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Articles by A.A. Ajayi
Total Records ( 5 ) for A.A. Ajayi
  A.A. Ajayi , A.O. Adejuwon and P.O. Olutiola
  The production of polygalacturonase during the deterioration of tomato (Lycopersicon esculentum Mill.) by Rhizopus arrhizus Fisher was investigated. The enzyme was partially purified by a combination of ammonium sulphate precipitation, gel filtration and ion-exchange chromatography. Two peaks of absorption, with molecular weight estimates of approximately 166 000 Daltons and 60 260 Daltons were obtained.
  A.A. Ajayi , C.F. Peter-Albert , M. Akeredolu and A.A. Shokunbi
  Two varieties of tomato fruits commonly available in Nigerian markets are the Roma VF and Ibadan local varieties of tomato fruits. The Roma VF fruits are oval in shape. It is a common type of cultivar in the Northern region of Nigeria and it is not susceptible to cracking. The Ibadan local variety of tomato fruits is a local variety commonly found on farmers fields in South-western region of Nigeria. They are highly susceptible to cracking. The Ibadan local variety was employed for this research. There are lots of benefits derived from the consumption of tomato fruits. The fruits can be made into tomato juice clarified with pectinases. Polygalacturonase is one of the pectinases used commercially in the clarification of fruit juice from different fruits. This study examined the production of polygalacturonase during the deterioration of tomato fruits by Aspergillus niger and the role of the purified polygalacturonase in the clarification of tomato juice. Tomato fruits of the Ibadan local variety were inoculated with mycelia discs containing spores of a 96-h-old culture of Aspergillus niger served as the inoculum. The organism from the stock culture was subcultured onto potato dextrose agar plates. The extraction of polygalacturonase after 10 days of incubation at 27°C was carried out by homogenizing the fruits with liquid extractant using the MSE homogenizer after the deteriorated fruits had been chilled for 30 min inside a freezer. Control fruits were similarly treated except that sterile potato dextrose agar served as the inoculum. The effect of different temperature of incubation and different volume of enzyme on the tomato juice from the tomato fruits was investigated. Extracts from the inoculated fruits exhibited appreciable polygalacturonase activity. The juice with polygalacturonase was visually clearer and more voluminous than the juice treated with water for all parameters studied. The highest volume of juice was obtained after an incubation period of 30 min for the tomato fruits. The increase in juice yield can be attributed to the hydrolysis of pectin which releases the sap inside the cells of the pulp. The occurrence of polygalacturonase in tomato tissues infected by A. niger coupled with the trace amount in the non-infected tissues suggests that the enzyme is of fungal origin. The role of the polygalacturonase in the clarification process was established. This study will be very useful for industrial tomato juice production.
  O.M. Atolagbe , A.A. Ajayi and O. Edegbo
  Rhizopus stolonifer is a fungus and one of the most common species of the genus Rhizopus. The organism has been a very important microbe used in the field of industrial microbiology. It has been used in the production of many hydrolytic and extracellular enzymes among which is the α-amylase. This enzyme has found various uses in the industry. Fruit juices are important sources of nutrients and they contain several important therapeutic properties that may reduce the risk of various diseases. An investigation on α-amylase extracted from soursop fruits deteriorated by R. stolonifer and the effect of the enzyme on soursop juice clarification was carried out in this study. The results obtained shows that the soursop juice with low concentration of extracted enzyme and less incubation time was more viscous and cloudy compared with the juice with high concentrations of amylase and higher incubation time which was clearer and less viscous. The results of this research will be very useful in soursop juice producing companies.
  G.I. Olasehinde , J.A. Akinyanju and A.A. Ajayi
  Studies were carried out to determine the disinfectant property of naphthol and its derivatives. The sensitivity of some clinical organisms as compared with the activity of some selected commercial disinfectants was tested. The methods employed for assessing the efficacy of disinfectants in this study are Minimal Inhibitory Concentration (MIC) Test and Capacity Use Dilution Test. The clinical organisms used for the tests are Pseudomonas aeruginosa, Salmonella typhi and Proteus mirabilis while the commercial disinfectants used are Dettol (Chloroxylenol), Savlon (Cetrimide/chlorhexidine mixture) and TCP (Trichlorophenol) and the Naphtholics are alpha naphthol and 2-amino-1,4-naphthoquinonimine hydrochloride. Dettol showed highest antibacterial activity against all the test organisms. Savlon`s antibacterial activity was high against the test organisms except Pseudomonas aeruginosa. TCP showed low activity against all the test organisms while Purified ∞-naphthol and its derivative, 2-amino-1, 4-naphthoquinonimine hydrochloride were found to exhibit disinfecting properties, with the derivative showing more antimicrobial activity than ∞-naphthol. The compounds have bactericidal effect against the test organisms used in this study.
  A.A. Ajayi , E.A. Onibokun , F.O.A. George and O.M. Atolagbe
  Chitinases are hydrolytic enzymes that break down the glycosidic bonds in chitin. Chitin is a component of the cell walls of fungi and exoskeletal elements of some animals (including worms and arthropods), therefore, chitinases are generally found in organisms that either needs to reshape their own chitin or dissolve and digest the chitin of fungi or animals. The importance of chitinase in industries cannot be overemphasized as it has been applied in agriculture, as a biopesticide for control of plant fungi infections, in medicine, as indicators of fungi infection and in waste management, for biodegradation of fish waste. African catfish (Clarias gariepinus) which plays host to bacteria is very readily available and easy to cultivate thus providing a cheap means of obtaining chitinolytic bacteria for the production of chitinase in commercial quantity. Bacteria populations isolated from the skin and gut of catfish were screened on colloidal-chitin agar medium. Chitinase production was determined by zones of hydrolysis produced after 96 h of incubation at 37°C. The result of this investigation revealed thirty-six pure bacterial isolates from the skin and gut of catfish. Gram staining test revealed, twenty five Gram positive bacteria while eleven were Gram negative. After four days of incubation, twenty-six bacteria isolates obtained from the gut and skin of catfish were selected as chitinase producing bacteria based on the clear zones of hydrolysis produced. The bacterial isolates obtained will be very useful for the production of chitinase which can be employed for the biocontrol of fungal pathogens and harmful insects. This study presents a first time report of Chitinase producing Bacillus cereus from the gut of catfish (Clarias gariepinus).
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