RESPIRATORY ACTIVITY OF A GENETICALLY ENGINEERED PSEUDOMONAS-FLUORESCENS STRAIN IN SOIL MEASURED USING GAS-CHROMATOGRAPHY

A genetically engineered Pseudomonas fluorescens strain was introduced into 300 g of nonsterile sandy loam agricultural soil contained in 1-1 flask-microcosms and incubated at 10 and 20-degrees-C. O2 consumption, CO2 evolution and bacterial survival were monitored using gas chromatography and viable cell plating, respectively. Respiratory activity increased significantly during a 14-day period in soil inoculated with P. fluorescens and incubated at either 10 or 20-degrees-C compared to uninoculated soil. Respiratory activity at 10-degrees-C was less than at 20-degrees-C and the growth medium used to culture cells prior to inoculation into soil influenced respiratory activity after introduction of the cells into soil. Cells also survived better in soil incubated at 10-degrees-C than at 20-degrees-C. Measurements of O2 consumption and CO2 evolution may be useful when initially studying the introduction of a genetically engineered microbial strain into soil microcosms.