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

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.

Nitrification Kinetics in Activated Sludge with Both Suspended and Attached Biomasses

1994 ◽  
Vol 29 (7) ◽  
pp. 181-184 ◽  
Author(s):  
P. Chudoba ◽  
M. Pannier
Keyword(s):  
Activated Sludge ◽  
Aeration Tank ◽  
Continuous Systems ◽  
Biomass Growth ◽  
Batch Tests ◽  
Activated Sludge System ◽  
Nitrification Kinetics ◽  
Kinetic Tests ◽  
Suspended Biomass ◽  
Kinetics Of

A series of nitrification kinetic tests was carried out with both suspended and fixed biomasses originated from a combined activated sludge system with a plastic support for biomass growth introduced into the aeration tank (Experimental combined unit - ECU). The results of these batch tests were compared with kinetics calculated from continuously run pilot plant. It was concluded that nitrification kinetics of both suspended and attached biomasses were similar and, consequently, it was assumed that the percentage of autotrophs is the same in both biomasses. The kinetics determined in both batch and continuous systems were comparable. Kinetic constants measured for suspended biomass of the ECU were higher than those reported by the literature, which was attributed to an overaeration of the ECU and an energetic mixing

Biodegradation kinetics of 1,4-benzoquinone in batch and continuous systems

2011 ◽  
Vol 22 (6) ◽  
pp. 1087-1093 ◽  
Author(s):  
Pardeep Kumar ◽  
Mehdi Nemati ◽  
Gordon A. Hill
Keyword(s):  
Continuous Systems ◽  
Biodegradation Kinetics ◽  
Kinetics Of

Kinetics of Hydrocracking of Coal Extract with Molten Zinc Chloride Catalysts in Batch and Continuous Systems

1969 ◽  
Vol 8 (4) ◽  
pp. 546-551 ◽  
Author(s):  
Robert T. Struck ◽  
William E. Clark ◽  
Philip J. Dudt ◽  
William A. Rosenhoover ◽  
Clyde W. Zielke ◽  
...  
Keyword(s):  
Zinc Chloride ◽  
Continuous Systems ◽  
Molten Zinc ◽  
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.

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