Incidence of toxigenic Aspergillus and Fusarium species occurring in maize kernels from Kenyan households

Abstract

Aspergillus andFusarium are fungal genera that include toxigenic and pathogenic species, able to suffuse farmers’ crops and secrete an array of small molecular weight secondary metabolites which can cause health complications to humans and animals when ingested. In sub-Sahara Africa, contamination and persistence of these fungi is increased by the tropical climatic conditions which are ideal for the fungi to thrive. This study evaluated the incidence, regional distribution and toxigenic potential ofAspergillus andFusarium species occurring in maize kernels from Eastern, Western, Coastal and the Lake Victoria agro-ecological zones of Kenya. Maize kernels were collected from 16 households in each agro-ecological zone. Single spore technique was used to isolate pure cultures ofAspergillus andFusarium which were identified morphologically. Further, molecular analysis was done using the internal transcribed spacer 1 (ITS 1) region of the ribosomal DNA forAspergillus and the translation elongation factor-1 alpha (TEF-1α) forFusarium. The potential of the isolated fungi to produce mycotoxins was probed by polymerase chain reaction (PCR) based on the aflatoxin regulatoryaflaR gene inAspergillus, and the fumonisin backbone structure geneFUM1 inFusarium. Among the potentially aflatoxigenicA. flavus species isolated, 55% were from Eastern, 27% from the Coastal zone, 13% from Lake Victoria zone and 5% from Western Kenya. Among the potentially fumonisin producingF. verticillioides isolated, 45% were from the Lake Victoria agro-ecological zone, 30% were from Western, 15% from Eastern Kenya and 10% from the Coastal agro-ecological zone. This study adds data on potential mycotoxin hotspots in Kenya useful in employing targeted and regional mycotoxin mitigation strategies in efforts to avert future mycotoxicoses outbreaks in Kenya.