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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.
MICROBIOLOGICAL STUDIES OF GUINEA CORN FERMENTATION FOR OGI-BABA PRODUCTION
(1986-01) ADEYELE, S.
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.
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.
Environmental impact assessment of the rainforest vegetation in Agbara industrial estate, Southwestern Nigeria
(1996) Chukwuka, K. S.; Ayodele, A. E.; Osonubi, O.
The vegetation of Agbara industrial estate, South-western Nigerian was studied with a view to determining the floristic and structural composition before the full take off of the various industries. The area is a lowland rain forest, drier - type with the major growth forms including trees, shrubs, palms and climbers. A total of 897 plants were enumerated in five transect of 2 km. Species diversity index for the area is in the range of 0.01 - 0.24 while dominance values range from 0.00 - 0.01. Tree density was estimated to be 56.1 stems per km sq. The study shows evidences of regrowth vegetation, subsistence farming activities involving arable crops of previous land use. The area is also shown to have suffered previous encroachment or early succession. No particular species is dominant. It is suggested that adequate pollution control measures need to be put in place if the biotic communities of the estate are not to be endangered. Resettlement of the inhabitants away from the vicinity of the operating industries is also proposed.
Floristics and structure of the remnant forests of the Obafemi Awolowo University campus, Ile-Ife Nigeria and their potential for conservation
(Botanical Society of Nigeria, 1997) Chukwuka, K.; Isichei, A. O.
The floristic composition and the girth sizes of the woody plants in seventeen sample forest plots at the Obafemi Awolowo University, Ile-Ife, Nigeria were studied with a view to making recommendations on the conservation of the forest. The 120 species found are those typical of drier lowland forest of southern Nigeria. Twenty-six species occurred in 8 of the 17 plots while 28 occurred in one plot each and could be regarded as rare. About 70% of the stems are less than 30 cm girth at breast height, an indication of recent disturbance. Brachystegia eurycoma dominated the ≥ 120 cm girth class and was found on hilly slopes that were suitable for farming. The benefits of conservation of the Campus forest include protection of an important watershed and teaching and research.
Environmental audit of the tunu/kanbo forests of the Niger Delta, Nigeria
(1997-11) Chukwuka, K. S.; Ayodele, A. E.
The morphology and ecology of the genus synsepalum (A.Dc) Daniell (sapotaceae) in Nigeria
(Ecological Society of Nigeria, 1999) Ayodele, A. E.; Chukwuka, K. S.
The genus Synsepalum is represented by three species in Nigeria. It is confined to the lowland rainforest region of the country. Synsepalum dulcificum is called the ‘miraculous’ berry or the 'magic plant' on account of the protein based sweetening agent miraculin found in the pulp of the fruit. The plant also produces a fairly hardwood which is particularly used as firewood by the indigenous people while the twigs are used as chewsticks. S. stipulatum popularly called the "Blacksmiths' charcoal wood" is known to supply the best charcoal to the Benin blacksmiths. S. glycydorum is not of much economic importance to the people but it is restricted in its distribution to the Southeastern part of Nigeria. From the standpoint of uses and restricted distribution, there is need for in-situ and ex-situ conservation of these species for sustainable utilization. The largest leaves with-the longest petioles are found in S. stipulatum, while the smallest leaves with the shortest petioles are in S. dulcifcum. The leaves and petioles of S. glycydorum are intermediate of the other two species. The leaves generally are elliptic to oblong to oblanceolate in shape with acuminate apices. However, the apex in S. dulcificum may be acute, rounded or rarely refuse. The leaf bases in the genus are usually cuneate. The leaves are glabrous except in S. dulcificum which may be hairy on the abaxial surface.
Ecological utilization of the weed - tithonia diversifolia and sustainability of the paper industry in Nigeria
(Science Association of Nigeria, 2000) Chukwuka, K. S.
Tithonia diversifolia is found growing abundantly within the forest zone of Nigeria. The evaluation of the pulp and paper making properties of T. diverisifolia showed average fibre length, width, wall thickness and lumen of 827.66 ± 186.40αµm, 20.29 ± 3.92 αµm, 3.96 ± 0.28 αµm and 12.16 ± 3.96 µm respectively. This short fibre length and small wall thickness of T. diversifolia made it unsuitable for making strong papers. However, it is good material for making newsprints, toilet tissues, serviette papers, packing cartons and egg crates. This will go a long way towards improving the welfare and living conditions of Nigerian given that paper is a civilised material.
Studies on antimicrobial potentials of three ganoderma species
(2010-05) Jonathan, S. G.; Awotona, F. E
The fruit bodies of three Ganoderma species namely G. lucidium, G. applanatum and G. australe were collected from the decaying logs within the University of Ibadan Botanical Gardens .Invitro antagonistic effect of the ethanol, methanol and distilled water extracts of these macro fungi were tested against some disease causing microorganisms. Both crude and pure extracts of these Ganoderma species exhibited various degree of inhibition against the test organisms. The widest inhibitory zone (20.3mm) were obtained with the crude methanolic extract of G. lucidium against Proteus mirabilis while the highest in-vitro antifungal activity (24.3mm) was observed in the crude ethanolic extracts of G. lucidium against Aspergillus niger. The lowest zone of inhibition (2.3mm) was demonstrated with the aqueous extract of G. australe against Escherichia coli and 2.7mm with purified extract of G. australe against Penicillum oxalium . The minimum inhibitory concentration (MIC) for the ethanol extract ranged between 1.7 and 5.0mg/ml for bacteria and between 2.0 and 6.0mg/ml for fungi. The implications of these findings were discussed.
Antibacterial activities of daldina concentrica
(2011-01) Jonathan, S. G.; Olawuyi, O. J.; Popoola, O. O.; Aina, D. A.
Activities of the distilled water, ethanolic and chloroform extracts of Daldina concentrica an ascomycetous fungus was investigated on Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, Bacillus cereus and Staphylococcus aureus) using agar well diffusion method. Ethanolic extract of Daldina concentrica showed significantly antibacterial activity against all the test microorganisms except Bacilllus cereus (P ≤0.05). Staphylococcus aureus was the most sensitive organism to the extracts of this fungus with 17.0mm zone of inhibition with ethanol extract. It was also shown that chloroform extract of Daldinia concentrica possessed higher anti-bacterial activity against the five tested microorganisms. The effect of fresh tissues of the fungus on test bacteria indicated that Proteus mirabilis was the only sensitive organism with 5.0mm zone of inhibition while other bacteria were resistant. The implications of these findings were discussed.
Comparative study of antibacterial activities of ethanol extracts of the bark and seeds of garcinia kola and caricapapaya
(2011-05) Ogunjobi, A. A.; Ogunjobi, T. E.
A comparative study of the antimicrobial activities of the bark and seed extracts of Garcinia kola and Carica papaya were tested using the Agar well diffusion method on eight bacterial strains - Staphylococcus aureus; Salmonella typhi B; Shigelladysenteria; Pseudomonas aeruginosa; Serratiamarcescens; Pseudomonas fluorescens; Proteus vulgaris; and Bacillus subtillis. Phytochemical screening shows that both bark and seed of the two plants contain reducing sugars, phenols and alkaloids whereas the pawpaw extracts contained tannins which were absent in the bitter kola plant part. Garcinakola on the other hand has saponin that was not present in Caricapapaya. The Garcinia seed ethanol extract manifested the best inhibitory activities against the test bacteria, producing inhibition zones ranging from 12–23mm. There was no resistance from any of the test bacteria. The pawpaw seed extract was also effective against the test bacteria. The inhibition zone observed ranged from 11-16mm. The ethanol extract of both plants were active against Staphylococcus aureus, Shigelladysenteria, Pseudomonas fluorescens; and Salmonella typhi B. Pawpaw leaf ethanolic extract significantly inhibited Pseudomiasaeruginosa, while Garcinia seeds ethanolic extract also inhibited Bacillus substilis. The activity index of ethanol extract of Garcinia kola seed was higher than that of pawpaw seed when both gentamicin and tetracycline were used as a standard antibiotics. The aqueous extract of both plant parts were not as effective as the ethanol extract. The activities of these medicinal plants against the tested bacterial species in this study justified their common use in African traditional medicine in the treatment of various ailments.
STUDIES ON THE INFLUENCE OF VESICULAR ARBUSCULAR MYCORRHIZA AND FERTILIZATION ON CHILI PEPPER (Capsicum annuum L.) IN DIFFERENT CROPPING SYSTEMS
(2011-11) ADETUNJI, J. A.
Investigations were conducted with four pot and two field experiments on the influence of vesicular arbuscular mycorrhiza (VAM), and fertilization on chili pepper, Capsicum annuum var. tatase (Yoruba) in different cropping systems. All experiments were factorial in a randomized complete block design (RCBD) and each treatment was replicated three times. The first two pot experiments carried out in the Department of Botany and Microbiology, University of Ibadan under natural solar illumination and daily temperature, consisted of three types of VAM inoculation (Glomus mosseae, Glomus etunicatum and control), two levels of cropping systems (sole chili pepper and chili pepper intercropped with cowpea) and two levels of single superphosphate (0kg P/ha and 60kg P/ha) simultaneously in sterile and non-sterile soils. The third pot experiment consisted of three types of VAM inoculation (Glomus fasciculatum. Glomus mosseae and control), three levels of cropping systems (sole chili pepper, chili pepper with soybean intercrop and chili pepper with cowpea intercrop) and two levels of rock phosphate supplement (0kg P/ha and 60kg P/ha) in sterile. Finally the fourth pot experiment consisted of three species of VAM (Glomus mosseae, Glomus etunicatum and Glomus fasciculatum) three levels of organic fertilization (control, soybean intercrop and 5% organic manure) and three levels of rock P (0kg P/ha, 30kg P/ha and 60kg P/ha) also in sterile soil. The latter two pot experiments and the field experiments were located at National Horticultural Research Institute Ibadan, a derived savanna and transition zone between a tropical rain forest and southern guinea savanna. The first field experiment consisted of three types of VAM inoculation (Glomus mosseae, Glomus fasciculatum and control) three levels of cropping systems (sole chili pepper, chili pepper with cowpea intercrop and chili pepper with soya bean intercrop) and two levels of rock P (0kg P/ha and 60kg P/ha). The second field experiment consisted of three species of VAM fungi (Glomus mosseae, Glomus fasciculatum and Glomus etunicatum), three levels of organic fertilization (control, soya bean intercrop and 5% organic manure) and three levels of rock P (0kg P/ha, 30kg P/ha and 60kg P/ha). The soil pH (6.5) was significantly (P<0.05) reduced with Glomus mosseae inoculation while there was significantly (P<0.05) higher %C and Ca at 60kg P/ha than 0kg P/ha inorganic P supplement in non-sterile soil. Apart from P, the uptake of N, K, Ca, Mg, Zn and Fe were significantly (P<0.05) improved by mycorrhizal inoculation. The dry matter yield of mycorrhizal plant was significantly (P<0.05) higher than non-mycorrhizal plant with Glomus mosseae performing best in sterile soil. However, there was a significant drop (16%) in dry matter yield with the addition of 60kg P/ha single superphosphate. Mycorrhizal inoculated pepper plants had a twofold increase in fruit weight over uninoculated-mycorrhizal pepper plants. The use of rock P with organic manure in the presence of VAM enhanced fruit yield for chili pepper. There were significant (P<0.05) variations in the performance of mycorrhizal species in both pot and field experiments subject to soil environment and cropping systems. The experiment has provided the basis for the recognition of the fact that mycorrhizal activity is not only a component of plant system but also a soil-plant system improver.
EVALUATION OF RHIZOBIUM AND MYCORRHIZA INTERACTIONS IN SUSTAINABLE MAIZE (Zea mays L.) AND SOYABEAN (Glycine max L.) PRODUCTION
(2014-09) AMUSAT, M.A.
Maize and soyabean are among the staples in the world. Their sustainable production through the use of synthetic fertilizer causes soil degradation and ground water contamination. An alternative means of boosting and sustaining the production of these staples through the use of rhizobium and mycorrhiza have been reported but there are contradictory reports on interactions between the two organisms. Therefore, the objective of this study was to assess the influence of Rhizobium japonicum and Glomus etunicatum on maize and soyabean production. Three farmlands in Oyo town were purposively selected. In the first and second farmlands were planted sole maize and soyabean respectively and were rotated the following season while both crops were intercropped on the third farmland. The experimental layout was randomised complete block design in split plot with three replications. The treatments were mycorrhizal, rhizobium, combined inoculations and uninoculated (controls). Maize was inoculated with Glomus etunicatum, while soyabean was inoculated with Glomus etunicatum and broth of Rhizobium japonicum. The plants’ population densities were 66,667 and 266,667 respectively. Growth parameters were measured using established methods at two weeks interval. The plants’ biomass, yield, proximate and nutrient analyses were determined usin g standard methods. Data were analysed using descriptive statistics and ANOVA at p = 0.05. The average heights (cm) of mycorrhiza, rhizobium and combined inoculated plants were 59.8±3.0, 68.3 ±1.8 and 63.7±1.2 respectively while that of their uninoculated counterparts was 52.7±3.4 in both sole and intercropped soyabean. Similarly, significant differences in biomass production were obtained between inoculated (3.7, 3.9, 3.9 g) and uninoculated (2.9 g) soyabean. Sole and rotated soyabean had significant biomass values which were 34.7 and 23.4 % respectively higher than the intercropped soyabean. There was no significant difference in nutrient contents of soyabean; its percentage proximate contents showed significant effects of rhizobium (4.5), mycorrhiza (4.0) or combined inoculation (4.2) in relation to uninoculated treatments (3.1). In intercropped and rotated maize, higher values of number of leaves and plant height were obtained in the mycorrhizal inoculated treatments compared with uninoculated counterparts. Biomass values of the intercropped and rotated maize were 15.5 and 12.5 % respectively higher than that of sole maize. There was significant main effect of mycorrhizal inoculation on nutrient contents of maize in intercropped and rotated farmlands. The grain yields of sole and combined inoculated soyabean ranged between 648.1–738.7 kgha-1 and significantly outweighed that of the uninoculated counterparts (524.6–584.9 kgha-1). There were no significant differences in grain yield of sole and intercropped maize, however, grain yield of rotated maize (585 kgha-1) was significantly higher than that of sole maize (512.9 kgha-1). Interactions between R. japonicum and G. etunicatum stimulated growth of both crops, while intercropping enhanced growth and biomass production of maize but had negative effects on soyabean. Interaction between Rhizobium japonicum and Glomus etunicatum had synergistic effects on growth of maize and soyabean. The combination of the two organisms and the systems of farming favoured the yield of both crops. The use of both microsymbionts combined with the cultural farming systems is therefore recommended to boost soyabean and maize production.
MODELLING OF HEAVY METAL BIOACCUMULATION OF Eichhornia crassipes [MART.] SOLMS AND Pistia stratiotes L. IN OLOGE LAGOON, LAGOS, NIGERIA
(2016-03) NDIMELE, C. C.
Macrophytes such as Eichhornia crassipes and Pistia stratiotes are known bioaccumulators found in the Ologe Lagoon which receives effluents mainly from Agbara Industrial Estate. However, the mechanism of heavy metal bioaccumulation by these macrophytes has not been fully understood. This study was designed to determine the mechanism of heavy metal bioaccumulation and model the phytoremediation capabilities of the macrophytes. Five sampling stations: Owo (before the point of discharge of effluent as control), Agbara, Otto Jetty, Morogbo and Etegbin (after the point of effluent discharge) were selected for the study. Water samples, sediments, E. crassipes and P. stratiotes were collected using standard procedures in these stations from July, 2013 to December, 2014 from the lagoon and analysed for heavy metals using standard methods. Temperature, pH, Conductivity, Total Suspended Solids (TSS), Total Dissolved Solids (TDS), Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), and Dissolved Oxygen (DO) were determined according to APHA methods. Selected heavy metals: Zn, Fe, Cu, Pb and Cd in water, sediments and the two macrophytes were determined in accordance with FAO/SIDA method. Eichhornia crassipes and P. stratiotes were grown in three different concentrations (10, 15 and 20 mg/L) of CuSO4.5H2O; ZnSO4; FeSO4.7H2O and Pb(NO3)2 in three replicates for six weeks. Thereafter, plant leaves, stems and roots were harvested and analysed for metal bioaccumulation and translocation. Time evolution of pollution was determined using first and second-order kinetic models. Data were analysed using descriptive statistics, ANOVA and Fisher’s LSD test (α0.05). Water temperature ranged from 28.7±0.37-29.4±0.69°C, pH (6.7±0.1-6.9±0.1), Conductivity (1565±784.7-3088±1478.6 µS/cm), TSS (10.4±0.5-20.6±1.2 mg/L), TDS (89.2±1.8-1739±872.2 mg/L), BOD (2.9±0.7-3.7±0.2 mg/L), COD (13.8±0.8-23.9±1.0 mg/L) and DO (4.2±0.2-4.9±0.2 mg/L). The concentration of Zn (30±2.0 µg/L) in water sample was higher than the USEPA limit (6 µg/L at 45 mg/L hardness) for the protection of aquatic ecosystems. The highest {Fe (2310±613 mg/kg) and Cu (38.20±10.21 mg/kg)} and lowest {Fe (1305±848 mg/kg) and Cu (2.92±0.37 mg/kg)} concentrations in sediment were recorded in Agbara and Etegbin respectively. The concentration (mg/kg) of heavy metals in E. crassipes and P. stratiotes from Agbara was significantly higher (Fe=1368±236.12; Zn=42.60±5.62) than values obtained from other sampling stations (Fe=470±55.96-642.58±303.26; Zn=11.14±1.83-20.41±4.31). In the laboratory experiment, metals were accumulated through the roots to the shoot (phytoextraction) via a concentration gradient (for E. crassipes pots spiked with 10, 15 and 20 mg/L of Zn, the average quantity of the metal absorbed were 5.56±0.09, 8.89±0.60 and 15.58±0.15 mg/L respectively). The bioaccumulation factor in E. crassipes varied from 10 (Pb) to 9000 (Fe) while in P. stratiotes, it varied from 9 (Pb) to 8500 (Cu). Translocation factors were higher in root/stem (7.06±1.09 for Pb) than stem/leaf (5.42±1.12 for Pb). Iron accumulation in different parts of E. crassipes {(mg/kg) was: {leaf (0.45±0.06-15.58±0.15); stem (0.33±0.05-16.48±0.44); root (0.40±0.07-18.50±3.16)} and P. stratiotes was: {leaf (0.36±0.06-6.67±1.17) and root (0.45±0.08-7.49±1.78)}. Pots seeded with Fe maintained green colouration for a longer time than those seeded with Cu, Zn and Pb. The time evolution of pollution was best described by first-order kinetic model. Eichhornia crassipes and Pistia stratiotes bioaccumulated heavy metals and the mechanism of bioaccumulation is a function of time and level of concentration of the heavy metals.
MYCOTOXIN PRODUCTION AND MOLECULAR CHARACTERISATION OF Penicillium SPECIES ISOLATED FROM MILLET GRAINS (Pennisetum glaucum) (L.) R. Br.) IN SOUTHWESTERN NIGERIA
(2017-01) KOTUN, B. C.
Millet, a widely consumed food crop, is subject to fungal contamination during storage. These fungi produce mycotoxins in stored food products. Mycotoxins such as citrinin and ochratoxin produced by Penicillium species have been reported to be injurious to consumers. Knowledge of the fungi involved in the production of these mycotoxins will help in the control of its spread in food products. However, there is dearth of information on the mycotoxins produced by Penicillium on millet grain and the species characterisation with molecular technique in Nigeria. Hence, this study was designed to investigate the distribution of Penicillium species and determine the presence of mycotoxins in the millet grains with molecular techniques. Samples of millet grains were purchased from three randomly selected markets each in Lagos, Ogun, Ondo, Oyo and Ekiti states all in southwestern Nigeria. One hundred grains from each of the millet samples were employed for isolation of fungi using Dichloran rose bengal chloramphenicol agar. Morphological identification of the fungal isolates was done using Pitt`s manual. The DNA of the Penicillium species were isolated using standard procedures. Similarities between species were determined by amplifying their internal transcribed spacer (ITS1, ITS4) region and partial beta tubulin gene (Bt2a, Bt2b). Physiological assessment of the Penicillium isolates which includes optimum pH, carbon and nitrogen sources, temperature and incubation time for mycelial growth were carried out using standard methods. Toxigenic screenings of the isolates were carried out by amplifying the genes pksCT, ctnA, orf3 and otanps responsible for citrinin and ochratoxin production. The effects of pH and temperature on mycotoxin production were determined and quantified using Enzyme linked immunosorbent assay. Data were analysed using descriptive statistics. Thirty-four isolates were obtained, out of which twenty-three were identified as Penicillium citrinum (17), P. capsulatum (1), P. simplicissimum (1), P. oxalicum (1), P. steckii (2) and P. chrysogenum (1). Distributions among the states were Ondo: Penicillium citrinum, P. simplicissimum and P. oxalicum, Ogun: Penicillium citrinum and P. chrysogenum while only Penicillium citrinum was obtained from Lagos, Oyo and Ekiti states. Twenty-one isolates showed amplification to the beta tubulin gene with a uniform amplicon size of 500 base pair, while P. simplicissimum and P. oxalicum exhibited variation in amplicon fragement sizes (450 and 550 base pair), respectively. Physiological assessment of the isolates showed optimum growth at pH 8 having 2.51 g Mycelia Weight (MW) and starch as carbon source having (2.14 g MW), (NH4)2SO4 as nitrogen source having (0.86 g MW), optimum temperature was at 30 °C having (0.96 g MW) and 14 days as best incubation time with 0.94 g as dry MW. Toxigenic genes ctnA (678-679 base pair), orf3 (428-447 base pair) and otanps (788 base pair) was detected in six Penicillium (26%) isolates. Ochratoxin production was highest at pH 8 with 7.0 ppb, and at 25 °C with 5.0 ppb. Distribution of Penicillium on millet grain across the study area was determined, the isolates were characterised and mycotoxin from Penicillium citrinum was found to be above the standard permissible limit of ochratoxin.