Evaluation of Antibiotic Resistant Gene in Abattoir Environment

Pseudomonas aeruginosa is a ubiquitous gram-negative pathogen with susceptibility to cause opportunistic infections in humans. Among the total of 75 isolated presumptive Pseudomonas aeruginosa, by cultural and morphology characteristic, 55 were identified as Pseudomonas aeruginosa by the specie-specific primer employing PCR assay which was more sensitive for confirmation of the isolates. Fifty-five Pseudomonas aeruginosa isolates were screened using PCR for the presence of integrons and associated resistance gene cassette. Thirty-four isolates harbored class 1 integrons (61.8%), of which 27 isolates (79.4%) carried gene cassettes. PCR was performed targeting the presence of these genes:- blaOXA 11(32.4%); blaIMP 5(14.7%); blaAMPC 5(14.7%); blaTEM 4(11.8%); and TetC 2(5.8%). Some of these genes were only recently described from clinical isolates, demonstrating genetic exchange between clinical and environmental Pseudomonas aeruginosa stains. Multi- resistance was observed in the isolates, revealing strong correlation between integron presence and multi-resistance. These results demonstrate that abattoir milieu is potential reservoirs of various antibiotics resistance genes, thus constituting a serious health risk to the communities dependent on the receiving water bodies

Development of Naphthalene Catabolism in Al and Fe contaminated soil

Metals have the potential to affect the biodegradation of polycyclic aromatic hydrocarbons (PAHs) in mixed contaminated soils. This investigation considered the effects of Al and Fe (50, 100, 250 and 500 mg/kg) on 14C-naphthalene biodegradation in soil over 63 d contact time. The presence of Al at low concentrations (50 and 100 mg/kg) stimulated (p < 0.05) naphthalene biodegradation in fresh Al amendments; however, naphthalene mineralisation was significantly reduced (p < 0.05) in 500 mg/kg aged Al amendment, but this reduction only occurred at 1 and 21 d in 500 mg/kg fresh Al. Naphthalene mineralisation was stimulated (p < 0.05) in the highest Fe concentration (500 mg/kg) in both aged and fresh Fe amendments at 42 d. This suggests that Al has a greater impact than Fe on the development of PAH catabolism in soil. Studies on metal-PAH impact in soil facilitates the assessment of risk, hazard and bioremediation potential at sites contaminated with both contaminants

Evaluation of Escherichia coli as indicator of point-of-use chlorination efficiency of drinking water

In this study, the relevance of the presence of Escherichia coli in drinking water as an indicator of point-of-use chlorination efficiency is examined. The survival of clinical isolates of human enteric pathogenic bacteria (Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi, Shigella dysenteriae, Staphylococcus aureus, Streptococcus faecalis and Vibrio cholerae) as well as E. coli was monitored as a function of effective germicidal concentration and contact time. The  inactivation kinetics indicated that the minimum effective dose for three-log units (99.9%) inactivation of E. coli (C·T99.9% = 10 mgl-1-min) can sufficiently  eliminate the other pathogens (C·T99.9% ranged from 5.6–10.5 mgl-1-min); the exception being K. pneumoniae, which required more than 1.4-times higher dose. In general, the results implied that the branded hypochlorite solution should effectively inactivate almost all vegetative  bacteria in household drinking water at the manufacturer’s recommended dosage of 0.5 mgl-1 after at least 30 minutes contact time. The application of point-of-use chemical disinfectants to drinking water in households will significantly reduce the incidence of water-borne infections  particularly in rural communities where central treatment of water is mostly unavailable.Keywords: Effective dose; Point-of-use disinfectants; Indicator bacteria; Pathogen; Escherichia coli; Chlorinatio

Development of Naphthalene Catabolism in Al and Fe contaminated soil

Metals have the potential to affect the biodegradation of polycyclic aromatic hydrocarbons (PAHs) in mixed contaminated soils. This investigation considered the effects of Al and Fe (50, 100, 250 and 500 mg/kg) on 14C-naphthalene biodegradation in soil over 63 d contact time. The presence of Al at low concentrations (50 and 100 mg/kg) stimulated (p < 0.05) naphthalene biodegradation in fresh Al amendments; however, naphthalene mineralisation was significantly reduced (p < 0.05) in 500 mg/kg aged Al amendment, but this reduction only occurred at 1 and 21 d in 500 mg/kg fresh Al. Naphthalene mineralisation was stimulated (p < 0.05) in the highest Fe concentration (500 mg/kg) in both aged and fresh Fe amendments at 42 d. This suggests that Al has a greater impact than Fe on the development of PAH catabolism in soil. Studies on metal-PAH impact in soil facilitates the assessment of risk, hazard and bioremediation potential at sites contaminated with both contaminants

Impact of Zn, Cu, Al and Fe on the partitioning and bioaccessibility of (14)C-phenanthrene in soil

This investigation considered the effects of Zn, Cu, Al and Fe (50 and 500 mg kg(-1)) on the loss, sequential extractability, using calcium chloride (CaCl2), hydroxypropyl-β-cyclodextrin (HPCD) and dichloromethane (DCM) and biodegradation of (14)C-phenanthrene in soil over 63 d contact time. The key findings were that the presence of Cu and Al (500 mg kg(-1)) resulted in larger amounts of (14)C-phenanthrene being extracted by CaCl2 and HPCD. Further, the CaCl2 + HPCD extractions directly predicted the biodegradation of the PAH in the presence of the metals, with the exception of 500 mg kg(-1) Cu and Zn. The presence of high concentrations of some metals can impact on the mobility and accessibility of phenanthrene in soil, which may impact on the risk assessment of PAH contaminated soil

Impact of zinc-copper mixtures on the development of phenanthrene catabolism in soil

Anthropogenic pollutants rarely occur in the environment as single constituents, thus combination effects rather than separate effects of pollutants are expected to occur in the environment. PAH contamination of soil is often associated with the presence of high levels of potentially toxic metals which may impact on PAH biodegradation. In this study, the impact of zinc and copper mixtures (0, 50,100, 500 and 1000 mg kg(-1)) on the development of phenanthrene catabolism and impact on bacterial numbers in soil were investigated over 168 day incubation. The presence of low concentrations of Zn and Cu (50 and 100 mg kg(-1)) had no significant effect (p > 0.05) on the development of phenanthrene catabolism, but phenanthrene biodegradation was significantly reduced at higher concentrations of Zn + Cu mixture (p <0.05). Bacterial cell numbers decreased significantly in the higher concentrations of the mixtures relative to the control. Thus, in soils impacted with organic and metallic contaminants, biodegradation may be inhibited. (C) 2013 Elsevier Ltd. All rights reserved

Impact of Al and Fe on the development of phenanthrene catabolism in soil

Heavy metals often occur as co-contaminants with polycyclic aromatic hydrocarbons (PAHs) and reportedly have adverse effects on biodegradation. In this study, the development of C-14-phenanthrene mineralisation in soil co-contaminated with aged or freshly added Al or Fe amendment was assessed. C-14-phenanthrene mineralisation was assessed using respirometry; respirometers incorporated a Teflon-lined screw-capped CO2 trap containing 1-M NaOH within a glass scintillation vial. The production of (CO2)-C-14 was assessed by the addition of Ultima Gold liquid scintillation fluid to the CO2 traps and subsequent liquid scintillation counting. Enumeration of phenanthrene-degrading bacteria was achieved by counting the colony forming unit count using the spread plate method. This investigation considered the effects of Al and Fe (50, 100, 250 and 500 mg/kg) on C-14-phenanthrene biodegradation in soil over 63-day contact time. Fresh Al amendments at lower concentrations (50 and 100 mg/kg) stimulated phenanthrene catabolism (p <0.05) at t = 21 and 42 days which may reflect an 'Arndt-Schulz' effect, but phenanthrene catabolism was significantly reduced (p <0.05) in 500 mg/kg aged Al this could be due to Al toxicity to phenanthrene degraders. Phenanthrene mineralisation was stimulated in the highest Fe concentration (500 mg/kg) in aged and fresh Fe amendments at t = 21 days. This could be because Fe is an essential requirement for microbial growth. The impact of Al or Fe on the catabolism of C-14-phenanthrene was dependent on incubation time and Al was more toxic than Fe to soil PAH catabolic activity. This could be because Al is a non-essential microbial requirement. Bioremediation of soils co-contaminated with PAH and heavy metal is a complex problem; therefore, studies on the impact of metals on PAHs biodegradation highlight the risks and biodegradation potential in contaminated soil

Biochar-facilitated batch co-digestion of food waste and cattle rumen content: An assessment of process stability, kinetic studies, and pathogen fate

Anaerobic digestion is an established sustainable route for managing the organic fraction of municipal solid waste. The commonly adopted mono digestion of organic waste is often beset by many challenges chief of which is process instability. This study assessed the role of biochar in process stability and pathogen fate for batch co-digestion of food waste (FW) and cattle rumen content (CRC). Biochar had different functional groups, a large surface area (627.50 m2/g), and a pore volume (0.32 cm3/g). Biochar amendments helped stabilize the pH and reduce the accumulation of volatile fatty acids (VFAs) and total ammonia nitrogen (TAN). Biochar amendment using 5 g biochar also facilitated biogas production at low pH conditions (3.72 – 4.45), yielding a cumulative biogas yield of 706.11 ml/gVS with a biomethane composition of 64.3%. Pathogen counts revealed significant log reductions in the range 3.0–3.2 for E. coli, Bacillus, and Salmonella within the first 7 days of digestion, corresponding to 99.9% removal, indicating the safety of the resulting digestate for agricultural use. The modified Gompertz model adequately represented the kinetics of the anaerobic digestion process. The study has provided insights into biochar-facilitated digestion of CRC and FW for enhanced process stability

Assessment of Anaerobic Digestate Amended with Wood Ash and Green Vegetable Matter and Impacts on Microbial Growth

Anaerobic digestion (AD) is a waste management method worldwide, that results in biogas and digestate production. The digestate remains is a potential biofertilizer but may fall short of vital nutrients required for optimal plant growth, hence, requires amendment with other biomass residues. This study was aimed at investigating the microbial quality of digestate amended with wood ash and vegetable matter during treatment. Digestate from cattle rumen content (CR), food waste (FW), fruit waste (FRW) and their combinations were amended with wood ash, vegetable (green) matter and a blend of both. Amendment was carried out for 5 weeks, and samples were analyzed weekly. Enumeration and identification of bacteria and fungi were carried out on culture media. The rhizobacterial potential of the identified bacterial isolates was also investigated using standard microbiological procedures. The results showed high bacterial and fungal load in vegetable amended digestate from the first to the fourth week. Comparatively, cattle rumen content and food waste digestate amended with vegetables were highly significant, with mean values of 0.8 and 0.6, respectively. The identified bacterial isolates namely, Bacillus subtilis, Salmonella sp, Pseudomonas sp, Proteus sp, Enterobacter sp, Chromobacterium sp Bacillus spp. and Escherichia coli were found to be involved in the solubilization of phosphate, nitrogen fixation, ammonia production and induction of indole acetic acid. Specifically, feedstocks amended with vegetable (green) waste was found to have a significant influence on microbial growth (bacterial and fungal loads) between week 1 and 4. This suggests that digestate amendment is a crucial recipe for microbial growth which has considerable benefits in nutrient enhancement and increase in carbon levels