Investigating intraspecies interaction in Bacillus subtilis

Bacillus subtilis is a Gram-positive bacterium that lives in a wide range of environments from concrete fissures and intestinal tracts to soil and on the surfaces of plant seeds and roots. Alongside other Bacillus species, B. subtilis is of significant economic importance and is used as a bioactive agent with a variety of commercial uses. For a live biologic, such as B. subtilis, to have the desired impact, the introduced bacteria must first integrate into the established ecosystem to which it is being added. One of the critical steps of integration into an ecosystem is opening space in the niche already occupied by resident strains of the same species. This integration process requires intraspecies interactions.
The overarching aim of this project is to investigate how B. subtilis achieves dominance over competing isolates with a focus on polymorphic toxin systems.
Aims and Objectives:
1. Define the minimal genetic region needed for the activity of a novel polymorphic toxin system.
We will introduce genetic material into the chassis organism Bacillus subtilis. We will assess the impact to confer toxicity using a range of interbacterial competition assays.
2. Define the environmental conditions that promote intoxification of target bacteria.
We will define the impact of environmental conditions on toxin activity. For example, we will alter the physical parameters of the experimental conditions and the time during which toxin and target bacteria interact.
3. Define the mode of action of an exemplar polymorphic toxin.
We will use biochemical approaches informed by structural predictions. We will construct variants of the toxin where potential active site residues have been substituted. We will use single-cell imaging to monitor the fate of target cells and can use in vitro biochemical assays to explore enzyme functions.