|Mahaffee, Walter - Walt|
|VAN VUURDE, J.W.|
|VAN DER WOLF, J.|
|VAN DEN BRINK, M.|
Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/1997
Publication Date: N/A
Interpretive Summary: The manuscript describes experiments on the field assessment of three systems for tracking bacteria released into the environment. This work demonstrates that the most popular system (antibiotic resistance) for tracking bacteria could underestimate the actual population in the environment.
Technical Abstract: Field releases of wild-type plant growth-promoting rhizobacteria (PGPR) Pseudomonas fluorescens strain 89B-27, its bioluminescent derivative (GEM-8; 89B-27::Tn4431), and a spontaneous rifampicin resistant variant (R34) were established on cucumber in 1994 and 1995 to examine the efficiency of these marker systems for estimating the wild type population. Seed and root samples were taken 0, 7, 14, 21, 35 or 42, and 70 days after planting (DAP) in each year and processed for enumeration by spiral plating or immunofluorescent colony staining (IFC). In both years, populations of 89B-27, R34, and GEM-8, as measured by IFC, were not significantly different (P>0.05) from each other at each sampling time. However, populations of R34 and GEM-8, as measured by spiral plating and differentiation based on their respective phenotypes, were significantly lower (P<0.05) than the wild type and their IFC determined populations. These data indicate that traditional marker systems may underestimate populations and therefore survival and colonization of genetically marked bacteria.