The presence of
steroid hormones in
the aquatic environment is potentially threatening
the population dynamics of all kinds of sea animals
and public health. Environmental estrogens in water have been reported to be associated with abnormal sexual development
and abnormal feminizing responses in some animals. New approaches for
the bioremediation of
steroid hormones from
the environment are
therefore urgently sought. We have previously isolated a
steroid degrading bacterial strain (H5) from
the Baltic Sea, at Kiel, Germany. In
the present investigation, 16S rRNA analysis showed that marine strain H5 belongs to
the genus
Vibrio, family
Vibrionaceae and class
Gamma-Proteobacteria. To enable identification of
steroid inducible genes from bacterial strain H5, a library was constructed of H5 chromosomal DNA fragments cloned into a fluorescent reporter (pKEGFP-2). A reporter plasmid pK3伪-4.6-EGFP3 containing
the estrogen-inducible gene 3伪-hydroxy
steroid dehydrogenase/carbonyl reductase (3伪-HSD/CR) from
Comamonas testosteroni (
C. testosteroni) was created as a positive control. Steroid induction could be detected by a microplate fluorescence reader, when
the plasmids were transformed into
Escherichia coli (
E. coli) HB101 cells. With our meta-genomic pKEGFP-2 approach, we identified two estradiol-inducible genes from marine strain H5, which are obviously involved in
steroid degradation. Sequencing of
the pKEGFP-2 inserts
and data base research at NCBI revealed that one gene corresponds to 3-keto
steroid-delta-1-dehydrogenase from several
Mycobacterium strains, while
the o
ther showed high similarity to carboxylesterase in
Sebadella termitidis and Brachyspira murdochii. Both 3-keto
steroid-delta-1-dehydrogenase
and carboxylesterase are one of
the first enzymes in
steroid degradation. In addition, we identified a strain H5 specific DNA sequence of 480 bp which allows sensitive PCR detection
and quantification of strain H5 bacteria in 鈥渦nknown鈥?seawater samples. Currently,
the exact characterization
and systematic classification of
the marine
steroid degrading bacterial strain H5 is envisaged, which might be used for
the bioremediation of
steroid contaminations in seawater.
Article from a special issue on steroids and microorganisms.