DoE-based medium optimization for improved biosurfactant production with Aureobasidium pullulans

Abstract

Polyol lipids (a.k.a. liamocins) produced by the polyextremotolerant, yeast-like fungus Aureobasidium pullulans are amphiphilic molecules with high potential to serve as biosurfactants. So far, cultivations of A. pullulans have been performed in media with complex components, which complicates further process optimization due to their undefined composition. In this study, we developed and optimized a minimal medium, focusing on biosurfactant production. Firstly, we replaced yeast extract and peptone in the best-performing polyol lipid production medium to date with a vitamin solution, a trace-element solution, and a nitrogen source. We employed a design of experiments approach with a factor screening using a two-level-factorial design, followed by a central composite design. The polyol lipid titer was increased by 56% to 48 g L−1, and the space-time yield from 0.13 to 0.20 g L−1 h−1 in microtiter plate cultivations. This was followed by a successful transfer to a 1 L bioreactor, reaching a polyol lipid concentration of 41 g L−1. The final minimal medium allows the investigation of alternative carbon sources and the metabolic pathways involved, to pinpoint targets for genetic modifications. The results are discussed in the context of the industrial applicability of this robust and versatile fungus.

Advances in Aureobasidium research: Paving the path to industrial utilization

“…Based on the same medium, Haala et al. ( 2024 ) developed the first minimal medium for polyol lipid production. For this purpose, yeast extract and peptone were replaced by NH 4 NO 3 , trace elements, and vitamins, followed by a media optimization using a design of experiments approach.…”