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.