Toward application of biocontrol to inhibit wine spoilage yeasts: The use of statistical designs for screening and optimisation

Benjamin Kuchen,Fabio Vazquez,Gustavo J E Scaglia,Martha Dina Vallejo,Licia María Pera,Yolanda Paola Maturano

doi:10.20870/oeno-one.2021.55.2.4510

Abstract

Spoilage yeasts generate considerable economic losses in the wine industry, and although sulphur dioxide (SO2) is traditionally used for control, its use has become controversial because of its negative effects on health. Biocontrol has emerged as a partial alternative to SO2, and most research has focused on the selection of biocontrol yeasts and/or the mechanisms involved, while little research has been directed to the environmental conditions that make biocontrol effective for application. When there are two or more interacting yeasts, the physicochemical factors that affect their antagonism are many and therefore the application of biocontrol is complex. To reduce SO2, the present study aimed to elucidate biocontrol mechanisms of two yeast interactions and to establish optimal physicochemical conditions for biocontrol of the spoilage yeast during grape must fermentation. Through the use of statistical design, it was possible to find relevant physicochemical factors and optimise them. Wickerhamomyces anomalus “BWa156” developed an active supernatant against ZygoSaccharomyces rouxii “BZr6” while supernatant from Metschnikowia pulcherrima “BMp29” was ineffective. In mixed must fermentations, the first interaction (BWa156 vs. BZr6) showed fewer physicochemical factors impacting biocontrol compared to the second interaction (BMp29 vs. BZr6). However, the fewer factors of the first interaction had a stronger effect on the decline in the spoilage population. Validations showed that the optimal conditions for biocontrol with the first interaction could be predicted. Analysis of the results with BWa156 vs. BZr6 and BMp29 vs. BZr6 suggests that the first interaction is a competition that includes a killer toxin, while the second interaction involves competition for iron resources. Response surface methodology (RSM) allowed a reduction in the number of experiments and permitted to find the optimal biocontrol conditions (SO2: 0 mg mL-1; pH: 3.7; Reducing sugars: 23 °Brix) for the interaction between BWa156 and BZr6.

Highlights

Wine spoilage yeasts generate considerable economic losses because they produce unfavourable organoleptic characteristics (Rojo et al, 2015)
The results obtained with Wickerhamomyces anomalus (BWa156, biocontroller) supernatants to inhibit Zygosaccharomyces rouxii (BZr6, spoilage yeast) suggest the development of an interference competition type interaction, probably the result of a proteinaceous toxin
The screening results revealed an interaction of exploitation competition for iron resources between Metschnikowia pulcherrima (BMp29, biocontroller) and Zygosaccharomyces rouxii (BZr6, spoilage yeast)

Summary

Introduction

Wine spoilage yeasts generate considerable economic losses because they produce unfavourable organoleptic characteristics (Rojo et al, 2015). Several authors have hypothesised about mixed co-inoculations during wine fermentation so that yeast populations that positively affect the fermentation process could control wine spoilage yeasts in the initial fermentation stages This would result in a reduction in the use of chemical compounds such as SO2 (Oro et al, 2014; Berbegal et al, 2017; Simonin et al, 2020). There is little information about the conditions under which biocontrol is effective in the real environment, the wine fermentation (Boynton, 2019) This may have its origin in the fact that controlled fermentations for the application of certain yeast strains are characterised by complex interactions between the members of the consortium inoculated in the grape must and the yeast microbiota in the original must (Ciani and Comitini, 2015)

Methods

Results

Discussion

Conclusion