Start
Dec 12, 2012 - 12:00
End
Dec 12, 2012 - 13:00
Venue
Room 118 (Creativity Hall) Ground Floor Chemical Engineering Department
Event Type
Speaker
Dr. Sujata Sohoni Research Scientist at Novozymes
Title
Promoter engineering and energy perturbation to improve antibiotic production in /Streptomyces coelicolor
Two third of the antibiotics and many other pharmaceuticals such as anti-tumor drugs and immunosuppressants are produced by Actinomycetes - mostly belonging to the genus /Streptomyces/. The need for new antibiotics is emerging as a result of continuous evolution of disease causing bacteria into drug resistant strains due to their extra ordinary ability to adapt to changes in their environment. The ultimate aim of this work was to design a cell factory that can be used as a plug and play superhost for enhanced production of new polyketide pharmaceuticals. To approach this goal we used the actinomycete /Streptomyces coelicolor/A3(2) and the blue colored polyketide antibiotic actinorhodin produced by it as a model system. We explored two strategies to improve actinorhodin production. One of the strategies involved studying the effect of energy perturbation on actinorhodin production in /S. coelicolor/. This was achieved by over-expressing NADH kinase and NADH oxidase that led to changes in the NADH/NAD^+ ratio in the cell. Overexpression of NADH oxidase resulted in decreased yield of biomass on glucose and increased yield of actinorhodin while overexpression of NADH kinase led to increased yield of biomass on glucose and decreased yield of actinorhodin. The other strategy focused on the principle of “promoter engineering” by constructing a synthetic promoter library to obtain promoters with a range of expression levels. The promoter of /actII orf4/ – the positive activator of the actinorhodin gene cluster was randomized in this study and a library of different promoter strengths was constructed and characterized. One of the strains ScoSPL20 in the library demonstrated 2.8 times higher yields of actinorhodin than compared to wild type strain. We report the successful application of promoter engineering in improving actinorhodin production.