Exemplar Abstract for Pseudomonas chlororaphis piscium Burr et al. 2010.

2003 ◽  
Author(s):  
Charles Thomas Parker ◽  
Dorothea Taylor ◽  
George M Garrity
Keyword(s):  
Pseudomonas Chlororaphis

scholarly journals Reduction of Landscape Pathogens in Florida by Soil Solarization

Plant Disease ◽  
2002 ◽  
Vol 86 (12) ◽  
pp. 1388-1395 ◽  
Author(s):  
R. J. McGovern ◽  
R. McSorley ◽  
M. L. Bell
Keyword(s):  
Biological Control ◽  
Crown Rot ◽  
Soil Solarization ◽  
Shoot Biomass ◽  
Infested Soil ◽  
Pseudomonas Chlororaphis ◽  
Biological Control Agents ◽  
Central Florida ◽  
Air Space ◽  
Polyethylene Mulch

Two experiments were conducted during autumn 1997 and 1998 in west-central Florida to evaluate the effectiveness of soil solarization alone and in combination with the biological control agents Streptomyces lydicus (Actinovate) and Pseudomonas chlororaphis (syn. P. aureofasciens, AtEze) and the reduced-risk fungicide fludioxonil (Medallion) in managing soilborne pathogens of impatiens (Impatiens × wallerana, ‘Accent Burgundy’). Naturally infested soil was solarized for 47 or 48 days during September and October using two layers of 25-μm clear, low-density polyethylene mulch, separated by an air space of up to 7.5 cm. Solarization decreased the final incidence and progress of Rhizoctonia crown rot and blight, incidence of Pythium spp. in roots, and root discoloration, and increased shoot biomass in both experiments. The technique also consistently reduced root-knot severity and population densities of Meloidogyne incognita, Dolichodorus heterocephalus, Paratrichodorus minor, and Criconemella spp. The incidence of Rhizoctonia crown rot and blight was reduced by fludioxonil, but not by the biological control agents.

scholarly journals Transcriptional Regulation of the Nitrile Hydratase Gene Cluster in Pseudomonas chlororaphis B23

2008 ◽  
Vol 190 (12) ◽  
pp. 4210-4217 ◽  
Author(s):  
Toshihide Sakashita ◽  
Yoshiteru Hashimoto ◽  
Ken-Ichi Oinuma ◽  
Michihiko Kobayashi
Keyword(s):  
Gene Cluster ◽  
Nitrile Hydratase ◽  
Transcriptional Regulator ◽  
Pseudomonas Chlororaphis ◽  
Reading Frame ◽  
Transcription Start Sites ◽  
Reverse Transcription Pcr ◽  
Enormous Amount ◽  
Extension Analysis ◽  
Arac Family

ABSTRACT An enormous amount of nitrile hydratase (NHase) is inducibly produced by Pseudomonas chlororaphis B23 after addition of methacrylamide as the sole nitrogen source to a medium. The expression pattern of the P. chlororaphis B23 NHase gene cluster in response to addition of methacrylamide to the medium was investigated. Recently, we reported that the NHase gene cluster comprises seven genes (oxdA, amiA, nhpA, nhpB, nhpC, nhpS, and acsA). Sequence analysis of the 1.5-kb region upstream of the oxdA gene revealed the presence of a 936-bp open reading frame (designated nhpR), which should encode a protein with a molecular mass of 35,098. The deduced amino acid sequence of the nhpR product showed similarity to the sequences of transcriptional regulators belonging to the XylS/AraC family. Although the transcription of the eight genes (nhpR, oxdA, amiA, nhpABC, nhpS, and acsA) in the NHase gene cluster was induced significantly in the P. chlororaphis B23 wild-type strain after addition of methacrylamide to the medium, transcription of these genes in the nhpR disruptant was not induced, demonstrating that nhpR codes for a positive transcriptional regulator in the NHase gene cluster. A reverse transcription-PCR experiment revealed that five genes (oxdA, amiA, nhpA, nhpB, and nhpC) are cotranscribed, as are two other genes (nhpS and acsA). The transcription start sites for nhpR, oxdA, nhpA, and nhpS were mapped by primer extension analysis, and putative −12 and −24 σ54-type promoter binding sites were identified. NhpR was found to be the first transcriptional regulator of NHase belonging to the XylS/AraC family.

scholarly journals The Compound 2-Hexyl, 5-Propyl Resorcinol Has a Key Role in Biofilm Formation by the Biocontrol Rhizobacterium Pseudomonas chlororaphis PCL1606

2019 ◽  
Vol 10 ◽  
Author(s):  
Claudia E. Calderón ◽  
Sandra Tienda ◽  
Zaira Heredia-Ponce ◽  
Eva Arrebola ◽  
Gerardo Cárcamo-Oyarce ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Pseudomonas Chlororaphis

A GacS deficiency does not affectPseudomonas chlororaphisPA23 fitness when growing on canola, in aged batch culture or as a biofilm

2006 ◽  
Vol 52 (12) ◽  
pp. 1177-1188 ◽  
Author(s):  
N Poritsanos ◽  
C Selin ◽  
W G.D Fernando ◽  
S Nakkeeran ◽  
T.R. de Kievit
Keyword(s):  
Antifungal Activity ◽  
Batch Culture ◽  
Hydrogen Cyanide ◽  
Fungal Pathogen ◽  
Biocontrol Agent ◽  
Antifungal Compounds ◽  
Pseudomonas Chlororaphis ◽  
Wild Type ◽  
Biocontrol Activity ◽  
Competition Assays

Pseudomonas chlororaphis PA23 is a biocontrol agent that protects against the fungal pathogen Sclerotinia sclerotiorum. Employing transposon mutagenesis, we isolated a gacS mutant that no longer exhibited antifungal activity. Pseudomonas chlororaphis PA23 was previously reported to produce the nonvolatile antibiotics phenazine 1-carboxylic acid and 2-hydroxyphenazine. We report here that PA23 produces additional compounds, including protease, lipase, hydrogen cyanide, and siderophores, that may contribute to its biocontrol ability. In the gacS mutant background, generation of these products was markedly reduced or delayed with the exception of siderophores, which were elevated. Not surprisingly, this mutant was unable to protect canola from disease incited by S. sclerotiorum. The gacS mutant was able to sustain itself in the canola phyllosphere, therefore, the loss of biocontrol activity can be attributed to a reduced production of antifungal compounds and not a declining population size. Competition assays between the mutant and wild type revealed equivalent fitness in aged batch culture; consequently, the gacS mutation did not impart a growth advantage in the stationary phase phenotype. Under minimal nutrient conditions, the gacS-deficient strain produced a tenfold less biofilm than the wild type. However, no difference was observed in the ability of the mutant biofilm to protect cells from lethal antibiotic challenge.Key words: Pseudomonas, biocontrol, gacS, fitness, biofilms.

scholarly journals Altering the Ratio of Phenazines in Pseudomonas chlororaphis (aureofaciens) Strain 30-84: Effects on Biofilm Formation and Pathogen Inhibition

2008 ◽  
Vol 190 (8) ◽  
pp. 2759-2766 ◽  
Author(s):  
V. S. R. K. Maddula ◽  
E. A. Pierson ◽  
L. S. Pierson
Keyword(s):  
Fungal Pathogen ◽  
Biofilm Formation ◽  
Flow Cell ◽  
Gaeumannomyces Graminis ◽  
Pseudomonas Chlororaphis ◽  
Wild Type ◽  
Initial Attachment ◽  
Pathogen Inhibition ◽  
Biofilm Development ◽  
Derivatives Of

ABSTRACT Pseudomonas chlororaphis strain 30-84 is a plant-beneficial bacterium that is able to control take-all disease of wheat caused by the fungal pathogen Gaeumannomyces graminis var. tritici. The production of phenazines (PZs) by strain 30-84 is the primary mechanism of pathogen inhibition and contributes to the persistence of strain 30-84 in the rhizosphere. PZ production is regulated in part by the PhzR/PhzI quorum-sensing (QS) system. Previous flow cell analyses demonstrated that QS and PZs are involved in biofilm formation in P. chlororaphis (V. S. R. K. Maddula, Z. Zhang, E. A. Pierson, and L. S. Pierson III, Microb. Ecol. 52:289-301, 2006). P. chlororaphis produces mainly two PZs, phenazine-1-carboxylic acid (PCA) and 2-hydroxy-PCA (2-OH-PCA). In the present study, we examined the effect of altering the ratio of PZs produced by P. chlororaphis on biofilm formation and pathogen inhibition. As part of this study, we generated derivatives of strain 30-84 that produced only PCA or overproduced 2-OH-PCA. Using flow cell assays, we found that these PZ-altered derivatives of strain 30-84 differed from the wild type in initial attachment, mature biofilm architecture, and dispersal from biofilms. For example, increased 2-OH-PCA production promoted initial attachment and altered the three-dimensional structure of the mature biofilm relative to the wild type. Additionally, both alterations promoted thicker biofilm development and lowered dispersal rates compared to the wild type. The PZ-altered derivatives of strain 30-84 also differed in their ability to inhibit the fungal pathogen G. graminis var. tritici. Loss of 2-OH-PCA resulted in a significant reduction in the inhibition of G. graminis var. tritici. Our findings suggest that alterations in the ratios of antibiotic secondary metabolites synthesized by an organism may have complex and wide-ranging effects on its biology.

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