Effective dose of a microbial inoculant is one to four cells in the rhizosphere

2002 ◽  
Vol 48 (10) ◽  
pp. 940-944 ◽  
Author(s):  
Bo Normander ◽  
Niels Bohse Hendriksen
Keyword(s):  
Risk Assessment ◽  
Biological Control ◽  
Growth Rate ◽  
Single Cell ◽  
Pseudomonas Fluorescens ◽  
Specific Growth ◽  
Growth Potential ◽  
Bacterial Cells ◽  
Population Sizes ◽  
Number Of Bacteria

A single-cell approach for studying the growth potential and the establishment of bacteria in the barley phytosphere is presented, using Pseudomonas fluorescens strain with the capability for biological control. The incidence of growth of one to four bacterial cells dispersed to the young rhizosphere approximated to 100%, and specific growth rate averaged 0.05. Net growth occurred for cells added to the rhizosphere at densities between 1 and 100 000 cells, while at higher densities population sizes declined, but always approached 105–106cells per rhizosphere. No net growth was observed in bulk soil, and cells died in the phyllosphere. Our results showed that bacterial establishment was more related to the availability of microhabitats supporting growth, than related to the number of bacteria released. Key words: risk assessment, bacterial fate, single-cell, Pseudomonas fluorescens, gfp.

scholarly journals Control of Fire Blight by Pseudomonas fluorescens A506 and Pantoea vagans C9-1 Applied as Single Strains and Mixed Inocula

2010 ◽  
Vol 100 (12) ◽  
pp. 1330-1339 ◽  
Author(s):  
V. O. Stockwell ◽  
K. B. Johnson ◽  
D. Sugar ◽  
J. E. Loper
Keyword(s):  
Biological Control ◽  
Pseudomonas Fluorescens ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Field Trials ◽  
Disease Suppression ◽  
Biological Control Agents ◽  
Population Sizes ◽  
Mixed Inocula ◽  
Pantoea Vagans

The biological control agents Pseudomonas fluorescens A506 and Pantoea vagans C9-1 were evaluated individually and in combination for the suppression of fire blight of pear or apple in 10 field trials inoculated with the pathogen Erwinia amylovora. The formulation of pathogen inoculum applied to blossoms influenced establishment of the pathogen and the efficacy of biological control. Pantoea vagans C9-1 suppressed fire blight in all five trials in which the pathogen was applied as lyophilized cells but in none of the trials in which the pathogen was applied as freshly harvested cells. In contrast, Pseudomonas fluorescens A506 reduced disease significantly in only one trial. A mixture of the two strains also suppressed fire blight, but the magnitude of disease suppression over all field trials (averaging 32%) was less than that attained by C9-1 alone (42%). The two biological control agents did not antagonize one another on blossom surfaces, and application of the mixture of A506 and C9-1 to blossoms resulted in a greater proportion of flowers having detectable populations of at least one bacterial antagonist than the application of individual strains. Therefore, the mixture of A506 and C9-1 provided less disease control than expected based upon the epiphytic population sizes of the antagonists on blossom surfaces. We speculate that the biocontrol mixture was less effective than anticipated due to incompatibility between the mechanisms by which A506 and C9-1 suppress disease.

scholarly journals Technical bias of microcultivation environments on single-cell physiology

Lab on a Chip ◽  
2015 ◽  
Vol 15 (8) ◽  
pp. 1822-1834 ◽  
Author(s):  
Christian Dusny ◽  
Alexander Grünberger ◽  
Christopher Probst ◽  
Wolfgang Wiechert ◽  
Dietrich Kohlheyer ◽  
...  
Keyword(s):  
Growth Rate ◽  
Single Cell ◽  
Specific Growth ◽  
Cell Physiology ◽  
Cell Cultivation ◽  
Division Rate ◽  
Platform Comparison ◽  
Cross Platform ◽  
Technical Bias ◽  
Single Cell Physiology

The cross-platform comparison of three different single-cell cultivation methods demonstrates technical influences on biological key parameters like specific growth rate, division rate and cellular morphology.

scholarly journals Optimization of Transpiration and Potential Growth Rates of `Kardinal' Rose with Respect to Root-zone Physical Properties

2001 ◽  
Vol 126 (5) ◽  
pp. 638-643 ◽  
Author(s):  
Michael Raviv ◽  
J. Heinrich Lieth ◽  
David W. Burger ◽  
Rony Wallach
Keyword(s):  
Growth Rate ◽  
Hydraulic Conductivity ◽  
Stomatal Conductance ◽  
Specific Growth Rate ◽  
Transpiration Rate ◽  
Water Availability ◽  
Specific Growth ◽  
Root Zone ◽  
Growth Potential ◽  
Potential Growth

Physical characteristics of two media were studied concerning water availability to roots, as reflected in specific transpiration rate, stomatal conductance, and specific growth rate of very young leaflets of `Kardinal' rose (Rosa ×hybrida L.), grafted on Rosa canina L. `Natal Brier'. Plants were grown in UC mix [42% composted fir bark, 33% peat, and 25% sand (by volume)] or in coconut coir. Water release curves of the media were developed and hydraulic conductivities were calculated. Irrigation pulses were actuated according to predetermined media moisture tensions. Transpiration rate of plants was measured gravimetrically using load cells. Specific transpiration rate (STR) was calculated from these data and leaf area. STR and stomatal conductance were also determined using a steady-state porometer. Specific growth rate (RSG) of young leaflets was calculated from the difference between metabolic heat rate and respiration rate, which served as an indicator for growth potential. Low STR values found at tensions between 0 and 1.5 kPa in UC mix suggest this medium has insufficient free air space for proper root activity within this range. Above 2.3 kPa, unsaturated hydraulic conductivity of UC mix was lower than that of coir, possibly lowering STR values of UC mix-grown plants. As a result of these two factors, STR of plants grown in coir was 20% to 30% higher than that of plants grown in UC mix. STR of coir-grown plants started to decline only at tensions around 4.5 kPa. Yield (number of flowers produced) by coir-grown plants was 19% higher than UC mix-grown plants. This study demonstrated the crucial role of reaching sufficient air-filled porosity in the medium shortly after irrigation. It also suggests that hydraulic conductivity is a more representative measure of water availability than tension.

Oscillating conditions for influencing the composition of mixed biological cultures

1998 ◽  
Vol 37 (4-5) ◽  
pp. 259-262 ◽  
Author(s):  
Bjarne R. Horntvedt ◽  
Morten Rambekk ◽  
Rune Bakke
Keyword(s):  
Growth Rate ◽  
Specific Growth ◽  
Heterotrophic Bacteria ◽  
Bacterial Species ◽  
Rate Reduction ◽  
Similar Strategy ◽  
Sinusoidal Oscillations ◽  
Specific Growth Rates ◽  
Rate Limiting ◽  
Concentration Levels

This paper presents a strategy in which mixed biological cultures are exposed to oscillating concentration levels, to improve the potential for coexistence of desired bacterial species. A mechanistic mathematical model is constructed to investigate and illustrate this strategy. This paper is focused on competition between nitrifying, denitrifying and aerobic heterotrophic bacteria in a CSTR with sludge recycle. For nitrifying and aerobic heterotrophic cultures, the effect of sinusoidal oscillations in DO levels with an amplitude of 1.0 mg/l is a 16% specific growth rate reduction compared to that at a constant DO level. The denitrifiers growth rate is increased by an average of 59%, compared to the constant DO level situation. A similar strategy has been tested in a pilot plant. It is concluded that the influence on specific growth rates is a function of the amplitude of the oscillations. The effects are greatest when concentrations fluctuate around the half saturation concentration of the rate limiting component(s).

scholarly journals Understanding the Interaction Effects between Dietary Lipid Content and Rearing Temperature on Growth Performance, Feed Utilization, and Fat Deposition of Sea Bass (Dicentrarchus labrax)

Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 392
Author(s):  
Lydia Katsika ◽  
Mario Huesca Flores ◽  
Yannis Kotzamanis ◽  
Alicia Estevez ◽  
Stavros Chatzifotis
Keyword(s):  
Growth Rate ◽  
Body Weight ◽  
Specific Growth ◽  
Dicentrarchus Labrax ◽  
Sea Bass ◽  
Dietary Lipid ◽  
Lipid Levels ◽  
Final Body Weight ◽  
Temperature Regimes ◽  
Fish Group

This study was conducted to elucidate the interaction effects of temperature and dietary lipid levels (2 × 2 factorial experiment) on the growth performance, muscle, and liver composition in adult farmed European sea bass (Dicentrarchus labrax). Two groups of fish (190 g; 60 fish per group) were distributed in 12 tanks in triplicates and kept at two different temperature regimes; one starting at 23 °C and then changed to 17 °C for 61 days, and the other starting at 17 °C and then changed to 23 °C for 39 days. Two commercial diets containing both ~44% crude protein but incorporating different dietary lipid levels, 16.5% (D16) and 20.0% (D20) (dry matter (DM)), were fed to the fish to apparent satiation; the type of diet fed to each fish group remained constant throughout the experiment. Final body weight, weight gain, and specific growth rate were significantly higher for the fish group held at 23 °C compared to the fish group at 17 °C (before the temperature changes), while the dietary fat content did not have any profound effect in both groups. Furthermore, the different temperature regimes did not affect muscle or liver composition, but, on the contrary, dietary lipids affected hepatosomatic, perivisceral fat, and visceral indexes. Feed conversion ratio and specific growth rate were not affected by the dietary lipid level. An interaction of temperature and dietary lipid content was observed in daily feed consumption (DFC) and final body weight (FBW).

scholarly journals Effects of cofD gene knock-out on the methanogenesis of Methanobrevibacter ruminantium

AMB Express ◽  
2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jian Ma ◽  
Xueying Wang ◽  
Ting Zhou ◽  
Rui Hu ◽  
Huawei Zou ◽  
...  
Keyword(s):  
Growth Rate ◽  
Specific Growth ◽  
Production Capacity ◽  
Maximum Amount ◽  
Logarithmic Phase ◽  
Wild Type ◽  
Knock Out ◽  
Maximum Biomass ◽  
Reproductive Ability ◽  
Methanobrevibacter Ruminantium

AbstractThis study aimed to investigate the effects of cofD gene knock-out on the synthesis of coenzyme F420 and production of methane in Methanobrevibacter ruminantium (M. ruminantium). The experiment successfully constructed a cofD gene knock-out M. ruminantium via homologous recombination technology. The results showed that the logarithmic phase of mutant M. ruminantium (12 h) was lower than the wild-type (24 h). The maximum biomass and specific growth rate of mutant M. ruminantium were significantly lower (P < 0.05) than those of wild-type, and the maximum biomass of mutant M. ruminantium was approximately half of the wild-type; meanwhile, the proliferation was reduced. The synthesis amount of coenzyme F420 of M. ruminantium was significantly decreased (P < 0.05) after the cofD gene knock-out. Moreover, the maximum amount of H2 consumed and CH4 produced by mutant were 14 and 2% of wild-type M. ruminantium respectively. In conclusion, cofD gene knock-out induced the decreased growth rate and reproductive ability of M. ruminantium. Subsequently, the synthesis of coenzyme F420 was decreased. Ultimately, the production capacity of CH4 in M. ruminantium was reduced. Our research provides evidence that cofD gene plays an indispensable role in the regulation of coenzyme F420 synthesis and CH4 production in M. ruminantium.

CONTINUOUS CULTURE OF BRUCELLA ABORTUS S.19

1961 ◽  
Vol 7 (4) ◽  
pp. 491-505 ◽  
Author(s):  
Andreas H. W. Hauschild ◽  
Hilliard Pivnick
Keyword(s):  
Growth Rate ◽  
Continuous Culture ◽  
Dilution Rate ◽  
Brucella Abortus ◽  
Specific Growth ◽  
Limiting Factor ◽  
Continuous Growth ◽  
Viable Cells ◽  
Metabolic Products ◽  
Growth Of Bacteria

An apparatus is described for the continuous growth of bacteria. Brucella abortus S.19 has been grown in continuous culture for periods up to 3 weeks with populations up to 2 × 1011viable cells per ml and without the establishment of nonsmooth variants.Concentrations between 3 × 109and 2 × 1011cells per ml could be maintained as a function of the dilution rate without the requirement of a known limiting factor in the medium. In a series of steady-state conditions, the specific growth rate increased steadily up to 0.28 hour−1with decreasing population levels.Incidence of mutants was governed by the dilution rate and could also be reduced by various chelating substances.In continuous growth combined with continuous dialysis, population levels were approximately twice those obtained in continuous growth without dialysis. The effect of dialysis appears to be the continuous removal of growth-limiting metabolic products.

scholarly journals Precise regulation of the relative rates of surface area and volume synthesis in bacterial cells growing in dynamic environments

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Handuo Shi ◽  
Yan Hu ◽  
Pascal D. Odermatt ◽  
Carlos G. Gonzalez ◽  
Lichao Zhang ◽  
...  
Keyword(s):  
Growth Rate ◽  
Time Delay ◽  
Surface Area ◽  
Environmental Changes ◽  
Volume Ratio ◽  
Dynamic Environments ◽  
Bacterial Cells ◽  
Bacterial Growth Rate ◽  
State Size ◽  
Insight Into

AbstractThe steady-state size of bacterial cells correlates with nutrient-determined growth rate. Here, we explore how rod-shaped bacterial cells regulate their morphology during rapid environmental changes. We quantify cellular dimensions throughout passage cycles of stationary-phase cells diluted into fresh medium and grown back to saturation. We find that cells exhibit characteristic dynamics in surface area to volume ratio (SA/V), which are conserved across genetic and chemical perturbations as well as across species and growth temperatures. A mathematical model with a single fitting parameter (the time delay between surface and volume synthesis) is quantitatively consistent with our SA/V experimental observations. The model supports that this time delay is due to differential expression of volume and surface-related genes, and that the first division after dilution occurs at a tightly controlled SA/V. Our minimal model thus provides insight into the connections between bacterial growth rate and cell shape in dynamic environments.

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