SCELSE-Graduates & Postdocs Seminar Series: Extracellular components of biofilms

TITLE: RNA is a key component of extracellular DNA networks in Pseudomonas aeruginosa biofilms
SPEAKER: Sudarsan Mugunthan | PhD student | Biofilm Biology cluster, SCELSE

Speaker’s Biography:
Mr. Sudarsan Mugunthan is working with Professor Staffan Kjelleberg, Associate professor Thomas Seviour and A/P Scott Rice at SCELSE. He holds a master degree in industrial biotechnology. His current PhD work predominantly focuses on an ongoing project that aims to provide an explanation for the role of extracellular DNA/RNA in Pseudomonas biofilms and how the process of eDNA/eRNA secretion is regulated. He also has various side projects with SCELSE collaborators (i.e. UVC control of biofilms, coculturing of Pseudomonas with Gluconoacetobacter biofilms as enhanced biomaterials and effect of nanoplastics on denitrifiers and global biogeochemical cycle). The above projects apply a range of disciplines from outside microbiology, including analytical chemistry, molecular biology, biochemistry, fluorescence imaging and engineering.

Abstract:
The roles of extracellular RNAs present in bacterial biofilms are poorly understood. In my study, I show that specific mRNAs associate with extracellular DNA in the matrix of bacterial biofilms, facilitating the formation of viscoelastic networks in P. aeruginosa biofilms enabling structural stability.

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TITLE: Anammosurface (S-) layer protein mediates extracellular matrix assembly in community biofilms
SPEAKER: Wong Lan Li | PhD student | Biofilm Biology cluster, SCELSE

Speaker’s Biography:
Lan Li joined SCELSE as a research assistant under the supervision of Prof Staffan Kjelleberg in Microbial biofilm, biofilm matrix cluster. Her research focuses on understanding the collaboration between physical and biological factors to gain better understanding of factors contributing to biofilm formation, dynamics, organization, and function. Key to this involves resolving the structures and functions of biofilm extracellular polymeric substances (EPS), which Lan Li has tackled across several model biofilms (e.g., anaerobic ammonium oxidation (anammox) bacteria and Pseudomonas aeruginosa). Lan Li has also developed several methods for EPS extraction and isolation techniques as well as biophysical and chemical characterizations. Lan Li is particularly interested in understanding the role of higher order structures of key EPS in implementing the biological program of microorganisms, pertaining to both single and mixed species biofilm formation.

Abstract:
The research focuses on understanding function of extracellular polymeric substances (EPS) in wastewater treatment related anaerobic ammonium oxidation (anammox) biofilm. A comprehensive approach that includes exopolymer extraction, purification, and in-situ identification of EPS using microscopy techniques was conducted for the analysis. A key finding of the study is the identification of a surface (S-) laver protein as the predominant EPS in the matrix. The S-laver protein envelops the surface of anammo bacteria. Additionally, this protein was observed to be abundant, potentially acting as an adhesive at the junction of the filamentous Chloroflexi cells that form scaffold in the biofilm. Overall, studying anammox biofilm EPS provides insights into the structural organization and the associated syntrophic relationship established within the polymicrobial biofilms.