Understanding the Dynamics of Biomass Deconstruction by the Cellulolytic Anaerobe C. thermocellum

Abstract

Clostridium thermocellum is one of the most efficient microorganisms for the deconstruction of cellulosic biomass. To achieve this high level of cellulolytic activity, C. thermocellum uses large multienzyme complexes known as cellulosomes to break down complex polysaccharides, notably cellulose, found in plant cell walls. The attachment of bacterial cells to the nearby substrate via the cellulosome has been hypothesized to be the reason for this high efficiency. The region lying between the cell and the substrate has shown great variation and dynamics that are affected by the growth stage of cells and the biomass used for growth. Here, we utilized both photoactivation localization microscopy (PALM) and stochastic optical reconstruction microscopy (STORM) in combination with Density-Based Spatial Clustering of Applications with Noise (DBSCAN) to study the distribution of C. thermocellum cellulosomes at different stages of growth when actively growing on soluble and insoluble substrates, providing a clearer picture of the dynamics of cellulosome populations at the enzyme microbe substrate interface. This research demonstrates the promising application of novel optical methodologies in tandem with targeted mutations within C. thermocellum to test the prevailing theories regarding the mechanisms of cellulosomes and their potential to shuttle onto the biomass for the attachment of C. thermocellum to improve biomass deconstruction.