Monitoring ofgfp-taggedMoraxella sp. under starvation condition

Abstract

A PNP(p-nitrophenol)-degradingMoraxella sp. was genetically marked bygfp gene for monitoring. Stable chromosomal integration of the introducedgfp gene was confirmed by examining the transformants under epifluorescent microscope. The survival ofgfp-taggedMoraxella sp. cells during long-term storage under starvation condition was examined by viable cell counting and direct fluorescence microscopic counting. The number of green fluorescent cells obtained by direct microscopic counting was approximately 10 times greater than viable cell counts by plating. The number of cells from both counting methods was higher at lower temperature (4°C), although the drop of cell number after 8 weeks of starvation was comparable (approximately 100 fold drop from initial counts). Results obtained by two different methods correlated well with each other indicating that thegfp markedMoraxella sp. can be directly monitored following environmental release using epifluorescence microscopy.