Faculty of Science and Technology

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Browsing Faculty of Science and Technology by Author "Asita, A. O."

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    Clastogenic and Cytotoxic Effects of Four Pesticides Used to Control Insect Pests of Stored Products on Root Meristems of Allium cepa
    (Environment and Natural Resources Research, 2013) Asita, A. O.; Mokhobo, M. M
    While the use of pesticides of stored product has increased productivity in agriculture, there is concern about their use because some are mutagens and/or carcinogens, harm non-target organisms or cause pest resistance. In this study Grain Treat (GT) (Mercaptothion, 10 g kg-1, Permethrin 1.5 g kg-1); QuickPhos (QP) (Aluminium Phosphide, 560 g kg-1); Nuvan Profi (NP) (Dichlorvos, 124 g kg-1) and Eriocephalus punctulatus plant smoke condensate (EPSC) were evaluated for cytotoxicity and the induction of genotoxicity in the onion (Allium cepa) test. Onion seeds were germinated and exposed to pesticides (mg ml-1), GT (12.5, 25, 50); QP (0.75, 1.5, 3.0); NP (0.064, 0.128, 0.256); EPSC (0.0025, 0.0049, 0.0098) for 24 hours. For each concentration, three root tips were transferred to three microscope slides, stained with aceto-carmine, covered with cover slip, squashed and observed microscopically. The cytotoxicity and genotoxicity induced by each pesticide concentration was compared with the value for the concomitant negative control using t-test. Only QP (3.0 mg mL-1) and NP (0.256 mg mL-1) significantly depressed the MI, i.e. cytotoxic (P < 0.05). Genotoxicity was determined by examining, 100 anaphase and telophase cells on each of three slides per concentration for chromosome aberration (CA). The three concentrations of each pesticide induced CAs (P < 0.05) in the following general order of frequency; stickiness > multipolarity > c-mitosis > anaphase and telophase bridges > chromosome Largards. The induction of sticky chromosomes indicated that the pesticides caused abnormal DNA condensation, abnormal chromosome coiling and inactivated the spindles. Because abnormalities of the cell division process results from the genotoxic effects of environmental chemicals, the four pesticides have the potential to cause aneuploidy in exposed organisms and adverse human health and environmental effects.
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    Microbial and Physicochemical Characterization of Maize and Wheat Flour from a Milling Company, Lesotho
    (FoodHACCP.com Publishing, 2013) Ntuli, V.; Mekbib, Sissay Bekele; Asita, A. O.; Molebatsi, Ntseliseng; Makotoko, Makotoko; Chatanga, Peter
    Maize meal flour and wheat flour are the most widely consumed cereals in Lesotho. The present study was undertaken to investigate the physicochemical and microbiological quality of special, super and extra super brands of maize meal flour; cake, white wheat and whole brown wheat brands of wheat flour produced by a mill company in Maseru, Lesotho. Three samples of each flour were collected on each of five sampling trips during January to May 2012, making a total of 90 samples, and were analysed physico-chemically for ash, fat, protein, moisture content and pH. Microbiologically, total plate count, total coliforms, Bacillus cereus, Salmonella spp, E. coli, yeasts and moulds were also determined. A series of biochemical tests were done to characterize the isolated micro-flora. Moisture content (9.89±0.76% to 13.31±0.64%) and pH (5.83±0.06 to 6.40±0.12) of the flours were within recommended legal limits. However, fat content (33% (n=90)) in maize samples exceeded the maximum recommended limit. The fat content (2.00±0.08% to 5.29±0.10%) of all maize meal brands was significantly higher (P<0.05) than that of wheat flour (0.90±0.03% to 1.87±0.02%). Protein content in maize meal was significantly lower than that of wheat flour, ranging from 7.01±0.91% to 9.64±0.09%. Ash content for the samples ranged from 0.29-1.21%. Statistically, bacterial counts in the different brands of flours showed significant differences (p < 0.05). In a more qualitative assessment, microbes of the genera Escherichia, Klebsiella, Aerobacter, Enterobacter, Salmonella, Bacillus, Aspergillus, Penicillium, Fusarium, Candida, Saccharomyces and Rhodotorula were identified in the flours. Pathogens (Bacillus cereus and Salmonella spp) and indicator organisms (coliforms and E. coli) were above World Food Programm (WFP) recommended limits. This study highlighted the need for stringent cleaning and sanitation regimes to be fully implemented in such companies for consumer safety and public health protection.
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    Qualitative Assessment of Livestock Faeces and Sewage for Antibiotic Resistant Strains of E. coli in Roma, Lesotho
    (Greener Journals, 2013) Mekbib, Sissay Bekele; Marole, T. A.; Asita, A. O.
    Sewage water (SW) and fresh livestock faeces: Chicken (ChNF), Sheep (SF), and Cattle (CF) were taken randomly from the farm of the National University of Lesotho aseptically during the 2012 academic year. Twenty ml of sewage water or 20 grams of fresh animal faeces was dissolved in 80 ml of sterilized Ringer�s solution and serially diluted. A 0.1 ml of sample suspension at 10-4 dilution was spread plated on Nutrient Agar (NA) and Eosine Methyl Blue (EMB) and plates were incubated for 24-48h at 24 and 37�C, respectively. A disc diffusion method was used to test the reaction of selected strains of Enterobacteriaceae to nine antibiotics. In total, 24 strains under Enterobacteriaceae were isolated from the respective sources and the number of each that were Escherichia coli, as confirmed by the biochemical tests were: SW (7 and 3); ChNF (5 and 3); SF (8 and 6) and CF (4 and 2). Thirteen E. coli strains fermented lactose and were Catalase positive, while only one E. coli strain from SW was non-lactose fermenter and Catalase negative. The lethal potencies, as number of isolates sensitive to the 9 antibiotics, ranked as: Colistin = Amikacin (24/24) > Kanamycin (23/24) > Chloramphenicol (22/24) > Cefotaxime (21/24) > Sulphafurazole (7/24) > Methicillin (1/24) > Penicillin G = Rifampicin (0/24). Sensitivity of the E. coli strains ranked as follows, Colistin = Amikacin = Kanamycin (14/14) > Chloramphenicol (13/14) > Cefotaxime (12/14) > Sulphafurazole (6/14) > Methicillin (1/14) > Penicillin G = Rifampicin (0/14). This result showed that the development of antibiotic resistant E. coli strains, which can pass through food chain to humans and other organisms if stringent control measures are not taken. Strict quarantine procedures have to be applied to control such potential health risks.
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    Qualitative Assessment of Livestock Faeces and Sewage for Antibiotic Resistant Strains of E. coli in Roma, Lesotho
    (Greener Journals, 2013) Mekbib, Sissay Bekele; Marole, T. A.; Asita, A. O.
    Sewage water (SW) and fresh livestock faeces: Chicken (ChNF), Sheep (SF), and Cattle (CF) were taken randomly from the farm of the National University of Lesotho aseptically during the 2012 academic year. Twenty ml of sewage water or 20 grams of fresh animal faeces was dissolved in 80 ml of sterilized Ringer’s solution and serially diluted. A 0.1 ml of sample suspension at 10-4 dilution was spread plated on Nutrient Agar (NA) and Eosine Methyl Blue (EMB) and plates were incubated for 24-48h at 24 and 37°C, respectively. A disc diffusion method was used to test the reaction of selected strains of Enterobacteriaceae to nine antibiotics. In total, 24 strains under Enterobacteriaceae were isolated from the respective sources and the number of each that were Escherichia coli, as confirmed by the biochemical tests were: SW (7 and 3); ChNF (5 and 3); SF (8 and 6) and CF (4 and 2). Thirteen E. coli strains fermented lactose and were Catalase positive, while only one E. coli strain from SW was non-lactose fermenter and Catalase negative. The lethal potencies, as number of isolates sensitive to the 9 antibiotics, ranked as: Colistin = Amikacin (24/24) > Kanamycin (23/24) > Chloramphenicol (22/24) > Cefotaxime (21/24) > Sulphafurazole (7/24) > Methicillin (1/24) > Penicillin G = Rifampicin (0/24). Sensitivity of the E. coli strains ranked as follows, Colistin = Amikacin = Kanamycin (14/14) > Chloramphenicol (13/14) > Cefotaxime (12/14) > Sulphafurazole (6/14) > Methicillin (1/14) > Penicillin G = Rifampicin (0/14). This result showed that the development of antibiotic resistant E. coli strains, which can pass through food chain to humans and other organisms if stringent control measures are not taken. Strict quarantine procedures have to be applied to control such potential health risks.