Characterization of the steroid degrading bacterium S19-1 from the Baltic Sea at Kiel, Germany

Steroid contamination of sea water is an ever growing problem and impacts population dynamics of all kinds of sea animals. We have long experience with the soil bacterium Comamonas testosteroni ATCC11996 which is able to catabolize a variety of steroids and polycyclic aromatic hydrocarbons, and which might be used in the bioremediation of contaminated places. In C. testosteroni about 20 enzymes which are involved in steroid degradation could be induced by 0.5 mM testosterone. In this work, we isolated a marine bacterial strain, S19-1, from the Baltic Sea at Kiel (Germany) which degrades steroids and is able to use steroids as carbon source. S19-1 was characterized as being Gram negative, and 16S rRNA analysis showed that it belongs to the genus Buttiauxella of the Enterobacteriaceae family. Strain S19-1 could be best grown in SIN medium supplemented with 0.6–4.1% NaCl at 20 °C. As a carbon source, testosterone, estradiol or cholesterol in minimal medium could be used by S19-1. Moreover, S19-1 could grow up in medium with 50 μg/ml erythromycin. Plasmids pK18 and other plasmids were successfully transformed into S19-1 by chemical transformation (CaCl2) and shown to replicate in the cells. Currently, work is ongoing to find the steroid inducible genes.