Postgraduate Seminar Presentation : Copper-tripeptide complexes for rapid deactivation of bacterial endospores and co-culture of bacterium and yeast to produce butyl acetate

Speaker Cui Yong Hao (Supervisor(s): Dr Zhou Kang and A/Prof Yang Kun-Lin)

Host Department of Chemical and Biomolecular Engineering

Date/Time 28 Sep - 28 Sep, 10.00am

Venue E5-02-32 , Faculty of Engineering, National University of Singapore

Synopsis

Two projects are reported here. One aimed to kill bacteria for biomedical and healthcare applications, and the other harnessed benign microbes to advance manufacturing practices.
 
Some bacteria such as Bacillus subtilis can generate endospores when exposed to harsh environment. Conventional sterilization methods are either inefficient or costly to kill endospores. Herein, we report a cost-effective disinfectant by utilizing a copper-tripeptide complex and hydrogen peroxide which can reduce 106.7-fold viable B. subtilis endospores within 60 minutes under ambient temperature. 
 
Clostridium acetobutylicum is another endospore-producing bacterium, which can produce acetone, butanol and ethanol (ABE) in anaerobic environment. However, it is costly and time-consuming to establish and maintain anaerobic environment. Besides, it would be more desirable if ABE can be converted into other more valuable products such as butyl acetate. Nevertheless, it is usually difficult to metabolically engineer Clostridium because of its thick cell wall and the requirement for anaerobic environment. Hence, we utilized another strategy by co-culturing a butanol-producing Clostridium strain (BOH3) with a facultative anaerobe (Saccharomyces cerevisiae) to maintain the anaerobic environment. Meanwhile, butanol produced by Clostridium can also be converted into butyl acetate by engineering S. cerevisiae which is easier to engineer. Our preliminary results showed that by co-culturing these two strains, 2.8 g/L butanol and 0.015 g/L butyl acetate could be produced, which validated the feasibility of the co-culture approach.

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