Characterization and Optimization of L-Malic Acid Production by Some Clinical Isolates of Aureobasidium pullulans

Abstract

Background: Poly-L-malic acid (PLMA) comprises aliphatic polyester polymers with broad applications in pharmaceutical industries. The fungal microorganisms are among the best natural sources recruited to supply L-malic acid (MA) as a precursor of PLMA. In this study, we investigated MA production ability of 7 clinical isolated of the fungus Aureobasidium pullulans. Materials and Methods: Seven clinical isolates of A. pullulans acquired from Westerdijk Fungal Biodiversity Institute were studied, and the isolate with the highest total MA production was selected for the optimization process. We tried to optimize the output by applying different concentrations of CaCO3 in fungus medium (1.5%, 3%, and 6%) and various incubation temperatures (27°C, 32°C, and 37°C) during 3, 7, and 14 days. Results: Intra-strains variation was significantly strong (P0.05). Conclusion: Overall, we obtained the highest MA production in Sabouraud dextrose agar (SDA)medium with 3% CaCO3 at 27°C after 7 days of incubation. Our study indicated that the fermentation period and CaCO3 concentration significantly alter MA production in A. pullulans var. melanigenum.

Keywords

• poly-l-malic acid
• l-malic acid
• aureobasidium pullulans
• fungi
• fungal natural products