Transcriptional and Metabolic Response of Wine-Related Lactiplantibacillus plantarum to Different Conditions of Aeration and Nitrogen Availability

Renato L Binati,Maret Du Toit,Sandra Torriani,Jacky L Snoep,Elisa Salvetti

doi:10.3390/fermentation7020068

Renato L Binati, Maret Du Toit + Show 3 more

Open Access

https://doi.org/10.3390/fermentation7020068

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Abstract

Lactic acid bacteria (LAB) perform the process of malolactic fermentation (MLF) in wine. Availability of oxygen and nitrogen nutrients could influence LAB growth, malolactic activity, and other metabolic pathways, impacting the subsequent wine quality. The impact of these two factors has received limited investigation within LAB, especially on a transcriptome level. The aim of this study was to evaluate metabolic changes in the strain Lactiplantibacillus plantarum IWBT B063, growing in synthetic grape juice medium (GJM) under different oxygen exposure conditions, and with low availability of nitrogen-based nutrients. Next-generation sequencing was used to analyze expression across the transcriptome (RNA-seq), in combination with conventional microbiological and chemical analysis. L. plantarum consumed the malic acid present in all the conditions evaluated, with a slight delay and impaired growth for nitrogen limitation and for anaerobiosis. Comparison of L. plantarum transcriptome during growth in GJM with and without O2 revealed differential expression of 148 functionally annotated genes, which were mostly involved in carbohydrate metabolism, genetic information processing, and signaling and cellular processes. In particular, genes with a protective role against oxidative stress and genes related to amino acid metabolism were differentially expressed. This study confirms the suitability of L. plantarum IWBT B063 to carry out MLF in different environmental conditions due to its potential adaption to the stress conditions tested and provides a better understanding of the genetic background of an industrially relevant strain.

Highlights

Transformation of grape must in wine is a multifaceted process from a microbiological point of view, with a succession of different groups of microorganisms, more or less adapted to specific conditions throughout the course of winemaking
Aeration control and grape must composition are of major importance for successful completion of malolactic fermentation (MLF), due to their relevant impact on Lactic acid bacteria (LAB) development
B063 was able to carry out MLF under challenging conditions, but anaerobic conditions and limitation of nitrogen nutrients reduced its growth in grape juice medium, delaying the completion of MLF

Summary

Introduction

Transformation of grape must in wine is a multifaceted process from a microbiological point of view, with a succession of different groups of microorganisms, more or less adapted to specific conditions throughout the course of winemaking. Lactic acid bacteria (LAB) are among the most relevant groups, mainly responsible for carrying out malolactic fermentation (MLF). The decarboxylation of L-malic acid to L-lactic acid is relevant in most red wines and some white wines as well, where it contributes to deacidification, microbial stability, and aroma complexity [1,2,3]. Lactiplantibacillus plantarum (formerly Lactobacillus plantarum [4]) has gained increased attention from researchers and winemakers, with proven suitability to drive this process [2,5]. The principal sensory effect of LAB is the conversion of tart malic acid into the softer and rounder lactic acid, but

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