We have isolated a strain C611 that used methane as the sole carbon sources for growth from paddy soil in Taiyuan of Shanxi province. Based on the physiological characteristics and 16S rDNA sequence analysis, we identified the strain as Klebsiella sp.. We used statistic-based experimental design (RSM) to optimize the culture conditions for C611 strain. The optimum conditions were as follows: temperature of 24.4 degrees C, inoculum volume of 6.7% and methane content of 25%. We studied the response time and the relationship between consumption of dissolved oxygen and methane gas contents with PVA-H3BO3 immobilized cell of C611 using electrochemical method. The response time was no more than 100 s of this reaction system, and the linear range of detection of methane content was from 0 to 10%. The standard gas sample 3% methane was measured by this method with the mean content value of 3.09%, RSD of 3.48%, and the relative error of 3%. Hence, it has the potential in developing biosensor for methane.