Proximate and Mineral Composition of Aerial Potato (Dioscorea bulbifera Linn) after using Different Fermentation Methods

This study evaluated the nutritional value of aerial yam potato fermented with different methods and other food processing. Aerial potato was subjected to different treatments (peeled, unpeeled, peeled and blanched, unpeeled and blanched, peeled and boiled, unpeeled and boiled) before fermentation with different methods like submerged fermentation and back slope (BS) fermentation. The proximate and mineral compositions were monitored using standard methods. Crude Protein (%) of the peeled aerial potato significantly increased from 4.12 ±0.13 at the initial to 10.11±0.85 at the end of the fermentation while unpeeled aerial potato slightly increased from 3.66a±0.04 at the initial to 4.19±0.03 at the end of the fermentation. Peeled and blanched; unpeeled and blanched as well as the unpeeled and boiled samples had the highest iron (0.143±0.01 ppm), magnesium (6.40±0.02 ppm) and calcium (6.32±0.03 ppm) contents in fermented aerial potato sample. Generally, the different of methods of fermentation employed improved the nutrient contents of fermented aerial potato.

Production of β-Mannanase by Penicillium italicum Subjected to Different Growth Conditions

Aims: The process parameters affecting enzyme production were optimized to ascertain the best optimal conditions for β-mannanase production by Penicillium italicum in solid state fermentation. Study Design: Four stages of experimental processes were designed for this study. The first experiment, samples were withdrawn after 24, 48, 72, 96, 120, 144,168 and 192 h incubation. In second experiment, the fermentation media were incubated at different temperatures. In third experiment, the effect of different pH values on β-mannanase production was evaluated, while the fourth experiment described the supplementation of surfactants in mineral salt solution for β-mannanase production. Place and Duration of Study: Microbiology Research Laboratory, Federal University of Technology, Akure Nigeria between September 2011 and March 2012. Methodology: β-mannanase production was conducted using Locust Bean Gum (LBG) as the sole carbon source; moisten with mineral salt solution, and enzyme activity determined by dinitrosalicylic acid method, while protein content was determined by Lowry method. Results: Maximum enzyme activity (146.389 U/ml) was observed after 72 h of incubation. Different surfactants were supplemented in the basal medium, and Sodium Dodecyl Sulfate (SDS) was observed to give the highest β-mannanase activity of 53.335 U/ml. Initial pH of the culture medium was optimized and a pH of 6.0 was found to support maximum enzyme activity (173.241 U/mg protein). The optimum incubation temperature was achieved at 35°C. Conclusion: The results obtained provide information on optimal process parameters that might improve the yield of β-mannanase by P. italicum for better fish feed formulation, especially in the larval stages of fish fingerlings when the enzyme system is not efficient.

Screening of Bacterial Strains of Agricultural Waste Origin for Βeta-mannanase Production and Optimization of Process Parameters.

Aims: This study was carried out to screen bacterial strains of agricultural wastes origin for β-mannanase production and optimization of culture conditions. Study Design: The first experiment, bacterial strains were screened for β-mannanase production. In the second experiment, the best incubation time was determined. In the third experiment, different agricultural wastes were screened. In the fourth experiment, different nitrogen sources were screened. In the fifth and sixth experiments described the effect of different pH values and incubation temperatures on β-mannanase production. The best moisture content was determined in the seventh experiment, while in experiment eight; effect of different inoculum concentrations was evaluated. Place and Duration of Study: Microbiology Research Laboratory, Federal University of Technology, Akure, Nigeria between September 2011 and March 2012. Methodology: Bacterial strains were screened and β-mannanase production from optimization studies was conducted on Locust Bean Gum. Enzyme activity was determined by dinitrosalicylic acid method. Results: Out of the sixteen bacterial strains screened, Klebsiella edwardsii designated 1A was selected as the most potent in producing enzyme of high activity and it was therefore selected for further studies. Pineapple peels were found to be the most effective carbon source with a highest β-mannanase activity of 8.533±0.08U/ml. Ammonium nitrate (NH4NO3) was obtained to be the best nitrogen source out of all the nitrogen sources screened. The best moisture content was obtained at 1:11 (ratio of substrate to salt solution). Inoculum concentration of 1.0% (v/v) yielded highest β-mannanase activity of 15.833±0.01U/ml. Addition of simple carbon sources to medium containing LBG caused a catabolic repression of β-mannanase synthesis. Conclusion: The optimal culture conditions obtained from this study will help to standardize the requirements for optimum β-mannanase production using cheaper substrates.

Kinetic Properties of Purified β-Mannanase from Penicillium italicum.

Aim: The study aimed at purification and characterization of β-mannanase from Penicillium italicum. Study Design: The first experiment, β-mannanase from Penicillium italicum was produced in basal medium supplemented with Locust Bean Gum (LBG). The second described the purification of crude β-mannanase, while the third experiment dealt with characterization and kinetic studies of purified β-mannanase from Penicillium italicum. Place and Duration of Study: Microbiology Research Laboratory, Federal University of Technology, Akure Nigeria between July and August 2012. Methodology: β-mannanase from Penicillium italicum was produced in basal medium supplemented with LBG. The enzyme was purified by ammonium sulphate precipitation, ion exchange chromatography (DEAE-Sephadex A-50) and gel filtration (Sephadex G-150). The purified enzyme was characterized to determine its optimal conditions by standard assay procedures. The kinetic parameters of the purified enzyme were determined by Lineweaver-Bulk plot. Results: Fractionation of ammonium sulphate precipitated β-mannanase from Penicillium italicum on sephadex A-50 produced one major activity peak. Further fractionation of partially purified enzyme from ion exchange on Sephadex G-150 yielded one activity peak. A pH of 5.0 was optimum for purified enzyme activity and relatively stable between 40 to 100 min of incubation at this pH. The optimum temperature was 70ºC and 100% thermostable for 40 min after which a slight decline in activity was observed. The apparent Km for the hydrolysis of LBG from Lineweaver-Bulk plot was approximately 0.26 mg/mL, while the Vmax was 0.12 μmol/min/mL. The incubation of salts and organic compounds at 10 mM and 40 mM caused inhibition of enzyme activity. At 20 mM, enzyme activity was enhanced by FeSO4.7H2O, SDS and ZnSO4. 7H2O, while others caused inhibition of enzyme activity. The incubation of enzyme with CaCl2 and FeSO4.7H2O at 60 mM enhanced enzyme activity, while others caused inhibition. Conclusion: The result obtained from this study revealed that purified β-mannanase is active over a wide pH and temperature, and its stability implies that the enzyme will be useful during industrial processes where extreme conditions are required.

Comparative Study of the Antibacterial Effect of Mouth Washes and Vernonia amygdalina (del.) on Some Tooth Decay Causing Bacteria.

Aims: To determine the antibacterial effect of the ethanol stem extract of Vernonia amygdalina (bitter-leaf) and some mouth washes against some bacteria that have been implicated in causing tooth decay so as to establish the role of herbal medicine and chemical compounds in oral hygiene. Study Design: In vitro assay of antibacterial activities Place and Duration of Study: Dental Department of the State Specialist Hospital, Akure, Ondo State, Nigeria and Department of Microbiology, Federal University of Technology, Akure, Nigeria, between October, 2012 and January, 2013. Methodology: Bacterial isolates were collected, identified, standardized and the stem extract was prepared. Phytochemical screening of the extracts was carried out as well as the in vitro antibacterial assay using agar well diffusion technique. Minimum Inhibitory Concentration and antibiotics sensitivity test (disc diffusion assay) were also determined. Results: The stem extract showed the presence of anthraquinone, alkaloid, saponin, steroid and cardiac glycoside. The ethanolic stem extract of Vernonia amygdalina inhibited all the test isolates at a concentration of 50 mg/ml with the highest zone of inhibition observed against Staphylococcus aureus (26.0 mm) while the least zone of inhibition of 14.0 mm was observed against Streptococcus mutans. Colgate mouthwash exhibited the highest zone of inhibition against Staphylococcus aureus while the least was recorded by Brett against Staphylococcus epidermidis. The antibacterial assay compared well with Ciprofloxacin, and in most cases higher zones of inhibition were recorded than the commercial antibiotics. The Minimum Inhibitory Concentration of the mouth washes ranged from 30 to 70% while it was 12.5 mg/ml for the stem extract. Conclusion: Bioactive components of Vernonia amygdalina can be incorporated as ingredients in manufacturing mouthwashes and the plants’ stem can be used in the form of chewing stick. Further purification of the extract is necessary to further enhance greater antibacterial activity.

Comparative Studies on Citrullus vulgaris, Citrullus colocynthis and Cucumeropsis mannii for Ogiri Production.

Aim: This study investigated the microbiological, physicochemical and antinutritional properties of three varieties of fermenting melon seeds namely: Citrullus vulgaris (Schrad), Citrullus colocynthis (L) and Cucumeropsis mannii (Naud) for ogiri production. Methodology: Ogiri was produced from these three varieties of melon seeds following the traditional fermentation process while online monitoring was used to evaluate microbial hazards using standard microbiological techniques. Physicochemical and antinutritional properties were determined using standard methods. Results: Bacterial counts ranged from 7.0 x 103 cfu/g to 2.4 x 104 cfu/g for Citrullus vulgaris, 3.2 x 105 cfu/g to 3.7 x105 cfu/g for Citrullus colocynthis and 8.7 x 106 cfu/g to 9.1 x 106 cfu/g for Cucumeropsis mannii. Some of the isolated microorganisms from the fermenting melon seeds include Lactobacillus species, Bacillus species, Aerococcus viridans, Staphylococcus aureus, Micrococcus luteus, Aspergillus niger, Penicillium species and Fusarium eguseti. Cucumeropsis mannii had the highest crude fibre and protein (12.7 and 38.5 mg/g) but lowest values for fat and ash while Citrullus vulgaris recorded the highest values of 35.3 and 3.4 mg/g There were no significant differences in values obtained for sodium, Cucumeropsis mannii had highest values for potassium and phosphorus (0.36 and 0.29 mg/kg). Citrullus vulgaris was outstanding in mineral content for magnesium with the highest value of 0.27 mg/kg and lowest for calcium (0.29 mg/kg) compared to 0.30 and 0.34 for Cucumeropsis mannii and Citrullus colocynthis respectively. Anti-nutrients were highest in Citrullus vulgaris and lowest in Cucumeropsis mannii. Acidic pH of 5.78 was recorded in Citrullus colocynthis but increased to 8.91 and 8.69 in Citrullus vulgaris and Cucumeropsis mannii indicating that Citrullus colocynthis may not be appropriate for ogiri production. Conclusion: Cucumeropsis mannii compares favourably with traditionally used Citrullus vulgaris resulting in higher fibre, protein, mineral contents with lower values of anti-nutrients and therefore recommended as a good substitute for ogiri production.