Biosurfactants are surface active molecules that are produced by microorganisms. Their positive features attract the attention of many researchers compared to their chemically synthesized counterparts. This research studied the production of a biosurfactant by Pleurotus ostreatus in submerged fermentation (SmF) and solid-state fermentation (SSF), with and without shaking. | Turkish Journal of Biology Turk J Biol (2015) 39: 160-166 © TÜBİTAK doi: Research Article Biosurfactant production by Pleurotus ostreatus in submerged and solid-state fermentation systems 1 2, Zülfiye VELİOĞLU , Raziye ÖZTÜRK ÜREK * Department of Biotechnology, Graduate School of Natural and Applied Sciences, Dokuz Eylül University, Izmir, Turkey 2 Department of Chemistry, Faculty of Science, Dokuz Eylül University, Izmir, Turkey 1 Received: Accepted: Published Online: Printed: Abstract: Biosurfactants are surface active molecules that are produced by microorganisms. Their positive features attract the attention of many researchers compared to their chemically synthesized counterparts. This research studied the production of a biosurfactant by Pleurotus ostreatus in submerged fermentation (SmF) and solid-state fermentation (SSF), with and without shaking. Oil spreading efficiency, emulsification index, and surface tension were assessed during the study. The highest emulsification index (E24) values of SmF, SSF with shaking, and SSF without shaking were 60 ± , 29 ± , and 42 ± , respectively, and surface tension values were ± , ± , and ± mN m–1, respectively. Based on these data, the produced biosurfactant in SSF with and without shaking was extracted and the amounts were determined as ± and ± g L–1, respectively. In addition to these analyses, chemical composition of the extracted biosurfactant was determined and FT-IR spectroscopy was used to confirm the various functional groups. The obtained results of chemical composition and FT-IR indicated the probability of carbohydrate–peptide–lipid complex features of biosurfactants produced by P. ostreatus. Key words: Biosurfactant production, Pleurotus ostreatus, submerged fermentation, solid-state fermentation, surface tension 1. .