Olivia Biddle, Kathryn Morris. Xavier University, Cincinnati, OH.

Streptomyces bacteria are similar to fungi in structure, and fungi aid in the formation of soil aggregates, but no one has yet explored the potential of Streptomyces to stabilize soil. To determine the effect of Streptomyces on the formation of water stable soil aggregates, Streptomyces bacteria were first isolated from field collected soil, and one isolated colony was used to make a liquid culture. The culture was then distributed, in four different concentrations, to Petri dishes containing fine soil (<212 μm), and placed in the incubator (30 °C) for a month. During that month, I added water to plates several times to maintain their initial weight. I then quantified total bacteria and Streptomyces in the soil by doing viable plate counts onto LB and Actinomycete Isolation Agar, respectively. The distribution of soil aggregates in each dish was measured using a wet sieving technique, and the percentage of total water stable aggregates. Aggregates with 1-2 mm diameter were significantly more stable than control treatments in treatments receiving full and half doses of Streptomyces. There was not a linear relationship between Streptomyces number and stability of 1-2 mm aggregates. Streptomyces may be important for stabilizing intermediate sized aggregates in natural environments.