Search

Taro's production is characterized by low productivity due to a lack of sufficient improved cultivars suited to the different growing areas coupled with biotic and abiotic stresses. The first step in plant breeding program is to examine and quantify variations for traits of interest in a given set of genotypes so those variations can be exploited in breeding programmes. One hundred taro accessions were evaluated for 16 quantitative traits in a simple lattice design with the objective of estimating variability and determine and quantify association of characters with yield. Multienvironment trial analysis combined over seasons showed highly significant differences among taro accessions for several traits. Yield per plant showed a strong, positive, and highly significant genotypic correlation with plant height (0.99), leaf area (0.82), corm weight (0.99), and cormel weight (0.99). Genotypic path coefficient analysis showed plant height (1.49), leaf area (0.97), corm weight (0.76), and cormel weight (0.21) exerted a high positive direct effect on yield per plant indicating true relationship between the characters. Accessions EBNFC054, EBNFC045, EBNFC100, EBNFC046, EBNFC032, EBNFC075, EBNFC084, EBNFC057, and EBNFC037 were superior and could be promoted to field evaluation. This assessment of variability and associations can assist breeders to tap the potential of the genotypes for certain traits and identify major traits that could be used as a basis for the selection of superior taro genotypes. [ABSTRACT FROM AUTHOR]

Background: Taro has a long history of being consumed and remains orphan and on the hand Nigeria farmers. The role of farmer-driven artificial selection is not negligible to fit landraces to a particular ecological condition. Limited study has been conducted on genome-wide association and no study has been conducted on genome-environment association for clinal adaptation for taro. Therefore, the objective of this study was to detect loci that are associated with environmental variables and phenotype traits and forward input to breeders. The study used 92 geographical referred taro landraces collected from Southeast (SE) Nigeria. Results: The result indicates that SE Nigerian taro has untapped phenotype and genetic variability with low admixture. Redundancy analysis indicated that collinear explained SNP variation more than single climatic variable. Overall, the results indicated that no single method exclusively was able to capture population confounding effects better than the others for all six traits. Nevertheless, based on overall model performance, Blink seemed to provide slight advantage over other models and was selected for all subsequent assessment of genome-environment association (GEA) and genome-wide association study (GWAS) models. Genome scan and GEA identified local adapted loci and co-located genes. A total of nine SNP markers associated with environmental variables. Some of the SNP markers (such as S_101024366) co-located with genes which previously reported for climatic adaptation such as astringency, diaminopimelate decarboxylase and MYB transcription factor. Genome-wide association also identified 45, 40 and 34 significant SNP markers associated with studied traits in combined, year 1 and year 2 data sets, respectively. Out of these, five SNP markers (S1_18891752 S3_100795476, S1_100584471 S1_100896936 and S2_10058799) were consistent in two different data sets. Conclusions: The findings from this study improve our understanding of the genetic control of adaptive and phenotypic traits in Nigerian taro. However, the study suggests further study on identification of local adaptive loci and GWAS through collection of more landraces throughout the country, and across different agro-ecologies. [ABSTRACT FROM AUTHOR]

Potentially toxic elements (PTEs) in food crops have significant apprehension in the environment because of their impending human health risks. This study thus assessed PTEs concentrations in soils and crops from farmlands around quarry sites, quantifies their level of uptake by the crops and their potential health risks to human. Collection of Soil and crop (Dioscorea alata, Colocasia esculenta and Manihot esculenta ) samples were done and analysed for Fe, Mn, Pb, Zn, Cu, Cr, Co, Ni and Cd using suitable instrumentation methods Data were evaluated using accumulation factor (AF), calculated daily intakes (CDI), target hazard quotent (THQ) and hazard index (HI). Farmlands soils that are closer to studied sites had higher PTEs concentrations than those that are farther away. Mean PTEs concentrations in the crops were in the order of Dioscorea alata > Colocasia esculenta > Manihot esculenta. Mean values of AF are less than one indicating low potential PTEs accumulation in the crops. The mean CDI in mg/kg/day of PTEs in crops for children and adults were 0.0001 - 0.060 while THQ values are in order Pb> Mn>Cu> Cd>Ni> Co>Fe >Zn>Cr. Hazard index (HI) is greater than one in all the crops from the farmlands closer to quarry sites, indicating risk upon consumption. Thus, necessary remediation methods should be taken to reduce the effect of these PTEs on the environment. [ABSTRACT FROM AUTHOR]

Neglected and underutilized crops can play a vital role in achieving food security as humans concentrate on consuming a few food crops which have increased in price over time. Understanding the profitability of these crops can enhance farmers’ decisions to grow them. Therefore, this study investigated cocoyam production profitability, factors responsible for its profitability, and the constraints faced in cocoyam production in Cross River State, Nigeria. Data collected primarily with the use of questionnaires were analysed with descriptive statistics, cost and return analysis, multiple regression and the Likert rating scale. The results revealed that the majority of cocoyam farmers were male, married, in their economically active age and operated on a small scale. Cocoyam production was a profitable venture as the farmers had a gross margin of N175, 822.45 (USD 428.04) per hectare of cultivated land with an operating ratio of 0.24 and a return on capital invested of 3.17. The factors that influenced the profitability of cocoyam production were education, household size, farm size, farm output, cooperative membership, access to credit and annual income. The major constraints faced in cocoyam production were inadequate access to credit, poor government support, high cost of inputs and poor storage facilities. To enhance cocoyam profitability, the study recommends the provision of farm inputs and financial support to inform of credit or grants to the farmers. This would not only increase their profit but also enhance the decision to increase production which will increase food availability and, in turn, reduce the problem of food insecurity. [ABSTRACT FROM AUTHOR]

The works assessed the production characteristics of cocoyam farmers in Enugu State, Nigeria. Questionnaire was used to elicit relevant information from a sample of 80 randomly selected respondents. Frequency, percentage and mean were used for analysis. The mean household size was 6 with the mean farming experience of 24.0 years. 47.5% had mean farm size of 2.3 hectares with average annual income of N30543.8. Production practices utilized by cocoyam farmers are use of organic fertilizer (x=2.74) and use of manual labour in land preparation (x= 2.99). The information sources of farmers are friends (x=2.26), neighbour (x=2.46), co-farmers (x=2A6). Information needs of farmers were sourcing of farm inputs (x=3.88), sourcing of improved farm tools (x= 2.84) among otheis. Production constraints were incidences of pests and diseases (x=3.68), lack of extension contact (if=2.98) among others while ways of improving production are use of disease resistant varieties (x=2.95), formation of farmers' cooperative societies (x=2.44), among others. The study recommended among others that research institutes, federal and state government should in partnership, develop weed, pest and disease resistant cocoyam varieties, subsidized farm inputs, and provide extension services to cocoyam farmers. [ABSTRACT FROM AUTHOR]

Taro is a valuable staple food crop among resource-poor rural people in countries such as Nigeria and Ghana, among others. Characterization of genetic diversity is a prerequisite for proper management of breeding programs and conservation of genetic resources. Two hundred seventy one taro accessions obtained from Nigeria and Vanuatu were genotyped using DArTseq-based SNP markers with the objectives of investigating the genetic diversity and population structure. In the analysis, 10,391 SNP markers were filtered from the sequence and used. The analysis revealed higher transition than transversion types of SNPs in the ratio of 1.43:1. The polymorphism ranged from 0.26 to 0.29 for the markers, indicating moderate genetic diversity. A model-based Bayesian clustering analysis of taro accessions yielded five subgroups and revealed the admixture situation in 19.19% of all accessions in the study. Vanuatu taro accessions exhibited more genetic diversity than Nigerian taro accessions. The population diversity estimate (PhiPt) was relatively higher (0.52) for accessions originating from Vanuatu than for Nigerian accessions. Analysis of molecular variance (AMOVA) revealed that most variation existed among individuals within a population at 52%. Nei's genetic distance showed that relatedness is based on geographical proximity. Collection of taro genetic resources should give more emphasis to within regions to utilize diversity in taro breeding program. This study also demonstrated the efficiency of DArTseq-based SNP genotyping for large-scale genome analysis in taro. The genotypic markers provided in this study are useful for association mapping studies. [ABSTRACT FROM AUTHOR]

Quality tubers are required for industrial processes and their physicochemical contents vary from one region to another. This work determined the physicochemical differences of starch in six species of edible tubers (Dioscorea alata, Dioscorea bulbifera, Dioscorea cayenensis, Dioscorea rotunda, Manihot esculenta and Colocasia esculenta) harvested in Benin City, Nigeria from September-November, 2021, as potential sources of dietary substances and for industrial use. Methods for analysis were as described in the Official Methods of the Association of Analytical Chemists. The texture solution of Dioscorea cayenensis and Colocasia esculenta were opaque while the others were transparent and clear. Ash content were Dioscorea cayenensis (0.23±0.02%), Colocasia esculenta (0.19±0.01%), and Dioscorea alata (0.13±0.02%). The moisture content was Dioscorea alata (10.0±2.0%) while Dioscorea cayenensis (5.00±0.5%) the least. Crude protein was Dioscorea cayenensis (0.21±0.05) and least in Dioscorea alata (0.07±0.02%). Lipid was Dioscorea alata (0.22±0.03%) and least in Dioscorea cayenensis Dioscorea bulbifera (0.12±0.02%). Phosphorous was highest in Dioscorea cayenensis (0.025±0.05%) and least in Manihot esculenta (0.008±0.04%). Amylose values were Dioscorea bulbifera (21.8±4.37%), Dioscorea Dcayenensis (30.9±2.26%), Dioscorea rotunda (29.8±3.41%), Dioscorea alata (24.6±1.04%), Manihot esculenta (20.5±2.50%), and Colocasia esculenta (20.0±2.05%). The viscosity was Colocasia esculenta (0.800±0.04) and least in Dioscorea bulbifera (0.200±0.01). The density (0.99) was approximately the same. The pH was acidic except for Dioscorea alata (7.00±1.0). The water binding capacity (WBC) was highest in Dioscorea cayenensis (1.15±0.09) and least in Dioscorea rotunda (0.90±0.25). The characteristics of these edible starches would enhance their industrial uses as well as improve their nutritional values to man. [ABSTRACT FROM AUTHOR]

Cocoyam (Xanthosoma sagittifolium (L.) Schott) is an important crop which serves as a staple food for a large number of people in developing nations including Nigeria. Its perishability necessitates immediate processing after harvest to obtain products such as chips, flakes and flour with better storage stability. Proper selection of appropriate packaging materials for cocoyam flour is important to maintain the quality attributes during storage and to extend its shelf life. This study, therefore, examined the influence of packaging materials and storage period on the quality of cocoyam flour. Cocoyam flour was produced from fresh, wholesome cormels. The flour samples were stored in three packaging materials (polyethylene terephthalate [PET] bottles, polyethylene bags and woven polypropylene sacks) for six months under ambient conditions. The flour samples were then analyzed at four-week intervals for proximate composition, pH, colour and sensory analysis using standard methods. The results showed that packaging materials and length of storage significantly affected crude fibre and carbohydrate content of cocoyam flour. The moisture content of the flour packed in woven polypropylene decreased to a larger extent due to its higher water vapour permeability. The type of packaging did not significantly affect the crude fat content of the flour throughout the storage period. The PET bottle performed better in retaining the protein and ash content of the flour. Although significant differences were observed in the pH levels and colour of the cocoyam flour samples after storage in the different packaging materials, the type of packaging material did not affect these physicochemical properties. The sensory properties of the cocoyam flour in three packaging materials were found to be within acceptable limits at the end of storage. All the selected packaging materials performed well in retaining the quality attributes of the cocoyam flour throughout the period of storage. [ABSTRACT FROM AUTHOR]

This study examines the heat and mass transfer coefficient, thermal effusivity, and other thermal properties of solar-dried cocoyam chips, as well as the drying kinetics. The research also assessed the economics of the solar dryer. For these reasons, a solar dryer with a partitioned collector was developed that creates a double airflow travel distance to delay the airflow inside the collector. The partitioning of the collector delays the airflow and helps to create more turbulence for the airflow with increased energy. The solar dryer was locally developed at the Michael Okpara University of Agriculture and tested during the humid crop harvesting period of September for the worst-case scenario. The obtained drying curves and kinetics for cocoyam drying are subjected to the vagaries of weather conditions. The drying rate showed declining sinusoidal characteristics and took about 25 h to attain equilibrium. Analysis of the airflow velocity showed gravitation between laminar and turbulent flow, ranging from 171.69 to 5152.77. Specific heat capacity, thermal conductivity, and effusivity declined with moisture content while the thermal diffusivity increased. However, the values of thermal effusivity ranged from 12.2 to 47.94 W·s1/2·m−2·K−1, which is within the range of values for insulators. The heat and mass transfer coefficient varied as a function of the airflow velocity. Fitting the drying curve into semi-empirical models showed that the two-term model was the best-fitted model for the experimental data from drying cocoyam. Using the solar dryer in Nigeria can save $188.63–$1886.13 in running costs with a payback period of 0.059–0.59 years (21.54–215.35 days) at a rate of 10–100% of usage. [ABSTRACT FROM AUTHOR]

Background: Wild cocoyam (Caladium bicolar) is non-edible starchy material which is commonly known as 'Ede umuagbara' in the south-east region of Nigeria. Evaluating the potential of wild cocoyam for citric acid production was investigated using Aspergillus niger in a submerged culture. Results: This study showed that wild cocoyam flour concentration, pretreatment of wild cocoyam, inoculums size, initial pH of wild cocoyam and incubation temperature of wild cocoyam medium had significant effect on the amount of citric acid produced from wild cocoyam (p < 0.05). Citric acid concentration increased as the concentration wild cocoyam increased up to 15% with the maximum citric acid concentration of 10.0 ± 0.251 g/l after 96 h of fermentation. Also citric acid concentration increased as the pretreatment time of wild cocoyam increased from 5 to 20 min. A 20 min pretreatment time at 121 °C was the optimum with maximum concentration of 14.0 ± 0.325 g/l citric acid after 96 h of fermentation. 15% inoculums was the optimum with the maximum concentration of 16.0 ± 0.431 g/l citric acid. However, the wild cocoyam initial pH value of 5.5 was the optimum for maximum citric acid concentration of 19.0 ± 0.316 after 96 h of fermentation. Moreover, citric acid concentration increased as the incubation temperature of wild cocoyam medium increased from 20 to 30 °C. Incubation of wild cocoyam medium at 30 °C was the optimum with the maximum citric acid concentration of 23.0 ± 0.432 g/l after 96 h of fermentation. Conclusion: Therefore, the result revealed that wild cocoyam which is found plenty within the south-east region of Nigeria can be converted to citric acid if well harnessed. [ABSTRACT FROM AUTHOR]

Weather variability and its effects on agricultural and food systems are burgeoning global concerns. This study examined the effects of weather variability in the derived savannah and rainforest agroecologies, on crop yields in Southwest Nigeria, and what it portends for food and nutrition security in the region. The trends in the distribution of rainfall and temperature were analysed using the Sens method. The effects of weather variability on crop yield and inferences on what it portends for food security were determined using a stepwise regression model. The results revealed that rainfall fluctuations decreased the yields of cassava (Manihot esculenta) and yam (Dioscorea spp.) in the derived savannah; while a decrease in temperature may support improved yields for maize (Zea mays), sorghum (Sorghum bicolor) and cowpea (Vigna unguiculata). The increase in yields of cocoa (Theobroma cacao) and cocoyam (Colocasia esculenta) would be hampered by increasing maximum temperatures in the rainforest agroecology. Increasing rainfall and temperature would impact warmer conditions that support rapid crop putrefaction, flooding, droughts, challenging postharvest crop management, pest and disease proliferation, and ultimately, reduced crop yields. On the other hand, perpetually low rainfall and temperature conditions will cause poor seedling emergence and growth, seed and total crop loss. It is, therefore, imperative that effective climate adaptation and mitigation mechanisms be put in place across the agroecologies in the region. [ABSTRACT FROM AUTHOR]

Summary: Pseudomonas isolates from tropical environments have been underexplored and may form an untapped reservoir of interesting secondary metabolites. In this study, we compared Pseudomonas and cyclic lipopeptide (CLP) diversity in the rhizosphere of a cocoyam root rot disease (CRRD) suppressive soil in Boteva, Cameroon with those from four conducive soils in Cameroon and Nigeria. Compared with other soils, Boteva andosols were characterized by high silt, organic matter, nitrogen and calcium. Besides, the cocoyam rhizosphere at Boteva was characterized by strains belonging mainly to the P. koreensis and P. putida (sub)groups, with representations in the P. fluorescens, P. chlororaphis, P. jessenii and P. asplenii (sub)groups. In contrast, P. putida isolates were prominent in conducive soils. Regarding CLP diversity, Boteva was characterized by strains producing 11 different CLP types with cocoyamide A producers, belonging to the P. koreensis group, being the most abundant. However, putisolvin III‐V producers were the most dominant in the rhizosphere of conducive soils in both Cameroon and Nigeria. Furthermore, we elucidated the chemical structure of putisolvin derivatives—putisolvin III‐V, and described its biosynthetic gene cluster. We show that high Pseudomonas and metabolic diversity may be driven by microbial competition, which likely contributes to soil suppressiveness to CRRD. [ABSTRACT FROM AUTHOR]

Cocoyam (Xanthosoma sagittifolium) corms and cormels are among the staple foods in Nigeria. The cormels are processed into cocoyam flour and utilized for various purposes. Drying is an essential unit operation in the conversion of the cormels into cocoyam flour and the knowledge of the effect of drying variables on the drying characteristics of the cormels is necessary for analysis, optimization and control of the drying process. This study therefore, investigated the drying kinetics of cocoyam cormels as influenced by slice thickness and pre-drying treatment. White-fleshed (NXs. 001) and pink-fleshed (NXs. 002) cocoyam cormels were used for this study. Drying kinetics of the pre-treated cormels (blanched by soaking in hot water at 100oC for 5 minutes) and fresh cormel slices of 2, 3 and 4 mm thicknesses were examined at 60°C. Drying of the cocoyam slices was predominantly in the falling rate period which indicated that moisture removal occurred mainly by diffusion. Drying of thin pre-treated slices of cocoyam cormels is recommended to obtain the faster moisture removal and subsequently, a reduction in the drying period. [ABSTRACT FROM AUTHOR]

Physicochemical and functional properties of starches from some under-utilized yam ( D. cayenensis, D. dumetorum, and D. bulbifera) and cocoyam ( X. maffa ( Scoth) grown in Southeast Nigeria were determined. Analysis of variance showed that yam starches of D. cayenensis and D. bulbifera were characterized by large mean granule sizes (28 and 37.5 μm), high amylose content (37.8 and 35%), and high paste clarity (11.6 and 16%). Starches of D. dumetorum and cocoyam, X. maffa ( Scoth), were characterized by smaller granule sizes (about 6 and 5 μm), low amylose content (11.2 and 13%), and low paste clarity (6 and 9.8%). The gelatinization enthalpy (ΔH) of D. cayenensis starch (16.7 j/g) was higher than the other tuber starches (about 12 j/g). Onset, peak, and end temperatures ranged from 73 to 81.3°C, 77.3 to 85.2°C, and 85.4 to 93°C, respectively, with X. maffa ( Scoth) having the highest temperatures. The pasting temperatures ranged from 76 to 81°C. Hot paste, cold paste, and final viscosities were from 116.7 to 748 cP, 145.7 to 913.7 cP, and 156.7 to 966.3cP, respectively. D. bulbifera and D. cayenensis maintained higher viscosities than D. dumetorum and X. maffa ( Scoth). Low paste clarity of D. dumetorum and X. maffa ( Scoth) was associated with their small granule sizes and low amylose content. The physicochemical and functional properties of the yam and cocoyam tuber starches show that they can be used for specific food applications. [ABSTRACT FROM AUTHOR]

Cocoyam is a traditional crop and a cultural foodstuff in Nigeria. It has not received much research attention in spite of its great adaptability to varying farming systems and its nutritive and commercial food values. The crop is a yam substitute that occupies an inferior food status in the study area. It is mainly cultivated by women and in most cases planted as an intercrop in a previously established farm. It is, therefore, regarded as a lazy man's crop and consequently a poor man's food. The aim of this study was to revive the acceptability of cocoyam as foodstuff in order to solve the food crisis, which Nigeria has been experiencing since 1978. A structured interview schedule was used to obtain information from randomly selected 322 respondents from 24 cocoyam producing communities in four states in the region: Ondo, Ekiti, Ogun and Lagos states. The question items included personal and socio-economic characteristics of respondents and cocoyam utilization. The data were described using frequency counts, means and percentages while multiple regression analysis was used as inferential statistics to determine the relationship of the independent variables to the dependent variable. Results revealed that 64% of the respondents were males and 84% were married. Their ages ranged from 20-70 years with a mean of 44±16 years. About 68% of them were literate with 58% of their spouses literate. They were mostly (39%) farmers and artisans (12%) with no secondary occupation, only 28% of the farmers produced cocoyam but almost all (97%) of the respondents consumed cocoyam. Cocoyam was utilized in 24 different ways in three categories of unprocessed solid, processed solid and powder in the study area and utilization level was 20%. The multiple regression analysis was significant at p< 0.05 and R=0.3469, meaning that the independent variable:socio-economic characteristics had jointly accounted for 35% of cocoyam utilization level. F value was 5.334. The variables that contributed positively to utilization level were producers of cocoyam, sources of cocoyam and cocoyam being brought home from journey while cosmopolitan, flexibility on food choice and decision makers on menu contributed negatively. Commercial processing of cocoyam to flour for baking, canned foods, baby food formulae and other cocoyam products are recommended to increase utilization. Farmers were advised to increase cocoyam production in the study area. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to develop poundmix for reconstitution, such as pounded yam, from yam, cocoyam and breadfruit blends and to evaluate their nutritional compositions. Design/methodology/approach – Pregelatinized flours of yam, cocoyam and breadfruit were prepared separately. Three coded samples of 30, 40 and 50 per cent composite blends of poundmix were formulated. The proximate composition, starch, vitamin C and mineral elements contents of the poundmix were determined and the results were subjected to statistical analysis. Findings – The protein contents of poundmix samples were 5.6, 6.1 and 6.2 per cent for 30, 40 and 50 per cent composites, respectively, which is an increase from that of whole yam (4.8 per cent). Significant difference also existed between the starch content of the poundmix and that of the whole yam flour (p<0.05). However, there is no significant difference in the overall acceptability of the poundmix samples and that of the whole yam flour at p<0.05. Originality/value – The paper's findings show that supplementing poundo yam at 40 per cent composite level has the best nutritional composition and organoleptic scores and so it is recommended for both household and industrial practice. [ABSTRACT FROM AUTHOR]

This study carried out an analysis of the technical efficiency of cocoyam production among small scale farmers in Ondo State, Nigeria, and identified some socio-economic factors, which influence productive efficiency. The data used were generated from a farm survey involving fifty cocoyam farmers using combinations of purposive and random sampling techniques. Descriptive statistics, stochastic production frontier model as well as inefficiency model were applied to primary data. A Cobb Douglas production function was used to represent the production frontier of the cocoyam farms. The results indicate that the technical efficiencies of the farmers was found to be fairly high with a mean of 84.3% which suggests that average cocoyam output falls 15.7% short of the maximum possible level. The study further observed that only education was positively correlated and significantly influenced the level of technical efficiency of the farmers while increase in the other socio-economic variables, household size, off-farm income, access to credit and farming experience led to decrease in technical efficiency. [ABSTRACT FROM AUTHOR]

Le manioc est une des tubercules les importantes parmi celles cultivées pour l'alimentation en Afrique de l'ouest et du centre. L'article s'intéresse aux déterminants de la demande de manioc et aux perspectives pour cette culture dans le nord du Nigeria en estimant l'élasticité de la demande de manioc et d'autres racines et tubercules. Le modèle « Système de demande pratiquement idéal » (AIDS) a été utilisé pour estimer les paramètres. Les résultats montrent que la demande de manioc est inélastique par rapport aux prix. L'élasticité par rapport aux dépenses est positive bien que faible. Ceci témoigne de l'évolution du manioc, de bien inférieur à celui de première nécessité. Grâce à ses qualités de conservation, le gari, la forme transformée du manioc, est devenue très populaire. Ce produit qui constitue une excellente source d'énergie alimentaire ne devrait donc pas être seulement considéré comme une culture de subsistance ou la nourriture du pauvre.European Journal of Development Research (2009) 21, 435-447. doi:10.1057/ejdr.2009.15; published online 23 April 2009 [ABSTRACT FROM AUTHOR]

Extended storage of cocoyams ( Colocasia antiquorum and Colocasia esculenta) is achieved in parts of Nigeria by processing them into smoked and dried chips. In this study, cocoyam chips were collected from parts of Nigeria at the end of drying, at various periods of storage and from markets, and analysed for moisture content, moisture sorption characteristics and xerophilic moulds. Moisture content of chips ranged from 7.07 ± 1.1% for freshly dried samples to 16 ± 2.2% for samples stored up to 8 months. Six mould species from four groups of the genus Aspergillus (including five xerophiles) identified as Aspergillus fumigatus, Eurotium repens, Eurotium amstelodami, Eurotium chevalieri and Aspergillus flavus and Aspergillus niger and Mucor sp. were isolated. The variety of moulds increased with storage and moisture content of samples. Moisture sorption in dried chips showed type II sigmoidal behaviour. Wood smoke significantly protected chips from mould colonization, but in cooperation with reduced water activity. Simple and inexpensive storage of freshly dried samples in airtight bags led to prolonged storage of up to 14 months without deterioration. [ABSTRACT FROM AUTHOR]

Pseudomonas cyclic lipopeptides (CLPs) are encoded non-ribosomally by biosynthetic gene clusters (BGCs) and possess diverse biological activities. In this study, we conducted chemical structure and BGC analyses with antimicrobial activity assays for two CLPs produced by Pseudomonas strains isolated from the cocoyam rhizosphere in Cameroon and Nigeria. LC-MS and NMR analyses showed that the Pseudomonas sp. COR52 and A2W4.9 produce pseudodesmin and viscosinamide, respectively. These CLPs belong to the Viscosin group characterized by a nonapeptidic moiety with a 7-membered macrocycle. Similar to other Viscosin-group CLPs, the initiatory non-ribosomal peptide synthetase (NRPS) gene of the viscosinamide BGC is situated remotely from the other two NRPS genes. In contrast, the pseudodesmin genes are all clustered in a single genomic locus. Nano- to micromolar levels of pseudodesmin and viscosinamide led to the hyphal distortion and/or disintegration of Rhizoctonia solani AG2-2 and Pythium myriotylum CMR1, whereas similar levels of White Line-Inducing Principle (WLIP), another member of the Viscosin group, resulted in complete lysis of both soil-borne phytopathogens. In addition to the identification of the biosynthetic genes of these two CLPs and the demonstration of their interaction with soil-borne pathogens, this study provides further insights regarding evolutionary divergence within the Viscosin group. [ABSTRACT FROM AUTHOR]