DIVERSITY AND BIO-CONTROL OF MYCOTOXIN FUNGI FROM MAIZE, GROUNDNUTS AND SOILS OF WESTERN KENYA

Abstract

Mycotoxin adulteration in maize, groundnuts and agricultural lands have destabilized Kenya's food safety and healthcare status overtime. This study focused on assessing the diversity of mycotoxin fungi in maize, groundnut, and soils in Western Kenya, determining in-vitro inhibitory indices, and the efficacy of selected fungi against the mycotoxin-producing fungi under field conditions. This involved biased sampling of contaminated maize, groundnut, and soils from Homa Bay, Migori, Siaya, and Busia Counties. Respective farmers were assessed on their awareness on mycotoxin mitigation measures in grains. Pure fungal cultures were grown on PDA media and incubated at 25-27 oC in a Gallenkamp incubator. Fungal identification was done at X400 microscopic magnification and then confirmed using pathology reference books and journals. After identification, in-vitro inhibitory indices of toxigenic and non-toxigenic species were done to determine their degree of antagonism against mycotoxin-producing fungi using the dual culture and the modified techniques after a 10-day incubation period. The next stage comprised testing of nine fungal isolates for their inhibitory capacity against 6 mycotoxin fungi. Finally, field efficacy tests for successful antagonists against mycotoxin fungi under a split-plot layout in RCBD were done for two sites in two seasons. The arrangement comprised two maize varieties serving as the main plots and seven treatments as subplots. Fungal diversity findings were presented in plates and description tables, while in-vitro and field data were analysed using ANOVA and DMRT at 5% significance level applied as a mean separation post-hoc using Genstat software version 16.0. Additionally, farmers in Busia, Siaya, Homa Bay and Migori counties were unaware of field and off-field causes and mitigations of mycotoxins in maize and groundnuts. Pure cultures of thirty-five diverse fungal isolates were obtained where14 diverse pathotypes were Aspergillus species followed by 8 and 4 diverse isolates from Penicillium and Fusarium genera respectively. Busia County had the highest sum of diverse isolates and Siaya recorded the lowest. For isolation frequency per sample type, soil samples (30 isolates) and groundnuts (9 isolates) had the most and least number of diverse fungal isolates. Twenty-two isolates were specific to environments/counties while 13 were not specific to a single region. Over 80% inhibition levels were observed in T. harzianum, MCMT3, MCMT4b and Monascus species in-vitro against mycotoxin fungi. However, isolates MCMT3, MCMT4b and Monascus species had the best ZIs against mycotoxin fungal isolates. In field conditions, Monascus spp., T. harzianum, MCMT3, MCMT4b, and the mixed concoction MCMT3, MCMT4b, and Monascus spp significantly repressed mycotoxin fungi. In conclusion, Western Kenya farmers were unaware of mycotoxin causes and best pre- and post-harvest extenuation measures. Mycotoxin fungi dominated maize, groundnut, and soils of Busia, Siaya, Homa Bay, and Migori counties of Kenya. Isolates MCMT3, MCMT4b, Monascus spp., and T. harzianum best repressed mycotoxin-producing fungi but did not display synergism in field conditions. This study recommends adequate capacity building on mycotoxin management strategies among Western Kenya farmers and mass production of isolates MCMT3, MCMT4b, and Monascus species for the management of mycotoxin fungi in maize and susceptible economic valuable crops to mycotoxin fungi.