ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Evaluation of waste products in the synthesis of surfactants by yeasts

Ewelina Dzięgielewska and Marek Adamczak

Department of Food Biotechnology, University of Warmia and Mazury in Olsztyn, J. Heweliusz St. 1, 10-718, Olsztyn, Poland

E-mail: marek.adamczak@uwm.edu.pl

Abstract: The highest yields of biosurfactants were obtained by: (i) Pseudozyma antarctica (107.2 g L⁻¹) cultivated in a medium containing post-refining waste; (ii) Pseudozyma aphidis (77.7 g L⁻¹); and (iii) Starmerella bombicola (93.8 g L⁻¹) both cultivated in a medium with soapstock; (iv)Pichia jadinii (67.3 g L⁻¹) cultivated in a medium supplemented with waste frying oil. It was found that the biosurfactant synthesis yield increased in all strains when the cell surface hydrophobicity reached 70–80 %, enabling the microbial cells to make good contact with hydrophobic substrates. The lowest surface tension of the post-cultivation medium was from 32.0 mN m⁻¹ to 37.8 mN m⁻¹. However, this parameter (which was also determined by a drop collapse assay) was of limited use in monitoring biosurfactant synthesis in this study. The crude glycerol was not a good substrate for biosurfactant synthesis although, in the case of P. aphidis, 67.4 g L⁻¹ of biosurfactants were obtained after cultivation in the medium supplemented with glycerol fraction (GF2). In a low-cost medium containing soapstock and whey permeate or molasses, about 90 g L⁻¹ of mannosylerythritol lipids were synthesised by P. aphidis and approximately 40 g L⁻¹ by P. antarctica.

Keywords: biosurfactants – waste lipids – glycerol – glycolipids – surface tension

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-013-0349-1

Chemical Papers 67 (9) 1113–1122 (2013)