Genomic Analysis of a New Estrogen-Degrading Bacterial Strain,Acinetobactersp. DSSKY-A-001

Abstract

In this study, we isolated a new estrogen-degrading bacterium from a soil sample collected near a pharmaceutical factory in Beijing, China. Morphological observations, physiological and biochemical analyses, and sequence analysis showed that the strain was in the genus Acinetobacter, and it was named DSSKY-A-001. The estrogen degradation rate and growth density of strain DSSKY-A-001 were determined by high-performance liquid chromatography and a growth assay using a microplate reader, respectively. The estrogen degradation rate was 76% on the third day and 90% on the sixth day of culture. Three kinds of estrogen metabolism intermediates were detected by high-performance liquid chromatography and mass spectrometry, and the estrogen metabolic pathway and possible estrogen-degrading enzymes were predicted. RT-PCR was used to verify whether the three putative enzymes, catechol 1,2-dioxygenase, dioxygenase, and 7α-hydroxysteroid dehydrogenase, were expressed in the strain. The results of the validation were consistent with the predictions that these three enzymes were present and expressed in Acinetobacter DSSKY-A-001. To further understand the estrogen-degrading activity of the strain at the genetic level, we sequenced the genome and performed a functional gene annotation. Through this gene sequence analysis, we identified genes predicted to encode the previously detected enzymes, catechol 1,2-dioxygenase, dioxygenase, and 7α-hydroxysteroid dehydrogenase, as well as six other enzymes that may be involved in estrogen degradation. Therefore, a total of nine enzymes related to estrogen degradation were found.

Suitability of Immobilized Systems for Microbiological Degradation of Endocrine Disrupting Compounds

“…Estrone, estriol and 17β-estradiol are natural estrogens. The latter is considered to be the strongest among the endocrine factors in the environment [ 10 ]. Synthetic estrogens have been divided into steroidal, such as 17α-ethynylestradiol and 3-methyl ether of ethynylestradiol, used as ingredients of birth control pills, and nonsteroidal estrogens such as diethylstilbestrol used to prevent miscarriages [ 3 , 7 , 11 ].…”

“…Bacteria that degrade these hormones belong to genera such as Bacillus , Virgibacillus , Novosphingobium , Rhodococcus , Acinetobacter , Pseudomonas , Sphingomonas , Enterobacter , Klebsiella , Aeromonas , Comamonas , Thauera , Deinococcus , Stenotrophomonas and cyanobacteria [ 3 , 4 , 6 , 7 , 10 , 12 , 25 , 28 , 31 , 33 , 34 , 35 , 36 , 37 , 38 , 39 ]. Raphidocelis subcapitata , Chlorella vulgaris , Chlorococcus and Scenedesmus quadricauda belong to algae capable of removing hormones [ 11 , 26 , 40 , 41 ].…”

“…Usually the first step of 17β-estradiol degradation is its dehydrogenation to estrone. This reaction is of great environmental significance as this reduces the total estrogenic activity due to the oxygenation of the phenol group of 17β-estradiol to ketone moiety [ 6 , 10 , 22 , 35 , 38 ]. Xiong et al [ 38 ], during genome analysis of Deinococcus actinosclerus SJTR1, found 18 genes encoding short-chain dehydrogenase/reductase (SDR), probably engaged in transformation 17β-estradiol to estrone.…”

“…The obtained product is further oxidized to ( Z )-8-(7α-methyl-1n-5-dioxo-octahydro-1 H -inden-4-yl)-2o-6-dioxy-4-butenoic acid with the participation of the B ring cleaving oxygenase. In addition, hydroxylation at position 4 of the 17β-estradiol ring and conversion of 4-hydroxy-17β-estradiol to 4-hydroxyestrone were also observed [ 10 , 50 ].…”

“… Estrogens biodegradation by bacteria; the 4,5-seco pathway reactions are shown in blue; HIP–9,17-dioxo-1,2,3,4,10,19-hexanorandrostan-5-oic acid [ 10 , 12 , 21 , 25 , 50 ]. …”