antibiotic production by rhizobacteria
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Researcheres:
Abolfazl Moghadam,Shirin Amirtiemoori
Instructor:
Dr.Rokhbakhsh
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Rhizosphere : the rhizospher is the volume of soil surrounding and under the influence of plant roots, and the rhizoplane is the plant root surfaces and strongly adhering soil particles ( Kennedy,2005)
Rhizobacteria : Rhizobacteria are rhizospher competent bacteria that aggressively colonize plant roots ; they are able to multiply and colonize all the ecological niches found on the root at all stages of plant growth , in the presense of a competing microflora ( Antoun and Kloepper , 2001)
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Neutral bacteria
Pathogenic bacteria
Beneficial bacteria ( PGPR )Suslow, Kloepper, Schroth, Burr, 1979.
Figure 1 Nodules of bacteria soybean root4
PGPR (Plant growth promoting rhizobacteria) A group of bacteria that can actively colonize
plant roots and improve plant grows and yield by direct and indirect mechanisms (Noel et al.,1996)
(B )Legume root with nodules induced by B.japonicum
(A )Soybean plant infected
with Bradyrhizobium japonicim left,
uninfected control plant )right(.
Figure 2 5
Effective Two strain of PGPR icluding B.subtilis GB03 , B.amyloliquefaciens IN937a & the nongrowth-promotin strain E.coli DH5α on growth of A.thaliana.
(MS medium)
DH5α
Refrence ; chhong-min Ryu,mohamed A.Farag,…,2003.,Bacteria volatiles promote growth in Arabidopsis
Figure 3 Figure 4
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These mechanisms Plays a vital role in the management of plant diseases to increase crop productivity via various mechanisms .
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cycle Figure 4 N2 Fixation
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Using growth medium with Tricalcium phosphate (NBRIP). Bacterial mechanisms: phosphatase enzymes or production of
acids
No solubilizationSolubilization of P
Figure 5 Figure 6
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Figure 7 Siderophore10
Figure 8 type of phytohormone produced by PGPR
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Antibiotic encompass a chemically heterogeneous group of organic,low-molecular weight compounds produced by microorganisms at low concentrations that are deleterious to the growth of metabolic activities of other microorganisms (Fravel,1988;Thomashow et al.,1997).
Antibiotics produced by different PGPR have a broad-spectrum activity.
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PGPRDetailes
AcinetobacterGram-negative bacilli
Agrobacterium
Gram-negative bacilli
ArthrobacterGram-positive , rods during exponential growth and cocci in their stationary phase.
AzospirillumGram-negative bacilli
BacillusGram-Positive , rod-shaped
Bradyrhizobium
Gram-negative bacilli
Frankiafilamentous bacteria Gram-Positive,
PseudomonasGram-negative bacilli
RhizobiumGram-negative bacilli
SerratiaGram-negative , rod-shaped
ThiobacillusGram-negative , rod-shaped 13
PGPRAntibioti
cstructureFungusDisease
Reference
P.fluorescens
PhenazinesGaeumannomyces
graminis var.tritici
Strains of P.fluorescens may be involved in the
suppression of G.graminis var. tritici.
Raaijmakers & Weller ,
2000
P.fluorescensPyoluteorinPythium sp.
In pythium contaminated sites, and signficant
increases were observed in plant height,number of heads and grain yield of
winter wheat.
Weller and Cook,1986
P.fluorescens
2,4-Diacetyl phloroglucin
olRhizoctonia
solani
Out of 40 strains, 18 strains showed strong
antifungal activity.
Kumar et al.,2002
Figure 9
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One of the most effective mechanisms that PGPR employ to prevent proliferation of phytopathogens is the systhesis of antibiotic.
some well know PGPR strains are pseudomonas,Bacillus, Azospirillum,Rhizobium,and serratia species.the primary mechanism of biocontrol by PGPR involves the production of antibiotics such as phenazine-1-carboxyclic acid, 2,4-diacetyl phloroglucinol, oomycin, pyoluteorin, pyrrolnitrin, kanosamine, zwittermycin-A, and pantocin.
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AntibioticsPGPRPathogenCropReference
DAPGPseudomonas sp.
Pythium ultimum
sugarShanahan et al.(1992b)
Aerugine P,fluorescens
PhytophthorC.orbiculare
PepperCucumber
Lee et al.(2003)Lee et at.(2003)
Phenazine Pseudomonas sp.
Fusarium oxysporwn
tomatoChin-A-Woeng et al.(1998)
PCAP.fluorescens
G.g.Var.tritici
WheatThomashow and
Weller(1988)
PyrrolnitrinBurkholderia cepacia
Fusarium sambucinu
m
PotatoBurkhead et al.(1994)
Viscosinam ide
P.Fluorescens
RhizoctoniaSolani
Pythium ultimum
Sugarbeet
Nielsen et al.(1998)
PyoluteorinP.fluorescens
Pythium sppPythium spp
CottonSugarbeet
Howell and Stipanovic(19
80)
Gaeumannomyces graminis Var. tritici16
Primary site of Action pyrrolnitrin is terminal electron transport system.
Refrence : R. K. TRIPATHI AND DAVID GOTTLIEB , July 1969, Mechanism of Action of the Antifungal Antibiotic Pyrrolnitrin
Figure 10 Mechanism of Antibiotic Pyrrolnitrin
Figure 11Structure of pyrrolnitrin
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Refrence: Latifi, A. M., Winson, K., Foglino, M., Bycroft, B. W., Stewart, G. S. A. B., Lazdunski, A. and Williams, P., Multiple homologues of LuxR and LuxI control expression of virulence determinants and secondary metabolites through quorum sensing in Pseudomonas aeruginosa PA01. Mol. Microbiol., 1995, 17, 333–343.
Figure 11 Mechanism of action of Antibiotic Phenazines
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Biofertilizer : living organism which increase the nutrient status of the host plant through their on-going existence in associantion with the plant.( J. Kevin Vessey, 2003)
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Puts acid in the soil Strengthens pestecides(they become stronger and more
resistant to chemicals that should keep them away) It has very little carbon which is a key element in plants Chemical fertilizer also get a lot of water out of the soil
which it contaminated and therfor pollute water It degrades ecosytems It releases a green house gas called nitrous oxide
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Increase soil fertilityProduct increased to 20-30%Stimulate plant growthStimulate soil biological activityProtection against dryness and some
pathogenic factors of soilCoping with NatureReduce costs chemical fertilizers, especially
nitrogen and phosphorus fertilizer.Improve soil structure
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Figure 12 difference effect chemical fertilizer with biofertilizer in plant growth23
Bacterial biofertilizer (Azospirillum ,
…)
Fungi biofertilizer ( Mycorhiza,…)
Algae biofertilizer ( blue-green algae,
….)
Actinomycets (frankia,…)
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Pseudomonas fluorescence bacteria effectively control wilts and root rot diseases of Groundnut, Cotton, Banana, Soybean, Tomato, Pigeon pea etc., It also controls the rice blast and sheath blight of Paddy. This bacterium enters the plant system and act as a systemic biocontrol agent against diseases.
Suitable for: It is suitable for all kinds of Crops. Mode of action: By secreting an enzyme, it has the capability to destroy the cell wall of the
fungal pathogens and annihilate them. It secrets Hydrogen cyanide and antibiotics such as Pycocyanin and
Phenazine, which inhibit the growth of disease causing pathogens. Advantage: It also produces Siderospores which chelate with iron in the soil, and make
it difficult for the pathogens to proliferate. Further, it secretes several plant growth substances, and these
gibberellins like compounds contribute to vigorous crop growth.
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Bacillus subtilis is an antagonistic bacterial Biocontrol agent, which controls many soil and air borne diseases of Paddy, Groundnut, Cotton, Vegetables, Soybean etc., Foliar application of Bacillus subtilis with Pseudomonas fluorescence control leaf diseases of many crops.
Suitable for: Paddy, Millets, Oilseeds, Fruits & Vegetables, Sugarcane, Banana, Coconut, Oil palm, Cotton, Chilly, Lime, Coffee & Tea, Areca nut & Rubber, Flower, Spices, & Contiments, Herbs, Lawns & Ornaments, trees etc.
Mode of action: The bacterium colonizes the developing leaf & root system of the plant and thus
competes with & thereby suppresses plant diseases. Advantage: The Plant Growth Promoting Rhizobacteria (PGPR) having an antagonistic
interaction with various soil borne plant pathogens. It protects plants against seed and root diseases.
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PGPR are indigenouse to soil and plant rhizosphere that improve plant growth and yeild.
one of the important applications of PGPR to use in biological combating with pathogenic agents.
Some of important PGPR Rhizobacteria is Pseudomonas , Bacillus , Rhizobium ,
Azospirilium and … Important Antibiotic produced by PGPR include Pyrrolnitrin , Phenanzine , 2,4-
Diacetyl phloroglucinol , oomycin and… That PGPR have important role in biocontrol of plant pathogens and are used in biofertilizers .
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