Isolation and Physiological Characterization of Thiothrix sp.

1994 ◽  
Vol 29 (7) ◽  
pp. 261-269 ◽  
Author(s):  
V. Tandoi ◽  
N. Caravaglio ◽  
D. Di Dio Balsamo ◽  
M. Majone ◽  
M. C. Tomei
Keyword(s):  
Growth Yield ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Yield Coefficient ◽  
Simultaneous Presence ◽  
Mixotrophic Growth ◽  
Physiological Characterization ◽  
South Italy ◽  
Mixotrophic Conditions

Thiothrix CT3 was isolated in pure culture by micromanipulation technique. The growth of this microorganism was analyzed in autotrophic, heterotrophic and mixotrophic conditions, in a bicarbonate-containing mineral medium supplemented with thiosulphate and/or acetate. Thiothrix CT3 was able to grow in all the conditions examined: the maximum growth rates estimated were 1.8, 2.5 and 2.5 d−1 respectively. The capacity of this organism to grow autotrophically, as supposed by Winogradsky in 1888, is a strong advantage over the other bacteria present in activated sludge, when sulphides are produced or carried by the sewer. Both the maximum growth rate and growth yield coefficient shown during heterotrophic and mixotrophic growth were comparable, indicating that the simultaneous presence of two substrates (acetate and a reduced sulphur compound) does not give it any particular advantage. The strong presence of Thiothrix spp. in many plants located in South Italy can be explained by the wide nutritional versatility of this filamentous bacterium.

PHYSIOLOGICAL CHARACTERIZATION OF ADAPTIVE CLONES IN EVOLVING POPULATIONS OF THE YEAST, SACCHAROMYCES CEREVISIAE

Genetics ◽  
1985 ◽  
Vol 110 (2) ◽  
pp. 173-185
Author(s):  
Julian Adams ◽  
Charlotte Paquin ◽  
Paul W Oeller ◽  
Lester W Lee
Keyword(s):  
Glucose Uptake ◽  
Continuous Culture ◽  
Growth Parameters ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Yeast Saccharomyces Cerevisiae ◽  
Adaptive Mutations ◽  
Physiological Characterization ◽  
Evolving Populations

ABSTRACT Populations of a diploid strain of S. cerevisiae were grown in glucose-limited continuous culture for more than 260 generations. A series of seven sequential adaptive changes were identified by monitoring the frequency of cycloheximide resistance in these populations. Samples were taken from the continuous cultures following each adaptive shift and characterized physiologically to determine (1) the range of phenotypes that can be selected in a precisely defined constant environment and (2) the order and predictability of the occurrence of the adaptive mutations in evolving populations. The clones were characterized with respect to the growth parameters, maximum growth rate, saturation coefficient and yield, as well as for changes in cell size and geometry and rate of glucose uptake. The maximum growth rates of the seven adaptive clones were very similar, but in contrast the saturation coefficients differed substantially. Surprisingly, not all clones showed reductions in the saturation coefficients, in comparison to the immediately preceding clones, as would be predicted from classical continuous culture kinetics. In addition, yield estimates first increased and then decreased for later isolated adaptive clones. In general, the results suggest epistatic interactions between the adaptive clones, consistent with earlier published results. The rate of glucose uptake, as measured by 14Cxylose uptake, increased dramatically after the selection and fixation of seven adaptive clones. Progressive decreases in cell volume and changes in cell geometry, resulting in increased surface area to volume ratios, were also observed in the adaptive clones, but these changes were not always seen in other haploid and diploid yeast populations evolving under the same conditions. Such changes may be easily explainable in terms of the characteristics of the glucose-limited environment. The significance of the results to the evolution of microorganisms under nutrient-limiting conditions is discussed.

Modelling of the growth of a methanotrophic biofilm

1997 ◽  
Vol 36 (1) ◽  
pp. 199-204 ◽  
Author(s):  
Jean-Pierre Arcangeli ◽  
Erik Arvin
Keyword(s):  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Maximum Growth ◽  
Product Formation ◽  
Maximum Growth Rate ◽  
Influential Factors ◽  
Yield Coefficient ◽  
Biofilm Growth ◽  
Half Saturation Constant ◽  
Biofilm Structure

A model describing the growth of a methanotrophic biofilm is presented. This model involves simultaneous growth of methanotrophs, heterotrophs and nitrifiers. Heterotrophic biomass grows on soluble polymers which arise from the hydrolysis of dead biomass entrapped in the biofilm. Nitrifiers develop because of the presence of ammonia in the mineral medium. A comparison of this model with experimental data showed that the biofilm growth, methane removal, oxygen consumption, product formation and biofilm detachment could be fitted well. Parameter estimation yielded a maximum growth rate for methanotrophs, μm, of 1.17 ± 0.2 d−1, at 20°C, a decay rate, bm, of 0.34 ± 0.06 d−1, a half-saturation constant, KS(CH4), of 0.08 ± 0.05 mg CH4/l, and a yield coefficient, YCH4, of 0.21 ± 0.03 g X COD/g CH4 COD. In addition, a sensitivity analysis has been performed for this model. It indicated that the most influential factors were those related to the biofilm (i.e. density; solid volume fraction; thickness). This suggests that in order to improve the model, further research is needed in the field of biofilm structure and composition.

scholarly journals Characterization of Listeria monocytogenes Originating from the Spanish Meat-Processing Chain

Foods ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 542 ◽  
Author(s):  
Rosa Capita ◽  
Amanda Felices-Mercado ◽  
Camino García-Fernández ◽  
Carlos Alonso-Calleja
Keyword(s):  
Listeria Monocytogenes ◽  
Clinical Importance ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Meat Processing ◽  
Hygiene Practices ◽  
Adhesion Ability ◽  
Listeria Ivanovii ◽  
Good Hygiene

Using agglutination techniques, 118 Listeria monocytogenes isolates from red meat and poultry were serotyped. Strains were ascribed to the serotypes 4b/4e (44.1% of the strains), 1/2 (a, b or c; 28.0%), 4c (6.8%), 4d/4e (5.9%) and 3 (a, b or c; 2.5%). Among these are the serotypes most frequently involved in cases of human listeriosis. The susceptibility of 72 strains to 26 antibiotics of clinical importance was determined by disc diffusion (Clinical and Laboratory Standards Institute; CLSI). High levels of resistance were observed to cefoxitin (77.8% of the strains showed resistance), cefotaxime (62.5%), cefepime (73.6%), and nalidixic acid (97.2%), nitrofurantoin (51.4%) and oxacillin (93.1%). Less than 3% of the strains showed resistance to the antibiotic classes used in human listeriosis therapy (i.e., ampicillin, gentamicin, rifampicin, chloramphenicol, enrofloxacin, vancomycin, trimethoprim-sulfamethoxazole, erythromycin, and tetracycline). The influence of species and serotype on the growth kinetics (modified Gompertz equation) and on the adhesion ability (crystal violet staining) of nine isolates of L. monocytogenes (serotypes 1/2a, 1/2b, 1/2c, 3a, 3b, 3c, 4a, 4b, and 4d), and one strain of Listeria ivanovii were investigated. The maximum growth rate (ΔOD420-580/h) varied between 0.073 ± 0.018 (L. monocytogenes 1/2a) and 0.396 ± 0.026 (L. monocytogenes 4b). The isolates of L. monocytogenes belonging to serotypes 3a and 4a, as well as L. ivanovii, showed a greater (p < 0.05) biofilm-forming ability than did the remaining strains, including those that belong to the serotypes commonly implied in human listeriosis (1/2a, 1/2b, 1/2c and 4b). The need for training in good hygiene practices during the handling of meat and poultry is highlighted to reduce the risk of human listeriosis.

CHARACTERIZATION Of Bi-BASED WHISKERS BY THE METHOD OF Al2O3-SEEDED GLASSY QUENCHED PLATELETS

2002 ◽  
Vol 16 (28n29) ◽  
pp. 4497-4501 ◽  
Author(s):  
S. KISHIDA ◽  
H. UEMOTO
Keyword(s):  
Full Width Half Maximum ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Previous Method ◽  
Full Width ◽  
Temperature Transition ◽  
High Quality ◽  
Maximum Value ◽  
Good Crystallinity

We prepared the Bi 2 Sr 2 Ca n-1 Cu n O y (Bi-based) whiskers by the method of Al 2 O 3-seeded by the method was about 3 times larger than that by the previous method glassy quenched platelets (ASGQP). The maximum growth rate of the whiskers obtained without any Al 2 O 3 seeding. From the resistance-temperature (R-T) characteristics, we found that the temperature transition widths of the Bi-2212 and the Bi-2223 phases were about 2K and 4K, respectively. In addition, the whiskers showed that the FWHM (full-width-half-maximum) value of the (0010) XRD peak was less than 0.06°. The critical current density of the whiskers was more than 104 A/cm 2 at 60K and 0T. The results indicate that the whiskers grown by the ASGQP method have good crystallinity and high quality.

Aerobic microbial transformations of resuspended sediments in combined sewers - a conceptual model

1998 ◽  
Vol 37 (1) ◽  
pp. 69-76 ◽  
Author(s):  
Jes Vollertsen ◽  
Thorkild Hvitved-Jacobsen
Keyword(s):  
Conceptual Model ◽  
Energy Requirement ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Yield Coefficient ◽  
Microbial Transformations ◽  
Oxygen Utilisation ◽  
Maintenance Energy Requirement ◽  
Activated Sludge Processes

A methodology for characterisation and a concept for modelling of aerobic microbial transformations of resuspended sewer sediments based on long term measurements of oxygen utilisation rates (OUR's) are presented. The OUR measurements were evaluated applying a conceptual model for aerobic microbial transformations of sewer solids based on methodologies originating from description of activated sludge processes. Validation showed that yield coefficient and maximum growth rate could be considered constant when readily biodegradable substrate was added to the resuspended sewer solids during the OUR experiment. Maintenance energy requirement of the biomass was argued to be a better concept for modelling microbial transformations compared with either considering decay of biomass into hydrolysible substrate or including endogenous decay of biomass. OUR measurements are recommended as a valuable methodology for characterisation of suspended sewer sediments in terms of COD-fractions and related biotransformations.

Simulation of tertiary denitrification with methanol in an upflow biofilter

2000 ◽  
Vol 41 (4-5) ◽  
pp. 185-190 ◽  
Author(s):  
H. Horn ◽  
U. Telgmann
Keyword(s):  
Mass Transport ◽  
Filtration Rate ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Experimental Results ◽  
Yield Coefficient ◽  
Concentration Profiles ◽  
Measured Concentration ◽  
Biofilm Model ◽  
Mixed Reactor

A biofilm model for the simulation of denitrification with methanol in a 3 m high upflow biofilter is presented. This model considers mass transfer at the bulk/biofilm interface, mass transport in the liquid phase of the biofilter and mass transport and substrate utilization in the biofilm. The biofilter was run with different filtration rates between 11 and 29 m/h. The methanol dosage ranged between 2.6 and 3.8 g CH3OH/g NO3−N. The denitrification rate ranged between 1 and 4.8 kg/m3d and depended mainly on the filtration rate and the methanol dosage. To carry out a simulation, the biofilter was divided into five segments. Each segment was simulated as a totally mixed reactor tank. The experimental results were used to fit the maximum growth rate of the denitrifying bacteria and the yield coefficient for the process growth in the simulation. The simulation of nitrate and COD concentration in the effluent matches very well the experimental results even when the filtration rate changed. It was also possible to simulate the measured concentration profiles in the biofilter with the presented model.

scholarly journals Determination of kinetic parameters of a lab-scale upflow anaerobic sludge blanket reator (uasb) removing organic loading from swine manure effluents

2005 ◽  
Vol 29 (5) ◽  
pp. 1045-1051 ◽  
Author(s):  
Cláudio Milton Montenegro Campos ◽  
Bruno Botelho Saléh ◽  
Fernanda Ribeiro do Carmo
Keyword(s):  
Kinetic Parameters ◽  
Swine Manure ◽  
Oxygen Demand ◽  
Kinetic Studies ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Yield Coefficient

The present work aimed at determining and evaluating the kinetic parameters from the UASB reactor treating swine manure effluent in a lab-scale experiment. The research was carried out in the Laboratory of Water Analysis at the Engineering Department (LAADEG) at the campus of Federal University of Lavras - UFLA. The system was assembled with an acidification and equalization tank (AET), an UASB reactor and an aerated facultative pond (AFP). The hydraulic retention time (HRT) adopted in the UASB reactor were: 55; 39; 34; 24; 17; and 16 hours. The operational average temperature in the UASB reactor was 25 ± 2ºC. The kinetic studies used the following parameters: Chemical Oxygen Demand (COD T), Total Volatile Solids (TVS), Temperature, Flowrate and Total Solids Profile (TVS P), in the reactor, and the number of analyses were: 72; 72; 250; 250; and 30, respectively. The frequency was twice a week for COD T, and TVS, and daily for temperature and flowrate. The kinetic parameters determined were: yield coefficient Y=0.3046 to 0.4231mg COD T mgTVS-1.d-1, decay coefficient Kd=0.0125 to 0.0173d-1, maximum growth rate coefficient ìmax=0.2835 to 0.03938d-1 and limiting substrate concentration coefficient Ks= 51.70 to 71.80mg COD T.L-1. The values found were within the range appointed in the specific literatures and were determined based on linear regression studies, giving in this way, a technical scientific support to the physical chemical operational data collected during the operational research period.

MORPHOLOGICAL AND BIOCHEMICAL RESPOSES OF COW PEA (CV. PUSA BARSATI) GROWN ON FLY ASH AMENDED SOIL IN PRESENCE AND ABSENCE OF MELOIDOGYNE JAVANICA AND RHIZOBIUM LEGUMINOSARUM

1970 ◽  
Vol 17 ◽  
pp. 17-22 ◽  
Author(s):  
Kamal Singh ◽  
A. A. Khan ◽  
Iram Khan ◽  
Rose Rizvi ◽  
M. Saquib
Keyword(s):  
Fly Ash ◽  
Plant Growth ◽  
Rhizobium Leguminosarum ◽  
Growth Yield ◽  
Maximum Growth ◽  
Meloidogyne Javanica ◽  
Growth And Yield ◽  
Negative Effects ◽  
Positive Effects ◽  
Insignificant Difference

Plant growth, yield, pigment and protein content of cow-pea were increased significantly at lower levels (20 and 40%) of fly ash but reverse was true at higher levels (80 and 100%). Soil amended by 60% fly ash could cause suppression in growth and yield in respect to 40% fly ash treated cow-pea plants but former was found at par with control (fly ash untreated plants). Maximum growth occurred in plants grown in soil amended with 40% fly ash. Nitrogen content of cow-pea was suppressed progressively in increasing levels of fly ash. Moreover,  Rhizobium leguminosarum  influenced the growth and yield positively but Meloidogyne javanica caused opposite effects particularly at 20 and 40% fly ash levels. The positive effects of R. leguminosarum were marked by M. javanica at initial levels. However, at 80 and 100% fly ash levels, the positive and negative effects of R. leguminosarum and/or M. javanica did not appear as insignificant difference persist among such treatments.Key words:  Meloidogyne javanica; Rhizobium leguminosarum; Fly ash; Growth; YieldDOI: 10.3126/eco.v17i0.4098Ecoprint An International Journal of Ecology Vol. 17, 2010 Page: 17-22 Uploaded date: 28 December, 2010  

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