Competitiveness in root colonization by Pseudomonas putida requires the rpoS gene

2001 ◽  
Vol 47 (1) ◽  
pp. 41-48 ◽  
Author(s):  
Charles D Miller ◽  
Young-Cheol Kim ◽  
Anne J Anderson
Keyword(s):  
Pseudomonas Putida ◽  
Culture Medium ◽  
Wild Type Strain ◽  
Root Colonization ◽  
Plant Root ◽  
Wild Type ◽  
Rpos Gene ◽  
Activated Oxygen ◽  
Increased Sensitivity ◽  
Dose Dependent

The rpoS gene in Pseudomonas putida was essential for plant root colonization under competitive conditions from other microbes. The RpoS- mutant survived less well than the wild-type strain in culture medium, and unlike the wild-type, failed to colonize the roots in a peat matrix containing an established diverse microflora. The RpoS-deficient P. putida isolate was generated by insertion of a glucuronidase-npt cassette into the rpoS gene. The RpoS- mutant had dose-dependent increased sensitivity to oxidative stress and produced Mn-superoxide dismutase activity earlier than the parent. While extracts from wild-type P. putida stationary-phase cells contained three isozymes of catalase (CatA, CatB, and CatC), the σ38-deficient P. putida lacked CatB. These results are consistent with previous findings that CatB is induced in stationary-phase.Key words: catalase, starvation, activated oxygen species.

scholarly journals The davDT Operon of Pseudomonas putida, Involved in Lysine Catabolism, Is Induced in Response to the Pathway Intermediate δ-Aminovaleric Acid

2004 ◽  
Vol 186 (11) ◽  
pp. 3439-3446 ◽  
Author(s):  
Olga Revelles ◽  
Manuel Espinosa-Urgel ◽  
Soeren Molin ◽  
Juan L. Ramos
Keyword(s):  
Amino Acid ◽  
Pseudomonas Putida ◽  
Culture Medium ◽  
Wild Type Strain ◽  
Gene Products ◽  
Wild Type ◽  
Basal Expression ◽  
Efficient Uptake ◽  
High Level ◽  
Lysine Catabolism

ABSTRACT Pseudomonas putida KT2440 is a soil microorganism that attaches to seeds and efficiently colonizes the plant's rhizosphere. Lysine is one of the major compounds in root exudates, and P. putida KT2440 uses this amino acid as a source of carbon, nitrogen, and energy. Lysine is channeled to δ-aminovaleric acid and then further degraded to glutaric acid via the action of the davDT gene products. We show that the davDT genes form an operon transcribed from a single σ70-dependent promoter. The relatively high level of basal expression from the davD promoter increased about fourfold in response to the addition of exogenous lysine to the culture medium. However, the true inducer of this operon seems to be δ-aminovaleric acid because in a mutant unable to metabolize lysine to δ-aminovaleric acid, this compound, but not lysine, acted as an effector. Effective induction of the P. putida P davD promoter by exogenously added lysine requires efficient uptake of this amino acid, which seems to proceed by at least two uptake systems for basic amino acids that belong to the superfamily of ABC transporters. Mutants in these ABC uptake systems retained basal expression from the davD promoter but exhibited lower induction levels in response to exogenous lysine than the wild-type strain.

scholarly journals Safety and Protective Efficacy of Intramuscular Vaccination with a Live aroA Derivative of Pasteurella multocida B:2 against Experimental Hemorrhagic Septicemia in Calves

2007 ◽  
Vol 75 (12) ◽  
pp. 5837-5844 ◽  
Author(s):  
Mark P. Dagleish ◽  
J. Christopher Hodgson ◽  
Saeed Ataei ◽  
Anna Finucane ◽  
Jeanie Finlayson ◽  
...  
Keyword(s):  
Pasteurella Multocida ◽  
Wild Type Strain ◽  
Protective Efficacy ◽  
Vaccine Dose ◽  
Immunoglobulin M ◽  
Wild Type ◽  
Amyloid A ◽  
Challenge Control ◽  
Temperature Responses ◽  
Dose Dependent

ABSTRACT Three groups of five calves, namely, V1, V2, and V3, were immunized intramuscularly at 4 and 8 weeks of age with ca. 109, 108, and 107 CFU, respectively, of a derivative of Pasteurella multocida B:2 wild-type strain 85020 containing a deletion in the aroA gene (strain JRMT12). The first and second vaccinations resulted in significantly (P < 0.01) higher rectal temperature responses in groups V1 and V2 than in group V3. Serum immunoglobulin M (IgM) and IgG titers did not increase in any group until after the second vaccination and were then significantly higher in groups V1 and V2 than in group V3 (P = 0.001 for both IgM and IgG). All vaccinated groups and three unvaccinated challenge control calves (group CC) were injected subcutaneously at 10 weeks of age with ca. 107 CFU of strain 85020. Vaccinated calves survived the challenge, but two CC animals developed clinical disease and were killed for humane reasons. After challenge, mean serum amyloid A concentrations were significantly higher (P < 0.001) in the CC group than in the vaccinated groups. Postmortem examination revealed that calves in the CC group showed the most extensive range of bacteriologically positive tissues and gross and histopathological lesions. Overall, a clear dose-dependent response was present, with those receiving a higher vaccine dose being less affected clinically, bacteriologically, and pathologically by the wild-type challenge. The V2 treatment appeared to give the best combination of high immune response, protection, and safety.

scholarly journals A sterol C-14 reductase encoded by FgERG24B is responsible for the intrinsic resistance of Fusarium graminearum to amine fungicides

Microbiology ◽  
2011 ◽  
Vol 157 (6) ◽  
pp. 1665-1675 ◽  
Author(s):  
Xin Liu ◽  
Jing Fu ◽  
Yingzi Yun ◽  
Yanni Yin ◽  
Zhonghua Ma
Keyword(s):  
Fusarium Graminearum ◽  
Type Strain ◽  
Wild Type Strain ◽  
Ergosterol Biosynthesis ◽  
Deletion Mutants ◽  
Wild Type ◽  
Head Blight ◽  
Intrinsic Resistance ◽  
In The Wild ◽  
Increased Sensitivity

Fusarium graminearum, the causal agent of wheat head blight, shows intrinsic resistance to amine fungicides. It is commonly accepted that the amines target sterol C-14 reductase and sterol Δ8–Δ7 isomerase of ergosterol biosynthesis, encoded by the genes ERG24 and ERG2, respectively. Analysis of the genome sequence of F. graminearum revealed that the fungus contains two paralogous FgERG24 genes (FgERG24A and FgERG24B), which are homologous to the ERG24 of Saccharomyces cerevisiae. In this study, we disrupted FgERG24A and FgERG24B in F. graminearum. Compared to the wild-type strain HN9-1, FgERG24A and FgERG24B deletion mutants did not show recognizable phenotypic changes in mycelial growth on potato dextrose agar or in virulence on wheat heads. HPLC analysis showed that the amount of ergosterol in FgERG24A or FgERG24B deletion mutants was not significantly different from that in the wild-type strain. These results indicate that neither of the two genes is essential for growth, pathogenicity or ergosterol biosynthesis in F. graminearum. FgERG24B deletion mutants exhibited significantly increased sensitivity to amine fungicides, including tridemorph, fenpropidin and spiroxamine, but not to non-amine fungicides. In contrast, FgERG24A deletion mutants did not show changed sensitivity to any amine tested. The resistance of the FgERG24B deletion mutant to amines was restored by genetic complementation of the mutant with wild-type FgERG24B. These results indicate that FgERG24B controls the intrinsic resistance of F. graminearum to amines. The finding of this study provides new insights into amine resistance in filamentous fungi.

Peptides’ involvement in Pseudomonas putida biofilm formation

2020 ◽  
Author(s):  
Riho Teras ◽  
Hanna Ainelo ◽  
Marge Puhm
Keyword(s):  
Pseudomonas Putida ◽  
Mutant Strain ◽  
Type Strain ◽  
Deletion Mutant ◽  
Wild Type Strain ◽  
Positive Impact ◽  
Proteinase K ◽  
Wild Type ◽  
Positive Effect ◽  
Positively Charged

&lt;p&gt;Pseudomonas putida rapidly forms a biofilm, after which its biomass usually disperses to half its initial amount. We have observed different biofilm dynamics of P. putida in a complex medium LB and a minimal medium M9+glc+CAA and inquired about the importance of extracellular factors for the formation of P. putida biofilm.&lt;/p&gt; &lt;p&gt;The proteinaceous component of LB increases the biomass of P. putida biofilm. Supplementation of M9 with tryptone but not CAA increased the biofilm biomass. Proteinase K treatment of LB medium reduced the biomass of P. putida biofilm. At the same time, growth rate or maximum OD of planktic bacteria in used media did not correlate with biofilm biomass of the same media. Thus, peptides appeared to have a positive effect on the biofilm as an extracellular factor and not as a source of C and N.&lt;/p&gt; &lt;p&gt;We replaced tryptone in M9 medium with positively charged poly-L-lysine (MW. 1000-5000 Da), negatively charged poly-L-glutaminic acid (MW. 1500-5500 Da) or neutral poly-LD-alanine (MW. 3000-7000). Poly-lysine and poly-glutamic acid had a slight positive effect on the biomass of P. putida wild type strain PSm biofilm and poly-alanine did not affect the biofilm.&lt;/p&gt; &lt;p&gt;We have previously shown that overexpression of fis in P. putida strain F15 increases biofilm biomass by increasing the lapA expression, the main adhesin gene of biofilm. Using media similar to that used for the wild-type strain for strain F15, we ascertained that only poly-lysine out of these three polypeptides restored the positive effect of fis-overexpression on the biofilm biomass. At the same time, the positive impact of fis-overexpression was absent in lapA deletion mutant strain, but not in lapF deletion mutant strain.&lt;/p&gt; &lt;p&gt;In conclusion, the formation of P. putida biofilm depends on polypeptides in the environment. The enhancing effect of positively charged polypeptides appears to be evident in the presence of LapA, a key factor for P. putida biofilm.&lt;/p&gt;

scholarly journals Involvement of the Reserve Material Poly-β-Hydroxybutyrate in Azospirillum brasilense Stress Endurance and Root Colonization

2003 ◽  
Vol 69 (6) ◽  
pp. 3244-3250 ◽  
Author(s):  
Daniel Kadouri ◽  
Edouard Jurkevitch ◽  
Yaacov Okon
Keyword(s):  
Plant Growth ◽  
Mutant Strain ◽  
Azospirillum Brasilense ◽  
Type Strain ◽  
Wild Type Strain ◽  
Root Colonization ◽  
Cell Aggregation ◽  
Wild Type ◽  
Phb Production ◽  
Promote Plant Growth

ABSTRACT When grown under suboptimal conditions, rhizobacteria of the genus Azospirillum produce high levels of poly-β-hydroxybutyrate (PHB). Azospirillum brasilense strain Sp7 and a phbC (PHB synthase) mutant strain in which PHB production is impaired were evaluated for metabolic versatility, for the ability to endure various stress conditions, for survival in soil inoculants, and for the potential to promote plant growth. The carbon source utilization data were similar for the wild-type and mutant strains, but the generation time of the wild-type strain was shorter than that of the mutant strain with all carbon sources tested. The ability of the wild type to endure UV irradiation, heat, osmotic pressure, osmotic shock, and desiccation and to grow in the presence of hydrogen peroxide was greater than that of the mutant strain. The motility and cell aggregation of the mutant strain were greater than the motility and cell aggregation of the wild type. However, the wild type exhibited greater chemotactic responses towards attractants than the mutant strain exhibited. The wild-type strain exhibited better survival than the mutant strain in carrier materials used for soil inoculants, but no difference in the ability to promote plant growth was detected between the strains. In soil, the two strains colonized roots to the same extent. It appears that synthesis and utilization of PHB as a carbon and energy source by A. brasilense under stress conditions favor establishment of this bacterium and its survival in competitive environments. However, in A. brasilense, PHB production does not seem to provide an advantage in root colonization under the conditions tested.

scholarly journals A Set of Genes Encoding a Second Toluene Efflux System in Pseudomonas putida DOT-T1E Is Linked to the tod Genes for Toluene Metabolism

2000 ◽  
Vol 182 (4) ◽  
pp. 937-943 ◽  
Author(s):  
Gilberto Mosqueda ◽  
Juan-Luis Ramos
Keyword(s):  
Pseudomonas Putida ◽  
Culture Medium ◽  
Efflux Pump ◽  
Site Directed Mutagenesis ◽  
Solvent Tolerance ◽  
Directed Mutagenesis ◽  
Wild Type ◽  
Efflux System ◽  
Host Chromosome ◽  
Knock Out

ABSTRACT Sequence analysis in Pseudomonas putida DOT-T1E revealed a second toluene efflux system for toluene metabolism encoded by the ttgDEF genes, which are adjacent to thetod genes. The ttgDEF genes were expressed in response to the presence of aromatic hydrocarbons such as toluene and styrene in the culture medium. To characterize the contribution of the TtgDEF system to toluene tolerance in P. putida, site-directed mutagenesis was used to knock out the gene in the wild-type DOT-T1E strain and in a mutant derivative, DOT-T1E-18. This mutant carried a Tn5 insertion in the ttgABCgene cluster, which encodes a toluene efflux pump that is synthesized constitutively. For site-directed mutagenesis, a cassette to knock out the ttgD gene and encoding resistance to tellurite was constructed in vitro and transferred to the corresponding host chromosome via the suicide plasmid pKNG101. Successful replacement of the wild-type sequences with the mutant cassette was confirmed by Southern hybridization. A single ttgD mutant, DOT-T1E-1, and a double mutant with knock outs in the ttgD andttgA genes, DOT-T1E-82, were obtained and characterized for toluene tolerance. This was assayed by the sudden addition of toluene (0.3% [vol/vol]) to the liquid culture medium of cells growing on Luria-Bertani (LB) medium (noninduced) or on LB medium with toluene supplied via the gas phase (induced). Induced cells of the singlettgD mutant were more sensitive to sudden toluene shock than were the wild-type cells; however, noninduced wild-type andttgD mutant cells were equally tolerant to toluene shock. Noninduced cells of the double DOT-T1E-82 mutant did not survive upon sudden toluene shock; however, they still remained viable upon sudden toluene shock if they had been previously induced. These results are discussed in the context of the use of multiple efflux pumps involved in solvent tolerance in P. putida DOT-T1E.

scholarly journals Reproduction and endoreduplication in Drosophila melanogaster Meig. when influenced by lead nitrate

2020 ◽  
Vol 27 ◽  
pp. 303-308
Author(s):  
V. Yu. Strashnyuk ◽  
O. V. Taglina
Keyword(s):  
Drosophila Melanogaster ◽  
Salivary Glands ◽  
Type Strain ◽  
Wild Type Strain ◽  
Lead Nitrate ◽  
Wild Type ◽  
Reproductive Ability ◽  
Dose Dependent Decrease ◽  
Drosophila Cells ◽  
Dose Dependent

Aim. The purpose of investigation was to study the reproductive ability and polyteny degree of chromosomes in Drosophila melanogaster Meig. under the influence of various concentrations of lead nitrate. Methods. Canton-S wild-type strain was used as the material. Flies developed on standard sugar-yeast medium, to which in the experiment lead nitrate was added in concentrations of 0.1, 1, and 10 mg/ml. The reproductive ability of the strain was evaluated by the number of adult offspring. The polyteny degree of chromosomes was studied on squashed preparations of larva salivary glands stained with acetoorsein by cytomorphometry. The preparations were obtained at late 3rd instar. Results. The number of adult offsprings decreased when lead nitrate was added to the nutrient medium: at a concentration of 0.1 mg/ml – by 22.8 %, at 1 mg/ml – by 38.9 %. A concentration of 10 mg/ml was lethal. Males showed greater sensitivity to the drug compared to females. The degree of polyteny of chromosomes in the salivary glands of larvae decreased on average by 5.0–6.5 %. Conclusions. Lead nitrate causes a significant, dose-dependent decrease in the reproductive ability of fruit flies and has a toxic effect on Drosophila cells, inhibiting the process of endoreduplication. Keywords: Drosophila melanogaster Meig., heavy metals, fecundity, giant chromosomes, polyteny.

scholarly journals Potential Role of Flavobacterial Gliding-Motility and Type IX Secretion System Complex in Root Colonization and Plant Defense

2014 ◽  
Vol 27 (9) ◽  
pp. 1005-1013 ◽  
Author(s):  
Max Kolton ◽  
Omer Frenkel ◽  
Yigal Elad ◽  
Eddie Cytryn
Keyword(s):  
Plant Defense ◽  
Root Colonization ◽  
Plant Protection ◽  
Plant Root ◽  
Secretion System ◽  
Gliding Motility ◽  
Wild Type ◽  
In Planta ◽  
Clavibacter Michiganensis

Members of the Flavobacterium genus are often highly abundant in the rhizosphere. Nevertheless, the physiological characteristics associated with their enhanced rhizosphere competence are currently an enigma. Flavobacteria possess a unique gliding-motility complex that is tightly associated with a recently characterized Bacteroidetes-specific type IX protein secretion system, which distinguishes them from the rest of the rhizosphere microbiome. We hypothesize that proper functionality of this complex may confer a competitive advantage in the rhizosphere. To test this hypothesis, we constructed mutant and complement root-associated flavobacterial variants with dysfunctional secretion and gliding motility, and tested them in a series of in planta experiments. These mutants demonstrated significantly lower rhizosphere persistence (approximately 10-fold), plant root colonization (approximately fivefold), and seed adhesion capacity (approximately sevenfold) than the wild-type strains. Furthermore, the biocontrol capacity of the mutant strain toward foliar-applied Clavibacter michiganensis was significantly impaired relative to the wild-type strain, suggesting a role of the gliding and secretion complex in plant protection. Collectively, these results provide an initial link between the high abundance of flavobacteria in the rhizosphere and their unique physiology, indicating that the flavobacterial gliding-motility and secretion complex may play a central role in root colonization and plant defense.

scholarly journals Genetic Analysis of an Incomplete mutSGene from Pseudomonas putida

2000 ◽  
Vol 182 (18) ◽  
pp. 5278-5279 ◽  
Author(s):  
Yasurou Kurusu ◽  
Tomoaki Narita ◽  
Makoto Suzuki ◽  
Taeko Watanabe
Keyword(s):  
Escherichia Coli ◽  
Bacillus Subtilis ◽  
Genetic Analysis ◽  
Pseudomonas Putida ◽  
Type Strain ◽  
Mutation Frequency ◽  
Wild Type Strain ◽  
Wild Type

ABSTRACT We genetically characterized the Pseudomonas putida mutS gene and found that it encodes a smaller MutS protein than do the genes of other bacteria. This gene is able to function in themutS mutants of Escherichia coli andBacillus subtilis. A P. putida mutS mutant has a mutation frequency 1,000-fold greater than that of the wild-type strain.

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