Maria Rosa Morales, Maria Jose Rodriguez-Vaquero,* and Fabiana Maria Saguir  *CONICET-UNT, Ayacucho 471, 4000, Argentina (mariajo@fbqf.unt.edu.ar)

Wineries create large volumes of byproduct streams and waste, including grape pomace, wine lees, and grape stalk, which should be valorized or treated before disposal to prevent environmental pollution. Grape pomace is the solid residue left after juice extraction during winemaking and includes grape skins and seeds. Wine lees are the residue that forms at the bottom of recepticals containing wine, after fermentation or during storage. The aim of this work was to isolate and characterize the lactic acid bacteria (LAB) present in both pomace and lees to find LAB with optimal properties to be included in fermented food. Malbec grape pomace and wine lees samples were centrifuged and resuspended in MRS medium enriched with 5 g/L fructose and 3 g/L L-malic acid and adjusted to pH 5.0. After incubation at 30°C for 72 hr, samples were plated on MRS agar supplemented with 1% cycloheximide (MRS-C). All plates were incubated aerobically at 30°C for 72 hr. Twenty colonies of each sample were selected and preliminarily identified by cell morphology, Gram stain, catalase and dextran production, and growth under different conditions, such as NaCl concentrations (2.5, 5.0, or 7.5%), 
pH (4.0, 7.0, or 9.0), and temperature (15, 30, or 45°C). Glucose consumption and D- or L-lactic acid isomer production were also determined. Of 40 isolated bacteria, 28 were LAB and produced both isomers of lactic acid from glucose. All LAB isolated from grape pomace and most from lees isolated were homofermentative; only six were heterofermentative. Our results showed the presence of LAB in winery wastes generally had high lactic acid production and optimal properties for inclusion in wine or other beverages, but further studies must be conducted.

Funding Support: PICT 2015-1508 – Prestamo Bid PIP-CONICET CIUNT