[Seminar] Physiological and transcriptional response of the marine sulfate reducer Desulfobacterium autotrophicum HRM2 to substrate limitation

Title: Physiological and transcriptional response of the marine sulfate reducer Desulfobacterium autotrophicum HRM2 to substrate limitation

Speaker: Angeliki Marietou

Affilliation: Center for Geomicrobiology, Department of Bioscience, Aarhus University, Denmark

Host: Sofia Venceslau - Bacterial Energy Metabolism, Inês Pereira Lab

Abstract:

The marine seafloor constitutes one of the largest ecosystems on Earth. It is characterized by absence of light and low nutrient flow. In spite of the low nutrient availability, sediments from a wide range of depths harbor a diverse and active sulfate reducing microbial community. Sulfate reduction is in fact the predominant microbial metabolism, accounting for up to 70% of carbon remineralisation (Kasten and Jørgensen, 2006).  Due to its inaccessibility, we have a limited understanding of the strategies employed by microbial life to adapt at low nutrient availability. In this study, we employed a pure culture proxy in order to explore how microorganisms respond to low nutrient availability in the marine seafloor. We used continuous culturing (chemostats) to replicate the steady state nutrient flow and low growth rates observed in the marine subseafloor. Desulfobacterium autotrophicum, a common marine sulfate reducer, was used as the model organism. We measured the substrate utilization rates and residual substrate concentrations to determine the substrate uptake kinetics, while RNA sequencing allowed us to compare gene expression patterns under lactate and sulfate limitation. The physiological mechanisms that enable microbial life to adapt and survive at low energy/nutrient environments will be discussed.