU (BSF-S), 1 to 4 NTU (BSF-Z), 2 to 11 NTU (BF), and from 0.6 to 7 NTU (CCF) and 0.7 to 1 NTU for SIPP. The BSF-S, BSF-Z and CCF removed 2 to 4 log(10) (99% to 100%) of coliform bacteria, while the BF removed 1 to 3 log (90% to 99.9%) of these bacteria. The performance of the SIPP in removing turbidity and indicator bacteria (>5 log(10), 100%) was significantly higher compared to that of the other HWTS (p < 0.05). The findings of this study indicate that the SIPP can be an effective and sustainable HWTS for the Southern African Development Community (SADC) rural communities, as it removed the total concentration of bacteria from test water, can be manufactured using locally available materials, and is easy to operate and to maintain.

Cost-effective filter materials coated with silver nanoparticles for the removal of pathogenic bacteria in groundwater.

The contamination of groundwater sources by pathogenic bacteria poses a public health concern to communities who depend totally on this water supply. In the present study, potentially low-cost filter materials coated with silver nanoparticles were developed for the disinfection of groundwater. Silver nanoparticles were deposited on zeolite, sand, fibreglass, anion and cation resin substrates in various concentrations (0.01 mM, 0.03 mM, 0.05 mM and 0.1 mM) of AgNO(3). These substrates were characterised by SEM, EDS, TEM, particle size distribution and XRD analyses. In the first phase, the five substrates coated with various concentrations of AgNO(3) were tested against E. coli spiked in synthetic water to determine the best loading concentration that could remove pathogenic bacteria completely from test water. The results revealed that all filters were able to decrease the concentration of E. coli from synthetic water, with a higher removal efficiency achieved at 0.1 mM (21-100%) and a lower efficiency at 0.01 mM (7-50%) concentrations. The cation resin-silver nanoparticle filter was found to remove this pathogenic bacterium at the highest rate, namely 100%. In the second phase, only the best performing concentration of 0.1 mM was considered and tested against presumptive E. coli, S. typhimurium, S. dysenteriae and V. cholerae from groundwater. The results revealed the highest bacteria removal efficiency by the Ag/cation resin filter with complete (100%) removal of all targeted bacteria and the lowest by the Ag/zeolite filter with an 8% to 67% removal rate. This study therefore suggests that the filter system with Ag/cation resin substrate can be used as a potential alternative cost-effective filter for the disinfection of groundwater and production of safe drinking water.

Relationship of protozoan biomass to phosphate and nitrate removal from activated sludge mixed liquor.

The relationship between protozoan biomass concentration and phosphate and nitrate removal was investigated in mixed liquor using three different carbon sources as supplements. The study was carried out using three respective initial biomass concentrations in a shaking flask environment. Samples were taken every 24 h to determine phosphate, nitrate, dissolved oxygen and chemical oxygen demand. The results revealed a direct relationship between decreases in nutrient concentrations and increases in cell densities of the isolates. Between 24 and 96 h, the increases in the protozoan density corresponded to a phosphate decreases from initial ranges of 55.42-57.36 mg/L, 50.27-51.17 mg/L and 50.01-50.83 mg/L to final ranges of 2.46-11.90 mg/L, 0.61-11.80 mg/L and 1.29-13.89 mg/L, in the presence of Aspidisca, Trachelophyllum and Peranema, respectively. Nitrate concentrations were observed to decrease from initial ranges of 23.84-25.90 mg/L, 23.94-25.84 mg/L and 26.12-26.54 mg/L to final ranges of 0.11-6.32 mg/L, 0.16-5.60 mg/L and 0.24-9.04 mg/L, respectively. The study had revealed that an increase in cell density of the test isolates produces a corresponding increase in phosphate and nitrate removal.

Prevalence and characterization of Escherichia coli O157:H7 isolates from meat and meat products sold in Amathole District, Eastern Cape Province of South Africa.

Meat and meat products have been implicated in outbreaks of Escherichia coli O157:H7 in most parts of the world. In the Amathole District Municipality of the Eastern Cape Province of South Africa, a large number of households consume meat and meat products daily, although the microbiological quality of these types of food is questionable. The present study investigated the prevalence of E. coli O157:H7 isolated from selected meat and meat products (45 samples each of biltong, cold meat, mincemeat, and polony) sold in this area. Strains of E. coli O157:H7 were isolated by enrichment culture and confirmed by polymerase chain reaction (PCR). Also investigated were the antibiogram profiles of the E. coli O157:H7 isolates. Five (2.8%) out of 180 meat and meat products examined were positive for E. coli O157:H7 that carried the fliC(H7), rfbE(O157), and eaeA genes. Two of the E. coli O157:H7 isolates were resistant against all the eight antibiotics tested. To prevent E. coli O157:H7 infections, meat and meat products such as biltong, cold meat, mincemeat and polony should be properly handled, and packed in sterile polyvinyl wrappers.

Protozoan biomass relation to nutrient and chemical oxygen demand removal in activated sludge mixed liquor.

The relationship between biomass concentration to nutrient and chemical oxygen demand (COD) removal in mixed liquor supplemented with sodium acetate was investigated, using three protozoan isolates and three different initial biomass concentrations (10(1), 10(2) and 10(3) cells/mL). The study was carried out in a shaking flask environment at a shaking speed of 100 rpm for 96 h at 25 degrees C. Aliquot samples were taken periodically for the determination of phosphate, nitrate, COD and dissolved oxygen, using standard methods. The results revealed remarkable phosphate removal of 82-95% at biomass concentration of 10(3)cells/mL. A high nitrate removal of over 87% was observed at all initial biomass concentration in mixed liquor. There was an observed COD increase of over 50% in mixed liquor in at the end of 96-h incubation and this was irrespective of initial biomass concentration used for inoculation. The study shows the trend in nutrient and COD removal at different biomass concentrations of the test isolates in mixed liquor.

Abundance of pathogenic Escherichia coli, Salmonella typhimurium and Vibrio cholerae in Nkonkobe drinking water sources.

In order to study the prevalence of enteric pathogens capable of causing infection and disease in the rural communities of Nkonkobe, bacterial isolates were collected from several surface water and groundwater sources used by the community for their daily water needs. By making use of selective culture media and the 20E API kit, presumptive Escherichia coli, Salmonella spp. and Vibrio cholerae isolates were obtained and then analysed by polymerase chain reaction assays (PCR). The PCR successfully amplified from water samples a fragment of E. coli uidA gene that codes for beta-D-glucuronidase which is a highly specific characteristic of enteropathogenic E. coli, enterotoxigenic E. coli and entero-invasive E. coli. The PCR also amplified the epsM gene from water samples containing toxigenic V. cholerae. Although E. coli was mostly detected in groundwater sources, toxigenic V. cholerae was detected in both surface and groundwater sources. There was a possibility of Salmonella typhimurium in Ngqele and Dyamala borehole water samples. The presence of these pathogenic bacteria in the above drinking water sources may pose a serious health risk to consumers.

Regrowth and survival of indicator microorganisms on the surfaces of household containers used for the storage of drinking water in rural communities of South Africa.

The present study covered two rural communities of South Africa: Ncera and Ntselamanzi villages. Raw water from Ncera river is used by the community of Ncera village for drinking, while the community of Ntselamanzi receives their drinking water from Alice purification system. Treated water is supplied to the community by a public standpipe system. In rural communities of South Africa, many households use polyethylene (PE) and galvanized steel (GS) containers for the storage of their drinking water. To investigate the regrowth and survival of indicator microorganisms on the surface of household containers during the storage of drinking water, PE and GS slides were suspended in the appropriate household containers for a period of 48 h. This period of 48 h was chosen as the study period because results from the questionnaire indicated that the largest percentage (62%) of households store their water for that length of time. The experiment was performed to test drinking water as it is collected and stored by rural communities. No disinfection of household containers or slides was done during the study period. Attached coliphages (F-RNA (FP) and somatic phage (SP), coliform bacteria (total coliform (TC), presumptive Escherichia coli (EC), Salmonella (Sal) and Clostridium perfringens (CP) were measured during the study period. With the exception of CP, attached indicator microorganisms consisted of TC, presumptive E. coli and Salmonella, somatic and F-RNA coliphages, although the yield (average count) for the last four groups (EC: < 1-3 cfu cm(-2), Sal: < 1-15 cfu cm(-2), FP: < 1-7 pfu cm(-2), SP: < 1-7pfu cm(-2)) was lower than that of TC (3-183 cfu cm(-2)). However, the lowest yield of indicator microorganisms was noted for presumptive E. coli. Whereas the occurrence and survival of TC was noted on the surface of household containers during the entire period of the experimental study, other indicator microorganisms occurred from time to time. The regrowth of indicator microorganisms occurred 48 h after the exposure of slides to both types of test waters. This length of time mostly resulted in the regrowth of TC (with an increase in bacterial counts) while the persistence of other indicator organism groups on the surface of the slides was apparent. A comparison between PE and GS containers showed that more TC (average count) regrew on PE than on GS containers (for river water, PE: from 36 to 55 cfu cm(-2), GS: from 25 to 26 cfu cm(-2); for standpipe water, PE: from 147 to 183 cfu cm(-2), GS from 3 to 4 cfu cm(-2)). This study revealed that both types of household containers supported the growth and survival of indicator microorganisms due to the bad quality of the intake water before storage. The storage of drinking water for 48 h mainly resulted in the regrowth of TC. Nevertheless, the persistence of other indicator microorganisms was observed on the surface of household containers.