scholarly journals Production of Cyclic Lipopeptides by Pseudomonas fluorescens Strains in Bulk Soil and in the Sugar Beet Rhizosphere

2003 ◽  
Vol 69 (2) ◽  
pp. 861-868 ◽  
Author(s):  
Tommy Harder Nielsen ◽  
Jan Sørensen
Keyword(s):  
Sugar Beet ◽  
Pseudomonas Fluorescens ◽  
Maximum Level ◽  
Bulk Soil ◽  
Nonsterile Soil ◽  
Cyclic Lipopeptides ◽  
A Cell ◽  
Soil Strain ◽  
Significant Production ◽  
Cell Inoculum

ABSTRACT The production of cyclic lipopeptides (CLPs) with antifungal and biosurfactant properties by Pseudomonas fluorescens strains was investigated in bulk soil and in the sugar beet rhizosphere. Purified CLPs (viscosinamide, tensin, and amphisin) were first shown to remain highly stable and extractable (90%) when applied (ca. 5 μg g−1) to sterile soil, whereas all three compounds were degraded over 1 to 3 weeks in nonsterile soil. When a whole-cell inoculum of P. fluorescens strain DR54 containing a cell-bound pool of viscosinamide was added to the nonsterile soil, declining CLP concentrations were observed over a week. By comparison, addition of the strains 96.578 and DSS73 without cell-bound CLP pools did not result in detectable tensin or amphisin in the soil. In contrast, when sugar beet seeds were coated with the CLP-producing strains and subsequently germinated in nonsterile soil, strain DR54 maintained a high and constant viscosinamide level in the young rhizosphere for ∼2 days while strains 96.578 and DSS73 exhibited significant production (net accumulation) of tensin or amphisin, reaching a maximum level after 2 days. All three CLPs remained detectable for several days in the rhizosphere. Subsequent tests of five other CLP-producing P. fluorescens strains also demonstrated significant production in the young rhizosphere. The results thus provide evidence that production of different CLPs is a common trait among many P. fluorescens strains in the soil environment, and further, that the production is taking place only in specific habitats like the rhizosphere of germinating sugar beet seeds rather than in the bulk soil.

Secondary Metabolite- and Endochitinase-Dependent Antagonism toward Plant-Pathogenic Microfungi of Pseudomonas fluorescens Isolates from Sugar Beet Rhizosphere

1998 ◽  
Vol 64 (10) ◽  
pp. 3563-3569 ◽  
Author(s):  
Mette Neiendam Nielsen ◽  
Jan Sørensen ◽  
Johannes Fels ◽  
Hans Christian Pedersen
Keyword(s):  
Biological Control ◽  
Cell Wall ◽  
Sugar Beet ◽  
Pseudomonas Fluorescens ◽  
Secondary Metabolite ◽  
Pythium Ultimum ◽  
Medium Composition ◽  
Fungal Antagonism ◽  
Lipopeptide Antibiotic

ABSTRACT Forty-seven isolates representing all biovars of Pseudomonas fluorescens (biovars I to VI) were collected from the rhizosphere of field-grown sugar beet plants to select candidate strains for biological control of preemergence damping-off disease. The isolates were tested for in vitro antagonism toward the plant-pathogenic microfungi Pythium ultimum and Rhizoctonia solani in three different plate test media. Mechanisms of fungal inhibition were elucidated by tracing secondary-metabolite production and cell wall-degrading enzyme activity in the same media. Most biovars expressed a specific mechanism of antagonism, as represented by a unique antibiotic or enzyme production in the media. A lipopeptide antibiotic, viscosinamide, was produced independently of medium composition by P. fluorescens bv. I, whereas the antibiotic 2,4-diacetylphloroglucinol was observed only in glucose-rich medium and only in P. fluorescens bv. II/IV. Both pathogens were inhibited by the two antibiotics. Finally, in low-glucose medium, a cell wall-degrading endochitinase activity in P. fluorescens bv. I, III, and VI was the apparent mechanism of antagonism toward R. solani. The viscosinamide-producing DR54 isolate (bv. I) was shown to be an effective candidate for biological control, as tested in a pot experiment with sugar beet seedlings infested with Pythium ultimum. The assignment of different patterns of fungal antagonism to the biovars of P. fluorescens is discussed in relation to an improved selection protocol for candidate strains to be used in biological control.

scholarly journals The histidine utilization (hut) genes of Pseudomonas fluorescens SBW25 are active on plant surfaces, but are not required for competitive colonization of sugar beet seedlings

Microbiology ◽  
2006 ◽  
Vol 152 (6) ◽  
pp. 1867-1875 ◽  
Author(s):  
Xue-Xian Zhang ◽  
Andrew George ◽  
Mark J. Bailey ◽  
Paul B. Rainey
Keyword(s):  
Sugar Beet ◽  
Pseudomonas Fluorescens ◽  
Bacterial Colonization ◽  
Temporal Distribution ◽  
Tetracycline Resistance ◽  
Dependent Manner ◽  
In The Wild ◽  
Pseudomonas Fluorescens Sbw25 ◽  
Functional Analyses

The ability to monitor the spatial and temporal distribution of signals in complex environments is necessary for an understanding of the function of bacteria in the wild. To this end, an existing recombinase-based transcriptional reporter strategy (recombinase-based in vivo expression technology, RIVET) has been extended and applied to the plant-colonizing bacterium Pseudomonas fluorescens SBW25. Central to the project was a rhizosphere-inducible locus, rhi14, which functional analyses show is hutT, a histidine-inducible gene that is required for histidine utilization. A transcriptional fusion between hutT and a promoterless site-specific recombinase (tnpR mut168) results in excision of a chromosomally integrated tetracycline-resistance cassette in a histidine-dependent manner. The dose- and time-responsiveness of the promoterless recombinase to histidine closely mirrored the histidine responsiveness of an identical hutT fusion to promoterless lacZ. To demonstrate the effectiveness of the strategy, the activity of hutT was monitored on sugar beet seedlings. Low levels of transcriptional activity were detected in the phyllosphere, rhizosphere and in plant extract, but not in vermiculite devoid of seedlings. The histidine concentration in the rhizosphere was estimated to be 0.6 μg ml−1. The ecological significance of the hut locus was examined by competing a hutT deletion mutant against the wild-type during colonization of sugar beet seedlings. No impact on competitive fitness was detected, suggesting that the ability to utilize plant-derived histidine is not essential for bacterial colonization.

scholarly journals Variable survival ability of rhizobacteria in cumin (Cuminum cyminum L.) rhizosphere

2016 ◽  
Vol 8 (3) ◽  
pp. 1699-1703
Author(s):  
Anurag Yadav ◽  
Kusum Yadav
Keyword(s):  
Bacillus Subtilis ◽  
Pseudomonas Fluorescens ◽  
Rhizosphere Soil ◽  
Population Decline ◽  
Dry Weight ◽  
Bulk Soil ◽  
Subtilis Strain ◽  
Initial Population ◽  
Final Population ◽  
Better Than

A study was undertaken to compare the survival efficacy of two native, previously characterized bacterial biovars viz. Bacillus subtilis BCU5 and Pseudomonas fluorescens PCU17 with Bacillus subtilis strain MTCC1789 and Pseudomonas fluorescens strain MTCC4828, procured from Institute of Microbial Technology, Chandigarh,India in cumin rhizosphere and bulk soil. All the four bacterial types were made rifampicin resistant and the mutants were applied as inoculants at the dosage of 6 log, 7 log and 8 log colony forming units (cfu) g-1 dry soil weight in pots containing cumin seedlings. The cfu of rhizosphere and bulk soil of pots was observed per week for four weeks. The results show that the initial population decline is a common feature of bioinoculants. In rhizosphere and bulk soil, the native bacterial biovars survived better than their procured counterparts. The population of P. fluorescens strain MTCC4828r in rhizosphere soil declined faster and reached below detection limit whereas the P. fluorescens biovar PCUr rhizosphere final population dropped to 3.1 log, 2.9 log and 2.13 log cfu g-1 soil dry weight with 8 log, 7 log and 6 log cfu g-1 soil dry weight inoculum treatment, respectively. In contrast to P. fluorescens strain MTCC4828r, the population of B. subtilis strain MTCC1789r stabilized after some decline and was comparable with B. subtilis biovar BCU5 population. Study concludes that the inoculant population decline in soil was the result of lower microbial load carrying capacity of soil than the provided inoculum densities. Also, the native bacteria survived better than procured ones in rhizosphere soil.

scholarly journals Impact of storable lift of breeding material on yield and quality of sugar beet root

1970 ◽  
Vol 21 ◽  
pp. 164-167
Author(s):  
V. V. Polishchuk ◽  
A. F. Balabak ◽  
T. V. Polishchuk
Keyword(s):  
Sugar Beet ◽  
Shelf Life ◽  
Seed Storage ◽  
Weather Conditions ◽  
Hybrid Seed ◽  
Production Loss ◽  
Significant Difference ◽  
Duration Of Storage ◽  
Hybrid Seeds ◽  
Significant Production

Aim. It is well known that the sugar beet seed during the period of storage perish or are unfitted for seeding. A lot of scientists have studied the various seed storage technologies. It was found out, that seeds with a high germinating ability, under the favorable weather conditions, stay responsible for seeding for 5–7 years. Methods. Calibrated and uncalibrated components of hybrid seed of Ukrainian ChS 72 and its hybrid seed (F1) of different storable lift (2006 crop) – the starting material for the research. The method of randomized blocks was used for placing sections according to the standard practice. Results. Upon storage and sowing uncalibrated seeds the significant production loss is observed. The seeds of CMS component and O-type are the most sensitive, the seeds of polyspermic male parent and hybrid seeds are less sensitive. It was found out that, productive properties of calibrated seeds, specifically yield capacity and sugariness, vary with shelf life. A significant difference in yield indices, depending on the size of the seed is not determined. As to the sugariness of root crop, the specified modifications are observed, depending upon seed fraction and its shelf life, but substantial and regular decline of this index is not determined. Conclusions. In the course of the research, it was found out and proved, that the duration of storage of uncalibrated seeds the significant production loss of sugar beet is observed. Therefore, in seed breeding practice it is advisable to brood the seeds calibrated and plotted out on fractions. Keywords: sugar beets, fractions, sugariness, yield, shelf life, calibrated seeds, hybrid seeds.

Characterization of glycosidases produced by Pseudomonas fluorescens 261

1983 ◽  
Vol 46 (8) ◽  
pp. 676-680 ◽  
Author(s):  
A. MARIN ◽  
R. T. MARSHALL
Keyword(s):  
Pseudomonas Fluorescens ◽  
Activation Energies ◽  
Arrhenius Behavior ◽  
Minimal Growth ◽  
A Cell ◽  
Cell Free Filtrate

Six synthetic glycosides were used to characterize glycosidic activities of a cell-free filtrate of Pseudomonas fluorescens 26. The filtrate was prepared after growing the bacterium in glucose-enriched minimal growth broth. Temperature and pH optima for glycosidic activity were as follows, respectively, β-D-fucosidase: 15°C and 6.0, β-D-mannosidase: 25°C and 6.0, β-D-glucosidase: 25°C and 5.5, β-D-galactosidase: 30°C and 6.5, N-acetyl-β-D-glucosaminidase: 45°C and 7.0, and N-acetyl-β-D-galactosaminidase: 45°C and 6.0. Activation energies of B-D-galactosidase, β-D-mannosidase, β-D-glucosidase and N-acetyl-β-D-glucosaminidase were 25.4, 12.3, 9.8 and 6.0 Kcal/mol, respectively. β-D-fucosidase and N-acetyl-β-D-galactosaminidase appeared to have non-Arrhenius behavior, so activation energies were not calculated for them. All six glycosidases were heat-sensitive to conditions of pasteurization of milk.

scholarly journals Viscosinamide-producing Pseudomonas fluorescens DR54 exerts a biocontrol effect on Pythium ultimum in sugar beet rhizosphere

2000 ◽  
Vol 33 (2) ◽  
pp. 139-146 ◽  
Author(s):  
Charlotte Thrane ◽  
Tommy Harder Nielsen ◽  
Mette Neiendam Nielsen ◽  
Jan Sørensen ◽  
Stefan Olsson
Keyword(s):  
Sugar Beet ◽  
Pseudomonas Fluorescens ◽  
Pythium Ultimum

scholarly journals Effect of bacterium Pseudomonas fluorescens and low fungicide dose seed treatments on parasite fungus Aphanomyces cochlioides and sugar beet yield and quality

2011 ◽  
Vol 52 (No, 7) ◽  
pp. 314-320
Author(s):  
S. Kristek ◽  
A. Kristek ◽  
V. Guberac ◽  
A. Stanisavljević
Keyword(s):  
Sugar Beet ◽  
Pseudomonas Fluorescens ◽  
Sugar Content ◽  
Sugar Yield ◽  
Soil Types ◽  
Parasitic Fungus ◽  
Root Yield ◽  
Aphanomyces Cochlioides ◽  
Yield And Quality ◽  
Seed Inoculation

Effect of sugar beet seed inoculation with a bacterium Pseudomonas fluorescens and treatment by fungicides Thiram 42-S and Dithane S-60 with and without seed inoculation aiming to control Aphanomyces cochlioides – root decay agent was studied. The trial lasted for three years on two soil types (Mollic Gleysols and Eutric Cambisols). The following parameters of sugar beet yield and quality were investigated: root yield, sugar content, sugar in molasses, sugar yield as well as percentage of the infected and decayed plants as a consequence of parasite fungus infestation. The highest average sugar beet root yield was obtained in the variant of the seed treated with fungicide Thiram 42-S and inoculated with bacterium P. fluorescens (85.15 t/ha). However, there were no statistically significant differences (P < 0.05) between the above-mentioned variant and the one with seed inoculated only with bacterium P. fluorescens (84.63 t/ha). The highest mean sugar content of 16.39% was also accomplished during the three-year investigation in the variant of the inoculated seed treated by fungicide Thiram 42-S. All other variants accomplished statistically very significantly lower values of this parameter. The same variant was characterized by the highest mean sugar yield value (12.79 t/ha) on both soil types. Namely, an average sugar yield of the variants inoculated with bacteria was 11.22 t/ha and by 44.22% higher compared to an average yield of non-inoculated variants. The highest percent of the infected and decayed plants (average value on both soil types in the three year investigation) was reported in the control variant (28.92% infected and 25.00% decayed plants) whereas the lowest one was detected in the variant of the seed inoculated with bacterium P. fluorescens in combination with low dose of fungicide Thiram 42-S (4.70% infected plants and 2.88% decayed plants). An average percent of the infected plants inoculated with bacterium P. fluorescens was 9.13% whereas the aforesaid value of the plants infected with parasitic fungus A. cochlioides in non-inoculated variants was by 146.00% higher being 22.42%.

scholarly journals Suppression of Damping-Off Disease in Host Plants by the Rhizoplane Bacterium Lysobacter sp. Strain SB-K88 Is Linked to Plant Colonization and Antibiosis against Soilborne Peronosporomycetes

2005 ◽  
Vol 71 (7) ◽  
pp. 3786-3796 ◽  
Author(s):  
Md. Tofazzal Islam ◽  
Yasuyuki Hashidoko ◽  
Abhinandan Deora ◽  
Toshiaki Ito ◽  
Satoshi Tahara
Keyword(s):  
Sugar Beet ◽  
Microscopic Analysis ◽  
Inhibitory Effect ◽  
Root Surface ◽  
Plant Colonization ◽  
Damping Off ◽  
Electron Microscopic ◽  
Aphanomyces Cochlioides ◽  
Direct Inhibitory Effect ◽  
A Cell

ABSTRACT We previously demonstrated that xanthobaccin A from the rhizoplane bacterium Lysobacter sp. strain SB-K88 suppresses damping-off disease caused by Pythium sp. in sugar beet. In this study we focused on modes of Lysobacter sp. strain SB-K88 root colonization and antibiosis of the bacterium against Aphanomyces cochlioides, a pathogen of damping-off disease. Scanning electron microscopic analysis of 2-week-old sugar beet seedlings from seeds previously inoculated with SB-K88 revealed dense colonization on the root surfaces and a characteristic perpendicular pattern of Lysobacter colonization possibly generated via development of polar, brush-like fimbriae. In colonized regions a semitransparent film apparently enveloping the root and microcolonies were observed on the root surface. This Lysobacter strain also efficiently colonized the roots of several plants, including spinach, tomato, Arabidopsis thaliana, and Amaranthus gangeticus. Plants grown from both sugar beet and spinach seeds that were previously treated with Lysobacter sp. strain SB-K88 displayed significant resistance to the damping-off disease triggered by A. cochlioides. Interestingly, zoospores of A. cochlioides became immotile within 1 min after exposure to a SB-K88 cell suspension, a cell-free supernatant of SB-K88, or pure xanthobaccin A (MIC, 0.01 μg/ml). In all cases, lysis followed within 30 min in the presence of the inhibiting factor(s). Our data indicate that Lysobacter sp. strain SB-K88 has a direct inhibitory effect on A. cochlioides, suppressing damping-off disease. Furthermore, this inhibitory effect of Lysobacter sp. strain SB-K88 is likely due to a combination of antibiosis and characteristic biofilm formation at the rhizoplane of the host plant.

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