Identification of lactic acid bacteria isolated from wine using real-time PCR

ABSTRACT

Different lactic acid bacteria strains have been shown to cause wine spoilage, including the generation of substances undesirable for the health of wine consumers. The aim of this study was to investigate the occurrence of selected species of heterofermentative lactobacilli, specifically Lactobacillus brevis, Lactobacillus hilgardii, and Lactobacillus plantarum in six different Slovak red wines following the fermentation process. In order to identify the dominant Lactobacillus strain using quantitative (real time) polymerized chain reaction (qPCR) method, pure lyophilized bacterial cultures from the Czech Collection of Microorganisms were used. Six different red wine samples following malolactic fermentation were obtained from selected wineries. After collection, the samples were subjected to a classic plate dilution method for enumeration of lactobacilli cells. Real-time PCR was performed after DNA extraction from pure bacterial strains and wine samples. We used SYBR® Green master mix reagents for measuring the fluorescence in qPCR. The number of lactobacilli ranged from 3.60 to 5.02 log CFU mL⁻¹. Specific lactobacilli strains were confirmed by qPCR in all wine samples. The number of lactobacilli ranged from 10³ to 10⁶ CFU mL⁻¹. A melting curve with different melting temperatures (T_m) of DNA amplicons was obtained after PCR for the comparison of T_m of control and experimental portions, revealing that the most common species in wine samples was Lactobacillus plantarum with a T_m of 84.64°C.

KEYWORDS:

• Lactobacilli
• red wine
• real-time PCR

Acknowledgment

The authors are thankful to Eva Tvrda for linguistic revision of this paper.

Funding

This work was supported by VEGA 1/0611/14 grant and the European Community project No. 26220220180 Building Research Centre “AgroBioTech.”