Novel Antarctic Endo-Polygalacturonase for Pectin Extraction and Vegetal Tissue Maceration at Mild Temperatures.

The aim of the present work was to partially purify and characterize an Antarctic polygalacturonase and to determine the enzyme's potential in pectin extraction and vegetal maceration at 20 °C. Polygalacturonase was purified by chromatography to obtain an enzymatic preparation of specific activity 30.3 U.mg-1. Optimal conditions for the polygalacturonase activity were 45 °C and pH 5.0-6.0, and the activation energy for the reaction was 41.8 kJ.mol-1. Of the enzyme activity, 100% was retained after 3 h at 40 °C. The enzyme was remarkably stable for an hour over a wide range of pH (2.0-12.0). Polygalacturonase activity was slightly reduced in the presence of Ca+2, Fe+3, K+, Mn+2, and Zn+2, whereas Hg+2 reduced the activity by 60%, suggesting a thiol-dependent catalysis. The apparent molecular weight of the enzyme was 33 kDa. The kinetic constants evaluated against polygalacturonic acid were 0.17 mg.ml-1 (Km), 480 s-1 (Kcat), and 7.9 µmol.mg-1.min-1 (Vmax). The enzyme was active against different pectic substrates. Thin-layer chromatography revealed an endo-mechanism of action. Polygalacturonase digested lime pomace to aid the extraction of high-methoxylated pectin at 20 °C and increased the vegetal maceration of Capsicum annuum by 24% over the control values.

Cold-active pectinolytic activity produced by filamentous fungi associated with Antarctic marine sponges.

BACKGROUND: Pectinase enzymes catalyze the breakdown of pectin, a key component of the plant cell wall. At industrial level, pectinases are used in diverse applications, especially in food-processing industry. Currently, most of the industrial pectinases have optimal activity at mesophilic temperatures. On the contrary, very little is known about the pectinolytic activities from organisms from cold climates such as Antarctica. In this work, 27 filamentous fungi isolated from marine sponges collected in King George Island, Antarctica, were screened as new source of cold-active pectinases. RESULTS: In semi-quantitative plate assays, 8 out 27 of these isolates showed pectinolytic activities at 15 °C and one of them, Geomyces sp. strain F09-T3-2, showed the highest production of pectinases in liquid medium containing pectin as sole carbon source. More interesting, Geomyces sp. F09-T3-2 showed optimal pectinolytic activity at 30 °C, 10 °C under the temperature of currently available commercial mesophilic pectinases. CONCLUSION: Filamentous fungi associated with Antarctic marine sponges are a promising source of pectinolytic activity. In particular, pectinases from Geomyces sp. F09-T3-2 may be potentially suitable for biotechnological applications needing cold-active pectinases. To the best of our knowledge, this is the first report describing the production of pectinolytic activity from filamentous fungi from any environment in Antarctica.

Cold-active pectinolytic activity produced by filamentous fungi associated with Antarctic marine sponges

BACKGROUND: Pectinase enzymes catalyze the breakdown of pectin, a key component of the plant cell wall. At industrial level, pectinases are used in diverse applications, especially in food-processing industry. Currently, most of the industrial pectinases have optimal activity at mesophilic temperatures. On the contrary, very little is known about the pectinolytic activities from organisms from cold climates such as Antarctica. In this work, 27 filamentous fungi isolated from marine sponges collected in King George Island, Antarctica, were screened as new source of cold-active pectinases. RESULTS: In semi-quantitative plate assays, 8 out 27 of these isolates showed pectinolytic activities at 15 °C and one of them, Geomyces sp. strain F09-T3-2, showed the highest production of pectinases in liquid medium containing pectin as sole carbon source. More interesting, Geomyces sp. F09-T3-2 showed optimal pectinolytic activity at 30 °C, 10 °C under the temperature of currently available commercial mesophilic pectinases. CONCLUSION: Filamentous fungi associated with Antarctic marine sponges are a promising source of pectinolytic activity. In particular, pectinases from Geomyces sp. F09-T3-2 may be potentially suitable for biotechnological applications needing cold-active pectinases. To the best of our knowledge, this is the first report describing the production of pectinolytic activity from filamentous fungi from any environment in Antarctica.

Highly cold-active pectinases under wine-like conditions from non-Saccharomyces yeasts for enzymatic production during winemaking.

UNLABELLED: The influence of oenological factors on cold-active pectinases from 15 preselected indigenous yeasts belonging to Aureobasidium pullulans, Filobasidium capsuligenum, Rhodotorula dairenensis, Cryptococcus saitoi and Saccharomyces cerevisiae was investigated. Pectinolytic enzymes were constitutive or partially constitutive; and high glucose concentration (200 g l(-1) ) did not affect or increased pectinase production at 12°C and pH 3·5 (up to 113·9 U mg(-1) ) only in A. pullulans strains. SO2 (120 mg l(-1) ) slightly affected the growth of A. pullulans strains but did not affect pectinase production levels. Ethanol (15%) barely affected pectinase activity of A. pullulans strains but diminished relative activity to 12-79% of basidiomycetous yeasts. Moreover, non-Saccharomyces strains showed promising properties of oenological interest. This study demonstrates that cold-active pectinases from some A. pullulans strains were able to remain active at glucose, ethanol and SO2 concentrations usually found in vinification, and suggests their potential use as processing aids for low-temperature winemaking. SIGNIFICANCE AND IMPACT OF THE STUDY: Nowadays, there is increasing interest in low-temperature winemaking. Nevertheless, commercial oenological pectinases, produced by fungi, are rarely active at low temperatures. Cold-active pectinases that are stable under vinification conditions are needed. This study indicated that cold-active and acid-tolerant pectinases from non-Saccharomcyes yeasts were able to remain active at glucose, ethanol and SO2 concentrations usually found in winemaking. Furthermore, not only are these yeasts a source of cold-active pectinases, but the yeasts themselves are also potential adjunct cultures for oenology to produce these enzymes during cold-winemaking.