Identification and Toxigenic Potential of Fungi Isolated from Capsicum Peppers.

Gabriel Kojo Frimpong,Sudharsan Sadhasivam,Manoj Kumar Solanki,Edward Sionov,Oluwatoyin Temitayo Ogundipe,Adedotun Adeyinka Adekunle

doi:10.3390/microorganisms7090303

Gabriel Kojo Frimpong, Sudharsan Sadhasivam + Show 4 more

Open Access

https://doi.org/10.3390/microorganisms7090303

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Abstract

Capsicum peppers are among the most popular horticultural crops produced and consumed worldwide. This study aimed to assess the occurrence of spoilage fungi responsible for post-harvest losses in the most common varieties of Capsicum peppers collected from retail markets in Nigeria and Ghana. Forty fungal isolates belonging to 7 families, 8 genera, and 17 species were identified on the basis of morphology, culture characteristics, and DNA sequencing of the internal transcribed spacer (ITS) region. Aspergillus spp. (42.5%), Fusarium spp. (22.5%), and Colletotrichum spp. (15%) were found to be the predominant fungal pathogens. Furthermore, potential ability of the isolated mycotoxigenic fungi to produce some major mycotoxins was analyzed using high-performance liquid chromatography (HPLC). Among the 22 isolates analyzed, 11 strains belonging to the genera of Aspergillus, Fusarium, and Penicillium were found to be able to produce mycotoxins, such as aflatoxin B1, gliotoxin, deoxynivalenol, and citrinin. A better understanding of the role of fungal contaminants in pepper fruits, especially the prevalence of mycotoxigenic fungi and their associated mycotoxigenic potential, will assist in the development of management strategies to control mycotoxin contamination and to reduce toxicological risks related to pepper consumption by humans and animals.

Highlights

The Capsicum genus, which includes more than 30 species of flowering pepper plants, belongs to one of the most important families known as Solanaceae
Phylogenetic analysis of internal transcribed spacer (ITS) ribosomal RNA (rRNA) gene region sequences indicated that all sequences of the isolated fungi were assigned to the phylum Ascomycota, which were mainly represented by the fungal family of Trichocomaceae (47.5%), followed by the families of Nectriaceae (22.5%), Glomerellaceae (15%), Corynesporascaceae (5%), Dipodascaceae (5%), Bionectriaceae (2.5%), and Xylariaceae (2.5%) (Figure 1)
Forty fungal isolates, which were cultured from the pepper fruits, mainly consisted of the genera Aspergillus, followed by Fusarium and Colletotrichum; several species of Colletotrichum and other genera such as Corynespora, Xylaria, Clonostachys, and Geotrichum were found in pepper samples and identified based on morphological features and sequencing analysis (Tables S1 and S2)

Summary

Introduction

The Capsicum genus, which includes more than 30 species of flowering pepper plants, belongs to one of the most important families known as Solanaceae. The incidence of pre- and post-harvest diseases has become a major constraint for the growers. Such as any other agricultural crops, Capsicum peppers are susceptible to fungal infection and subsequent contamination with mycotoxins, which are toxic chemical products, formed as secondary metabolites by filamentous fungi. Many species of Alternaria, Fusarium, Cladosporium, and Rhizopus are associated with fungal infections of the growing plants in the field, while Aspergillus and Penicillium species are the predominant pathogens found in a high frequency of isolation from Capsicum by-products during the harvest and post-harvest stages, including drying, product transportation, and marketing (e.g., factory production, restaurants, retail markets) [3,11,12,13,14]. It has been reported that climatic conditions in tropical or sub-tropical regions, such as high temperature, humidity, and rainfall, contribute to the high fungal burden and mycotoxin contamination in pepper samples [15]

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