Steroid hormones, such as androgens, are common surface-water contaminants. However, literature on the ecophysiological relevance of steroid-degrading organisms in the environment, particularly in anoxic ecosystems, is extremely limited. We previously reported that Steroidobacter denitrificans anaerobically degrades androgens through the 2,3-seco pathway. In this study, the genome of Sdo. denitrificans was completely sequenced. Transcriptomic data revealed gene clusters that were distinctly expressed during anaerobic growth on testosterone. We isolated and characterized the bifunctional 1-testosterone hydratase/dehydrogenase, which is essential for anaerobic degradation of steroid A-ring. Because of apparent substrate preference of this molybdoenzyme, corresponding genes, along with the signature metabolites of the 2,3-seco pathway, were used as biomarkers to investigate androgen biodegradation in the largest sewage treatment plant in Taipei, Taiwan. Androgen metabolite analysis indicated that denitrifying bacteria in anoxic sewage use the 2,3-seco pathway to degrade androgens. Metagenomic analysis and PCR-based functional assays showed androgen degradation in anoxic sewage by Thauera spp. through the action of 1-testosterone hydratase/dehydrogenase. Our integrative 'omics' approach can be used for culture-independent investigations of the microbial degradation of structurally complex compounds where isotopelabeled substrates are not easily available.
Background: Cholesterol is ubiquitous on earth. Little is known about anoxic cholesterol catabolism. Results: We proposed a model for cholesterol uptake and subcellular compartmentation during cholesterol catabolism by a Gram-negative bacterium. Conclusion:The enzymes located in the periplasm are critical for cholesterol catabolism, especially during the steps of substrate activation. Significance: This study may have potential applications in the biotechnological production of steroid drugs.
Numerous studies have reported the masculinization of freshwater wildlife exposed to androgens in polluted rivers. Microbial degradation is a crucial mechanism for eliminating steroid hormones from contaminated ecosystems. The aerobic degradation of testosterone was observed in various bacterial isolates. However, the ecophysiological relevance of androgen-degrading microorganisms in the environment is unclear. Here, we investigated the biochemical mechanisms and corresponding microorganisms of androgen degradation in aerobic sewage. Sewage samples collected from the Dihua Sewage Treatment Plant (Taipei, Taiwan) were aerobically incubated with testosterone (1 mM). Androgen metabolite analysis revealed that bacteria adopt the 9, 10-seco pathway to degrade testosterone. A metagenomic analysis indicated the apparent enrichment of Comamonas spp. (mainly C. testosteroni) and Pseudomonas spp. in sewage incubated with testosterone. We used the degenerate primers derived from the meta-cleavage dioxygenase gene (tesB) of various proteobacteria to track this essential catabolic gene in the sewage. The amplified sequences showed the highest similarity (87–96%) to tesB of C. testosteroni. Using quantitative PCR, we detected a remarkable increase of the 16S rRNA and catabolic genes of C. testosteroni in the testosterone-treated sewage. Together, our data suggest that C. testosteroni, the model microorganism for aerobic testosterone degradation, plays a role in androgen biodegradation in aerobic sewage.
Image annotation is a common approach for biodiversity detection by labeling features of interest from images. However, annotation tools and data structures are usually developed and combined as platform for specific purposes. It makes tools hard to be adopted by different domains and hinders the interoperability of potentially related data from multiple sources. Following linked data principles and ontology design patterns, we proposed a platform-independent framework, and implemented a web-based prototype for semantic annotating images with persistent HTTP Uniform Resource Identifier (URI). Our framework is designed for breaking down data silos, i.e. scattered information annotated from active or legacy biodiversity databases, personal observation blogs, or albums can be queried and interoperated together. The prototype can be used without installation and easily integrated into other platforms. It pulls image links from a page and let people select features of interest (e.g. flowers, birds, or patterns) as tokens with bounding boxes from an image. Tokens can then be populated with properties or traits (e.g. colors, behaviors) derived from domain ontologies which are treated as choosable profiles. Meanwhile tokens can be described with measurement data in certain dimensions such as body weight or wing length. Relations can be created between any two tokens from arbitrary hosts. Tokens, properties, measurements and relations are assembled through framework ontologies such as Extensible Observation Ontology (OBOE). Each token is given a hash URI composed of an image URI and a Universally Unique Identifier (UUID). With URIs, relations can be explicitly kept as structured data instead of literal descriptions, and the data location can be ‡ ‡ ‡
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