Initial Spore Density Has an Influence on Ochratoxin A Content in Aspergillus ochraceus CGMCC 3.4412 in PDB and Its Interaction with Seeds.

Yanmin Song,Zhihong Liang,Lu Xiong,Caiyan Li,Kunlun Huang

doi:10.3390/toxins9040146

Abstract

The morphology and secondary metabolism of Aspergillus spp. are associated with initial spore density (ISD). Fatty acids (FA) are involved in the biosynthesis of aflatoxins (AF) through Aspergillus quorum sensing (QS). Here, we studied how ochratoxin A (OTA) was regulated by spore density in Aspergillus ochraceus CGMCC 3.4412. The results contribute to understanding the role of spore density in morphogenesis, OTA biosynthesis, and host–pathogen interactions. When A. ochraceus was grown in Potato Dextrose Broth (PDB) media at different spore densities (from 101 to 106 spores/mL), more OTA was produced when ISD were increased, but a higher level of ISD inhibited OTA biosynthesis. Seed infection studies showed that peanuts (Arachis hypogaea) and soybeans (Glycine max) with high FA content were more susceptible to OTA production when infected by A. ochraceus and reactive oxygen species (ROS)-induced OTA biosynthesis. These results suggested that FA was vital for OTA biosynthesis, and that oxidative stress was closely related to OTA biosynthesis in A. ochraceus.

Highlights

Ochratoxin A (OTA) is a mycotoxin found in a variety of agricultural commodities, which include cereal grains and dried fruits
Seed infection studies showed that peanuts (Arachis hypogaea) and soybeans (Glycine max) with high Fatty acids (FA) content were more susceptible to OTA production when infected by A. ochraceus and reactive oxygen species (ROS)-induced OTA biosynthesis
These results suggested that FA was vital for OTA biosynthesis, and that oxidative stress was closely related to OTA biosynthesis in A. ochraceus

Summary

Introduction

Ochratoxin A (OTA) is a mycotoxin found in a variety of agricultural commodities, which include cereal grains and dried fruits. It is produced mainly by A. ochraceus, A. carbonarius, and A. niger [1]. OTA has been shown to be carcinogenic in animals. The kidney is the main target organ [2,3]. It has been recognized as a Group 2B carcinogen by International Agency for Research on Cancer Collection. Center (IARC) [4], OTA-related carcinogenicity has not been determined conclusively to occur in humans [5,6]. Among the OTA-producing fungi, A. ochraceus is the most common in tropical regions [7], and Penicillium verrucosum predominates in temperate regions [8].

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