Engineering thickness-controllable biofilm by light-responsive c-di-GMP module in Comamonas testosteroni

• Main Author: Soh, Meng Chong
• Other Authors: Cao Bin
• Format: Final Year Project
• Language: English
• Published: 2017
• Subjects: DRNTU::Engineering::Environmental engineering
• Online Access: http://hdl.handle.net/10356/72984
• Institution: Nanyang Technological University

Biofilms are surface/interface-attached microbial communities embedded in an extracellular matrix. Numbers of studies have proposed that biofilm provides many benefits to the cells, notably under unfavourable conditions such as exposure to antimicrobial agents, high salinity, and antimicrobial agents. Hence, biofilm-based bioprocesses have been demonstrated to be a promising process for industrial and municipal wastewater treatment. A productive biofilm for environmental bioprocess activities is expected to have sufficient biomass and an effective mass transfer. Thus, it is of great significance to maintain a biofilm thickness in an optimal range. However, it is very challenging to control biofilm formation because its development is highly dynamic. The objective of this study is to control the thickness of biofilms through synthetic biology approaches. In the past one year, I have demonstrated a bidirectional c-di-GMP module that responds to the near infrared (NIR) light (660nm) and blue light (465 nm) in Comamonas testosteroni. I expected to achieve the controllable biofilm using NIR light and blue light. However, it was found that biofilm formation was not able to be enhanced by NIR light because of the high background activity of blue light-activated EB1. To solve this issue, I am currently constructing a double-plasmid system. To increase the activity of NIR light-responsive diguanylate cyclase (DGC) and decrease the background activity of blue light responsive phosphodiesterase (PDE), DGC gene and PDE gene will be inserted into the plasmids with high copy number and low copy number, respectively.