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.

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.

scholarly journals Distribution of Growth-Inhibiting Bacteria against the Toxic Dinoflagellate Alexandrium catenella (Group I) in Akkeshi-Ko Estuary and Akkeshi Bay, Hokkaido, Japan

2020 ◽  
Vol 11 (1) ◽  
pp. 172
Author(s):  
Yuka Onishi ◽  
Akihiro Tuji ◽  
Atsushi Yamaguchi ◽  
Ichiro Imai
Keyword(s):  
Surface Waters ◽  
Seagrass Bed ◽  
Bacterial Strains ◽  
Toxic Dinoflagellate ◽  
Sequence Analyses ◽  
Alexandrium Catenella ◽  
Group I ◽  
Colony Forming Units ◽  
Rrna Sequences ◽  
Growth Inhibiting

The distribution of growth-inhibiting bacteria (GIB) against the toxic dinoflagellate Alexandrium catenella (Group I) was investigated targeting seagrass leaves and surface waters at the seagrass bed of Akkeshi-ko Estuary and surface waters of nearshore and offshore points of Akkeshi Bay, Japan. Weekly samplings were conducted from April to June in 2011. GIBs were detected from surface of leaves of the seagrass Zostera marina in Akkeshi-ko Estuary (7.5 × 105–4.7 × 106 colony-forming units: CFU g−1 wet leaf) and seawater at the stations in Akkeshi Bay (6.7 × 100–1.1 × 103 CFU mL−1). Sequence analyses revealed that the same bacterial strains with the same 16S rRNA sequences were isolated from the surface biofilm of Z. marina and the seawater in the Akkeshi Bay. We therefore strongly suggested that seagrass beds are the source of algicidal and growth-inhibiting bacteria in coastal ecosystems. Cells of A.catenella were not detected from seawaters in Akkeshi-ko Estuary and the coastal point of Akkeshi Bay, but frequently detected at the offshore point of Akkeshi Bay. It is suggested that A.catenella populations were suppressed by abundant GIBs derived from the seagrass bed, leading to the less toxin contamination of bivalves in Akkeshi-ko Estuary.

scholarly journals PaReBrick: PArallel REarrangements and BReaks identification toolkit

2021 ◽  
Author(s):  
Alexey Zabelkin ◽  
Yulia Yakovleva ◽  
Olga Bochkareva ◽  
Nikita Alexeev
Keyword(s):  
Antigenic Variation ◽  
Phenotypic Diversity ◽  
Genome Rearrangements ◽  
Supplementary Information ◽  
High Plasticity ◽  
Bacterial Strains ◽  
Bacterial Genomes ◽  
Phyletic Pattern ◽  
Bacterial Populations ◽  
Different Strains

Abstract Motivation High plasticity of bacterial genomes is provided by numerous mechanisms including horizontal gene transfer and recombination via numerous flanking repeats. Genome rearrangements such as inversions, deletions, insertions, and duplications may independently occur in different strains, providing parallel adaptation or phenotypic diversity. Specifically, such rearrangements might be responsible for virulence, antibiotic resistance, and antigenic variation. However, identification of such events requires laborious manual inspection and verification of phyletic pattern consistency. Results Here we define the term “parallel rearrangements” as events that occur independently in phylogenetically distant bacterial strains and present a formalization of the problem of parallel rearrangements calling. We implement an algorithmic solution for the identification of parallel rearrangements in bacterial populations as a tool PaReBrick. The tool takes a collection of strains represented as a sequence of oriented synteny blocks and a phylogenetic tree as input data. It identifies rearrangements, tests them for consistency with a tree, and sorts the events by their parallelism score. The tool provides diagrams of the neighbors for each block of interest, allowing the detection of horizontally transferred blocks or their extra copies and the inversions in which copied blocks are involved.We demonstrated PaReBrick’s efficiency and accuracy and showed its potential to detect genome rearrangements responsible for pathogenicity and adaptation in bacterial genomes. Availability PaReBrick is written in Python and is available on GitHub https://github.com/ctlab/parallelrearrangements Supplementary information Supplementary data are available at Bioinformatics online.

Connecting Microbial Population Genetics with Microbial Pathogenesis Engineering Microfluidic Cell Arrays for High-throughput Interrogation of Host-Pathogen Interaction

2011 ◽  
pp. 533-548
Author(s):  
Palaniappan Sethu ◽  
Kalyani Putty ◽  
Yongsheng Lian ◽  
Awdhesh Kalia
Keyword(s):  
High Throughput ◽  
Bacterial Species ◽  
Human Cells ◽  
Bacterial Strains ◽  
Cell Array ◽  
Bacterial Populations ◽  
Host Pathogen Interaction ◽  
Gradient Generator ◽  
Molecular Events ◽  
Host Pathogen

A bacterial species typically includes heterogeneous collections of genetically diverse isolates. How genetic diversity within bacterial populations influences the clinical outcome of infection remains mostly indeterminate. In part, this is due to a lack of technologies that can enable contemporaneous systems-level interrogation of host-pathogen interaction using multiple, genetically diverse bacterial strains. This chapter presents a prototype microfluidic cell array (MCA) that allows simultaneous elucidation of molecular events during infection of human cells in a semi-automated fashion. It shows that infection of human cells with up to sixteen genetically diverse bacterial isolates can be studied simultaneously. The versatility of MCAs is enhanced by incorporation of a gradient generator that allows interrogation of host-pathogen interaction under four different concentrations of any given environmental variable at the same time. Availability of high throughput MCAs should foster studies that can determine how differences in bacterial gene pools and concentration-dependent environmental variables affect the outcome of host-pathogen interaction.

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.

Effects of glyphosate on Fusarium spp.: its influence on root colonization of weeds, propagule density in the soil, and crop emergence

1987 ◽  
Vol 33 (5) ◽  
pp. 354-360 ◽  
Author(s):  
C. André Lévesque ◽  
James E. Rahe ◽  
David M. Eaves
Keyword(s):  
Root Colonization ◽  
Plantago Lanceolata ◽  
Chenopodium Album ◽  
Holcus Lanatus ◽  
Fusarium Spp ◽  
Stellaria Media ◽  
Perennial Weeds ◽  
Colony Forming Units ◽  
Annual Weeds ◽  
Polygonum Persicaria

Glyphosate is a broad spectrum herbicide that can lead to root rot like damage on crops. This study was undertaken to investigate the effect of glyphosate on the root-colonizing Fusarium spp. The research was conducted at two sites. Site one was densely covered with perennial weeds, and site two with annuals. At site one, spraying the weed cover with glyphosate increased (p < 0.05) the level of colonization by Fusarium spp. in Ranunculus repens and Holcus lanatus, but not in Stellaria media and Plantago lanceolata. At site two, glyphosate enhanced colonization in Spergula arvensis, Stellaria media, Echinochloa crusgalli, and Chenopodium album, but not in Capsella bursa-pastoris and Polygonum persicaria. At both sites, the number of colony-forming units of Fusarium spp. per gram of dried soil was increased by the application of glyphosate. Nevertheless, crops subsequently sown in the field containing the annual weeds were not detrimentally affected by glyphosate treatment of these weeds.

Comparative analysis of five methods for recovering rhizobacteria from cotton roots

1991 ◽  
Vol 37 (12) ◽  
pp. 953-957 ◽  
Author(s):  
Joseph W. Kloepper ◽  
Walter F. Mahaffee ◽  
John A. McInroy ◽  
Paul A. Backman
Keyword(s):  
Bacillus Subtilis ◽  
Pseudomonas Fluorescens ◽  
Standard Error ◽  
Root Colonization ◽  
Glass Beads ◽  
Standard Errors ◽  
Subtilis Strain ◽  
Bacterial Populations ◽  
Recovery Method ◽  
Cotton Seeds

A variety of methods have been used for recovering introduced bacteria from plant roots. The objective of this study was to compare systematically five methods: agitation in buffer, agitation with glass beads in buffer, mixing in a StomacherR lab-blender, sonication, and trituration with mortar and pestle. Cotton seeds were treated with two previously reported rhizobacterial strains, Pseudomonas fluorescens strain Pf-5 and Bacillus subtilis strain GB03. The efficiency of recovery by each method was determined 3 weeks later by comparing average bacterial populations from whole root systems, single 2.0-cm root segments, and two root regions (the uppermost 5 cm of taproot and the lowermost 5 cm). Treatment with the StomacherR blender yielded significantly higher (P = 0.05) mean populations of GB03 compared with all other methods and significantly higher mean populations of Pf-5 compared with agitation with glass beads. From the lowermost 5 cm of taproot, populations of Pf-5 recovered by the StomacherR treatment were significantly higher than all other methods. The inclusion of glass beads for agitation treatments resulted in neither consistently higher absolute numbers of recovered bacteria nor reductions in variability. The mean standard error of each recovery method varied among root sources, and no single method consistently had the highest or lowest mean standard error. Mean standard errors for strain GB03 were generally lower than those for Pf-5 with each root source and each method of recovery. When viewed in composite, the data suggest that the StomacherR treatment was the best for recovering the greatest absolute numbers of rhizobacteria; however, this treatment had high mean standard errors. Investigations of root colonization by introduced rhizobacteria should include several recovery methods to optimize recovered numbers or to decrease variability, depending on the experimental objectives. Key words: root colonization, rhizobacteria, Pseudomonas fluorescens, Bacillus subtilis, cotton.

scholarly journals Crab Apple Blossoms as a Model for Research on Biological Control of Fire Blight

1997 ◽  
Vol 87 (11) ◽  
pp. 1096-1102 ◽  
Author(s):  
P. L. Pusey
Keyword(s):  
Fire Blight ◽  
Biocontrol Agents ◽  
Suitable Model ◽  
Bacterial Strains ◽  
Bacterial Populations ◽  
Cold Room ◽  
Series Of Experiments ◽  
Population Interactions ◽  
Intact Crab ◽  
Crab Apple

Nonseasonal availability of pomaceous flowers could improve laboratory detection and prefield testing of biocontrol agents for fire blight of pear and apple. Crab apple was selected as a model because of its high flower productivity on 1-year-old wood, high susceptibility to fire blight, and availability from nurseries. Cultivars Manchurian and Snowdrift were manipulated to bloom once by transferring dormant nursery trees from a cold room to a greenhouse and a second time by defoliating trees and applying 1% cytokinin and 0.1% gibberellins to the buds with a brush. Different sets of trees were induced at different times to bloom, so that flowers were produced 12 months in the year. When known bacterial antagonists (Erwinia herbicola strain C9-1 and Pseudomonas fluorescens strain A506) were applied alone or in combination to the stigmas of detached crab apple blossoms prior to inoculation with the pathogen (E. amylovora strain Ea153), population interactions over time were comparable to those reported in previous studies involving pear or apple. In a subsequent series of experiments, the relative effects of 12 bacterial strains on stigmatic populations of strain Ea153 were similar for detached blossoms of crab apple in the laboratory, blossoms of intact crab apple trees in the greenhouse, and blossoms of pear and apple in the field. Additionally, when stigmas of detached crab apple blossoms were inoculated with antagonists (strains C9-1 and A506) and the pathogen, and later subjected to a 24-h wetting period, bacterial populations in the flower hypanthium increased and disease was suppressed. These studies indicate that crab apple blossoms can serve as a suitable model for year-round evaluation and study of biocontrol agents for fire blight.

Safety Aspects and Implications of Regulation of Probiotic Bacteria in Food and Food Supplements

2008 ◽  
Vol 71 (8) ◽  
pp. 1734-1741 ◽  
Author(s):  
TRUDY M. WASSENAAR ◽  
GÜNTER KLEIN
Keyword(s):  
Antimicrobial Resistance ◽  
Safety Assessment ◽  
Bacterial Genome ◽  
The United States ◽  
Food Supplements ◽  
Probiotic Bacteria ◽  
The European Union ◽  
Bacterial Strains ◽  
Bacterial Populations ◽  
Safety Aspects

The application of living bacteria as probiotics in food or food supplements requires a careful safety assessment. This review summarizes key issues concerning the safety aspects of bacteria added to particular products marketed for improvement of general health or treatment of (post)infectious symptoms. The bacteria used in such products should be completely safe; however, it can be challenging to provide evidence for absence of all virulence properties. In some cases, virulence factors have been detected in probiotic bacterial strains, and the implications of these traits for safety assessments are discussed. Horizontal gene transfer can result in acquisition of virulence genes or antimicrobial resistance in probiotic bacteria. Antimicrobial resistance in these bacteria can possibly aid the spread of undesired resistance in intestinal bacterial populations. The relative risk of such gene transfers is considered. The generation of complete bacterial genome sequences can both resolve and create safety issues. Current practices of safety assessment procedures in the United States and the European Union are briefly reviewed and a future outlook is provided.

scholarly journals Comparative analysis of inoculated soybean in extinguishing soil

2017 ◽  
pp. 113-116
Author(s):  
Nikoletta Nagy ◽  
Péter Pepó ◽  
Lajosné Mándi
Keyword(s):  
Comparative Analysis ◽  
Seed Treatment ◽  
Soybean Seed ◽  
Nodule Formation ◽  
Bacterial Strains ◽  
Negative Effects ◽  
Soil Suspension ◽  
Core Saturation ◽  
Soybean Nodule ◽  
Technological Methods

In order to achieve higher yields, better technological methods offered in the current market, which aims to help the producers in the realization. To guarantee good yield because more and more people try with a variety of products, but you have to make the expected impact falls short.In this experiment, the following results were obtained: the soil suspension closely related to the inoculum of seed or seed treatment,which affects the soybean nodule formation, core saturation, and yield and protein-oil indicators. The soil suspension composition may exert positive and negative effects, which depend on how bacterial strains inoculum combined on the soybean seed surface. It is shown in our experiment very well, that between inoculum and inoculum as well as inoculum and seed treatment materials may be antagonism which setback to the soybean nodules formation and the yield, but not worsen the protein-oil indicators.

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