Selection of Psychrotolerant Microorganisms Producing Cold-Active Pectinases for Biotechnological Processes at Low Temperature

CABEZA, M. S.; BACA, F. L.; MUÑOZ PUNTES, E.; LOTO, F.; BAIGORÍ, M. D.; MORATA, V.I.

FOOD TECHNOLOGY AND BIOTECHNOLOGY

FACULTY FOOD TECHNOLOGY BIOTECHNOLOGY

Lugar: Zagreb, Croatia; Año: 2011 vol. 49 p. 187 - 195

1330-9862

In winemaking, low temperatures are favourable for the production and retention offlavour and colour components, requiring the use of cold-active enzymes. For this reason,´psychrotolerant´ microorganisms have been isolated and selected based on their ability toproduce pectinolytic enzymes with satisfactory activity at low temperatures. Different maturegrape 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 reducingsugars and viscosity reduction of pectin solution. Two bacteria (Bacillus sp. SC-G andSC-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. Accordingto their 16S rRNA profiles, Bacillus sp. SC-G and SC-H can be classified as membersof Bacillus subtilis. Among the assayed techniques, the rotary evaporation was found to bethe most appropriate to obtain enzymatic extracts with highest activity. The optimal conditionsfor the enzymatic activity were 30 °C and pH=5.0 for the concentrated extract, and45 °C and pH=6.0 for the filtered supernatant. The concentrated extract presented good activityat 3 °C, confirming that it was a cold-active enzyme. Natural extraction and enzymaticpreparation were used to extract pigments and polyphenols from Malbec grapes. Betterresults were obtained for the enzymatic extract with regard to index, shade, CIELab coordinates,CIELab colour differences and polyphenols (measured using Folin-Ciocalteu).