Critical Assessment of the Time-to-Detection Method for Accurate Estimation of Microbial Growth Parameters

2014 ◽  
Vol 35 (2) ◽  
pp. 179-192 ◽  
Author(s):  
Maria Baka ◽  
Estefanía Noriega ◽  
Ioanna Stamati ◽  
Filip Logist ◽  
Jan F.M. Van Impe
Keyword(s):  
Microbial Growth ◽  
Detection Method ◽  
Growth Parameters ◽  
Critical Assessment ◽  
Accurate Estimation ◽  
Time To Detection

scholarly journals Estimation of Staphylococcus aureus Growth Parameters from Turbidity Data: Characterization of Strain Variation and Comparison of Methods

2006 ◽  
Vol 72 (7) ◽  
pp. 4862-4870 ◽  
Author(s):  
R. Lindqvist
Keyword(s):  
Staphylococcus Aureus ◽  
Growth Rates ◽  
Growth Parameters ◽  
Growth Models ◽  
Viable Count ◽  
Detection Methods ◽  
Accurate Estimation ◽  
Data Set ◽  
Time To Detection ◽  
Strain Variability

ABSTRACT Turbidity methods offer possibilities for generating data required for addressing microorganism variability in risk modeling given that the results of these methods correspond to those of viable count methods. The objectives of this study were to identify the best approach for determining growth parameters based on turbidity data and use of a Bioscreen instrument and to characterize variability in growth parameters of 34 Staphylococcus aureus strains of different biotypes isolated from broiler carcasses. Growth parameters were estimated by fitting primary growth models to turbidity growth curves or to detection times of serially diluted cultures either directly or by using an analysis of variance (ANOVA) approach. The maximum specific growth rates in chicken broth at 17°C estimated by time to detection methods were in good agreement with viable count estimates, whereas growth models (exponential and Richards) underestimated growth rates. Time to detection methods were selected for strain characterization. The variation of growth parameters among strains was best described by either the logistic or lognormal distribution, but definitive conclusions require a larger data set. The distribution of the physiological state parameter ranged from 0.01 to 0.92 and was not significantly different from a normal distribution. Strain variability was important, and the coefficient of variation of growth parameters was up to six times larger among strains than within strains. It is suggested to apply a time to detection (ANOVA) approach using turbidity measurements for convenient and accurate estimation of growth parameters. The results emphasize the need to consider implications of strain variability for predictive modeling and risk assessment.

scholarly journals Degradation of Polycyclic Aromatic Hydrocarbon Pyrene by Biosurfactant-Producing Bacteria Gordonia cholesterolivorans AMP 10

2016 ◽  
Vol 8 (3) ◽  
pp. 336 ◽  
Author(s):  
Tri Handayani Kurniati ◽  
Iman Rusmana ◽  
Ani Suryani ◽  
Nisa Rachmania Mubarik
Keyword(s):  
Surface Tension ◽  
Polycyclic Aromatic Hydrocarbon ◽  
Aromatic Hydrocarbon ◽  
Microbial Growth ◽  
Growth Parameters ◽  
Biology Education ◽  
Pcr Analysis ◽  
Lubricant Oil ◽  
Polycyclic Aromatic ◽  
Pyrene Concentration

<p>Pyrene degradation and biosurfactant activity by a new strain identified as <em>Gordonia cholesterolivorans </em>AMP 10 were studied. The strain grew well and produced effective biosurfactants in the presence of glucose, sucrose, and crude oil. The biosurfactants production was detected by the decreased surface tension of the medium and emulsification activity.  Analysis of microbial growth parameters showed that AMP10 grew best at 50 µg mL<sup>-1</sup> pyrene concentration, leading to 96 % degradation of pyrene within 7 days. The result of nested PCR analysis revealed that this isolate possessed the <em>nah</em>Ac gene which encodes dioxygenase enzyme for initial degradation of Polycyclic Aromatic Hydrocarbon (PAH). Observation of both tensio-active and emulsifying activities indicated that biosurfactants which produced by AMP 10 when grown on glucose could lower the surface tension of medium from 71.3 mN/m to 24.7 mN/m and formed a stable emulsion in used lubricant oil with an emulsifying index (E24) of 74%. According to the results, it is suggested that the bacterial isolates <em>G. cholesterolivorans</em> AMP10 are suitable candidates for bioremediation of PAH-contaminated environments.</p><p><strong>How to Cite</strong></p><p>Kurniati, T. H.,  Rusmana, I. Suryani, A. &amp; Mubarik, N. R. (2016). Degradation of Polycyclic Aromatic Hydrocarbon Pyrene by Biosurfactant-Producing Bacteria <em>Gordonia cholesterolivorans</em> AMP 10. <em>Biosaintifika: Journal of Biology &amp; Biology Education</em>, 8(3), 336-343. </p>

scholarly journals Predicting microbial growth in a mixed culture from growth curve data

2019 ◽  
Vol 116 (29) ◽  
pp. 14698-14707 ◽  
Author(s):  
Yoav Ram ◽  
Eynat Dellus-Gur ◽  
Maayan Bibi ◽  
Kedar Karkare ◽  
Uri Obolski ◽  
...  
Keyword(s):  
Mixed Culture ◽  
Microbial Growth ◽  
Growth Curves ◽  
Growth Cycle ◽  
Relative Fitness ◽  
Accurate Estimation ◽  
Environmental Perturbations ◽  
Fitness Consequence ◽  
Culture Growth ◽  
Growth Differences

Determining the fitness of specific microbial genotypes has extensive application in microbial genetics, evolution, and biotechnology. While estimates from growth curves are simple and allow high throughput, they are inaccurate and do not account for interactions between costs and benefits accruing over different parts of a growth cycle. For this reason, pairwise competition experiments are the current “gold standard” for accurate estimation of fitness. However, competition experiments require distinct markers, making them difficult to perform between isolates derived from a common ancestor or between isolates of nonmodel organisms. In addition, competition experiments require that competing strains be grown in the same environment, so they cannot be used to infer the fitness consequence of different environmental perturbations on the same genotype. Finally, competition experiments typically consider only the end-points of a period of competition so that they do not readily provide information on the growth differences that underlie competitive ability. Here, we describe a computational approach for predicting density-dependent microbial growth in a mixed culture utilizing data from monoculture and mixed-culture growth curves. We validate this approach using 2 different experiments withEscherichia coliand demonstrate its application for estimating relative fitness. Our approach provides an effective way to predict growth and infer relative fitness in mixed cultures.

Land use effect on microbial growth and respiration under future climate

2020 ◽  
Author(s):  
Vusal Guliyev ◽  
Melissa Pfeiffer ◽  
Maria Udovenko ◽  
Christina Fasching ◽  
Thomas Reitz ◽  
...  
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Microbial Growth ◽  
Microbial Respiration ◽  
Growth Parameters ◽  
Vegetation Type ◽  
Interactive Effect ◽  
Organic Input ◽  
Organic C

&lt;p&gt;Fresh input of organic material in soil is continuously transformed and processed by growing microorganisms using this organic input as a substrate. Therefore, the quality and quantity of soil organic C stock is strongly dependent on the intensity of mineralization processes through microbial respiration and growth. We aimed to prove the sensitivity of microbial respiration and growth parameters to indicate an interactive effect of land use and climate warming. For this we used Global Change Experimental Facility in Bad Lauchst&amp;#228;dt, UFZ, Halle, Germany. This long-term experiment is designed in 5 land use strategies (Organic Farming, Conventional Farming, Intensive Meadow, Extensive Meadow, and Extensive Pasture) and 2 climate scenarios (ambient and future). We determined basal respiration by CO&lt;sub&gt;2&lt;/sub&gt; emission, microbial growth parameters by substrate-induced growth respiration (SIGR), and the quality of soil organic matter by Fourier-transformed infrared spectroscopy (FTIR). The effect of biotic (vegetation type) and abiotic (temperature and moisture) factors on microbial attributes and on chemical composition of soil organic matter will be compared.&lt;/p&gt;

scholarly journals Multicenter Clinical Evaluation of BacT/Alert Virtuo Blood Culture System

2017 ◽  
Vol 55 (8) ◽  
pp. 2413-2421 ◽  
Author(s):  
Michael R. Jacobs ◽  
Tony Mazzulli ◽  
Kevin C. Hazen ◽  
Caryn E. Good ◽  
Ayman M. Abdelhamed ◽  
...  
Keyword(s):  
Blood Culture ◽  
Culture System ◽  
Microbial Growth ◽  
Fungal Growth ◽  
Detection Algorithm ◽  
Blood Culture System ◽  
Gram Negative ◽  
Time To Detection ◽  
Clinically Significant ◽  
Organism Group

ABSTRACTBacT/Alert Virtuo is an advanced, automated blood culture system incorporating improved automation and an enhanced detection algorithm to shorten time to detection. A multicenter study of the investigational Virtuo system (bioMérieux, Inc., Durham, NC) compared to BacT/Alert 3D (BTA3D) for detection of bacteremia/fungemia in four bottle types, SA and FA Plus (aerobic) and SN and FN Plus (anaerobic), was performed in a clinical setting with patient samples in a matched system design clinical trial. Blood was added to paired aerobic or anaerobic bottles, with the volume in each bottle in each pair required to be ≤10 ml and with the volumes required to be within 30% of each other. Of 5,709 bottle sets (52.5% aerobic pairs and 47.5% anaerobic pairs), 430 (7.5%) were positive for bacterial or fungal growth, with 342 (6.0%) clinically significant and 83 (1.5%) contaminated. A total of 3,539 sets (62.0%) were volume compliant, with 203 sets (5.7%) clinically significant. The positivity rates for volume-compliant bottle pairs determined by the two systems were comparable, with 68.7% of clinically significant isolates detected by both instruments, 15.7% by Virtuo only, and 15.7% by BTA3D only. Virtuo detected microbial growth nearly 2 h sooner overall than BTA3D (mean, 15.9 h versus 17.7 h). Shorter time to detection by Virtuo was related to organism group, with the time to detection being significantly shorter for enteric Gram-negative bacilli and enterococci (means, 3.6 h and 2.3 h shorter, respectively). This large clinical study demonstrated that the Virtuo blood culture system produced results comparable to those seen with the long-established BTA3D system, with significantly shorter time to detection.

(Bio)Precipitation of Trivalent Arsenic Using an Anaerobic Bioreactor

2013 ◽  
Vol 825 ◽  
pp. 544-547 ◽  
Author(s):  
Letícia Paiva de Matos ◽  
Patricia Freitas ◽  
Mônica Cristina Teixeira
Keyword(s):  
Microbial Growth ◽  
Growth Parameters ◽  
Low Cost ◽  
Synthetic Medium ◽  
Experimental System ◽  
Waste Material ◽  
Chicken Feathers ◽  
Operation Costs ◽  
Experimental Apparatus ◽  
Sulphate Removal

This study aims to build and operate an experimental system to observe the metabolic activity of a mixed culture of SRB on removing sulphate and arsenic (AsIII). The experimental apparatus was operated semi-continuously. The synthetic medium utilized was modified Postgate C increased with a NaAsO2 solution (As concentrations ranging from 2 to 8 mg/L). Powdered chicken feathers (PCF) was used as nutrient and solid support for microbial growth. It is a cheap waste material produced by poultry industry and it was previously studied for As biosorption. Growth parameters analyzed were pH, Eh, sulphate and As(III) concentration. After 6 months of operation, As was introduced into the system, initially 2mg.L-1. The main results obtained are: pH changes were quit negligible, varying between 7 and 8, Eh decayed to a maximum of -400 eV, compatible with a reducing condition. Sulphate removal was of about 80%, and up to 90% of the arsenic was removed from the system. The methodology here presented is effective and innovative since arsenic is removed without any oxidation step. Considering the low cost of the waste material some operation costs may be reduced.

scholarly journals Robotic Platform for Parallelized Cultivation and Monitoring of Microbial Growth Parameters in Microwell Plates

2014 ◽  
Vol 19 (6) ◽  
pp. 593-601 ◽  
Author(s):  
Andreas Knepper ◽  
Michael Heiser ◽  
Florian Glauche ◽  
Peter Neubauer
Keyword(s):  
Microbial Growth ◽  
Growth Parameters ◽  
Robotic Platform

scholarly journals Soil depth gradients in microbial growth kinetics under deeply- vs. shallow-rooted plants

2021 ◽  
Author(s):  
Kyungjin Min ◽  
Eric Slessarev ◽  
Megan Patricia Kan ◽  
Karis Mcfarlane ◽  
Erik Oerter ◽  
...  
Keyword(s):  
Microbial Biomass ◽  
Growth Kinetics ◽  
Microbial Growth ◽  
Growth Parameters ◽  
Soil Depth ◽  
Rooting Depth ◽  
Deep Soil ◽  
Switch Grass ◽  
Microbial Growth Kinetics ◽  
Deep Soils

Climate-smart land management practices that replace shallow-rooted annual crop systems with deeply-rooted perennial plants can contribute to soil carbon sequestration. However, deep soil carbon accrual may be influenced by active microbial biomass and their capacity to assimilate fresh carbon at depth. Incorporating active microbial biomass, dormancy and growth in models can improve our ability to predict the capacity of soil to store carbon. But, so far, the microbial parameters that are needed for such modeling are poorly constrained, especially in deep soil layers. Here, we investigated whether a change in crop rooting depth affects microbial growth kinetics in deep soils compared to surface soils. We used a lab incubation experiment and growth kinetics model to estimate how microbial parameters vary along 240 cm of soil depth in profiles under shallow- (soy) and deeply-rooted plants (switch grass) 11 years after plant cover conversion. We also assessed resource origin and availability (total organic carbon, 14C, dissolved organic carbon, specific UV absorbance, total nitrogen, total dissolved nitrogen) along the soil profiles to examine associations between soil chemical and biological parameters. Even though root biomass was higher and rooting depth was deeper under switch grass than soy, resource availability and microbial growth parameters were generally similar between vegetation types. Instead, depth significantly influenced soil chemical and biological parameters. For example, resource availability, and total and relative active microbial biomass decreased with soil depth. Decreases in the relative active microbial biomass coincided with increased lag time (response time to external carbon inputs) along the soil profiles. Even at a depth of 210-240 cm, microbial communities were activated to grow by added resources within a day. Maximum specific growth rate decreased to a depth of 90 cm and then remained consistent in deeper layers. Our findings show that > 10 years of vegetation and rooting depth changes may not be long enough to alter microbial growth parameters, and suggest that at least a portion of the microbial community in deep soils can grow rapidly in response to added resources. Our study determined microbial growth parameters that can be used in models to simulate carbon dynamics in deep soil layers.

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