scholarly journals Disintegration Kinetics of Microbial Cells

10.5772/60797 ◽  
2015 ◽  
Author(s):  
Marek Solecki ◽  
Monika Solecka
Keyword(s):  
Microbial Cells ◽  
Kinetics Of

scholarly journals Growth Kinetics of Suspended Microbial Cells: From Single-Substrate-Controlled Growth to Mixed-Substrate Kinetics

1998 ◽  
Vol 62 (3) ◽  
pp. 646-666 ◽  
Author(s):  
Karin Kovárová-Kovar ◽  
Thomas Egli
Keyword(s):  
Growth Kinetics ◽  
Kinetic Data ◽  
Carbon Sources ◽  
Microbial Cells ◽  
Mixed Substrate ◽  
Single Substrate ◽  
Pure Cultures ◽  
Defined Culture ◽  
Kinetics Of ◽  
Substrate Kinetics

SUMMARY Growth kinetics, i.e., the relationship between specific growth rate and the concentration of a substrate, is one of the basic tools in microbiology. However, despite more than half a century of research, many fundamental questions about the validity and application of growth kinetics as observed in the laboratory to environmental growth conditions are still unanswered. For pure cultures growing with single substrates, enormous inconsistencies exist in the growth kinetic data reported. The low quality of experimental data has so far hampered the comparison and validation of the different growth models proposed, and only recently have data collected from nutrient-controlled chemostat cultures allowed us to compare different kinetic models on a statistical basis. The problems are mainly due to (i) the analytical difficulty in measuring substrates at growth-controlling concentrations and (ii) the fact that during a kinetic experiment, particularly in batch systems, microorganisms alter their kinetic properties because of adaptation to the changing environment. For example, for Escherichia coli growing with glucose, a physiological long-term adaptation results in a change in KS for glucose from some 5 mg liter−1 to ca. 30 μg liter−1. The data suggest that a dilemma exists, namely, that either “intrinsic” KS (under substrate-controlled conditions in chemostat culture) or μmax (under substrate-excess conditions in batch culture) can be measured but both cannot be determined at the same time. The above-described conventional growth kinetics derived from single-substrate-controlled laboratory experiments have invariably been used for describing both growth and substrate utilization in ecosystems. However, in nature, microbial cells are exposed to a wide spectrum of potential substrates, many of which they utilize simultaneously (in particular carbon sources). The kinetic data available to date for growth of pure cultures in carbon-controlled continuous culture with defined mixtures of two or more carbon sources (including pollutants) clearly demonstrate that simultaneous utilization results in lowered residual steady-state concentrations of all substrates. This should result in a competitive advantage of a cell capable of mixed-substrate growth because it can grow much faster at low substrate concentrations than one would expect from single-substrate kinetics. Additionally, the relevance of the kinetic principles obtained from defined culture systems with single, mixed, or multicomponent substrates to the kinetics of pollutant degradation as it occurs in the presence of alternative carbon sources in complex environmental systems is discussed. The presented overview indicates that many of the environmentally relevant apects in growth kinetics are still waiting to be discovered, established, and exploited.

Comparison of Capillary and Test Tube Procedures for Analysis of Thermal Inactivation Kinetics of Mold Spores

2000 ◽  
Vol 63 (10) ◽  
pp. 1404-1409 ◽  
Author(s):  
HIROSHI FUJIKAWA ◽  
SATOSHI MOROZUMI ◽  
GLEN H. SMERAGE ◽  
ARTHUR A. TEIXEIRA
Keyword(s):  
Aspergillus Niger ◽  
Kinetic Analysis ◽  
Thermal Inactivation ◽  
Test Tube ◽  
Inactivation Kinetics ◽  
Microbial Cells ◽  
Inactivation Kinetic ◽  
Kinetics Of ◽  
Linear Decline ◽  
Heating Medium

Characteristics of capillary and test tube procedures for thermal inactivation kinetic analysis of microbial cells were studied for mold spores. During heating, capillaries were submerged in a water bath and test tubes were held with their caps positioned above the level of the heating medium. Thermal inactivation curves of Aspergillus niger spores in capillaries at around 60°C consisted of a shoulder and a fast linear decline, whereas curves in test tubes consisted of a shoulder, a fast linear decline, and a horizontal tail. There were no significant differences in values of the rate and the delay of fast declines in curves between the procedures. Some experiments were done to clarify the cause for tailing with test tubes. There were no tails with test tubes whose inner walls were not contaminated by A. niger spores, suggesting that tails arise from A. niger spores contaminating the inner walls of test tubes. Temperature of the inner wall at the level of a heating medium was lower than that of the medium. Further, there were no tails for test tubes submerged in the heating medium. These results showed that the reason for survival of contaminants on the upper wall of test tubes was that cells were not subjected to sufficient inactivation temperature. Finally, thermal inactivation curves of A. niger spores in capillaries at various constant temperatures were studied. Curves consisted of a shoulder and a fast linear decline at 57°C and above, whereas curves at below 57°C consisted of a shoulder, a fast linear decline, and a sloping tail.

Kinetics of atrazine biodegradation by suspended and immobilized mixed microbial cells cultivated in continuous systems

2009 ◽  
Vol 84 (7) ◽  
pp. 982-991 ◽  
Author(s):  
Angélica Tafoya-Garnica ◽  
Alberto Macías-Flores ◽  
Nora Ruiz-Ordaz ◽  
Cleotilde Juárez-Ramírez ◽  
Juvencio Galíndez-Mayer
Keyword(s):  
Continuous Systems ◽  
Microbial Cells ◽  
Kinetics Of

Use of non-thermal atmospheric plasmas to reduce the viability ofBacillus subtilison spacecraft surfaces

2008 ◽  
Vol 7 (1) ◽  
pp. 47-57 ◽  
Author(s):  
Andrew C. Schuerger ◽  
Steven Trigwell ◽  
Carlos I. Calle
Keyword(s):  
Short Exposure ◽  
Inactivation Kinetics ◽  
Atmospheric Pressure Glow Discharge ◽  
Microbial Cells ◽  
Atmospheric Plasmas ◽  
Pressure Glow Discharge ◽  
The Common ◽  
Properties Of Materials ◽  
Physical Degradation ◽  
Kinetics Of

AbstractAtmospheric pressure glow-discharge (APGD) plasmas have been proposed for sterilizing spacecraft surfaces prior to launch. The advantages of APGD plasmas for the sterilization of spacecraft surfaces include low temperatures at treatment sites, rapid inactivation kinetics of exposed microbial cells, physical degradation and removal of microbial cells, physical removal of organic biosignature molecules, and short exposure times for the materials. However, few studies have tested APGD plasmas on spacecraft materials for their effectiveness in both sterilizing surfaces and removal of microbial cells or spores. A helium (He)+oxygen (O2) APGD plasma was used to expose six spacecraft materials (aluminum 6061, polytetrafluoroethylene (PTFE), polycarbonate, Saf-T-Vu, Rastex, and Herculite 20) doped with spores of the common spacecraft contaminant,Bacillus subtilis, for periods of time up to 6 min. Results indicated that greater than six orders of magnitude reductions in viability were observed forB. subtilisspores in as short of time as 40 s exposure to the APGD plasmas. Spacecraft materials were not affected by exposures to the APGD plasmas. However, Saf-T-Vu was the only material in which spores ofB. subtilisadhered more aggressively to plasma-treated coupons when compared to non-plasma treated coupons; all other materials exhibited no significant differences between plasma and non-plasma treated coupons. In addition, spores ofB. subtiliswere physically degraded by exposures to the plasmas beginning at the terminal ends of spores, which appeared to be ruptured after only 30 s. After 300 s, most bacteria were removed from aluminium coupons, and only subtle residues of bacterial secretions or biofilms remained. Results support the conclusion that APGD plasmas can be used as a prelaunch cleaning and sterilization treatment on spacecraft materials provided that the biocidal and cleaning times are shorter than those required to alter surface properties of materials.

Direct observations of radiation-enhanced transformations in glass

1983 ◽  
Vol 41 ◽  
pp. 354-355
Author(s):  
J. F. DeNatale ◽  
D. G. Howitt
Keyword(s):  
Glass Matrix ◽  
Diffusion Mechanism ◽  
Bubble Formation ◽  
Silicate Glasses ◽  
Phase Decomposition ◽  
Direct Observations ◽  
Thin Foils ◽  
Oxygen Bubble ◽  
Electron Energy Loss ◽  
Kinetics Of

The electron irradiation of silicate glasses containing metal cations produces various types of phase separation and decomposition which includes oxygen bubble formation at intermediate temperatures figure I. The kinetics of bubble formation are too rapid to be accounted for by oxygen diffusion but the behavior is consistent with a cation diffusion mechanism if the amount of oxygen in the bubble is not significantly different from that in the same volume of silicate glass. The formation of oxygen bubbles is often accompanied by precipitation of crystalline phases and/or amorphous phase decomposition in the regions between the bubbles and the detection of differences in oxygen concentration between the bubble and matrix by electron energy loss spectroscopy cannot be discerned (figure 2) even when the bubble occupies the majority of the foil depth.The oxygen bubbles are stable, even in the thin foils, months after irradiation and if van der Waals behavior of the interior gas is assumed an oxygen pressure of about 4000 atmospheres must be sustained for a 100 bubble if the surface tension with the glass matrix is to balance against it at intermediate temperatures.

Irradiation behavior of pyrolytic silicon carbide

1983 ◽  
Vol 41 ◽  
pp. 72-73
Author(s):  
R. J. Lauf
Keyword(s):  
Silicon Carbide ◽  
Fission Products ◽  
Thermodynamics And Kinetics ◽  
Neutron Fluences ◽  
Fuel Particles ◽  
Sic Coatings ◽  
Irradiation Behavior ◽  
Kinetics Of ◽  
Htgr Fuel

Fuel particles for the High-Temperature Gas-Cooled Reactor (HTGR) contain a layer of pyrolytic silicon carbide to act as a miniature pressure vessel and primary fission product barrier. Optimization of the SiC with respect to fuel performance involves four areas of study: (a) characterization of as-deposited SiC coatings; (b) thermodynamics and kinetics of chemical reactions between SiC and fission products; (c) irradiation behavior of SiC in the absence of fission products; and (d) combined effects of irradiation and fission products. This paper reports the behavior of SiC deposited on inert microspheres and irradiated to fast neutron fluences typical of HTGR fuel at end-of-life.

The Ordered Phase Formation in Ti-Al-Ga Alloys

1970 ◽  
Vol 28 ◽  
pp. 440-441
Author(s):  
Shiro Fujishiro ◽  
Harold L. Gegel
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Titanium Alloys ◽  
Growth Kinetics ◽  
Stoichiometric Composition ◽  
Good Potential ◽  
Alpha Titanium ◽  
Cold Rolled ◽  
Kinetics Of ◽  
Thermal Stability Of

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization

Sign in / Sign up

Export Citation Format

Share Document