Induction of biodeterioration on vegetables by three fungal species

Authors: ADUROJA, ESTER - Babcock University; Moore, Geromy; Beltz, Shannon; SOARES, CELIA - University Of Minho; LIMA, NELSON - University Of Minho; FAPOHUNDA, STEPHEN - Babcock University

Submitted to: Journal of Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/14/2018
Publication Date: 10/2/2018
Citation: Aduroja, E.D., Moore, G.G., Beltz, S.B., Soares, C., Lima, N., Fapohunda, S.O. 2018. Induction of biodeterioration on vegetables by three fungal species. Journal of Plant Pathology. 101(2):243-250. https://doi.org/10.1007/s42161-018-0175-y.
DOI: https://doi.org/10.1007/s42161-018-0175-y

Interpretive Summary: Spoilage of important vegetables, by fungi with the potential to produce mycotoxins, poses numerous risks to consumer health as well as trade, both locally and internationally. These vegetables may be salvaged by peeling or cutting away obvious mold growth, but this may not remove all of the contaminating organism, nor any potentially toxic compounds that may be secreted into vegetable tissue. The aim of this study was to evaluate the effects of sampled fungi (Aspergillus tamarii, A. violaceofuscus and Fusarium chlamydosporum) on the nutritional, metal content and possible mycotoxin contamination of onions and cucumbers in Nigeria, and to investigate two anti-fungal compounds as possible interventions. This study underscores the ability of fungi to degrade vegetables, their potentials to produce mycotoxins, and the need to focus on intervention through both chemical and best practices.

Technical Abstract: A sampling of contaminated foodstuffs throughout southwest Nigeria yielded one fungal isolates belonging to the genus Fusarium and two fungal isolates belonging to the genus Aspergillus. The species identities of the fungal isolates were first determined based on macro- and micro-morphological characters, before being confirmed using a molecular approach such as amplification of the internal transcribed spacer genomic region, as Fusarium chlamydosporum, Aspergillus tamarii and A. violaceofuscus. We then used each fungus to induce biodeterioration and performed proximate analysis of nutrient breakdown. We also assayed each fungus for the production of known mycotoxins and performed anti-fungal susceptibility tests using fluconazole and voriconazole. We found that F. chlamydosporum facilitated the highest rate of biodeterioration for onions and cucumber; however, analysis revealed the presence of Fusarium mycotoxins only in the onion sample. Our anti-fungal tests revealed that Aspergillus tamarii (a non-aflatoxigenic species) was susceptible to voriconazole, but resistant to fluconazole. A. violaceofuscus (a non-aflatoxigenic species) was susceptible to both, while F. chlamydosporum was resistant to both, of the anti-fungals.