Abstract
Native lactic acid bacteria (LAB) are capable of growing during winemaking, thereby strongly affecting wine quality. The species of LAB present in musts, wines during malolactic fermentation (MLF), and barrels/filters were investigated in wineries from the emerging wine region of Queretaro, México using multiplex PCR and culture. The resistance to wine-like conditions (WLC): ethanol (10, 12, and 13%), SO2 (30 mg⋅l-1), and low pH (3.5) of native LAB strains was also studied. Five species were detected within 61 samples obtained: Oenococcus oeni, Lactobacillus plantarum, Pediococcus parvulus, Lactobacillus hilgardi, and Lactobacillus brevis. Four species (excepting L. brevis) were found in must; O. oeni and P. parvulus were ubiquitous in wine and L. plantarum and L. brevis were mainly present at the initial stage of MLF, while L. hilgardii was mostly detected at the advanced stage. Furthermore, some species detected in barrel/filter, prove them to be hazardous reservoirs. From 822 LAB isolates, only 119 resisted WLC with 10% ethanol; the number of strains able to grow in WLC with 13% ethanol decreased approximately by 50%, O. oeni being the most versatile species with 65% of resistant isolates, while Lactobacillus spp. and P. parvulus were the most strongly affected, especially those recovered from barrel/filter, with less than 10% of resistant isolates. This study evidences the presence of local strains able to be used as starter cultures, and also enabled the assessment of the risks derived from the presence of spoilage LAB strains resistant to WLC.
Highlights
The conversion from grape must into wine is a complex process that involves the development of various microorganisms, including lactic acid bacteria (LAB)
The specie Oenococcus oeni is known as the main one responsible for malolactic fermentation (MLF), a process in which Lmalic acid is decarboxylated into L-lactic acid, causing a partial deacidification, conferring microbial stability, and improving wine flavor profile (Lerm et al, 2010)
The species O. oeni and L. plantarum were detected at all the wineries and P. parvulus was only absent at winery C
Summary
The conversion from grape must into wine is a complex process that involves the development of various microorganisms, including lactic acid bacteria (LAB). The LAB capable of overcoming these conditions mainly belong to Oenococcus, Lactobacillus, Pediococcus, and Leuconostoc genera (Lonvaud-Funel, 1999). The specie Oenococcus oeni is known as the main one responsible for malolactic fermentation (MLF), a process in which Lmalic acid is decarboxylated into L-lactic acid, causing a partial deacidification, conferring microbial stability, and improving wine flavor profile (Lerm et al, 2010). Some other LAB, such as Pediococcus spp. and some species of Lactobacillus, are widely associated with wine spoilage, often producing biogenic amines, off-odors, and other undesirable metabolites (Bartowsky, 2009)
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