NRU :: Browsing by Author "Wokorach, Godfrey"

Browsing by Author "Wokorach, Godfrey"

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Characterization of Ugandan Endemic Aspergillus Species and Identification of Non-Aflatoxigenic Isolates for Potential Biocontrol of Aflatoxins
(Toxins, 2022) Wokorach, Godfrey; Landschoot, Sofie; Lakot, Amerida; Arihona Karyeija, Sidney; Audenaert, Kris; Echodu, Richard; Haesaert, Geert
Acute stunting in children, liver cancer, and death often occur due to human exposure to aflatoxins in food. The severity of aflatoxin contamination depends on the type of Aspergillus fungus infecting the crops. In this study, Aspergillus species were isolated from households’ staple foods and were characterized for different aflatoxin chemotypes. The non-aflatoxigenic chemotypes were evaluated for their ability to reduce aflatoxin levels produced by aflatoxigenic A. flavus strains on maize grains. Aspergillus flavus (63%), A. tamarii (14%), and A. niger (23%) were the main species present. The A. flavus species included isolates that predominantly produced aflatoxins B1 and B2, with most isolates producing a high amount (>20 ug/ L) of aflatoxin B1 (AFB1), and a marginal proportion of them also producing G aflatoxins with a higher level of aflatoxin G1 (AFG1) than AFB1. Some non-aflatoxigenic A. tamarii demonstrated a strong ability to reduce the level of AFB1 by more than 95% when co-inoculated with aflatoxigenic A. flavus. Therefore, field evaluation of both non-aflatoxigenic A. flavus and A. tamarii would be an important step toward developing biocontrol agents for mitigating field contamination of crops with aflatoxins in Uganda.
Draft genome sequence of Acinetobacter haemolyticus strain MUWRP1017 isolated from the pus of a female inpatient at Bwera General Hospital in Uganda
(American Society for Microbiology, 2024-08-20) Wokorach, Godfrey; Erima, Bernard; Alafi, Stephen; Kabatesi, Hope O; Muhindo, Julius T; Najjuka, Florence; Kiyengo, James; Kibuuka, Hannah; Musinguzi, Ambrose K.; Wabwire-Mangen, Fred; Byarugaba, Denis K.
The bacterium Acinetobacter haemolyticus, with a genome size of 3.4 Mb, was isolated from a pus swab of a wound on the left lower limb above the ankle joint of a female patient. This strain carries the antimicrobial resistance genes cephalosporinase blaADC-25, oxallinase blaOXA-264, floR, and sul2 and other resistance and virulence genes.
Farmers' practices and their knowledge of biotic constraints to sweetpotato production in East Africa
(Physiological and molecular plant pathology, 2019) Echodu, Richard; Edema, Hilary; Wokorach, Godfrey; Zawedde, Christine; Otim, Geoffrey; Luambano, Nessie; Miinda Ateka, Elijah; Asiimwe, Theodore
Sweetpotato (Ipomoea batatas) is a vital crop for overcoming food insecurity in sub-Saharan Africa and its production is highest in East Africa where yields are high and the growing seasons are short. This cross-country study assessed farmers' local practices and their knowledge of the biotic constraints to sweetpotato production in Uganda, Rwanda, Kenya and Tanzania with the aim of providing empirical data that can ultimately be used to enhance sweetpotato production in these four countries. We collected data from 675 households using a standardized questionnaire integrated with a web-based mobile app. Survey results provided strong evidence that sweetpotato is valued as an important subsistence crop among smallholder farmers on pieces of land of less than 0.4 ha, and we observed that females were more involved than males in sweetpotato production. Sweetpotato was ranked as the second most important staple crop after cassava. Farmers noted an increase in sweetpotato production over the past five years in Uganda and Kenya but a decrease in Rwanda and Tanzania; the proportion of farmers who reported a decrease (33%) and an increase (36%) did not significantly differ. The main constraints to production were reported to be pests (32.6%), drought (21.6%), diseases (11.9%) and lack of diseasefree planting materials (6.8%). Farmers recognized the signs and symptoms associated with sweetpotato diseases on leaves, root tubers, and whole plants, but most were unable to assign the disease type (bacterial, fungal or viral) correctly. We suggest that regional governments improve education, increase the provision of clean planting materials and strengthen breeding programs to improve disease resistance.
Genetic Characterization of Fungal Biodiversity in Storage Grains: Towards Enhancing Food Safety in Northern Uganda
(Microorganisms, 2021) Wokorach, Godfrey; Landschoot, Sofie; Audenaert, Kris; Echodu, Richard; Haesaert, Geert
Worldwide fungal contamination leads to both quantitative and qualitative grain losses during crop growth and/or storage. A greater proportion of grains contamination with toxins often occurs in sub-Saharan Africa, where control measures are limited. We determined fungal diversity and their toxin production ability in household grains meant for human consumption to highlight the risk of mycotoxin exposure among people from northern Uganda. The study underlines the high diversity of fungi that group into 15 genera; many of which are plant pathogens with toxigenic potential. Fusarium verticillioides was the most common fungal species isolated from household grains. The study also indicates that northern Uganda is favored by a high proportion of toxigenic isolates of F. verticillioides, F. andiyazi, and F. proliferatum, which are characterized by a high fumonisins production capability. The fumonisins production ability was not dependent on the species, grain types, and haplotype group to which the isolates belong. The contamination of most household grains with fungi capable of producing a high amount of toxin shows that most people are exposed to an elevated amount of mycotoxins, which shows the frequent problems with mycotoxins that have been reported in most parts of sub-Saharan Africa.
Genomic analysis of Sweet potato feathery mottle virus from East Africa
(Physiological and Molecular Plant Pathology, 2020) Wokorach, Godfrey; Otima, Geoffrey; Njuguna, Joyce; Edema, Hilary; Njung'e, Vincent; Machuka, Eunice M.; Yaoc, Nasser; Stomeo, Francesca; Echodu, Richard
Sweet potato feathery mottle virus is a potyvirus that infect sweet potato. The genome of the virus was analysed to understand genetic diversity, evolution and gene flow. Motifs, nucleotide identity and a phylogenetic tree were used to determine phylogroup of the isolates. Gene flow and genetic diversity were tested using DnaSP v.5. Codons evolution were tested using three methods embedded in Datamonkey. The results indicate occurrence of an isolate of phylogroup B within East Africa. Low genetic differentiation was observed between isolates from Kenya and Uganda indicating evidence of gene flow between the two countries. Four genes were found to have positively selected codons bordering or occurring within functional motifs. A motif within P1 gene evolved differently between phylogroup A and B. The evidence of gene flow indicates frequent exchange of the virus between the two countries and P1 gene motif provide a possible marker that can be used for mapping the distribution of the phylogroups.
Mycotoxin profile of staple grains in northern Uganda: Understanding the level of human exposure and potential risks
(Food Control, 2021) Wokorach, Godfrey; Landschoot, Sofie; Anena, Juliet; Audenaert, Kris; Echodu, Richard; Haesaert, Geert
Mycotoxins are toxic metabolites of fungi that contaminate food and feed. These toxins can cause acute and chronic health threats to both humans and animals. In sub-Saharan Africa, exposure to mycotoxins is chronic and under-reported. The study explores contamination of grains (sorghum, maize, groundnut, millet) with four mycotoxins (aflatoxins, fumonisins, ochratoxins, and deoxynivalenol) and dietary exposure to quantify associated health risks in northern Uganda. The results underscored the high prevalence of mycotoxins, only 7% of the samples were free from toxins. Sorghum grains seemed to be the most susceptible to toxin contamination, whereas in millet the toxin levels were, in general, the lowest. Besides, the results showed that the majority of grains were contaminated with more than one mycotoxin and that the toxin pattern was dependent on the grain type. Co-contamination with all four mycotoxins mainly occurred in sorghum grains. Besides the differences between grain types, there were also significant differences in toxins levels depending on the district where the grains came from. The estimated daily intakes for the mycotoxins were far above the recommended tolerable daily intake (TDI), especially for sorghum. So, it can be concluded that the majority of the people whose diet is mainly based on sorghum are exposed to multiple mycotoxins in a single diet and at a dose above the TDI. Such exposure to multiple mycotoxins elevates the associated health risks. Millet grains, which were the least contaminated, can provide an alternative to sorghum. However, to tackle the mycotoxin problem, other control and prevention mechanisms, e.g. good agricultural practices and optimized storage must be further explored and implemented in sub-Saharan Africa.
Sweetpotato seed exchange systems and knowledge on sweetpotato viral diseases among local farmers in Acholi Sub Region-Northern Uganda
(African Journal of Agricultural Research, 2018) Wokorach, Godfrey; Edema, Hilary; Echodu, Richard
Viral infections greatly limit sweetpotato yields. Good farming practices are critical for effective disease management. 383 Ugandan farmers were surveyed to document symptom incidence, crop-management practices, and buyer preferences. Results showed that 89.27% farmers grow sweet potatoes yearly and 62.76% of these farmers were female. A total of 56.83% farmers obtained vine seeds from their previous gardens, 25.85% from neighbours, and 12.20% purchased. Only ~8% of sellers and ~4% of buyers were selected for disease-free materials. None of the farmers who used vine-cutting knives sterilised them. Almost half of farmers (47%) observed whitefly or aphids but most were unaware they are viral vectors. Most farmers (77%) observed viral symptoms, but few (<2%) recognised them as infections. Insufficient knowledge of sweetpotato viruses and their vectors is common and increases the risk of spread. Practices like vine selling, sharing of vines coupled with insufficient knowledge on sweet potato viruses and its vectors among farmers increase the risk of virus spread among different farms.

Browsing by Author "Wokorach, Godfrey"

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