The aerobic dechlorination activities of two bacterial species isolated from a refuse dumpsite in Nigeria

Two bacterial species isolated using enrichment culture techniquesfrom the topsoil of a main refuse dumpsite in Nigeria were assessed for their dehalogenation potentials. The bacterial isolates were identified asbelo nging to the Bacillus and Pseudomonas genera. Axenic culturesof the isolates utilized monochloroacetic acid (MCA), trichloroacetic acid (TCA), trichloromethane (CHCl3) and tetrachloromethane (CCl4) as the sole source of carbon for growth up to a final substrate concentration of 0.1% (w/v). The mean generation timesof the isolatesin all the growth media ranged significantly (P < 0.05) from 2.41 to 10.04 h and were generally higher than that observed in glucose medium (1.46—1.51 h). The numbers of the chloride atoms in the different organochlorides were negatively correlated with the ability of the organisms to degrade the compounds. Dehalogenase specific activities of the cell-mediated culturesranged from 0.1 to 0.96 μg ml-1 chloride release (mg protein)-1 h-1 and were significantly (P < 0.05) higher than that of the cell-free extract [0.09—0.8 μg ml-1 chloride release (mg protein)-1 h-1]. The optimal pH of the dehalogenase activity was found to be 8.0, and the optimal temperature was between 30 and 35°C

Effects of fermentation temperature on the composition of beer volatile compounds, organoleptic quality and spent yeast density

Production of good quality beer is dependent largely on the fermentation temperature and yeast strains employed during the brewing process, among others. In this study, effects of fermentation temperatures and yeast strain type on beer quality and spent yeast density produced after wort fermentation by two commercial yeast strains were investigated. Beer samples were assessed for colour, clarity and foam head stability using standard methods, whilst the compositions and concentration of Beer Volatile Compounds (BVCs) produced were assessed using GC-MS. The spent yeast density, measured as dry cell weight, ranged between 1.84 - 3.157 mg/ml for both yeast strains with the highest yield obtained at room temperature fermentation. A peak viable population of 2.56 x 107 cfu/ml was obtained for strain A, also during fermentation at room temperature. The foam head of the beers produced at 22.5\ubaC was most stable, with foam head ratings of 2.66 and 2.50 for yeast strain A and B, respectively. However, there was no significant (p = 0.242) difference in colour intensity between the beers produced at the different fermentation temperatures. Eight different BVCs were detected in all beer samples and were found to affect the organoleptic properties of the beer produced. Further optimizations are required to determine the effects of other parameters on beer quality

Factors Militating Against Prompt Delivery of Construction Projects in Lagos Megacity, Nigeria: Contractors’ Perspective

Delay is a common issue faced in the construction industry all over the world especially in developing countries. The aim of this study is to evaluate factors causing delays and their effects on construction projects in Lagos Mega City, Nigeria from the contractors’ perspective. It is predicated on the incessant delay experienced by contractors on construction projects. Purposive sampling method was adopted for the study;. Quantitative data was obtained by administration of One hundred (100) structured questionnaires distributed to contractors of construction project sites in Lagos State and Qualitative data was obtained from interview of key management personnel of the companies and journals. Ranking analysis of the 33 major causes of delays identified through literature review using Relative Importance Index (RII) showed that cash flow problems during construction (RII=4.81), clients’ financial difficulties (RII=4.47) and poor procurement (RII=4.40) were the most importantt causes of delays in construction project sites in Lagos State, Cost overrun (RII=4.92), late payment (RII=4.59) and project extension (RII=4.45) were predominant effects of delay in construction project. Hypotheses testing on relationship between shortage of skilled labour, improper equipment during construction and delay in construction project using One-Way ANOVA showed positive correlation. For improved efficiency and effective project delivery in the industry, proper payment from client (RII=4.78), competent project managers (RII=4.64), the use o

Antibiotic Producing Potentials of Three Freshwater Actinomycetes Isolated from the Eastern Cape Province of South Africa

Crude extracts of three actinomycetes species belonging to Saccharopolyspora (TR 046 and TR 039) and Actinosynnema (TR 024) genera were screened for antibacterial activities against a panel of several bacterial strains. The extracts showed antibacterial activities against both gram-negative and gram-positive test bacteria with inhibition zones ranging from 8 to 28 mm (TR 046); 8 to15 mm (TR 039); and 10 to 13 mm (TR 024). The minimum inhibitory concentrations ranged from 0.078 to 10 mg/mL (TR 046); 5 to >10 mg/mL (TR 039); and 1.25 to 5 mg/mL (TR 024). Time-kill studies revealed that crude extract of TR 046 showed strong bactericidal activity against Bacillus pumilus (ATCC14884), reducing the bacterial load by 104 cfu/mL and 102 cfu/mL at 4× MIC and 2× MIC, respectively, after 6 h of exposure. Similarly, against Proteus vulgaris (CSIR 0030), crude extract of TR 046 achieved a 0.9log10 and 0.13log10 cfu/mL reduction at 5 mg/mL (4× MIC) and 1.25 mg/mL (2× MIC) after 12 h of exposure. The extract was however weakly bactericidal against two environmental bacterial strains (Klebsiella pneumoniae and Staphylococcus epidermidis); and against Pseudomonas aeruginosa (ATCC 19582): the extract showed bacteriostatic activities at all concentrations tested. These freshwater actinomycetes appear to have immense potential as a source of new antibacterial compound(s)

Treated Wastewater Effluent as a Source of Microbial Pollution of Surface Water Resources

Since 1990, more than 1.8 billion people have gained access to potable water and improved sanitation worldwide. Whilst this represents a vital step towards improving global health and well-being, accelerated population growth coupled with rapid urbanization has further strained existing water supplies. Whilst South Africa aims at spending 0.5% of its GDP on improving sanitation, additional factors such as hydrological variability and growing agricultural needs have further increased dependence on this finite resource. Increasing pressure on existing wastewater treatment plants has led to the discharge of inadequately treated effluent, reinforcing the need to improve and adopt more stringent methods for monitoring discharged effluent and surrounding water sources. This review provides an overview of the relative efficiencies of the different steps involved in wastewater treatment as well as the commonly detected microbial indicators with their associated health implications. In addition, it highlights the need to enforce more stringent measures to ensure compliance of treated effluent quality to the existing guidelines

Treated Wastewater Effluent as a Source of Microbial Pollution of Surface Water Resources

Abstract: Since 1990, more than 1.8 billion people have gained access to potable water and improved sanitation worldwide. Whilst this represents a vital step towards improving global health and well-being, accelerated population growth coupled with rapid urbanization has further strained existing water supplies. Whilst South Africa aims at spending 0.5% of its GDP on improving sanitation, additional factors such as hydrological variability and growing agricultural needs have further increased dependence on this finite resource. Increasing pressure on existing wastewater treatment plants has led to the discharge of inadequately treated effluent, reinforcing the need to improve and adopt more stringent methods for monitoring discharged effluent and surrounding water sources. This review provides an overview of the relative efficiencies of the different steps involved in wastewater treatment as well as the commonly detected microbial indicators with their associated health implications. In addition, it highlights the need to enforce more stringent measures to ensure compliance of treated effluent quality to the existing guidelines

Prevalence of Antimicrobial Resistant and Virulent Salmonella spp. in Treated Effluent and Receiving Aquatic Milieu of Wastewater Treatment Plants in Durban, South Africa

In this study, we evaluated the impact of treated wastewater effluent from two wastewater treatment plants on the physicochemical parameters and Salmonella spp. load of receiving rivers. Presumptive Salmonella spp. were obtained at all sampled points including the discharge points, with counts ranging from 0 to 4.14 log cfu/mL at both plants. Turbidity, chemical and biological oxygen demand were found to be high and mostly above the required limit for treated wastewater discharge. However, recorded nitrate and phosphate values were very low. Of the 200 confirmed Salmonella spp. isolates recovered from the treated effluent and receiving surface waters, 93% harbored the spiC gene, 84% harbored the misL gene, and 87.5% harbored the orfL gene while 87% harbored the pipD gene. The antibiotic resistance profile revealed that the isolates were resistant to sulfamethoxazole, nalidixic acid and streptomycin, but susceptible to quinolones and third generation β-lactams. These results indicate that in South Africa treated effluents are still a major source of contamination of rivers with pathogens such as Salmonella. Appropriate steps by the regulatory authorities and workers at the treatment plants are needed to enforce stipulated guidelines in order to prevent pollution of surface water resources due to the discharge of poorly treated effluents

Does Chlorination Promote Antimicrobial Resistance in Waterborne Pathogens? Mechanistic Insight into Co-Resistance and Its Implication for Public Health

Chemical agents including chlorine and antibiotics are used extensively to control infectious microorganisms. While antibiotics are mainly used to treat bacterial infections, chlorine is widely used for microbial inactivation in the post-secondary disinfection steps of water treatment. The extensive use of these agents has been acknowledged as a driving force for the expansion of antimicrobial resistance (AMR) and has prompted discourse on their roles in the evolution and proliferation of resistant pathogens in the aquatic milieus. We live in a possible &ldquo;post-antibiotic&rdquo; era when resistant microbes spread at startling levels with dire predictions relating to a potential lack of effective therapeutic antibacterial drugs. There have been reports of enhancement of resistance among some waterborne pathogens due to chlorination. In this context, it is pertinent to investigate the various factors and mechanisms underlying the emergence and spread of resistance and the possible association between chlorination and AMR. We, therefore, reflect on the specifics of bacterial resistance development, the mechanisms of intrinsic and acquired resistance with emphasis on their environmental and public health implications, the co-selection for antibiotic resistance due to chlorination, biofilm microbiology, and multidrug efflux activity. In-depth knowledge of the molecular basis of resistance development in bacteria will significantly contribute to the more rational utilization of these biocidal agents and aid in filling identified knowledge gap toward curbing resistance expansion

Rotaviruses: From Pathogenesis to Disease Control&mdash;A Critical Review

Since their first recognition in human cases about four decades ago, rotaviruses have remained the leading cause of acute severe dehydrating diarrhea among infants and young children worldwide. The WHO prequalification of oral rotavirus vaccines (ORV) a decade ago and its introduction in many countries have yielded a significant decline in the global burden of the disease, although not without challenges to achieving global effectiveness. Poised by the unending malady of rotavirus diarrhea and the attributable death cases in developing countries, we provide detailed insights into rotavirus biology, exposure pathways, cellular receptors and pathogenesis, host immune response, epidemiology, and vaccination. Additionally, recent developments on the various host, viral and environmental associated factors impacting ORV performance in low-and middle-income countries (LMIC) are reviewed and their significance assessed. In addition, we review the advances in nonvaccine strategies (probiotics, candidate anti-rotaviral drugs, breastfeeding) to disease prevention and management

Chloroethenes contaminants in the environment: Still a cause for concern

Prior to 1980, chloroethenes were generally believed to be recalcitrant to degradation. Efforts to remediate sites polluted by this group of compounds were thus limited to the ineffective and tedious pump-and-treat method. The environmental significance of chloroethenes and the absence of effective alternative physical remediation methods have warranted intense scientific investigation into the role of microorganisms for detoxifying these environmentally important compounds to benign products. Several microbial mechanisms have therefore been identified to significantly degrade these compounds in soil and ground water polluted systems. This paper provides a mini-review of such mechanisms with the view of understanding the biodegradation processes for better exploitation for bioremediation of chloroethene contaminants, which continue to be of serious environmental challenges