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 which is able to catabolize a variety of steroids and polycyclic aromatic hydrocarbons, and which might be used in the bioremediation of contaminated soil. For our studies we use 3a-hydroxysteroid dehydrogenase/carbonyl reductase (3a-HSD/CR) as a reporter enzyme, since it is the key enzyme in steroid degradation. Moreover, the expression of the corresponding gene, hsdA, is induced by environmental steroids. In previous investigations we have identified and described several genes being involved in hsdA regulation. In this work we isolated several bacterial strains from the Baltic Sea at Kiel, Germany, which degrade steroids and which are able to use steroids as carbon source. Two of them, strain S19-1and H5, were characterized as being gram negative. 16S-rRNA analysis showed that S19-1 belongs to Buttiauxella noackiae and H5 is similar to Vibrio porteresiae. They could be best grown in SIN medium supplemented with 0.6 – 5.1 % NaCl and at 20°C. Both S19-1 and H5 can use testosterone, estradiol or cholesterol as a carbon source in minimum medium. In Comamonas testosteroni about 20 enzymes could be induced by 0.5 mM testosterone. A new plasmid pKEGFP-2, suitable for metagenomic studies, and pGEM-EGFP were prepared for isolation of steroid inducible genes in S19-1 and H5. A 4.610 kb DNA fragment which contains the 3a-HSD/CR gene and its regulation elements from Comamonas testosteroni was cloned into plasmid pGEM-EGFP and pKEGFP-2. The result showed that testosterone induction could be detected by a microplate fluorescence reader after the plasmids were transformed into E coli HB101 cells. Therefore, the system could be used to isolate steroid degradation and steroid regulatory genes from S19-1 and H5. In addition, the exact characterization and systematic classification of these marine steroid degrading bacterial strains is envisaged. The strains might be used for the bioremediation of steroid contaminations in sea water.
The project is funded by the Exellence Cluster "Future Ocean"



Ausgewählte Literatur zum Thema :



1. Göhler A, Xiong G, Paulsen S, Trentmann G and Maser E: Testosterone-inducible regulator is a kinase that drives steroid     sensing and metabolism in Comamonas testosteroni. J Biol Chem 283 (25): 17380-17390, 2008.

2. Zeilinger J, Steger-Hartmann T, Maser E, Goller S, Vonk R, Länge R: Effects of synthetic gestagens on fish reproduction. Environ Toxicol Chem, 2009


3. Xiong G, Draus E, Luo Y, Maser E: 3alpha-Hydroxysteroid dehydrogenase/carbonyl reductase as a tool for isolation and characterization of a new marine steroid degrading bacterial strain. Chem Biol Interact 178 (1-3): 206-210, 2009


4. Xiong G, Luo Y, Jin S, Maser E: Cis- and trans-regulatory elements of 3alpha-hydroxysteroid dehydrogenase/carbonyl reductase as biosensor system for steroid determination in the environment. Chem Biol Interact 178 (1-3): 215-220, 2009