Induction of Extracellular Lytic Enzymes from Aureobasidium pullulans

Abstract

Aims: The objective of this work was to analyze the production of some extracellular lytic enzymes of the fungus Aureobasidium pullulans. Methodology: The fungus was isolated from Valencian orange and was cultivated on Mathur medium modified with polygalacturonic acid (2% w/v) or xylan (2% w/v) as a carbon source, and they were incubated at 28°C, with constant stirring at 100 rpm, and at different times, the supernatant was harvested by filtration, and the extracellular lytic activity was determined by the Nelson method modified by Somogy, as well as the extracellular protein by the Lowry method. Results: The production of extracellular polygalacturonase and xylanase was induced, finding that the former has an optimal induction time at 7 days, with glutamic acid as a nitrogen source, and is stable at 4°C and 28°C and an optimal temperature and activity times of 60-80°C and 4 hours, while xylanase presents an optimal induction time of 9 days, with glutamic acid as nitrogen source, and very stable at 4 and 28°C, with optimal temperature and time of activity of 28°C and 8 hours. Conclusion: The fungus exhibits both polygalacturonase and xylanase activity. The polygalacturonase activity has a maximum induction time at 7 days, while xylanase has an optimal induction time at 9 days of incubation at 28°C. The xylanase activity was very stable at 4°C and 28°C, as it retains an activity of 100% at both temperatures after five days of incubation, while polygalacturonase retains 82.5% of its initial activity at 4°C, and 56.7% at 28°C.