Original scientific paper
Selection of Psychrotolerant Microorganisms Producing Cold-Active Pectinases for Biotechnological Processes at Low Temperature
María S. Cabeza
; National Council of Scientific and Technical Research (CONICET), Av. Rivadavia 1917, C1033AAJ, Buenos Aires, Argentina
Fanny L. Baca
; Biotechnology Laboratory, Biology and Food Department, Faculty of Applied Industrial Science, Bernardo de Irigoyen 375, AR-5600, San Rafael, Mendoza, Argentina
Ernesto Muñoz Puntes
; Biotechnology Laboratory, Biology and Food Department, Faculty of Applied Industrial Science, Bernardo de Irigoyen 375, AR-5600, San Rafael, Mendoza, Argentina
Flavia Loto
; National Council of Scientific and Technical Research (CONICET), Av. Rivadavia 1917, C1033AAJ, Buenos Aires, Argentina
Mario D. Baigorí
; Pilot Plant of Industrial and Microbiological Processes (PROIMI), Av. Belgrano and Pje. Caseros 4000, AR-4000 Tucumán, Argentina
Vilma I. Morata
; Biotechnology Laboratory, Biology and Food Department, Faculty of Applied Industrial Science, Bernardo de Irigoyen 375, AR-5600, San Rafael, Mendoza, Argentina
Abstract
In winemaking, low temperatures are favourable for the production and retention of flavour and colour components, requiring the use of cold-active enzymes. For this reason, 'psychrotolerant' microorganisms have been isolated and selected based on their ability to produce pectinolytic enzymes with satisfactory activity at low temperatures. Different mature grape varieties with designation of origin were sampled from the region of San Rafael (Mendoza, Argentina), and pectinolytic bacterial, fungal and yeast strains were isolated. The pectinolytic activity was measured by cup-plate assay, quantification of released reducing sugars and viscosity reduction of pectin solution. Two bacteria (Bacillus sp. SC-G and SC-H) and two yeast strains were selected for their good pectinase activity at low temperatures. Among them, the strain with the highest activity, Bacillus sp. SC-H, was selected. According to their 16S rRNA profiles, Bacillus sp. SC-G and SC-H can be classified as members of Bacillus subtilis. Among the assayed techniques, the rotary evaporation was found to be the most appropriate to obtain enzymatic extracts with highest activity. The optimal conditions for the enzymatic activity were 30 °C and pH=5.0 for the concentrated extract, and 45 °C and pH=6.0 for the filtered supernatant. The concentrated extract presented good activity at 3 °C, confirming that it was a cold-active enzyme. Natural extraction and enzymatic preparation were used to extract pigments and polyphenols from Malbec grapes. Better results were obtained for the enzymatic extract with regard to index, shade, CIELab coordinates, CIELab colour differences and polyphenols (measured using Folin-Ciocalteu).
Keywords
pectinase; cold-active enzymes; low temperature; Bacillus; pigment and polyphenol extraction
Hrčak ID:
69458
URI
Publication date:
15.6.2011.
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