Comparison of selective media for the enumeration and identification of fecal streptococci from natural sources

1980 ◽  
Vol 26 (11) ◽  
pp. 1320-1327 ◽  
Author(s):  
J. E. Pagel ◽  
G. M. Hardy
Keyword(s):  
Recovery Efficiency ◽  
Streptococcus Bovis ◽  
Good Recovery ◽  
High Background ◽  
Membrane Filters ◽  
Fecal Streptococci ◽  
Pure Cultures ◽  
Esculin Hydrolysis ◽  
Overall Performance ◽  
Lower Recovery

Five media and procedures were compared for their recovery of fecal streptococci on membrane filters. Growth and numbers of a variety of pure cultures were compared, and recoveries from raw sewage and sewage effluent were determined on the five media. A total of 512 isolates were identified and the specificity of each medium was determined from these results. While KF agar recovered significantly higher numbers of organisms, only 81% of the positive colonies were fecal streptococci. Slanetz and Bartley (SB) medium showed similarly low specificity and the mE procedure gave low recoveries. Best overall results were obtained on mEnterococcus (mEnt) agar with high (91%) specificity for enterococci, and very good recovery efficiency with low background counts. This medium was also the only one demonstrating any appreciable recovery of other fecal streptococci with 93% of the background colonies being confirmed as fecal streptococci of which most were Streptococcus bovis, S. equinus, or S. salivarius. Pfizer selective enterococcus (PSE) agar was second in overall performance with a high (94%) rate of specificity but this medium had lower recovery efficiency and high background counts. Performance of PSE agar could be considerably improved, without impairing specificity, by using a total count disregarding esculin hydrolysis.

SHORT-TIME MEMBRANE FILTER METHOD FOR ESTIMATION OF NUMBERS OF BACTERIA1

1968 ◽  
Vol 31 (6) ◽  
pp. 177-179 ◽  
Author(s):  
W. C. Frazier ◽  
D. F. Gneiser
Keyword(s):  
Membrane Filter ◽  
Plate Count ◽  
Filter Method ◽  
Good Recovery ◽  
Green Beans ◽  
Pure Cultures ◽  
Viable Bacteria ◽  
Membrane Filter Method ◽  
Short Time

Directions are given for the 8- to 12-hr membrane filter-colony technique for the estimation of numbers of viable bacteria in rinsings or swabbings from the surfaces of foods or equipment. Tests on 6 species of bacteria often found in foods demonstrated good recovery of organisms from pure cultures or mixtures of 2 or 3 cultures. Tests with dairy rinses and fresh green beans and sweet com gave counts almost as high as by the 48-hr plate, count. Results with frozen or blanched and frozen beans and corn and with chlorinated flume waters were unsatisfactory.

The isolation of blue-green bacteria in pure culture

1974 ◽  
Vol 20 (2) ◽  
pp. 272-273 ◽  
Author(s):  
Howard D. McCurdy Jr. ◽  
Walter Hodgson
Keyword(s):  
Pure Culture ◽  
Green Bacteria ◽  
Membrane Filters ◽  
Convenient Means ◽  
Pure Cultures

Omnimixer treatment followed by surface plating of colonies from membrane filters provides a convenient means for the isolation of pure cultures of blue-green bacteria.

THE CHARACTERIZATION OF FECAL STREPTOCOCCI

1967 ◽  
Vol 30 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Richard C. Tilton ◽  
Warren Litsky
Keyword(s):  
Streptococcus Bovis ◽  
Streptococcus Faecalis ◽  
Positive Correlation ◽  
Fecal Streptococci ◽  
Streptococcus Faecium ◽  
Animal Feces

Summary Fecal streptococci were isolated from human and animal feces and frozen meat and poultry pies. Organisms from these sources could be classified in three major groups: Streptococcus faecalis, Streptococcus faecium, and Streptococcus bovis. Attempts to relate the presence of such organisms to their fecal source using the heat-tellurite test were unsuccessful. A positive correlation was noted between the ability of these organisms to reduce tetrazolium and tellurite and their fecal source.

scholarly journals Strategies to improve the fluorescent signal of the tripartite sfGFP system

2020 ◽  
Vol 52 (9) ◽  
pp. 998-1006
Author(s):  
Jing Shen ◽  
Wenlu Zhang ◽  
Chunyang Gan ◽  
Xiafei Wei ◽  
Jie Li ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Fluorescent Protein ◽  
Fluorescent Proteins ◽  
Bimolecular Fluorescence Complementation ◽  
Fluorescence Signal ◽  
Recovery Efficiency ◽  
Good Recovery ◽  
Protein Protein Interactions ◽  
Bifc Assay ◽  
Green Fluorescent

Abstract Bimolecular fluorescence complementation (BiFC) is a popular method used to detect protein–protein interactions. For a BiFC assay, a fluorescent protein is usually split into two parts, and the fluorescence is recovered upon the interaction between the fused proteins of interest. As an elegant extension of BiFC, a tripartite superfold green fluorescent protein (sfGFP) system that has the advantages of low background fluorescence and small fusion tag size has been developed. However, the tripartite system exhibits a low fluorescence signal in some cases. To address this problem, we proposed to increase the affinity between the two parts, G1–9 and G11, of the tripartite system by adding affinity pairs. Among the three affinity pairs tested, LgBiT-HiBiT improved both the signal and signal-to-noise (S/N) ratio to the greatest extent. More strikingly, the direct covalent fusion of G11 to G1–9, which converted the tripartite system into a new bipartite system, enhanced the S/N ratio from 20 to 146, which is superior to the bipartite sfGFP system split at 157/158 or 173/174. Our results implied that the 10th β-strand of sfGFP has a low affinity and a good recovery efficiency to construct a robust BiFC system, and this concept might be applied to other fluorescent proteins with similar structure to construct new BiFC systems.

scholarly journals Consequences and mitigation of saltwater intrusion induced by short-circuiting during aquifer storage and recovery (ASR) in a coastal subsurface

2016 ◽  
Author(s):  
Koen Gerardus Zuurbier ◽  
Pieter Jan Stuyfzand
Keyword(s):  
Coastal Aquifers ◽  
Saltwater Intrusion ◽  
Field Measurements ◽  
Aquifer Storage And Recovery ◽  
Recovery Efficiency ◽  
Transport Modelling ◽  
Aquifer Storage ◽  
Ambient Groundwater ◽  
Asr System ◽  
Lower Recovery

Abstract. Coastal aquifers and the deeper subsurface are increasingly exploited. The accompanying perforation of the subsurface for those purposes has increased the risk of short-circuiting of originally separated aquifers. This study shows how this short-circuiting negatively impacts the freshwater recovery efficiency (RE) during aquifer storage and recovery (ASR) in coastal aquifers. ASR was applied in a shallow saltwater aquifer overlying a deeper saltwater aquifer, which was targeted for seasonal aquifer thermal energy storage (ATES). Although both aquifers were considered properly separated, intrusion of deeper saltwater into the shallower aquifer quickly terminated the freshwater recovery. The presumable pathway was a nearby ATES borehole. This finding was supported by field measurements, hydrochemical analyses, and SEAWAT transport modelling. The potentially rapid short-circuiting during storage and recovery can reduce the RE of ASR to null. When limited mixing with ambient groundwater is allowed, a linear RE decrease by short-circuiting with increasing distance from the ASR well within the radius of the injected ASR-bubble was observed. Interception of deep short-circuiting water can mitigate the observed RE decrease, although complete compensation of the RE decrease will generally be unattainable. Brackish water upconing from the underlying aquitard towards the shallow recovery wells of the MPPW-ASR system was observed. This "leakage" may lead to a lower recovery efficiency than based on current ASR performance estimations.

Performance Analysis of a Hybrid Solar Gas Turbine Plant Combined With Chemical Recuperation

2019 ◽  
Author(s):  
Zhitao Wang ◽  
Wanling Qi ◽  
Tielei Li ◽  
Shuying Li
Keyword(s):  
Gas Turbine ◽  
Fuel Consumption ◽  
Output Power ◽  
Thermal Efficiency ◽  
Heat Recovery ◽  
Simulation Models ◽  
Aspen Plus ◽  
Recovery Efficiency ◽  
Reduce Fuel Consumption ◽  
Overall Performance

Abstract This paper studies the influence of the high-temperature solar preheating system and chemical recuperation system on the overall performance of a MW-level three-shaft gas turbine. In order to obtain accurate simulation results, this paper adopts an integrated simulation method, where the simulation models of the solar receiver and gas turbine are established on the Matlab/Simulink platform, the simulation model of the chemical recuperation system is established on the Aspen Plus platform, and the interface between Matlab and Aspen Plus is developed for mutual communication. With the component maps, the Newton-Raphson iteration method is used to solve the thermodynamic performance of the gas turbine. Based on the above simulation models and solution method, the effects of the mean receiver wall temperature (Ts) and steam-to-methane ratios (R) on the overall performance of the gas turbine are studied in this paper. From the perspective of safe operation, the influence of Ts and R on the net output power of the gas turbine is first calculated. The results show that in the safe operating range, chemical recuperation can significantly increase the net output power of the gas turbine, while the net output power increases first and then decreases with the increase of Ts. When the output power is constant, increasing Ts or R both can effectively reduce fuel consumption, and increasing R can also improve the heat recovery efficiency and the overall thermal efficiency. However, the heat losses of the receiver increase as Ts increasing, meanwhile, the heat recovery efficiency and the overall efficiency also decrease gradually. Therefore, in actual operation, various factors should be taken into account in order to reduce fuel consumption and improve the overall thermal efficiency.

Nature of Incorporated 14C-Labeled Material Retained by Sulfuric Acid Fixed Bacteria in Pure Cultures and in Natural Aquatic Populations

1975 ◽  
Vol 32 (10) ◽  
pp. 1876-1879 ◽  
Author(s):  
John A. Baross ◽  
F. J. Hanus ◽  
Robert P. Griffiths ◽  
Richard Y. Morita
Keyword(s):  
Molecular Weight ◽  
Sulfuric Acid ◽  
Glutamic Acid ◽  
Fresh Water ◽  
Water Samples ◽  
Trichloroacetic Acid ◽  
Low Molecular Weight ◽  
Bacterial Populations ◽  
Membrane Filters ◽  
Pure Cultures

The levels of 14C-substrates (glutamic acid, alanine, glucose, and uracil) retained by aquatic bacteria in pure cultures and natural marine and fresh water samples after fixation with 2 N sulfuric acid (H2SO4 to reduce pH to 2) were found to be identical to the amount of 14C-labeled material associated with cold 10% trichloroacetic acid (TCA) precipitates collected on filters. Both TCA and H2SO4 were also equally effective in driving CO2 from solution. In heterotrophic potential studies, therefore, the 14C activity associated with natural bacterial populations collected on membrane filters after H2SO4 fixation represents macromolecules only, and not free substrate pools or low molecular weight metabolites.

scholarly journals Utility of Green Fluorescent Nucleic Acid Dyes and Aluminum Oxide Membrane Filters for Rapid Epifluorescence Enumeration of Soil and Sediment Bacteria

1998 ◽  
Vol 64 (12) ◽  
pp. 5000-5003 ◽  
Author(s):  
Markus G. Weinbauer ◽  
Christiane Beckmann ◽  
Manfred G. Höfle
Keyword(s):  
Nucleic Acid ◽  
Aluminum Oxide ◽  
Acid Dyes ◽  
Polycarbonate Membrane ◽  
High Background ◽  
Membrane Filters ◽  
Cell Counts ◽  
Green Fluorescent ◽  
Oxide Membrane ◽  
Soil And Sediment

ABSTRACT High background fluorescence and unspecific staining hampered the epifluorescence enumeration of bacteria in 45% of the tested soil and sediment samples with 4′,6-diamidino-2-phenylindole (DAPI) and polycarbonate membrane filters. These problems of the determination of total cell counts can be circumvented by using green fluorescent high-affinity nucleic acid dyes and aluminum oxide membrane filters. Due to the bright staining of cells, we recommend SYBR Green II as dye.

Transfer Technique for Electron Microscopy of Membrance Filter Samples

1974 ◽  
Vol 32 ◽  
pp. 554-555
Author(s):  
Lawrence W. Ortiz ◽  
Bonnie L. Isom
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Pore Size ◽  
Membrane Filters ◽  
Size Dependent

A procedure is described for the quantitative transfer of fibers and particulates collected on membrane filters to electron microscope (EM) grids. Various Millipore MF filters (Millipore AA, HA, GS, and VM; 0.8, 0.45, 0.22 and 0.05 μm mean pore size) have been used with success. Observed particle losses have not been size dependent and have not exceeded 10%. With fibers (glass or asbestos) as the collected media this observed loss is approximately 3%.

Scattering-angle dependence of signal/background ratio of inner-shell electron excitation loss in EELS

1983 ◽  
Vol 41 ◽  
pp. 390-391
Author(s):  
T. Oikawa ◽  
M. Inoue ◽  
T. Honda ◽  
Y. Kokubo
Keyword(s):  
Energy Loss ◽  
Electron Excitation ◽  
Heavy Elements ◽  
Background Intensity ◽  
Light Elements ◽  
Energy Analyzer ◽  
High Background ◽  
Scattering Angle ◽  
Angle Dependence ◽  
Shell Electron

EELS allows us to make analysis of light elements such as hydrogen to heavy elements of microareas on the specimen. In energy loss spectra, however, elemental signals ride on a high background; therefore, the signal/background (S/B) ratio is very low in EELS. A technique which collects the center beam axial-symmetrically in the scattering angle is generally used to obtain high total intensity. However, the technique collects high background intensity together with elemental signals; therefore, the technique does not improve the S/B ratio. This report presents the experimental results of the S/B ratio measured as a function of the scattering angle and shows the possibility of the S/B ratio being improved in the high scattering angle range.Energy loss spectra have been measured using a JEM-200CX TEM with an energy analyzer ASEA3 at 200 kV.Fig.l shows a typical K-shell electron excitation edge riding on background in an energy loss spectrum.

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