Fluctuations in the fluorescent pseudomonad and actinomycete populations of rhizosphere and rhizoplane during the growth of spring wheat

1990 ◽  
Vol 36 (4) ◽  
pp. 254-258 ◽  
Author(s):  
H. J. Miller ◽  
E. Liljeroth ◽  
G. Henken ◽  
J. A. van Veen
Keyword(s):  
Agar Medium ◽  
Fluorescent Pseudomonads ◽  
Rapid Decline ◽  
Fluorescent Pseudomonad ◽  
Wheat Line ◽  
Bacterial Populations ◽  
Nutrient Agar Medium ◽  
Colony Forming Units ◽  
Survival Studies ◽  
Wheat Lines

The total bacterial populations, fluorescent pseudomonads, and actinomycetes in the rhizosphere, rhizoplane, and endorhizosphere of two wheat lines (C-R5B and C-R5D) were investigated weekly during plant growth. The total numbers of bacteria (colony-forming units) were counted on a low-nutrient agar medium, while the numbers of fluorescent pseudomonads and actinomycetes were determined by means of selective media. Fluorescent pseudomonads generally constituted less than 0.5% of the total bacterial numbers and the percentage significantly decreased with time in the rhizosphere, rhizoplane, and root-free soil. The percentages of fluorescent pseudomonads were lower in the rhizoplane than in the rhizosphere, and in the endorhizosphere they were barely detectable. The rapid decline of fluorescent pseudomonads frequently observed in survival studies may be explained by the inability of the plant to support this group of bacteria during later development of its rhizosphere. Actinomycetes generally represented no more than 7% of the total bacterial numbers. Actinomycete percentages were highest in the rhizosphere and root-free soil and lowest in the endorhizosphere. Only minor differences were found in total bacterial numbers and in the numbers of fluorescent pseudomonads between the two wheat lines. However, numbers of actinomycetes were significantly different over the whole experiment between wheat line C-R5B and C-R5D in the rhizosphere, rhizoplane, and endorhizosphere. Key words: actinomycetes, bacteria, fluorescent pseudomonads, rhizosphere, sampling time.

A method for assessing the root-colonizing capacity of bacteria on maize

1984 ◽  
Vol 30 (2) ◽  
pp. 151-157 ◽  
Author(s):  
F. M. Scher ◽  
J. S. Ziegle ◽  
J. W. Kloepper
Keyword(s):  
Seed Treatment ◽  
Root Colonization ◽  
Substantial Effect ◽  
Test Tube ◽  
Fluorescent Pseudomonad ◽  
Bacterial Strains ◽  
Sand Soil ◽  
Bacterial Populations ◽  
Colony Forming Units ◽  
Maize Roots

A closed test tube assay was developed for measuring the root colonization capacity of bacteria in raw soil–sand. Bacteria were coated onto seeds at inoculum levels of 103 – 109 colony-forming units (cfu) per seed, and root-colonizing bacterial strains successfully grew along the emerging radicle. Quantification of specific bacterial populations on roots was highly reproducible between experiments with the assay. Of 54 strains tested, 24 colonized roots at populations of 104 to 106 cfu/g root. All root-colonizing strains were Gram negative. Two fluorescent pseudomonad strains that failed to colonize maize roots in raw soil did colonize in autoclaved soil. Captan seed treatment and temperature of incubation (14 and 24 °C) had no substantial effect on subsequent root colonization. Root population densities determined in the sand–soil assay were comparable with those determined with plants grown in soils under greenhouse conditions.

Screening of Fluorescent Pseudomonad Isolates Against Sclerotium Rolfsii Sacc., of Soybean (Glycine Max)

2019 ◽  
Author(s):  
Priyanka . ◽  
Geeta. Goudar
Keyword(s):  
Rhizosphere Soil ◽  
Agar Medium ◽  
Uv Light ◽  
Functional Characterization ◽  
Sclerotium Rolfsii ◽  
Antagonistic Activity ◽  
Fluorescent Pseudomonads ◽  
Fluorescent Pseudomonad ◽  
Clear Zone ◽  
Culture Experiment

An attempt was made to isolate and characterize Fluorescent pseudomonads from the rhizosphere soil samples and further screening of the isolates for their antagonistic properties against Sclerotium rolfsii Sacc., of soybean. The isolates were subjected for morphological, biochemical and functional characterization. All the isolates exhibited fluorescence under UV light. Cells were rods and gram negative. All the isolates produced clear zone of P- solubilization (TCP) (18.80-21.71mm diameter) on Pikovskaya’s agar medium. The fluorescent pseudomonads produced significantly varying quantities of IAA (19.97 mg to 28.89 mg IAA/25 ml of broth) and GA (18.52 µg per 25 ml broth). All the isolates showed antagonistic activity against Sclerotium rolfsii. The per cent inhibition ranged from 36.85 to 70.37. Under pot culture experiment, lowest PDI was observed in DFP48 followed by DFP47, among the FP isolates. These isolates also showed maximum peroxidase activity and also plant growth promotional activities.

Effect of nitrogen supply on rhizosphere interactions and take-all disease of wheat

1991 ◽  
Vol 37 (1) ◽  
pp. 42-51 ◽  
Author(s):  
M. E. Leggett ◽  
K. Sivasithamparam ◽  
M. J. McFarlane
Keyword(s):  
Nitrogen Deficiency ◽  
Gaeumannomyces Graminis ◽  
Fluorescent Pseudomonads ◽  
Root Weight ◽  
Fluorescent Pseudomonad ◽  
Fresh Weight ◽  
Colony Forming Units ◽  
Rhizosphere Interactions ◽  
Shoot Weight ◽  
Take All

The effect of NH4NO3 on the expression of take-all in wheat and on the ability of fluorescent pseudomonad bacteria to decrease the growth of the pathogen and the symptoms of the disease was examined in a nitrogen-deficient acidic soil from Western Australia. Application of NH4NO3 increased the fresh weight of shoots, decreased root weight and length, and offset some of the deleterious effects of infection. Inoculation with Gaeumannomyces graminis var. triciti reduced shoot weight and root weight and length at all but the highest level of applied nitrogen. Fluorescent pseudomonads applied to wheat seed (at approximately 108 colony-forming units/seed) reduced seed germination and failed to reduce the severity of take-all expressed as weight or length of shoots or N content. Although the density of black runner hyphae of G. graminis var. triciti was reduced at 40 days and the proportion of root colonized by the pathogen was lower at 28 days with bacterization under severe nitrogen deficiency, no effect of the bacteria was observed if N was added. Key words: Gaeumannomyces graminis var. triciti, fluorescent pseudomonads, wheat, nitrogen.

Inhibition of Salmonella typhimurium on Agar Medium and Poultry Skin by Ultraviolet Energy

1996 ◽  
Vol 59 (3) ◽  
pp. 319-321 ◽  
Author(s):  
SUSAN S. SUMNER ◽  
EVA A. WALLNER-PENDLETON ◽  
GLENN W. FRONING ◽  
LA VERNE E. STETSON
Keyword(s):  
Ultraviolet Radiation ◽  
Salmonella Typhimurium ◽  
Agar Medium ◽  
Uv Light ◽  
Light Treatment ◽  
Complete Elimination ◽  
Bacterial Reduction ◽  
Colony Forming Units ◽  
Ultraviolet Energy ◽  
Different Doses

Ultraviolet radiation (UV) was effective in destroying Salmonella typhimurium on agar plates and poultry skin. Agar plates inoculated with varying numbers of colony-forming units (CFU) of S. typhimurium (1.2 × 102 to 1.7 × 109) were subjected to different doses of UV light to determine optimal killing. Poultry skin was also inoculated with varying CFU of S. typhimurium per 2 cm2 of skin and subjected to UV light. UV light treatment of inoculated agar plates revealed almost complete elimination (99.9%) of S. typhimurium at 2,000 μW · s · cm−2. Bacterial reduction was less effective on the surface of poultry skin when a 80.5% reduction in S. typhimurium was obtained at 2,000 μW · s · cm−2.

scholarly journals Association of Alcaligenes Faecalis Strain in Juvenile Earthworms, from Cocoons of Eudrilus Eugeniae

2019 ◽  
Vol 9 (2S2) ◽  
pp. 688-692
Keyword(s):  
16S Rrna ◽  
Gene Sequence ◽  
Agar Medium ◽  
Alcaligenes Faecalis ◽  
Rrna Gene ◽  
Eudrilus Eugeniae ◽  
Zone Of Inhibition ◽  
Chain Reaction ◽  
Nutrient Agar Medium ◽  
Polymerase Chain

Cocoons of earthworm Eudrilus eugeniae were collected from vermiculture bed and found that it had antibacterial activity. The size of zone of inhibition was directly proportional to the size of cocoons examined. Along with nutritious fluid and embryos, culturable bacterial community was found inside the cocoons. Bacterial colonies were isolated from the trails of newly hatched, juvenile worms in the nutrient agar medium and examined. Gram negative, rod shaped bacterium was found to be abundant in the trails of juvenile earthworms. Polymerase chain reaction was performed from this bacterium to amplify the gene of 16S rRNA and analyzed. Subsequent bi-directional DNA sequencing revealed that this abundant bacterium is highly related to 16S rRNA gene sequence of a strain, Alcaligenes faecalis. Based on available literature, we hypothesize that this bacterium could be symbiotically associated with cocoons of earthworms.

Comparison of a simple butterfat agar medium with other media used for isolation and enumeration of lipolytic bacteria from dairy products

1987 ◽  
Vol 54 (3) ◽  
pp. 413-420 ◽  
Author(s):  
Arthur W. Shelley ◽  
Hilton C. Deeth ◽  
Ian C. MacRae
Keyword(s):  
Melting Point ◽  
Bacterial Growth ◽  
Dairy Products ◽  
Agar Medium ◽  
Nutrient Agar ◽  
Nutrient Agar Medium

SummaryA nutrient agar medium containing 0·1 % of a low melting point fraction of butterfat was shown to be suitable for detection, enumeration and isolation of lipolytic bacteria from milk. Bacterial growth was not inhibited by the butterfat and lipolytic reactions were clearly visible and easily interpreted. Lipolytic counts on the butterfat agar compared favourably with lipolytic counts obtained with other commonly used media.

Molecular and Metabolic Typing of Resident and Transient Fluorescent Pseudomonad Flora from a Meat Mincer

1997 ◽  
Vol 60 (12) ◽  
pp. 1515-1519 ◽  
Author(s):  
CHRIS W. MICHIELS ◽  
MIA SCHELLEKENS ◽  
CARINE C. F. SOONTJENS ◽  
KRISTEL J. A. HAUBEN
Keyword(s):  
Carbon Sources ◽  
Fluorescent Pseudomonads ◽  
Fluorescent Pseudomonad ◽  
Raw Meat ◽  
Homogeneous Cluster ◽  
Predominant Type ◽  
Biolog System ◽  
Working Day ◽  
Endemic Flora ◽  
Cleaning And Disinfection

Nine spots on a meat mincer in a large catering facility were sampled four times over a three-month period after routine cleaning and disinfection. Spot 2 carried a significantly higher average microbial load than the other spots and was the only spot with a persistent population of fluorescent pseudomonads. The predominant type of fluorescent pseudomonads produced a yellow diffusible pigment and were always found in turkey meat. Since turkey was also the last type of meat minced on each working day, it was considered the likely source of these bacteria on the mincer. Sixty-three yellow-fluorescing pseudomonad strains from un-minced turkey and 17 strains from mincer spot 2 after mincing, cleaning, and disinfection were subjected to fingerprint analysis by random amplification of polymorphic DNA (RAPD) and by analysis of the assimilation patterns of 95 carbon sources using the Biolog system. Cluster analysis of the RAPD and the metabolic fingerprints revealed that all the mincer strains formed a homogeneous cluster, exclusive of all the turkey strains which displayed a higher degree of heterogeneity. Six strains isolated 1 week earlier and six strains isolated 11 weeks earlier from spot 2 were also subjected to RAPD analysis. Their fingerprints fell within the existing cluster of 17 spot 2 strains. These results suggest the existence on mincer spot 2 of an endemic flora of fluorescent pseudomonads, probably in the form of a biofilm. The genetic and physiological homogeneity of this flora, as opposed to the heterogeneity of the raw meat flora, indicates that only a fraction of the raw meat population of P. fiuorescens is successful in forming biofilm in this environment.

Microbiological and Sensory Attributes of Retail Cuts of Beef Treated with Acetic and Lactic Acid Solutions

1994 ◽  
Vol 57 (8) ◽  
pp. 665-670 ◽  
Author(s):  
KATHRYN L. KOTULA ◽  
RAVINDRANATH THELAPPURATE
Keyword(s):  
Lactic Acid ◽  
Acid Treatment ◽  
Inhibitory Effect ◽  
Practical Significance ◽  
Bacterial Populations ◽  
E Coli ◽  
Microbial Inhibition ◽  
Colony Forming Units ◽  
Sensory Qualities ◽  
Retail Cuts

This research characterized the effect of 0.6 and 1.2% acetic and lactic acids applied for 20 and 120 s at a temperature of 1 to 2°C on total colony forming units (CFU) and Escherichia coli counts, and sensory qualities including shear value, expressible moisture, color and sensory panel of retail cuts of beef rib steaks. Microbial inhibition was directly proportional to the concentration and times of treatment with a 1.2% acid treatment for 120 s being the most effective treatment for reducing microbial counts, for both acids. Although there were significant reductions (p <0.05) in bacterial populations, these reductions which had a maximum of 2.0 log, were of questionable practical significance. The inhibitory effect of the acids decreased with storage time, up to 9 days. Treatment with both the acids resulted in paler meat (p <0.05) than the non-treated control. There were no significant differences (p >0.05) in shear values or expressible moisture due to acid treatment. Sensory panels reported only small differences between the samples. These results indicate that an aqueous acetic or lactic acid treatment of retail beef reduced total CFU and E. coli numbers immediately after treatment, but the magnitude was less than 1 log. However, a residual influence was observed so that after 3 and 9 days both acid treatments inhibited total CPU and E. coli growth by up to 2 logs compared with the non-treated control samples.

Enumeration of Polyhydroxyalkanoate (PHA) Producing Bacteria from Dairy Sewage Samples

2019 ◽  
pp. 1-4
Author(s):  
K. Shivalkar Yadav ◽  
D. B. Puranik ◽  
Mohamed Nadeem Fairoze ◽  
R. Prabha
Keyword(s):  
Agar Medium ◽  
Synthetic Polymers ◽  
Synthetic Polymer ◽  
Serial Dilution ◽  
Nutrient Agar ◽  
Sewage Sample ◽  
Bacterial Strains ◽  
Nutrient Agar Medium ◽  
Contemporary Life ◽  
Soil And Water

Aims: The synthetic polymer plastics have become an integral part of contemporary life. Excess use of plastics and indiscriminate dumping of it in soil and water is polluting the environment. In order to overcome this problem, the production and applications of eco-friendly biodegradable products from microbes are becoming inevitable from the last decade and also are the good alternatives for synthetic polymers. Methods and Results: Polyhydroxyalkanoate producing bacterial strains were confirmed by serial dilution of sewage samples from dairies and pour plating using modified nutrient agar medium with 2% glucose and 0.3% sudan black. Commercial dairy sewage sample from III Dairy showed highest count of PHA producers (3.80 log10cfu/ml) followed by II Dairy (3.68 log10cfu/ml) and I Dairy (3.35 log10cfu/ml). On an average, 70 per cent were PHA producers among TBC of sewage samples. Conclusion: Dairy sewage sample from III Dairy showed highest count of PHA producers (3.80log10cfu/ml) Significance and Impact of the Study: This study provides importance of polyhydroxyalkanoates and their role against synthetic plastic by enumerating the polyhydroxyalkanoate (PHA) producing bacteria from Dairy sewage samples that can be effectively utilized for the synthesis of bioplastics.

Fluorescent pseudomonad population sizes baited from soils under pure birch, pure Douglas-fir, and mixed forest stands and their antagonism towardArmillaria ostoyaein vitro

2002 ◽  
Vol 32 (12) ◽  
pp. 2146-2159 ◽  
Author(s):  
R L DeLong ◽  
Kathy J Lewis ◽  
Suzanne W Simard ◽  
Susan Gibson
Keyword(s):  
Douglas Fir ◽  
Fluorescent Pseudomonads ◽  
Dual Culture ◽  
Fluorescent Pseudomonad ◽  
Percent Cover ◽  
Forest Stands ◽  
Mixed Stands ◽  
Relative Population ◽  
Population Sizes ◽  
Paper Birch

The relationship between forest stand composition in southern interior British Columbia and fluorescent pseudomonad bacteria populations was investigated using seedling bioassays. The objectives of this study were to (i) compare the relative population sizes of fluorescent pseudomonads baited from soils in pure paper birch (Betula papyrifera Marsh.), pure Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), and mixed stands of the two species and (ii) determine if fluorescent pseudomonads from these soils have inhibitory effects against the root pathogen Armillaria ostoyae (Romagn.) Herink in vitro. Soil from birch stands supported four times more pseudomonads on seedling baits than soil from Douglas-fir stands, with the mixed stands intermediate. Soil from young stands yielded twice as many rhizosphere pseudomonads as soil from mature stands. Pseudomonad population size was positively correlated with percent cover and density of birch, and negatively correlated with basal area of Douglas-fir, percent cover of Douglas-fir, and carbon/nitrogen ratio of the soil. Greater than 50% of the fluorescent isolates reduced radial growth of A. ostoyae by more than 20% and greater than 90% reduced biomass of the fungus in dual culture tests. Cell-free bacterial culture filtrates added to the growth medium also reduced growth of A. ostoyae. This study provides evidence that paper birch provides a more favorable environment for fluorescent pseudomonads than Douglas-fir and suggests a mechanism by which paper birch can positively influence the susceptibility of managed forest stands to Armillaria root disease.

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