The course of the environmental monitoring experiment is one of the important course in environmental science specialty. And it is also a compositive and practical required course. At present, there are some questions in the practical teaching of this course. Based on these questions, the experimental teaching model of three phases are put forward. That is, the course of the environmental monitoring experiment is divided into three training phases and carried out the teaching models of three phases. It was proved that this teaching model would be fit to develop the teaching quality, strengthenthe operational ability, shorten the adaptive time at working.

A new technique for conducting site-directed mutagenesis was developed. This method allows the color selection of mutants through the simultaneous activation or deactivation of the α-peptide of ß-galactosidase. The method can efficiently create mutations at multiple sites simultaneously and can be used to perform multiple rounds of mutation on the same construct. In this paper, in order to develop an efficient site-directed mutagenesis method in vivo, the tests were tested by the following methods. The methods that the fragment knock-out ompR gene was constructed through overlapping PCR, digested by Notand SalⅠⅠ, ligated to plasmid pKOV were applied. The recombination plasmid was transformed into Escherichia coli WMC-001 strain, integrated into the genomic DNA through two step homologous recombination. The Escherichia coli WMC-001/ompR- mutant was obtained due to gene replacement. The fragment of the mutant ompR gene was amplified through overlapping PCR, cloned into pKOV vector. The recombinant plasmid was introduced into Escherichia coli WMC-001/ompR- mutant. The Escherichia coli WMC-001/ompR mutant was also obtained due to gene replacement. Results: The site-directed mutagenesis has been successfully constructed in the ompR gene by sequencing. Conclusion: The method is effective for construction of gene site-directed mutagenesis in vivo.