Identification of <i>Pseudomonas tolaasi:</i> the White Line in Agar and Mushroom Tissue Block Rapid Pitting Tests

Wong, Wendy; Preece, T.F.

doi:10.1111/j.1365-2672.1979.tb01200.x

Cited by 121 publications

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“…The Escherichia coli and P. tolaasii strains used in this study are described in Table 1. P. tolaasii strains were grown on Pseudomonas agar F (PAF [56]) or in PB (Difco) liquid medium at 28ЊC, and E. coli strains were grown in Luria broth (43) at 37ЊC. Recombinants were grown in the same media containing appropriate antibiotics at the following concentrations: kanamycin, 25 g ml…”

Section: Methodsmentioning

confidence: 99%

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Identification and characterization of a locus which regulates multiple functions in Pseudomonas tolaasii, the cause of brown blotch disease of Agaricus bisporus

1995

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Pseudomonas tolaasii, the causal agent of brown blotch disease of Agaricus bisporus, spontaneously gives rise to morphologically distinct stable sectors, referred to as the phenotypic variant form, at the margins of the wild-type colonies. The phenotypic variant form is nonpathogenic and differs from the wild type in a range of biochemical and physiological characteristics. A genomic cosmid clone (pSISG29) from a wild-type P. tolaasii library was shown to be capable of restoring a range of characteristics of the phenotypic variant to those of the wild-type form, when present in trans. Subcloning and saturation mutagenesis analysis with Tn5lacZ localized a 3.0-kb region from pSISG29, designated the pheN locus, required for complementation of the phenotypic variant to the wild-type form. Pseudomonas tolaasii causes the economically important brown blotch disease of the mushroom Agaricus bisporus (Lange) Imbach (53). Synthesis of the low-molecular-weight (M r , 1,985) lipodepsipeptide extracellular toxin tolaasin by P. tolaasii is primarily responsible for eliciting disease symptoms (6,38,39). Tolaasin causes disruption of cell membranes from a range of cell types and has both ion channel-forming and biosurfactant properties (6,26,38). The ability of P. tolaasii to show a positive chemotactic response to A. bisporus exudates (20) and its ability to attach to mycelial surfaces (9, 35, 37) may also be important as steps in the early stages of development of brown blotch disease.P. tolaasii undergoes phenotypic variation, a strategy frequently used by bacteria to survive disparate environmental conditions. Old colonies of P. tolaasii frequently produce sectors which, when subcultured onto fresh medium, show different phenotypically distinct colonial forms (10, 29, 36). The wild-type strain is opaque, mucoid, pathogenic, and nonfluorescent, whereas the sectors are translucent, nonmucoid, nonpathogenic, and fluorescent (10, 57). In addition to alteration in virulence, qualitative analysis has revealed that a number of biochemical properties are also changed in the transition from the wild type to a phenotypic variant. These include the loss of the ability to produce tolaasin, hydrolyze casein, and grow normally on medium containing cetrimide (10). Finally, the variant form swims faster and shows a more rapid chemotactic response than the wild type (20). Phase change from the pathogenic to the nonpathogenic form in P. tolaasii has been referred to as a smooth-to-rough transition (10). This description generally designates a difference in the lipopolysaccharide (LPS) content of the two forms (16,29). Recent studies by Hutchison (25) have demonstrated that there is no difference in the LPS profiles of the smooth and rough forms of P. tolaasii. Therefore, the terms ''wild type'' and ''phenotypic variant'' are used here instead of ''smooth'' and ''rough,'' respectively.The aim of this study was to identify the molecular switch controlling the transition from the wild type to the phenotypic variant in P. tolaasii. First, we ...

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Identification and characterization of a locus which regulates multiple functions in Pseudomonas tolaasii, the cause of brown blotch disease of Agaricus bisporus

1995

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“…Table 2. Identification of isolates of P. tolaasii and P." reactans" using Biolog identification system FPP=Fluorescent pigment production, YG=Yellowish-green pigment, Y=Yellow pigment; *White line assay run on KB medium (Wong and Preece, 1979), -= absence of character whereas + = a weak WLA reaction and ++ = a strong WLA reaction. Pathogenic variation in isolates of Pseudomonas …”

Section: Biolog Profile Of Pseudomonas Isolatesmentioning

confidence: 99%

Pathogenic variation in isolates of Pseudomonas causing the brown blotch of cultivated mushroom, Agaricus bisporus

Abou-Zeid¹

2012

Braz. J. Microbiol.

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Twenty seven bacterial isolates were isolated from superficial brown discolorations on the caps of cultivated Agaricus bisporus. After White Line Assay (WLA) and the assist of Biolog computer-identification system, isolates were divided into groups: (I) comprised ninteen bacterial isolates that positively responded to a Pseudomonas "reactans" reference strain (NCPPB1311) in WLA and were identified as Pseudomonas tolaasii, (II) comprised two isolates which were WLA+ towards the reference strain (JCM21583) of P.tolaasii and were proposed to be P. "reactans". The third group comprised six isolates, two of which weakly responded to the strain of P. tolaasii and were identified as P. gingeri whereas the other four were WLAand identified as P. fluorescens (three isolates) and P. marginalis (one isolate). Isolates of P. tolaasii showed high aggressiveness compared with those of P. "reactans" in pathogenicity tests. Cubes of 1 cm 3 of A. bisporus turned brown and decreased in size when were inoculated with 10 µl of P. tolaasii suspension containing 10 8 CFU ml, whereas a similar concentration of P. "reactans" caused only light browning.Fifty µl of the same concentration of P. tolaasii isolates gave typical brown blotch symptoms on fresh mushroom sporophores whereas the two P. "reactans" isolates caused superficial light discoloration only after inoculation with 100 µl of the same concentration. Mixture from both bacterial suspensions increased the brown areas formed on the pileus. This is the first pathogenicity report of P. tolasii and P. "reactans" isolated from cultivated A. bisporus in Egypt.

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“…The higher extent of reversion from the avirulent 1116R form to the virulent 1116S form may be important in the epidemiology of brown blotch disease. The failure to find the origin of primary inoculum in mushroom farms may be due to the inadequacy of current diagnostic tests, which are able to detect only the 1116S form (21). Thus, the 1116R form may constitute the primary inoculum, which could revert to the virulent form either spontaneously or as a result of receiving environmental cues.…”

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Analysis of the Role of recA in Phenotypic Switching of Pseudomonas tolaasii

2000

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Switching between the pathogenic smooth (1116S) and nonpathogenic rough (1116R) forms of Pseudomonas tolaasii occurs due to the reversible duplication of a 661-bp element within thepheN locus. Disruption of the chromosomal recAlocus of 1116S and 1116R produced strains 1116SrecAand 1116RrecA, respectively, which showed typical loss of UV resistance. Switching from the smooth to the rough form was virtually eliminated in the 1116SrecA strain, whereas the extent of switching from the rough to the smooth form was almost identical in 1116R and 1116RrecA. It is concluded that phenotypic switching from 1116S to 1116R is recAdependent whereas that from 1116R to 1116S is recAindependent.

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Identification of Pseudomonas tolaasi: the White Line in Agar and Mushroom Tissue Block Rapid Pitting Tests

Cited by 121 publications

References 2 publications

Identification and characterization of a locus which regulates multiple functions in Pseudomonas tolaasii, the cause of brown blotch disease of Agaricus bisporus

Identification and characterization of a locus which regulates multiple functions in Pseudomonas tolaasii, the cause of brown blotch disease of Agaricus bisporus

Pathogenic variation in isolates of Pseudomonas causing the brown blotch of cultivated mushroom, Agaricus bisporus

Analysis of the Role of recA in Phenotypic Switching of Pseudomonas tolaasii

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