Selection and Characterisation of Oenococcus oeni and Lactobacillus plantarum South African Wine Isolates for Use as Malolactic Fermentation Starter Cultures

Abstract

This study focused on characterising 23 Oenococcus oeni and 19 Lactobacillus plantarum strains isolated from the South African wine environment for the development of potential commercial malolactic fermentation (MLF) starter cultures. These strains were characterised with regards to oenological important characteristics, including the genetic screening for enzyme-encoding genes (enzymes that are involved/implicated in wine aroma modification, as well as enzymes pertaining to the wholesomeness of the final wine product), their fermentation capabilities, the ability to maintain viability during MLF, as well as the volatile acidity production. A total of three O. oeni and three L. plantarum strains were selected at the completion of this study. These six strains showed the most potential during the characterisation stages of the study and were able to successfully complete MLF in Pinotage wine. It was also found that L. plantarum strains displayed a more diverse enzyme profile than O. oeni strains, particularly with regards to the presence of the aroma-modifying enzymes β-glucosidase and phenolic acid decarboxylase (PAD), which implies the future use of this species in the modification of the wine aroma profile and use as commercial starter culture.

Selection and characterization of Oenococcus oeni strains for use as new malolactic fermentation starter cultures

“…Esterase that originates from wine LAB are responsible for biosynthesis and hydrolysis of esters (Pérez-Martín et al 2013;Sumby et al 2013a, b). Different from previous studies, only three strains were positive for esterase-encoding genes (Lerm et al 2011). The results of the enzymatic screening confirm the presence or absence of the genes, and indicate that these strains have the potential to express the corresponding enzyme; however, they give no indication about the enzymatic activity during MLF in wine.…”

“…All isolates could survive and degrade L-malic acid under mild conditions (pH 3.8 and 10 % ethanol), but only nine strains could tolerate the harsh condition (pH 3.2 and 14 % ethanol). In this study, O. oeni strains showed a better L-malic degradation capability in the synthetic wine medium than previous studies (Capozzi et al 2010;Ruiz et al 2010;Lerm et al 2011). This result was expected since the synthetic wine media used in this study were designed to meet the essential nutrient demands of different O. oeni strains.…”

“…Since the first commercial starter was selected in 1974, related research has been done worldwide for the screening of new commercial starters (Coucheney et al 2005;Ruiz et al 2010;Lerm et al 2011;Bordas et al 2013;del Mónaco et al 2014;Li et al 2014). Selections were made based mainly on the Electronic supplementary material The online version of this article (doi:10.1007/s13213-016-1217-3) contains supplementary material, which is available to authorized users.…”

“…evaluation of each strain's ability to grow and to degrade Lmalic acid. Several criteria have been made for the selection of possible starters (Lerm et al 2011;Torriani et al 2011). These criteria include the ability to tolerate low pH, high ethanol concentration and SO 2 , good growth characteristics under severe winemaking conditions, and the inability to produce biogenic amines, etc.…”

Microbial Resources and Innovation in the Wine Production Sector

“…They also exhibit a wider range and greater spectrum of enzymatic activities than O. oeni, and can contribute to a greater modification of wine aroma. Several authors have demonstrated that many wine-associated lactobacilli contain genes encoding important enzymes that are active under winemaking conditions (Du Toit et al, 2011;Lerm et al, 2011). Besides, the use of L. plantarum has been suggested as a biological acidification method because of its ability to produce high concentrations of lactic acid (Onetto & Bordeu, 2015;Lucio et al, 2016).…”