Plants in their natural habits are constantly competing with other organisms.Arabidopsis thaliana is a model plant that must germinate and grow in the presence ofcommon soil bacteria such as Pseudomonas aeruginosa and Bacillus subtilis. A.thalianamay compete with soil bacteria such as for water, micronutrients, and the carbohydrate produced by photosynthesis. If there is competition between plants and soil bacteria, conditions that favor the growth of microorganisms will negatively impact plant development.A. thaliana was grown in petri dishes inoculated with Pseudomonas aeruginosa and Bacillus subtilis. Murashige and Skoog agar, a plant growth media, was used initially, to favor plant growth. The experiment was done in both warm conditions, that favor bacteria, and cool conditions, that discourage bacterial growth, and at high and low concentrations of bacteria. Later in the experiment, the growth of P. aureginosa and B. subtilis was enhanced by adding nutrient broth to the petri dishes. We found that, under these conditions, the plants are only vulnerable to bacterial competition at the earliest stages, and only with low concentration of B. subtilis under warm conditions. Bacterial growth later in plant development actually seems to promote plant growth
