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Project Progress

Caroline Turner joined the laboratory as a post-doctoral associate in September 2015. She has been studying the ecological conditions of the biofilm evolution experiment with Burkholderia cenocepacia, in which adaptive diversification of an ancestral clone led to a consortium of generalist and specialist genotypes with synergistic productivity. She has found that during the 24 hour growth cycle used in the evolution experiment, the bacteria acidify the growth medium, bringing the media from about pH 7 down to pH 4-5. The bacteria appear to have adapted to this acidification with all 3 ecotypes exhibiting higher tolerance of acidic conditions compared to their ancestor. This improved acid tolerance is observed even under planktonic conditions in the absence of biofilm formation. Caroline has also been exploring the factors which limit growth in the experiment. Both ancestral and evolved strains continue to grow between 24 and 48 hours, indicating that there is no limiting nutrient which is exhausted during that time. Assays of galactose availability also confirm that abundant galactose (the sole carbon source in the media) remains at 24 hours. Caroline has begun to explore the effects of lowering galactose availability and imposing carbon limitation on the ecology and evolution of the biofilm evolution experiment.