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1981 - 19884

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Start date: 1981End date: 1989

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    BIOSYSTEMATIC STUDIES IN SOME NIGERIAN SPECIES OF ANTHERICUM LIN. AND CHLOROPHYTUM KER-GAWL. (LILIACEAE)
    (1981-03) ADEYEMI, F. A.
    Field surveys and investigations of representatives of Anthericum L. and Chiprophytum Ker-Gawl. complex in Nigeria were carried out in their natural habitats in at least sixteen States of the Nigerian Federation. All herbarium specimens in the Forestry Research Institute, Ibadan and in nine Nigerian Univetfsities visited were examined (if any). So far, ten species of Anthericum and fifteen species of Chlorophytum have been reported and collected in Nigeria. They were all studied morphologically. Detailed ecological analyses including the Chemical composition of their soils were carried out on three taxa of Anthericum and ten taxa of Chrolophytum. Many living populations were sampled from their different natural habitats in Nigeria, Their representatives were cultivated in three locations for experimental studies. Data were collected on the morphology by conventional methods and analysed. Anatomical data were amassed from the leaf surface patterns and the roots. Types of leaf margin anatomy were noted. Cytological studies were carried out in five taxa of Anthericum and eleven taxa of Chlorophytum. There were inter-generic hybridization tests. The use of lea f vein spacing interval and anther: filament ratio as taxonomic criteria have been suggested and their usefulness in the monocotyledon taxonomy, especially in Liliaceae, needed to be further explored. The importance of leaf margin anatomy as a taxonomic criterion above species level was highlighted. Chromosome counts for seven taxa were confirmed, viz; C. macrophvllum (A. Rieh.) Aschers 2n = 28. C. blepharophvllum gchwinf. ex Bak. 2n = 28. C. atenopetalum I Bak. 2n = 14. C. atenopetalum II (sp. nov.) 2n = 14. C. laxum R. Br. 2n = 14. C. inomatum Ker-Gawl. 2n = 14. C. togoense Engl. 2n = 14. New chromosome counts were recorded in :- C. geophilum Peter ex. v. Poelln. 2n = 28. C. alisaifolium Bak. 2n = 16. Chiprophytum X ( related to C. elatum ) 2n = 16. C . caulescens (Bak.) Marais & Reilly ( formerly A. caulescens Bak.) 2n = 16. A. Limosum Bak. 2n = 16. A. pterooaulon I Welw. ex Bak 2n = 24. A. Pterocaulon II 2n = 16. A. nubicum Bak. 2n = 16. A. pubirhachis Bak. 2n = 16. A. uvuiense 2n = 16. The possible evolution o f chromosome numbers in the complex has been postulated. The possible chromosome evolution o f the complex based on the available data from this work and existing literature has been proposed. Evidence was adduced to Support the Suggestion that the possible basic Chromosome number in the complex was x = 4, and that n = 8 Was a secondary basic number. It has also been contended that n =7 and n= 6 evolved from a more primitive n = 8. Supplementary evidence in Support of Marais and Reilly’ s (1978) transfer of A. caulescens from Anthericum into Chloronhytum as C. caulescens was adduced. A form of C.stenopetalum has been elevated to species level on account of its morphological, cytological and genetic differences. A new taxonomic key has been proposed for the Separation of Anthericum and Chiprophytum. The possible mode of evolution of some Nigerian species of Anthericum and Chlorophytum. based mainly on their leaf surface patterns, has been proposed.
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    PHYSIOLOGICAL STUDIES ON BACILLUS SPECIES ISOLATED EROM FERMENTED AFRICAN LOCUST BEAN [PARKIA BIGLOBOSA (JACQ.) BENTH-]
    (1988-09) ADERIBIGBE, E. Y.
    The physiological activities of Bacillus species that ferment African locust bean (Parkia biqlobosa (Jacq.) Benth] to produce ‘iru’ were investigated. The strains studied belong to the B. subtillis group and were designated BS1, BS2, BS3, BLl, BL2, BL4 and BP2. These seven strains showed significant differences (at α= 0.05) in growth and extracellular proteinases production. The following (descending) order was obtained for the growth of the organisms in liquid medium: BS3 > BS1 > BL4 > BL2 > BS2 > BL1 > BP2 The order of proteolytic activity (in descending Order) of the strains in nutrient broth medium containing African locust beans was: BL2 > BP2 > BS2 > BL4 > BS3 > BL1 > BS1 The best three strains (oh the basis of proteinase production) BL2, BP2 and BS2 showed further Variation in the production of other extracellular enzymes. The three strains produced amylase and polygalacturonase constitutively and varied amounts of sucrase and galactanase. Phytase activity was not detected in culture broth of strain BS2. None of the strains BS2, BL2 and BP2 produced pectinmethylesterase in nutrient broth medium with or without African locust bean. The three strains were lipolytic on tributyrate agar plates and produced trace amounts of lipase in broth medium containing African locust bean. In most cases, presence of African locust bean in culture medium enhanced production of extracellular enzymes significantly in the three strains. Agitation was found to be necessary for optimal production of extracellular proteinases by the strains BS2 and BL2. Among the carbon sources used, fructose and glucose repressed proteinase production significantly (at α = 0.05) in strain BS2 while raffinose and starch favoured proteinase production. Among the carbohydrates which favoured the production of proteinases are, inorder raffinose > starch > arabinose > galactose > sucrose. The effects of different nitrogen sources on proteinase production by strain BS2 were also investigated. Casein enchanced preduction but the effect was not significant (at α = 0.05) while other nitrogen sources repressed proteinase production significantly. The nitrogen sources repressed proteinase production in the Order: Leucine > Urea > KNO3 > NH4NO3 > Aspartic acid > Glutamic acid > Alanine. The presence of African locust bean in culture medium enhanced proteinase production in the three strains, but the effect was not significant (at α = 0.05). The crude proteinases of sttain BS2 had Optimum activity at pH 7.5. Optimum temperature for activity of the proteinases was 35°C, and the proteinases were relatively stable at 60°C, but were quickly denatured at temperatures > 70 C. The apparent Km of the crude proteinases of the strains BS2, BL2 and BP2 were approximately 39.14mg/ml, 33.29mg/ml and 44.1mg/ml respectively. Multiple proteinase bands were obtained after electrophoretic Separation of the crude enzymes in all strains. During purification, the proteinases were precipitated out between 55 - 70% of ammonium sulphate Saturation levels. There was a substantial loss in proteolytic activity during the salting out process. Three proteolytic activity peaks were obtained during ion-exchange chromatography of crude enzymes of strains BS2 and BL2. The peaks I, II and III were identified to be serine proteinase, neutral proteinase and an esterase (with low proteolytic activity) respectively. The serine proteinases of the two strains BS2 and BL2 showed hydrophobic properties. The molecular weights of the serine, neutral and esterase proteinases for strain BS2 were 29800, 24000 - 27400 and 33900 - 38400 respectively while those of strain BL2 were 18200 - 19700, 22600 and 33500 respectively. The purified neutral proteinase had higher specific activity than the serine proteinase while the esterase was characterized by low specific activity. The esterase was responsible for the multiple proteinase bands pattern observed in the electrophoresed crude enzymes. The possibility of selecting strains capable of producing wider variety and higher yields of extracellular enzymes to bring about more digestible fermented product is discussed.
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    STUDIES OF TOXIGENIC AND ZOOPATHOGENIC FUNGI ASSOCIATED WITH THE SPOILAGE OF NIGERIAN POULTRY FEEDS
    (1988-03) ADEBAJO, L. O.
    Six species of known toxigenic and zoopathogenic fungi were isolated from Nigerian poultry feeds. These include Aspergillus flavus Link: Fr. (IMI 280819), A. fumigatus Fres. (1M1 280822), A. niger v. Tieghem (IM1 280823), A. oryzae (Ahlburg) Cohn (IM1 280831), Rhizopus arrhizus Fischer (1M1 280827) and Rhizomucorpusillus Lindt Schipper (1MI 280824). Growth-temperature range for the fungi was between 15° and 45°C. Aspergillus fumigatus and Rhizomucor pusillus are thermotolerant with optimum growth 40° C while Rhizopus arrhizus had optimum growth at 30° C. For Aspergillus flavus, A. niger and A. oryzae the optimum growth was at 35° C. The pH growth studies showed that all the fungi had good mycelial growth at pH 4-8 with optimal growth at pH 5.5 for Aspergillus fumigatus, A. flavus and A. oryzae. Aspergillus niger, Rhizomtlcor pusillus and Rhizopus arrhizus had optimal growth at pH 6.0. Nutritional studies showed that all the fungi were capable of utilizing the various forms of carbon and nitrogen provided to varying extents. Starch and dextrin were excellent sources of carbon for mycelia growth and sporulation while pectin and carboxymethyl cellulose (CMC) were poorly utilized by all the fungal isolates. The fungal species grew poorly on native cellulose (filter papers) except Rhizomucor and Rhizopus arrhizus which showed no growth pusillus on this carbon source. Apart from tryptophan, all the nitrogen sources supplied were utilized for growth and sporulation by the test fungi though to the best nitrogen source varying extents. Casein was for all the fungi. Feed infusion medium also supported growth and sporulation of all the isolates. Varying quantities of aflatoxins (B(1), B(2_ and G(2)) were produced by Aspergillus flavus and A. oryzae on modified Czapek-Dox media. None of the remaining fungal species produced afaltoxin. Peak aflatoxin B(1) production was on the 8th day of incubation by the two toxigenic fungi. Optimum pH and temperature for the production of toxins were pH 5 and 300 C respectively. Major sources of aflatoxins in poultry feeds due to mould infestation in increasing order of importance were: palm kernel, corn and groundnut cake meals. Studies on aflatoxin production on feed concentrates by A. flavus and A. oryzae showed that under suitable conditions of moisture and temperature, dried brewers grains, wheat offals, palm kernel, corn and groundnut cake meals were suitable substrates for toxin production. Other feed concentrates: fish, blood, oyster shell and bone meals were found to be unsuitable substrates for aflatoxin production. Aflatoxins were not detected in poultry droppings before and after inoculation with the toxin producing fungi. All the fungal isolates produced extracellular amylases, cellulases, proteases and lipases. The synthesis and activity of these enzymes were affected by external factors such as the pH, incubation temperature and type of carbon source in the growth medium. Optimum activity for all the enzymes produced by the isolates was in acidic media (pH 4-6) and within a temperature range of between 40°C and 50°C. On the basis of these findings recommendations were made for the control of the toxigenic and zoopathogenic fungi in poultry feeds and other stored agricultural products.