High Efficacy of the Volatile Organic Compounds of Streptomyces yanglinensis 3-10 in Suppression of Aspergillus Contamination on Peanut Kernels.

Ang Lyu,Long Yang,Guoqing Li,Jing Zhang,Mingde Wu

doi:10.3389/fmicb.2020.00142

Ang Lyu, Long Yang + Show 3 more

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https://doi.org/10.3389/fmicb.2020.00142

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Abstract

Aspergillus flavus and Aspergillus parasiticus are saprophytic fungi which can infect and contaminate preharvest and postharvest food/feed with production of aflatoxins (B1, B2, and G). They are also an opportunistic pathogen causing aspergillosis diseases of animals and humans. In this study, the volatile organic compounds (VOCs) from Streptomyces yanglinensis 3-10 were found to be able to inhibit mycelial growth, sporulation, conidial germination, and expression of aflatoxin biosynthesis genes in A. flavus and A. parasiticus in vitro. On peanut kernels, the VOCs can also reduce the disease severity and inhibit the aflatoxins production by A. flavus and A. parasiticus under the storage conditions. Scanning electron microscope (SEM) observation showed that high dosage of the VOCs can inhibit conidial germination and colonization by the two species of Aspergillus on peanut kernels. The VOCs also showed suppression of mycelial growth on 18 other plant pathogenic fungi and one Oomycetes organism. By using SPME-GC-MS, 19 major VOCs were detected, like in other Streptomyces, 2-MIB was found as the main volatile component among the detected VOCs. Three standard chemicals, including methyl 2-methylbutyrate (M2M), 2-phenylethanol (2-PE), and β-caryophyllene (β-CA), showed antifungal activity against A. flavus and A. parasiticus. Among them, M2M showed highest inhibitory effect than other two standard compounds against conidial germination of A. flavus and A. parasiticus. To date, this is the first record about the antifungal activity of M2M against A. flavus and A. parasiticus. The VOCs from S. yanglinensis 3-10 did not affect growth of peanut seedlings. In conclusion, our results indicate that S. yanglinensis 3-10 may has a potential to become a promising biofumigant in for control of A. flavus and A. parasiticus.

Highlights

Volatile organic compounds (VOCs) are lipophilic chemicals with a low boiling point and low molecular mass (100– 500 Da), but with high vapor pressure (Effmert et al, 2012)
We found that the VOCs from Streptomyces yanglinensis 3-10 showed strong antifungal activity on mycelial growth and conidia germination, as well as on suppression of expression of aflatoxin biosynthesis genes in A. flavus and A. parasiticus
Results showed that the genes coding for all of these VOCs biosynthetic enzymes expressed in S. yanglinensis 3-10 (Figure 1)

Summary

Introduction

Volatile organic compounds (VOCs) are lipophilic chemicals with a low boiling point and low molecular mass (100– 500 Da), but with high vapor pressure (Effmert et al, 2012). The VOCs from Streptomyces platensis showed inhibitory activity against Botrytis cinerea on strawberry, Rhizoctonia solani on rice seedlings, and Sclerotinia sclerotiorum on oilseed rape (Wan et al, 2008). The VOCs from Streptomyces globisporus showed inhibitory activity against Penicillium iltalicum on citrus and B. cinerea on tomato (Li et al, 2010, 2012). The VOCs from Streptomyces alboflavus was able to inhibit the mycelial growth of several filamentous fungi (Wang et al, 2013). The VOCs produced by Streptomyces spp. showed inhibition of mycelial growth (IMG) of R. solani and promote the growth of Arabidopsis thaliana (Cordovez et al, 2015). Previous studies demonstrated that VOCs from endophytic fungus Muscodor albus and VOCs from Saccharomyces cerevisiae can be used as mycofumigant to control of many postharvest fruit diseases (Schnabel and Mercier, 2006; Toffano et al, 2017)

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