Stimulation of rhamnolipid biosurfactants production in Pseudomonas aeruginosa AK6U by organosulfur compounds provided as sulfur sources

• Main Authors: Wael Ismail, Sultanah AL. Shammary, Wael S. El-Sayed, Christian Obuekwe, Ashraf M. El Nayal, Abdul Salam Abdul Raheem, Abdulmohsen Al-Humam
• Format: Article
• Language: English
• Published: Elsevier 2015-09-01
• Series: Biotechnology Reports
• Subjects: Surface tension; Biodesulfurization; Dibenzothiophene
• Online Access: http://www.sciencedirect.com/science/article/pii/S2215017X15000156
• ISSN: 2215-017X

A Pseudomonas aeruginosa AK6U strain produced rhamnolipid biosurfactants to variable extents when grown on MgSO4 or organosulfur compounds as sulfur sources and glucose as a carbon source. Organosulfur cultures produced much higher biosurfactants amounts compared to the MgSO4 cultures. The surface tension of the growth medium was reduced from 72 mN/m to 54 and 30 mN/m in cultures containing MgSO4 and 4,6-dimethyldibenzothiophene (4,6-DM-DBT), respectively. AK6U cultures produced different rhamnolipid congener profiles depending on the provided sulfur source. The dibenzothiophene (DBT) culture produced more diverse and a higher number of rhamnolipid congeners as compared to the DBT-sulfone and MgSO4 cultures. The number of mono-rhamnolipid congeners in the DBT culture was also higher than that detected in the DBT-sulfone and MgSO4 cultures. Di-rhamnolipids dominated the congener profiles in all the analyzed cultures. The sulfur source can have a profound impact on the quality and quantity of the produced biosurfactants.