Regulatory mutations affecting the synthesis of cellulase in Pseudomonas fluorescens

Pseudomonas fluorescens, was cultured in basal medium containing carboxymethyl-cellulose (CMC) as inducer and glucose or glycerol as carbon and energy sources. Ethylmethanesulphonate (EMS) was used to mutagenize the wild-type organism to produce mutants. The isolated mutants were screened for the isolation of catabolite repression resistant mutants in the presence of 1% (w/v) glucose as carbon source. A total of fifty mutants were isolated. All the mutants produced cellulase in the presence of CMC as an inducer with specific activity of 0.057, 0.088 and 0.074 units/mg protein for the wild-type, catabolite repression resistant mutant4 (CRRmt4) and catabolite repression resistant mutant24 (CRRmt24), respectively. It was observed that addition of glucose or glycerol as carbon and energy sources to the culture medium resulted into considerable reduction in the cellulolytic activity. However, glycerol appeared to be a better carbon and energy source than glucose which inhibited enzyme expression in most of the strains used in this study. It was also observed that potent cellulase production occurred at the exponential growth phase of the organism. The isolated mutants were grouped into three classes based on their induction ratios namely; unimproved mutants, catabolite repression resistant mutants and mutants with highest induction ratio but sensitive to catabolite repression in the presence of high glucose concentration. The overall results obtained showed that cellulolytic activity in P. fluorescens was regulated by catabolite repression.Key words: Pseudomonas fluorescens, ethylmethanesulphonate, mutants, cellulose, catabolite repression, induction ratio.African Journal of Biotechnology Vol. 4 (8), pp. 838-84

CHEMICAL AND MICROBIOLOGICAL PROFILE OF ‘LEGO’-A LOCALLY PRODUCED FLAVOURED DRINKS

The study assessed the chemical and microbial safety of street vended local drink ‘Lego’ collected from three different vendors in Abeokuta metropolis. A control sample was prepared in the laboratory and nine samples of three different flavours (orange, pineapple and blackcurrant) were collected.  Total Vibrio count, total faecal Coliform and total staphylococcus count were estimated in all the samples. Total Vibrio cholera is completely absent while Five samples were found to harbour total staphylococci counts of bacteria within the range of 0.7-1.5x104cfu/ml. All the samples exhibited the presence of Coliform counts within the range of 1.0-9.5x104cfu/ml and Staphylococcus aurous, Micrococcus acidophilus and Klebsiella aerogenes species were bacteria isolated from the samples collected. Heavy metals were also estimated in all the collected samples. Chromium and lead were absent but cadmium was present and is within 0.01-0.025mg/g. The lowest is from orange flavour at camp with 0.01 mg/g while the highest is from Lafenwa in pineapple flavour with 0.025mg/g. Total titratable acidity ranges from 0.175 – 0.219 and the pH ranges from 4.21±0.14 and 5.40±0.00. Hence, these implies that Lego flavoured drink is bacteriologically and chemically unsafe for consumption.      &nbsp

EFFECTS OF COOKING CONDITIONS ON THE TEXTURE PROFILE, SENSORY AND PROXIMATE QUALITIES OF PRESSURE COOKED BAMBARA NUTS

This study evaluated the effects of pressure cooking on the textural attributes of Bambara nuts using Response Surface Methodology (RSM).The  study optimized cooking condition {Weight of Bambara (250 – 1000g), cooking time (20 -90 min) and post cooking resident time (2-12 min)} for the pressure boiling on the textural and qualities of Bambara. Five out of the eleven optimised solutions (Desirability Index range of 0.919 to 0.936) were compared with samples from conventionally boiled Bambara for proximate and sensory (colour, texture, aroma and Overall acceptance) qualities.  Data were analysed using RSM, analysis of variance and PPMC. Models for hardness, springiness, cohesiveness, fracturability and sensory texture with adjusted R2 values of 83.41%, 80.99%, 67.37% ,  93,75%  and  88.96%  respectively adequately explained the textural and sensory qualities of boiled bambara. The range of values for moisture, fat, ash, crude protein and carbohydrate were 47.88, 2.24, 1.98, 24.30, 20.91 % to 50.58, 2.58, 2.19, 25.49, 21.87% respectively.  Boiled Bambara produced at verified optimisation solutions (527.62g, 82.55, 10.43 min and 591.69g, 82.96, 9.52 minutes) were not significantly different (p >0.05) from that produced by conventional  method (weight and Cooking time: 500g and 125 min.) in spite of the relatively longer cooking time  of the later.   &nbsp

Assessment of Landfill-emitted Gaseous Pollutants and Particulate Matters in Alimosho Local Government of Lagos state, Nigeria

Information on landfill-emitted pollutants in Nigeria cities has consequently become a priority. This study was designed to assess the air quality of landfill sites and the nearby communities in the Alimosho Local Government Area of Lagos state, Nigeria. Five public landfills in use since about thirty years ago were chosen for this study. A lightly populated area, free from other sources of air pollution served as control. Target points for the study were the centre of landfill (CLF), 50M from CLF, 100M from CLF, and a radius of 100M away from landfill. Levels of selected gaseous pollutants (NO2, O3, H2S and CO) and particulate matters (PM2.5 and PM10) were determined in the landfill environments and control (unpolluted area), using Aeroqual Series 500 with sensors for NO2, O3, H2S, CO, PM2.5 and PM10. The result showed that levels of H2S were significantly (p<0.001) higher at the CLF, 50M from CLF and 100M from CLF compared with unpolluted area. There was no significant (p>0.05) difference when the level of H2S in 100M radius was compared with the unpolluted area. Levels of CO were significantly (p<0.001) higher at the CLF, 50M from CLF, 100M from CLF and 100M radius compared with unpolluted area. The levels of O3 were significantly (p<0.001) higher at the CLF, 50M from CLF, 100M from CLF and 100M radius compared with unpolluted area. Levels of VOC were significantly (p<0.001) higher at the CLF, 50M from CLF, 100M from CLF and 100M radius compared with unpolluted area. The levels of NO2 were significantly (p<0.001) higher at the CLF, 50M from CLF, 100M from CLF and 100M radius compared with the unpolluted area. The levels of PM2.5 increased significantly (p<0.001) at the CLF, 50M from CLF, 100M from CLF and 100M radius compared with the unpolluted area. The levels of PM10 were also significantly (p< 0.001) higher at the CLF, 50M from CLF, 100M from CLF and 100M radius compared with the unpolluted area. In conclusion, communities close to landfills may be polluted with toxic gases and particulate matters. Further investigation is needed to validate the safe distance of residential areas from landfills to avert the risks of toxicity associated with gaseous pollutants

Technical innovations in processing cassava peels into new products for feeding livestock and fish and for food safety

Poster prepared for international conference on Integrated Systems Research for Sustainable Intensification in Smallholder Agriculture, Ibadan, Nigeria, 3-6 March 201

Changes in nutritional, texture, rancidity and microbiological properties of composite biscuits produced from breadfruit and wheat flours enriched with edible fish meal

Open Access Article; Published online: 30 Apr 2021The use of indigenous crops in the preparation of nutritious snacks such as biscuits has been reported as a means of alleviating the perennial problem of malnutrition among Nigerians, especially children. However, storage has been recognised as a factor affecting the attributes of these biscuits. This study investigated the quality changes of biscuit produced from fish meal enriched-composite flour of breadfruit and wheat. Freshly harvested seedless variety of breadfruit, matured catfish, wheat flour and other ingredients were procured from local outlets in Ogun State, Nigeria. Breadfruit flour (BF) was produced by washing, manual peeling, washing, grating, bagging, dewatering, pulverizing and drying. Edible fish meal (EFM) was produced by washing, eviscerating, steaming and drying Catfish. Five blends of BF, WF and EFM were obtained from the optimised solutions of the D-optimal mixture design. Samples were stored (HDPE; 28 ± 2 °C) for 12 weeks. The proximate and mineral compositions, rancidity, texture profile and microbial counts of the biscuits were determined. Data were subjected to Analysis of Variance (ANOVA) and independent sample t-test. The means from ANOVA were separated using Duncan’s Multiple Range Test at p ≤ 0.05. At the end of the storage period, the biscuit blends were significantly (p ≤ 0.05) different in moisture, protein, fat, fibre, ash, carbohydrate, calcium, iron and zinc. Increased levels of EFM in the blends led to increase in protein, fat, calcium, peroxide value (PV) and free fatty acid (FFA) value of the biscuits. At the end of the storage period, moisture increased, while fat decreased. The PV and FFA of most samples increased significantly (p ≤ 0.05) with storage, and were within the maximum permissible level. Total bacterial and mould counts also increased significantly (p ≤ 0.05) and exceeded the permissible level after 4 weeks of storage. Hence, the biscuits are suitable for consumption within 4 weeks under the investigated storage conditions

The first-line antituberculosis drugs, and their fixed-dose combination induced abnormal sperm morphology and histological lesions in the testicular cells of male mice

Rifampicin (RIF), Isoniazid (INH), Ethambutol (EMB), Pyrazinamide (PZA), and/or their fixed-dose combination (FDC) are extensively prescribed in the cure of Tuberculosis (TB) globally. In spite of the beneficial effect, these drugs are capable of inducing cellular toxicity. Existing information on the genotoxic effects of the first-line anti-TB drugs is limited and contentious. Herein, we evaluated the reproductive genotoxicity of RIF, INH, EMB, PZA, and their FDC utilizing the mouse sperm morphology assay. Histological examination of the testes of exposed mice was also performed. Male Swiss albino mice (11–13 weeks old) were intraperitoneally exposed for 5 consecutive days to each of the anti-TB drugs at four different doses of 6.25, 12.5, 25, and 50 mg/kg bw of PZA; 2.5, 5.0, 10, and 20 mg/kg bw of RIF; 1.25, 2.5, 5.0 and 10 mg/kg bw of INH; 3.75, 7.5, 15 and 30 mg/kg bw of EMB; and 7, 14, 28 and 56 mg/kg bw of FDC corresponding respectively to ×0.25, ×0.5, ×1 and ×2.0 of the standard daily dose. In comparison with the negative control (normal saline), there was no significant difference in the testicular weight and organo-somatic index of exposed mice. There was an increase (p > 0.05) in the frequency of abnormal spermatozoa at most of the tested doses of each drug and a dose-dependent decrease with the FDC. Each of the anti-TB drugs except the FDC induced pathological lesions in the testes. These findings suggest that the individual first-line anti-TB drug unlike the FDC has the potential to provoke testicular anomalies in male mice