We report the cloning of the pykA and pykF genes from Escherichia coli, which code for the two pyruvate kinase isoenzymes (ATP:pyruvate 2-O-phosphotransferases; EC 2.7.1.40) in this microorganism. These genes were insertionally inactivated with antibiotic resistance markers and utilized to interrupt one or both pyk genes in the E. coli chromosome. With these constructions, we were able to study the role of these isoenzymes in pyruvate biosynthesis.

Abstract. Nonylphenol is a metabolic intermediate from the microbial transformation of detergents used worldwide. While nonylphenol shows some acute toxicity, it is also able to mimic important hormones resulting in the disruption of several processes by interfering with the signals that control the overall physiology of the organism. This work perform a critical reviews on the origin, environmental fate, microbial transformation, ecosystems impact and endocrine disruption capacity of nonylphenol. Due to mass production of parent products and potential toxicity, nonylphenol is an example of a microbial decay product that may pose an environmental risk. The analysis supports the need for better tests to evaluate, model and monitor the potential long-term environmental impact of single compounds produced as a result of an environmentallymediated degradation.

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