scholarly journals Pseudomonas fluorescens 134 as a Biological Control Agent (BCA) Model in Cell Immobilization Technology

2008 ◽  
Vol 21 (1) ◽  
pp. 309-314 ◽  
Author(s):  
Anna Russo ◽  
Marina Basaglia ◽  
Sergio Casella ◽  
Marco Paolo Nuti
Keyword(s):  
Biological Control ◽  
Pseudomonas Fluorescens ◽  
Biological Control Agent ◽  
Cell Immobilization ◽  
Control Agent ◽  
Immobilization Technology

scholarly journals Stress Tolerance and Environmental Fitness of Pseudomonas fluorescens A506, Which Has a Mutation in rpoS

2009 ◽  
Vol 99 (6) ◽  
pp. 679-688 ◽  
Author(s):  
Mary J. Hagen ◽  
Virginia O. Stockwell ◽  
Cheryl A. Whistler ◽  
Kenneth B. Johnson ◽  
Joyce E. Loper
Keyword(s):  
Biological Control ◽  
Stress Response ◽  
Pseudomonas Fluorescens ◽  
Biological Control Agent ◽  
Environmental Stresses ◽  
Control Agent ◽  
Full Length ◽  
Site Directed Mutagenesis ◽  
Plant Surfaces

Establishment of suppressive populations of bacterial biological control agents on aerial plant surfaces is a critical phase in biologically based management of floral diseases. Periodically, biocontrol agents encounter inhospitable conditions for growth on plants; consequently, tolerance of environmental stresses may contribute to their fitness. In many gram-negative bacteria, including strains of Pseudomonas spp., the capacity to survive environmental stresses is influenced by the stationary phase sigma factor RpoS. This study focused on the role of RpoS in stress response and epiphytic fitness of Pseudomonas fluorescens A506, a well-studied bacterial biological control agent. We detected a frameshift mutation in the rpoS of A506 and demonstrated that the mutation resulted in a truncated, nonfunctional RpoS. Using site-directed mutagenesis, we deleted a nucleotide from rpoS, which then encoded a full-length, functional RpoS. We compared the stress response and epiphytic fitness of A506 with derivative strains having the functional full-length RpoS or a disrupted, nonfunctional RpoS. RpoS had little effect on stress response of A506 and no consistent influence on epiphytic population size of A506 on pear or apple leaves or flowers. Although the capacity of strain A506 to withstand exposure to environmental stresses was similar to that of other fluorescent pseudomonads, this capacity was largely independent of rpoS.

Movement through soil of a biological control agent, Pseudomonas fluorescens

1991 ◽  
Vol 23 (9) ◽  
pp. 821-825 ◽  
Author(s):  
Y. Tan ◽  
W.J. Bond ◽  
A.D. Rovira ◽  
P.G. Brisbane ◽  
D.M. Griffin
Keyword(s):  
Biological Control ◽  
Pseudomonas Fluorescens ◽  
Biological Control Agent ◽  
Control Agent

scholarly journals Assessment of the Environmental Fate of the Biological Control Agent of Fire Blight, Pseudomonas fluorescens EPS62e, on Apple by Culture and Real-Time PCR Methods

2006 ◽  
Vol 72 (4) ◽  
pp. 2421-2427 ◽  
Author(s):  
Marta Pujol ◽  
Esther Badosa ◽  
Charles Manceau ◽  
Emilio Montesinos
Keyword(s):  
Biological Control ◽  
Pseudomonas Fluorescens ◽  
Real Time ◽  
Real Time Pcr ◽  
Environmental Fate ◽  
Biological Control Agent ◽  
Field Trials ◽  
Control Agent ◽  
Cell Counting ◽  
Standard Curve

ABSTRACT The colonization of apple blossoms and leaves by Pseudomonas fluorescens EPS62e was monitored in greenhouse and field trials using cultivable cell counting and real-time PCR. The real-time PCR provided a specific quantitative method for the detection of strain EPS62e. The detection level was around 102 cells g (fresh weight)−1 and the standard curve was linear within a 5-log range. EPS62e actively colonized flowers reaching values from 107 to 108 cells per blossom. In apple flowers, no significant differences were observed between population levels obtained by real-time PCR and plating, suggesting that viable but nonculturable (VBNC) cells and residual nondegraded DNA were not present. In contrast, on apple leaves, where cultivable populations of EPS62e decreased with time, significant differences were observed between real-time PCR and plating. These differences indicate the presence of VBNC cells or nondegraded DNA after cell death. Therefore, the EPS62e population was under optimal conditions during the colonization of flowers but it was stressed and poorly survived on leaves. It was concluded that for monitoring this biological control agent, the combined use of cultivable cell count and real-time PCR is necessary.

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