scholarly journals The role of bacterial motility in the survival and spread of Pseudomonas fluorescens in soil and in the attachment and colonisation of wheat roots

2001 ◽  
Vol 36 (1) ◽  
pp. 21-31 ◽  
Author(s):  
Gillian A. Turnbull ◽  
J.Alun W. Morgan ◽  
John M. Whipps ◽  
Jon R. Saunders
Keyword(s):  
Pseudomonas Fluorescens ◽  
Bacterial Motility ◽  
Wheat Roots

scholarly journals Role of endomycorrhizae and Pseudomonas fluorescens on the acclimatization of micropropagated Stevia rebaudiana Bert. plantlets

2017 ◽  
Vol 11 (3) ◽  
pp. 38-47
Author(s):  
S. Zayed Mona ◽  
Abd El-Moneim Hegazi Ghada ◽  
Mohammed Salem Hanaa ◽  
Mohammed Ibrahim Ali Adas Walaa
Keyword(s):  
Pseudomonas Fluorescens ◽  
Stevia Rebaudiana

scholarly journals Increased Fitness of Pseudomonas fluorescens Pf0-1 Leucine Auxotrophs in Soil

2008 ◽  
Vol 74 (12) ◽  
pp. 3644-3651 ◽  
Author(s):  
Wook Kim ◽  
Stuart B. Levy
Keyword(s):  
Pseudomonas Fluorescens ◽  
Bacterial Genome ◽  
Physiological Role ◽  
Underlying Mechanism ◽  
Growth Conditions ◽  
Soil Environment ◽  
Fitness Advantage ◽  
Gene Structures

ABSTRACT The annotation process of a newly sequenced bacterial genome is largely based on algorithms derived from databases of previously defined RNA and protein-encoding gene structures. This process generally excludes the possibility that the two strands of a given stretch of DNA can each harbor a gene in an overlapping manner. While the presence of such structures in eukaryotic genomes is considered to be relatively common, their counterparts in prokaryotic genomes are just beginning to be recognized. Application of an in vivo expression technology has previously identified 22 discrete genetic loci in Pseudomonas fluorescens Pf0-1 that were specifically activated in the soil environment, of which 10 were present in an antisense orientation relative to previously annotated genes. This observation led to the hypothesis that the physiological role of overlapping genetic structures may be relevant to growth conditions outside artificial laboratory media. Here, we examined the role of one of the overlapping gene pairs, iiv19 and leuA2, in soil. Although iiv19 was previously demonstrated to be preferentially activated in the soil environment, its absence did not alter the ability of P. fluorescens to colonize or survive in soil. Surprisingly, the absence of the leuA2 gene conferred a fitness advantage in the soil environment when leucine was supplied exogenously. This effect was determined to be independent of the iiv19 gene, and further analyses revealed that amino acid antagonism was the underlying mechanism behind the observed fitness advantage of the bacterium in soil. Our findings provide a potential mechanism for the frequent occurrence of auxotrophic mutants of Pseudomonas spp. in the lungs of cystic fibrosis patients.

scholarly journals The cellodextrinase from Pseudomonas fluorescens subsp. cellulosa consists of multiple functional domains

1991 ◽  
Vol 279 (3) ◽  
pp. 793-799 ◽  
Author(s):  
L M A Ferreira ◽  
G P Hazlewood ◽  
P J Barker ◽  
H J Gilbert
Keyword(s):  
Pseudomonas Fluorescens ◽  
Catalytic Domain ◽  
Genomic Library ◽  
Terminal Region ◽  
Crystalline Cellulose ◽  
Nucleotide Sequencing ◽  
Reading Frame ◽  
Strong Homology ◽  
Cellulose Binding

A genomic library of Pseudomonas fluorescens subsp. cellulosa DNA was constructed in pUC18 and Escherichia coli recombinants expressing 4-methylumbelliferyl beta-D-cellobioside-hydrolysing activity (MUCase) were isolated. Enzyme produced by MUCase-positive clones did not hydrolyse either cellobiose or cellotriose but converted cellotetraose into cellobiose and cleaved cellopentaose and cellohexaose, producing a mixture of cellobiose and cellotriose. There was no activity against CM-cellulose, insoluble cellulose or xylan. On this basis, the enzyme is identified as an endo-acting cellodextrinase and is designated cellodextrinase C (CELC). Nucleotide sequencing of the gene (celC) which directs the synthesis of CELC revealed an open reading frame of 2153 bp, encoding a protein of Mr 80,189. The deduced primary sequence of CELC was confirmed by the Mr of purified CELC (77,000) and by the experimentally determined N-terminus of the enzyme which was identical with residues 38-47 of the translated sequence. The N-terminal region of CELC showed strong homology with endoglucanase, xylanases and an arabinofuranosidase of Ps. fluorescens subsp. cellulosa; homologous sequences included highly conserved serine-rich regions. Full-length CELC bound tightly to crystalline cellulose. Truncated forms of celC from which the DNA sequence encoding the conserved domain had been deleted, directed the synthesis of a functional cellodextrinase that did not bind to crystalline cellulose. This is consistent with the N-terminal region of CELC comprising a non-catalytic cellulose-binding domain which is distinct from the catalytic domain. The role of the cellulose-binding region is discussed.

scholarly journals The Catabolite Repressor/Activator Cra Is a Bridge Connecting Carbon Metabolism and Host Colonization in the Plant Drought Resistance-Promoting Bacterium Pantoea alhagi LTYR-11Z

2018 ◽  
Vol 84 (13) ◽  
Author(s):  
Lei Zhang ◽  
Muhang Li ◽  
Qiqi Li ◽  
Chaoqiong Chen ◽  
Meng Qu ◽  
...  
Keyword(s):  
Carbon Source ◽  
Carbon Metabolism ◽  
Carbon Sources ◽  
Endophytic Bacterium ◽  
Bacterial Attachment ◽  
Gene Encoding ◽  
Wheat Roots ◽  
Host Colonization ◽  
Content Type

ABSTRACT Efficient root colonization is a prerequisite for application of plant growth-promoting (PGP) bacteria in improving health and yield of agricultural crops. We have recently identified an endophytic bacterium, Pantoea alhagi LTYR-11Z, with multiple PGP properties that effectively colonizes the root system of wheat and improves its growth and drought tolerance. To identify novel regulatory genes required for wheat colonization, we screened an LTYR-11Z transposon (Tn) insertion library and found cra to be a colonization-related gene. By using transcriptome (RNA-seq) analysis, we found that transcriptional levels of an eps operon, the ydiV gene encoding an anti-FlhD 4 C 2 factor, and the yedQ gene encoding an enzyme for synthesis of cyclic dimeric GMP (c-di-GMP) were significantly downregulated in the Δ cra mutant. Further studies demonstrated that Cra directly binds to the promoters of the eps operon, ydiV , and yedQ and activates their expression, thus inhibiting motility and promoting exopolysaccharide (EPS) production and biofilm formation. Consistent with previous findings that Cra plays a role in transcriptional regulation in response to carbon source availability, the activating effects of Cra were much more pronounced when LTYR-11Z was grown within a gluconeogenic environment than when it was grown within a glycolytic environment. We further demonstrate that the ability of LTYR-11Z to colonize wheat roots is modulated by the availability of carbon sources. Altogether, these results uncover a novel strategy utilized by LTYR-11Z to achieve host colonization in response to carbon nutrition in the environment, in which Cra bridges a connection between carbon metabolism and colonization capacity of LTYR-11Z. IMPORTANCE Rapid and appropriate response to environmental signals is crucial for bacteria to adapt to competitive environments and to establish interactions with their hosts. Efficient colonization and persistence within the host are controlled by various regulatory factors that respond to specific environmental cues. The most common is nutrient availability. In this work, we unraveled the pivotal role of Cra in regulation of colonization ability of Pantoea alhagi LTYR-11Z in response to carbon source availability. Moreover, we identified three novel members of the Cra regulon involved in EPS synthesis, regulation of flagellar biosynthesis, and synthesis of c-di-GMP and propose a working model to explain the Cra-mediated regulatory mechanism that links carbon metabolism to host colonization. This study elucidates the regulatory role of Cra in bacterial attachment and colonization of plants, which raises the possibility of extending our studies to other bacteria associated with plant and human health.

scholarly journals The Role of the Motility of Methylobacterium in Bacterial Interactions in Drinking Water

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1386 ◽  
Author(s):  
Erifyli Tsagkari ◽  
William Sloan
Keyword(s):  
Drinking Water ◽  
Biofilm Formation ◽  
Bacterial Motility ◽  
Water Industry ◽  
Water Pipes ◽  
Bacterial Interactions ◽  
Available Energy ◽  
Potential Tool

Bacterial motility is one important factor that affects biofilm formation. In drinking water there are key bacteria in aggregation, whose biology acts to enhance the formation of biofilms. However, it is unclear whether the motility of these key bacteria is an important factor for the interactions between bacteria in drinking water, and, subsequently, in the formation of aggregates, which are precursors to biofilms. Thus, the role of the motility of one of these key bacteria, the Methylobacterium strain DSM 18358, was investigated in the interactions between bacteria in drinking water. The motility of pure Methylobacterium colonies was initially explored; if it was affected by the viscosity of substrate, the temperature, the available energy and the type of substrate. Furthermore, the role of Methylobacterium in the interactions between mixed drinking water bacteria was investigated under the mostly favourable conditions for the motility of Methylobacterium identified before. Overall, the motility of Methylobacterium was found to play a key role in the communication and interactions between bacteria in drinking water. Understanding the role of the motility of key bacteria in drinking water might be useful for the water industry as a potential tool to control the formation of biofilms in drinking water pipes.

scholarly journals Effect of Wheat Roots Infected with the Pathogenic Fungus Gaeumannomyces graminis var. tritici on Gene Expression of the Biocontrol Bacterium Pseudomonas fluorescens Pf29Arp

2009 ◽  
Vol 22 (12) ◽  
pp. 1611-1623 ◽  
Author(s):  
Matthieu Barret ◽  
Pascale Frey-Klett ◽  
Anne-Yvonne Guillerm-Erckelboudt ◽  
Morgane Boutin ◽  
Gregory Guernec ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Fluorescens ◽  
Pathogenic Fungus ◽  
Pathogenic Fungi ◽  
Gaeumannomyces Graminis ◽  
Type Vi Secretion System ◽  
Gene Encoding ◽  
Wheat Roots ◽  
Gaeumannomyces Graminis Var Tritici ◽  
Biocontrol Bacterium

Traits contributing to the competence of biocontrol bacteria to colonize plant roots are often induced in the rhizosphere in response to plant components. These interactions have been studied using the two partners in gnotobiotic systems. However, in nature, beneficial or pathogenic fungi often colonize roots. Influence of these plant–fungus interactions on bacterial behavior remains to be investigated. Here, we have examined the influence of colonization of wheat roots by the take-all fungus Gaeumannomyces graminis var. tritici on gene expression of the biocontrol bacterium Pseudomonas fluorescens Pf29Arp. Bacteria were inoculated onto healthy, early G. graminis var. tritici-colonized and necrotic roots and transcriptomes were compared by shotgun DNA microarray. Pf29Arp decreased disease severity when inoculated before the onset of necrosis. Necrotic roots exerted a broader effect on gene expression compared with early G. graminis var. tritici-colonized and healthy roots. A gene encoding a putative type VI secretion system effector was only induced in necrotic conditions. A common pool of Pf29Arp genes differentially expressed on G. graminis var. tritici-colonized roots was related to carbon metabolism and oxidative stress, with a highest fold-change with necrosis. Overall, the data showed that the association of the pathogenic fungus with the roots strongly altered Pf29Arp adaptation with differences between early and late G. graminis var. tritici infection steps.

Survival of Pseudomonas fluorescens containing plasmids RP4 or pRK2501 and plasmid stability after introduction into two soils of different texture

1989 ◽  
Vol 35 (10) ◽  
pp. 951-959 ◽  
Author(s):  
J. D. Van Elsas ◽  
J. T. Trevors ◽  
L. S. Van Overbeek ◽  
M. E. Starodub
Keyword(s):  
Pseudomonas Fluorescens ◽  
Plasmid Stability ◽  
Loamy Sand ◽  
Conjugative Plasmid ◽  
Detectable Effect ◽  
Wheat Roots ◽  
Soil Extracts ◽  
Plasmid Maintenance ◽  
Plasmid Loss ◽  
Introduced Populations

Survival of Pseudomonas fluorescens R2f containing either the conjugative plasmid RP4 or the nonconjugative plasmid pRK2501, and stability of the plasmids were studied in two soils, Ede loamy sand and Guelph loam, and in extracts prepared from these soils. In sterile soils, the introduced bacterial populations initially increased and then remained stable over a 47-day period. The presence of wheat roots did not significantly influence bacterial numbers in Guelph loam, whereas a slight increase occurred in Ede loamy sand. In Guelph loam, both plasmids were stably maintained in the introduced populations, but in Ede loamy sand substantial plasmid loss was observed. The presence of added phosphate in Ede loamy sand enhanced plasmid maintenance in the introduced R2f population. In nonsterile Guelph loam, a slow decline in the introduced populations was noted, regardless of plasmid type, whereas in Ede loamy sand the decline was more rapid. There was no detectable effect of plasmid type on host survival. Both plasmids RP4 and pRK2501 remained present in the R2f populations in these soils. The results obtained with sterile soil extracts substantiated the data on plasmid loss in both soils; both plasmids were rather unstable during starvation in minimal medium. The results indicated the absence of an effect of plasmid type on host survival. Soil type significantly affected host survival and plasmid maintenance, and higher survival and stability were observed in the heavier-textured Guelph loam.Key words: survival, plasmid stability, Pseudomonas spp., soil, microcosms.

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