Background: Climate-induced challenge remains a growing concern in the dry tropics, threatening carbon sink potential of tropical dry forests. Hence, understanding their responses to the changing climate is of high pr...Background: Climate-induced challenge remains a growing concern in the dry tropics, threatening carbon sink potential of tropical dry forests. Hence, understanding their responses to the changing climate is of high priority to facilitate sustainable management of the remnant dry forests. In this study, we examined the long-term climate-growth relations of main tree species in the remnant dry Afromontane forests in northern Ethiopia. The aim of this study was to assess the dendrochronological potential of selected dry Afromontane tree species and to study the influence of climatic variables (temperature and rainfall) on radial growth. It was hypothesized that there are potential tree species with discernible annual growth rings owing to the uni-modality of rainfall in the region. Ring width measurements were based on increment core samples and stem discs collected from a total of 106 trees belonging to three tree species (Juniperus procera, Olea europaea p. cuspidate and Podocarpus falcatus). Thesubsp. collected samples were prepared, crossdated, and analyzed using standard dendrochronological methods. The formation of annual growth rings of the study species was verified based on successful crossdatability and by correlating tree-ring widths with rainfall. Results: The results showed that all the sampled tree species form distinct growth boundaries though differences in the distinctiveness were observed among the species. Positive and significant correlations were found between the tree-ring widths and rainfall, implying that rainfall plays a vital role in determining tree growth in the region. The study confirmed the formation of annual growth rings through successful crossdating, thus highlighted the potential applicability of dendroclimatic studies in the region. Conclusions: Overall, the results proved the strong linkage between tree-ring chronologies and climate variability in the study region, which further strengthens the potential of dendrochronological studies developing in Ethiopia, and also has great i展开更多
Vegetable oil Spills are becoming frequent and are potentially more challenging than petroleum hydrocarbon spills. Microbial lipases occupy a place of prominence among biocatalysts are often used for remediation of ve...Vegetable oil Spills are becoming frequent and are potentially more challenging than petroleum hydrocarbon spills. Microbial lipases occupy a place of prominence among biocatalysts are often used for remediation of vegetable oil-polluted sites. This work was carried out to isolate microorganisms from oil-polluted sites and screen them for their lipolytic activity. Microorganisms were isolated from eight experimental soil samples contaminated with different types of vegetable oil, soil from an oil mill in Ibadan, and normal uncontaminated soil as a control. The isolates were characterized, identified and those common to at least one of the experimental sites and oil mill sites were screened for their lipolytic activity. Data obtained were analysed using Duncan Multiple Range Test. Seventy three microorganisms were isolated from the polluted soil and identified as species of Bacillus (16), Pseudomonas (12), Flavobacterium (6), Alcaligenes (2), Proteus (3), Micrococcus (1), Aspergillus (9), Penicillium (6), Saccharomyces (4), Geotrichum (1), Kluveromyces (1). Bacillus subtilis, Bacillus licheniformic, Pseudomonas cepacia, Pseudomonas fluorescens, Flavobacterium sp., Alcaligenes sp. and Candida parapsilosis which were common to at least one of the experimental site and oil mill site were preliminarily screened for lipolytic activity and all nine confirmed by presence of halos around the colonies. These screened organisms have potential for the degradation of fatty waste. They could therefore be employed in environmental clean-up of vegetable oil spill site.展开更多
The Ikogosi Warm Spring is a unique ecological niche in Western Nigeria with an average temperature and pH of 38°C and 5.8 respectively. It mixes with an adjacent cold spring (28°C & pH 7.6), about 100 m...The Ikogosi Warm Spring is a unique ecological niche in Western Nigeria with an average temperature and pH of 38°C and 5.8 respectively. It mixes with an adjacent cold spring (28°C & pH 7.6), about 100 meters from source, yielding a confluence body of water of 32°C and pH 7.7. To explore the bacterial community structure of this uncommon environment and to scan for potentially useful bacteria, metagenomes extracted directly from five samples (source and mid-point of warm spring;source and midpoint of cold spring, and the confluence) were analyzed. Using the MiSeq Illumina next generation sequencing protocols, the V3-V4 region of the 16S rRNA gene pool was sequenced and analyzed by QIIME (Quantitative Insights into Microbial Ecology) and R software. At least 11% (47,446) of all the sequences were unknown to any of the databases employed. Bacterial diversity and abundance at the source of both springs were extremely low, accounting for less than 0.07% of the total sequence reads at the confluence, 100 m downstream. In contrast to the highly diversified mesophilic confluence community where 21 different phyla were identified, only 4 and 5 phyla were recovered from the source-point of the warm spring and cold spring respectively. The most prevalent phyla in all samples were members of the versatile Proteobacteria (35% - 50% relative abundance), and the hardy Firmicutes (33% - 40%). Operational taxonomic units (OTUs) obtained from all the samples averaged at 1414. Temperature and pH were equally significant predictors of genomic diversity and richness, with the warm and cold spring sources having less than 5 bacteria phyla. Exiguobacterium sp. (a potential plastic degrader) and other deep rooted bacteria were found in the warm spring while the cold spring outflow contained among others such as Rubrobacter sp. and Chloroflexi sp. (which is close to the phylogenetic root of the domain Bacteria). Many taxonomically unresolved sequences could indicate the presence of potentially novel bacteria in this unique body of wa展开更多
Antibiotic resistance among enteric bacterial pathogens complicates the heavy diarrhoea disease burden. Antimicrobial resistance of Campylobacter spp. to fluoroquinolones, which are generally used for the treatment of...Antibiotic resistance among enteric bacterial pathogens complicates the heavy diarrhoea disease burden. Antimicrobial resistance of Campylobacter spp. to fluoroquinolones, which are generally used for the treatment of bacterial gastroenteritis, has increased during the past two decades, mainly as a result of the approval of this group of antimicrobials for use in food-producing animals. The aim is to determine the frequency of resistance of campylobacter to various antimicrobial agents and the relationship between antimicrobial agents of the isolates and the presence of plasmid. Twenty five Campylobacter isolates gotten from humans were subjected to antibiotics testing using Kirby Bauer disc diffusion method as well as standard E-test method. The plasmid profile of the isolates was determined using the Alkaline phosphatise procedure. The antimicrobial susceptibility testing of these isolates showed that all were sensitive to Erythromycin and Ciprofloxacin while none was sensitive to co-trimoxazole. The standard organisms were sensitive to co-trimoxazole (80%) and ciprofloxacin (65%) but were resistant to erythromycin (70%). No plasmid was found in streptomycin and ampicillin resistant strains, with the exception of four isolates which were co-trimoxazole-resistant and which contained around 24.4kb plasmids.展开更多
Death of infants from diarrhoea is a common occurrence in sub-Saharan Africa. This is attributed to unhygienic practices which aid the proliferation of diarrhoea-causing microorganisms. Among these microorganisms, Cam...Death of infants from diarrhoea is a common occurrence in sub-Saharan Africa. This is attributed to unhygienic practices which aid the proliferation of diarrhoea-causing microorganisms. Among these microorganisms, Cam- pylobacter species have been reported as one of the causal agents, Campylobacter spp. are human intestinal pathogens of global importance and their pathogenicity mechanisms are not well understood. This study was designed to investigate the molecular characterisation of Campylobacter gotten from cultural methods in Osun State. Campylobacters isolated were biochemically characterized and biotyped. Confirmation of Campylobacter was done using flaA gene, hippuricase O for Campylobacter jejuni and aspartokinase gene for Campylobacter coli and single locus sequencing glnA gene were performed by PCR. Twenty five samples were amplified by PCR out of 57 Campylobacter strains that were positive for cultural methods from 815 stool samples with diarrhoea and 100 stool samples without diarrhoea. No Campylobacter was isolated from stools of children in the control group. Twenty-five isolates comprising of 18 Campylobater jejuni and 7 C. coli were identified. The nucleotide sequence of the gln A for all the isolated Campylobacter spp. showed 91.0% similarity with the ones in the GenBank. The C. jejuni was classified into biotypes I (44.4%) and II (55.6%) and all C. coli were of biotype I.展开更多
The genus Chrysobalanus is one of the classes of medicinal plants used in the treatment and management of several diseases.This study is aimed at providing up-to-date information on the phytochemical composition and p...The genus Chrysobalanus is one of the classes of medicinal plants used in the treatment and management of several diseases.This study is aimed at providing up-to-date information on the phytochemical composition and pharmacological uses of Chrysobalanus icaco.Current literature on the Chrysobalanus species was obtained by searching electronic databases such as Pub Med,Google Scholar and Web of Science.Of the species in this genus,four have been reported in the literature,but only one(C.icaco)has been extensively studied.C.icaco is rich in several minerals,including potassium,magnesium,calcium and sodium.The plant also contains a host of phytochemicals,such as flavonoids,diterpenes and triterpenes,which have been shown to have pharmacological activity.It can be concluded that C.icaco is a good source of phytochemicals that contribute to its therapeutic uses.However,bioassay-guided isolation of its bioactive compounds is necessary for promoting the development of drugs from this medicinal plant.展开更多
Traditional methods of preparation were simulated in the laboratory fermentations of cassava and maize to produce fufu and ogi respectively. Changes in pH, temperature and titratable acidity, as well as the diversity ...Traditional methods of preparation were simulated in the laboratory fermentations of cassava and maize to produce fufu and ogi respectively. Changes in pH, temperature and titratable acidity, as well as the diversity of lactic acid bacteria species were investigated during both fermentations. Lactic acid bacteria strains involved in the fermentation processes were isolated at twelve hourly intervals, characterized and identified using phenotypic and biochemical methods. A rapid decrease in pH, 5.6 to 3.7 in fufu and 5.9 to 3.8 in ogi, were observed with temperature increasing from 26℃?to 30℃and 25℃?to 31℃?in fufu and ogi respectively. Most of the lactic acid bacteria strains isolated were homofermentative and heterofermentative Lactobacillus species and heterofermentative Leuconostoc species. Lactobacillus plantarum and Leuconostoc mesenteroides were the dominant lactic acid bacteria species in fufu while L. cellobiosus, L. plantarum and Lc. lactis were dominant in ogi fermentation. An ecological succession pattern in which Leuconostoc species were mostly isolated during early stages of fermentation with the final stages populated with Lactobacillus species was observed in both cases and is attributable to differential acid tolerance of the two genera. The frequencies of dominance of the strains in fufu were L. plantarum (56.25%), Lc. mesenteroides (18.75%), L. lactis (6.25%), L. coprophillus (6.25%), L. acidophilus (6.25%) and L. brevis (6.25%). The frequencies of dominance in ogi were L. cellobiosus (26.6%), Lc. lactis (26.6%), L. plantarum (20.0%), L. acidophilus (13.33%) and Lc. paramesenteroides (13.33%). The dominant strains can serve as potential starter cultures for fufu and ogi production.展开更多
基金financial supports for this study were obtained from the Pan African University(PAU)African Union(AU)Addis Ababa,Ethiopia as part of its PhD scholarship scheme
文摘Background: Climate-induced challenge remains a growing concern in the dry tropics, threatening carbon sink potential of tropical dry forests. Hence, understanding their responses to the changing climate is of high priority to facilitate sustainable management of the remnant dry forests. In this study, we examined the long-term climate-growth relations of main tree species in the remnant dry Afromontane forests in northern Ethiopia. The aim of this study was to assess the dendrochronological potential of selected dry Afromontane tree species and to study the influence of climatic variables (temperature and rainfall) on radial growth. It was hypothesized that there are potential tree species with discernible annual growth rings owing to the uni-modality of rainfall in the region. Ring width measurements were based on increment core samples and stem discs collected from a total of 106 trees belonging to three tree species (Juniperus procera, Olea europaea p. cuspidate and Podocarpus falcatus). Thesubsp. collected samples were prepared, crossdated, and analyzed using standard dendrochronological methods. The formation of annual growth rings of the study species was verified based on successful crossdatability and by correlating tree-ring widths with rainfall. Results: The results showed that all the sampled tree species form distinct growth boundaries though differences in the distinctiveness were observed among the species. Positive and significant correlations were found between the tree-ring widths and rainfall, implying that rainfall plays a vital role in determining tree growth in the region. The study confirmed the formation of annual growth rings through successful crossdating, thus highlighted the potential applicability of dendroclimatic studies in the region. Conclusions: Overall, the results proved the strong linkage between tree-ring chronologies and climate variability in the study region, which further strengthens the potential of dendrochronological studies developing in Ethiopia, and also has great i
文摘Vegetable oil Spills are becoming frequent and are potentially more challenging than petroleum hydrocarbon spills. Microbial lipases occupy a place of prominence among biocatalysts are often used for remediation of vegetable oil-polluted sites. This work was carried out to isolate microorganisms from oil-polluted sites and screen them for their lipolytic activity. Microorganisms were isolated from eight experimental soil samples contaminated with different types of vegetable oil, soil from an oil mill in Ibadan, and normal uncontaminated soil as a control. The isolates were characterized, identified and those common to at least one of the experimental sites and oil mill sites were screened for their lipolytic activity. Data obtained were analysed using Duncan Multiple Range Test. Seventy three microorganisms were isolated from the polluted soil and identified as species of Bacillus (16), Pseudomonas (12), Flavobacterium (6), Alcaligenes (2), Proteus (3), Micrococcus (1), Aspergillus (9), Penicillium (6), Saccharomyces (4), Geotrichum (1), Kluveromyces (1). Bacillus subtilis, Bacillus licheniformic, Pseudomonas cepacia, Pseudomonas fluorescens, Flavobacterium sp., Alcaligenes sp. and Candida parapsilosis which were common to at least one of the experimental site and oil mill site were preliminarily screened for lipolytic activity and all nine confirmed by presence of halos around the colonies. These screened organisms have potential for the degradation of fatty waste. They could therefore be employed in environmental clean-up of vegetable oil spill site.
文摘The Ikogosi Warm Spring is a unique ecological niche in Western Nigeria with an average temperature and pH of 38°C and 5.8 respectively. It mixes with an adjacent cold spring (28°C & pH 7.6), about 100 meters from source, yielding a confluence body of water of 32°C and pH 7.7. To explore the bacterial community structure of this uncommon environment and to scan for potentially useful bacteria, metagenomes extracted directly from five samples (source and mid-point of warm spring;source and midpoint of cold spring, and the confluence) were analyzed. Using the MiSeq Illumina next generation sequencing protocols, the V3-V4 region of the 16S rRNA gene pool was sequenced and analyzed by QIIME (Quantitative Insights into Microbial Ecology) and R software. At least 11% (47,446) of all the sequences were unknown to any of the databases employed. Bacterial diversity and abundance at the source of both springs were extremely low, accounting for less than 0.07% of the total sequence reads at the confluence, 100 m downstream. In contrast to the highly diversified mesophilic confluence community where 21 different phyla were identified, only 4 and 5 phyla were recovered from the source-point of the warm spring and cold spring respectively. The most prevalent phyla in all samples were members of the versatile Proteobacteria (35% - 50% relative abundance), and the hardy Firmicutes (33% - 40%). Operational taxonomic units (OTUs) obtained from all the samples averaged at 1414. Temperature and pH were equally significant predictors of genomic diversity and richness, with the warm and cold spring sources having less than 5 bacteria phyla. Exiguobacterium sp. (a potential plastic degrader) and other deep rooted bacteria were found in the warm spring while the cold spring outflow contained among others such as Rubrobacter sp. and Chloroflexi sp. (which is close to the phylogenetic root of the domain Bacteria). Many taxonomically unresolved sequences could indicate the presence of potentially novel bacteria in this unique body of wa
文摘Antibiotic resistance among enteric bacterial pathogens complicates the heavy diarrhoea disease burden. Antimicrobial resistance of Campylobacter spp. to fluoroquinolones, which are generally used for the treatment of bacterial gastroenteritis, has increased during the past two decades, mainly as a result of the approval of this group of antimicrobials for use in food-producing animals. The aim is to determine the frequency of resistance of campylobacter to various antimicrobial agents and the relationship between antimicrobial agents of the isolates and the presence of plasmid. Twenty five Campylobacter isolates gotten from humans were subjected to antibiotics testing using Kirby Bauer disc diffusion method as well as standard E-test method. The plasmid profile of the isolates was determined using the Alkaline phosphatise procedure. The antimicrobial susceptibility testing of these isolates showed that all were sensitive to Erythromycin and Ciprofloxacin while none was sensitive to co-trimoxazole. The standard organisms were sensitive to co-trimoxazole (80%) and ciprofloxacin (65%) but were resistant to erythromycin (70%). No plasmid was found in streptomycin and ampicillin resistant strains, with the exception of four isolates which were co-trimoxazole-resistant and which contained around 24.4kb plasmids.
文摘Death of infants from diarrhoea is a common occurrence in sub-Saharan Africa. This is attributed to unhygienic practices which aid the proliferation of diarrhoea-causing microorganisms. Among these microorganisms, Cam- pylobacter species have been reported as one of the causal agents, Campylobacter spp. are human intestinal pathogens of global importance and their pathogenicity mechanisms are not well understood. This study was designed to investigate the molecular characterisation of Campylobacter gotten from cultural methods in Osun State. Campylobacters isolated were biochemically characterized and biotyped. Confirmation of Campylobacter was done using flaA gene, hippuricase O for Campylobacter jejuni and aspartokinase gene for Campylobacter coli and single locus sequencing glnA gene were performed by PCR. Twenty five samples were amplified by PCR out of 57 Campylobacter strains that were positive for cultural methods from 815 stool samples with diarrhoea and 100 stool samples without diarrhoea. No Campylobacter was isolated from stools of children in the control group. Twenty-five isolates comprising of 18 Campylobater jejuni and 7 C. coli were identified. The nucleotide sequence of the gln A for all the isolated Campylobacter spp. showed 91.0% similarity with the ones in the GenBank. The C. jejuni was classified into biotypes I (44.4%) and II (55.6%) and all C. coli were of biotype I.
文摘The genus Chrysobalanus is one of the classes of medicinal plants used in the treatment and management of several diseases.This study is aimed at providing up-to-date information on the phytochemical composition and pharmacological uses of Chrysobalanus icaco.Current literature on the Chrysobalanus species was obtained by searching electronic databases such as Pub Med,Google Scholar and Web of Science.Of the species in this genus,four have been reported in the literature,but only one(C.icaco)has been extensively studied.C.icaco is rich in several minerals,including potassium,magnesium,calcium and sodium.The plant also contains a host of phytochemicals,such as flavonoids,diterpenes and triterpenes,which have been shown to have pharmacological activity.It can be concluded that C.icaco is a good source of phytochemicals that contribute to its therapeutic uses.However,bioassay-guided isolation of its bioactive compounds is necessary for promoting the development of drugs from this medicinal plant.
文摘Traditional methods of preparation were simulated in the laboratory fermentations of cassava and maize to produce fufu and ogi respectively. Changes in pH, temperature and titratable acidity, as well as the diversity of lactic acid bacteria species were investigated during both fermentations. Lactic acid bacteria strains involved in the fermentation processes were isolated at twelve hourly intervals, characterized and identified using phenotypic and biochemical methods. A rapid decrease in pH, 5.6 to 3.7 in fufu and 5.9 to 3.8 in ogi, were observed with temperature increasing from 26℃?to 30℃and 25℃?to 31℃?in fufu and ogi respectively. Most of the lactic acid bacteria strains isolated were homofermentative and heterofermentative Lactobacillus species and heterofermentative Leuconostoc species. Lactobacillus plantarum and Leuconostoc mesenteroides were the dominant lactic acid bacteria species in fufu while L. cellobiosus, L. plantarum and Lc. lactis were dominant in ogi fermentation. An ecological succession pattern in which Leuconostoc species were mostly isolated during early stages of fermentation with the final stages populated with Lactobacillus species was observed in both cases and is attributable to differential acid tolerance of the two genera. The frequencies of dominance of the strains in fufu were L. plantarum (56.25%), Lc. mesenteroides (18.75%), L. lactis (6.25%), L. coprophillus (6.25%), L. acidophilus (6.25%) and L. brevis (6.25%). The frequencies of dominance in ogi were L. cellobiosus (26.6%), Lc. lactis (26.6%), L. plantarum (20.0%), L. acidophilus (13.33%) and Lc. paramesenteroides (13.33%). The dominant strains can serve as potential starter cultures for fufu and ogi production.
