Volatile Organic Compounds (VOCs) Produced by Gluconobacter cerinus and Hanseniaspora osmophila Displaying Control Effect against Table Grape-Rot Pathogens.

Ninoska Delgado,Matías Olivera,Alejandro Madrid,Guillermo Bravo,Romina Pedreschi,Iván Montenegro,Eduardo Salgado,Fabiola Cádiz,Claudia Fuentealba,Ximena Besoain

doi:10.3390/antibiotics10060663

Abstract

Table grapes (Vitis vinifera) are affected by botrytis bunch rot and summer bunch rot, the latter a complex disease caused by Botrytis cinerea, Aspergillus spp., Penicillium expansum and Rhizopus stolonifer. To search for biocontrol alternatives, a new bioproduct composed of Gluconobacter cerinus and Hanseniaspora osmophila, a consortium called PUCV-VBL, was developed for the control of fungal rots in table grapes. Since this consortium presents new biocontrol species, the effect of their VOCs (volatile organic compounds) was evaluated under in vitro and in vivo conditions. The VOCs produced by the PUCV-VBL consortium showed the highest mycelial inhibition against Botrytis cinerea (86%). Furthermore, H. osmophila was able to inhibit sporulation of A. tubingensis and P. expansum. VOCs’ effect in vivo was evaluated using berries from Red Globe, Thompson Seedless and Crimson Seedless grapes cultivars, demonstrating a mycelial inhibition by VOCs greater than 70% for all evaluated fungal species. The VOC identification of the PUCV-VBL consortium was analyzed by solid-phase microextraction coupled to gas chromatography-mass spectrometry (SPME-GCMS). A total 26 compounds were identified, including 1-butanol 3-methyl, propanoic acid ethyl ester, ethyl acetate, phenylethyl alcohol, isobutyl acetate and hexanoic acid ethyl ester. Our results show that VOCs are an important mode of action of the PUCV-VBL biological consortium.

Highlights

The objectives of this work were to evaluate the effect of the volatile organic compounds (VOCs) produced by the PUCV-VBL consortium; the following were studied: (i) the in vitro effects on Aspergillus, Botrytis, Penicillium and Rhizopus fungi; (ii) the in vivo effects against pathogens in Thompson Seedless, Crimson Seedless, and Red Globe cultivars; and (iii) the VOCs cs 2021, 10, x FOR PEER REVIEW
Results show that Hanseniaspora osmophila is most responsible for VOCs in grapes
(1-butanol 3-methyl, 2-methyl butanoic acid, 2-methyl 1-butanol, hexanoic ethyl acid, 3methyl 1-butanol, 2-phenyl acetic acid, propyl acetate, phenylethyl alcohol, ethyl acetate, 2-propanoic acid, isobutyl acetate, and propanoic acid); the same VOCs were present in the PUCV-VBL biocontrol

Summary

Introduction

Summer bunch rot complex and botrytis bunch rot (“gray mold”) are responsible for the most significant reductions in table grape yield and quality worldwide [1]. In late summer, these microorganisms along with bacteria and yeasts, cause sour rot, a polymicrobial disease that attacks ripe, thin-skinned grapes [2]. In Chile, Botrytis cinerea pathologies have been shown to seriously affect susceptible cultivars, such as Thompson Seedless [3]. It was determined that the causal agents associated with summer bunch rot in cv.

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