Formation of Biofilms on Small Suspended Particles in Airlift Reactors

1992 ◽  
Vol 26 (9-11) ◽  
pp. 2015-2019 ◽  
Author(s):  
L. Tijhuis ◽  
L. P. M. van der Pluym ◽  
M. C. M. van Loosdrecht ◽  
J. J. Heijnen
Keyword(s):  
Growth Rate ◽  
Dilution Rate ◽  
Biofilm Formation ◽  
New Technologies ◽  
Loading Rate ◽  
Specific Growth ◽  
Waste Water Treatment ◽  
Maximum Specific Growth Rate ◽  
Biofilm Development ◽  
Micro Organisms

To overcome the current problems of waste water treatment systems new technologies have to be developed. A promising system is the Biofilm Airlift Suspension-reactor. The aim of these experiments was to determine the effect of dilution rate and acetate loading rate on the early stages of biofilm development in BAS-reactors. During biofilm development bacteria colonize the carrier surface at specific sites in the form of microcolonies which gradually grow out to a full biofilm. Biofilm formation only occurs if the dilution rate is greater than the maximum specific growth rate of the micro-organisms. The yield of biomass on substrate might decrease with decreasing growth rate. More than 95% of the biomass production in the biofilm is transferred by detachment processes to the liquid phase and washed out of the reactor. To elucidate the mechanisms of this detachment processes more experiments are needed.

scholarly journals Elucidating the competition between heterotrophic denitrification and DNRA using the resource-ratio theory

2019 ◽  
Author(s):  
Mingsheng Jia ◽  
Mari K.H. Winkler ◽  
Eveline I.P. Volcke
Keyword(s):  
Growth Rate ◽  
Organic Carbon ◽  
Dilution Rate ◽  
Nitrate Reduction ◽  
Specific Growth ◽  
Nitrogen Loss ◽  
Maximum Specific Growth Rate ◽  
Comprehensive Understanding ◽  
Continuous Cultures ◽  
Heterotrophic Denitrification

AbstractDenitrification and dissimilatory nitrate reduction to ammonium (DNRA) are two microbial processes competing for nitrate and organic carbon (COD). Their competition has great implications for nitrogen loss, conservation, and greenhouse gas emissions. Nevertheless, a comprehensive and mechanistic understanding of the governing factors for this competition is still lacking. We applied the resource-ratio theory and verified it with competition experiments of denitrification and DNRA reported in the literature. Based on this theory, we revealed how COD/N ratio, influent resource concentrations, dilution rate, and stoichiometric and kinetic parameters individually and collectively define the boundaries for different competition outcomes in continuous cultures. The influent COD/N ratio alone did not drive competition outcome as the boundary COD/N ratio for different competition outcomes changed significantly with influent resource concentrations. The stoichiometry of the two processes was determinative for the boundaries, whereas the affinity for the resources (Ks), maximum specific growth rate (μmax) of the two species and the dilution rate had significant impacts as well but mainly at low influent resource concentrations (e.g., <100 μM nitrate). The proposed approach allows for a more comprehensive understanding of the parameters controlling microbial selection and explains apparently conflicting experimental results. The results from this model also provide testable hypotheses and tools for understanding and managing the fate of nitrate in ecosystems and for other species that compete for two resources.

CONTINUOUS CULTURE OF BRUCELLA ABORTUS S.19

1961 ◽  
Vol 7 (4) ◽  
pp. 491-505 ◽  
Author(s):  
Andreas H. W. Hauschild ◽  
Hilliard Pivnick
Keyword(s):  
Growth Rate ◽  
Continuous Culture ◽  
Dilution Rate ◽  
Brucella Abortus ◽  
Specific Growth ◽  
Limiting Factor ◽  
Continuous Growth ◽  
Viable Cells ◽  
Metabolic Products ◽  
Growth Of Bacteria

An apparatus is described for the continuous growth of bacteria. Brucella abortus S.19 has been grown in continuous culture for periods up to 3 weeks with populations up to 2 × 1011viable cells per ml and without the establishment of nonsmooth variants.Concentrations between 3 × 109and 2 × 1011cells per ml could be maintained as a function of the dilution rate without the requirement of a known limiting factor in the medium. In a series of steady-state conditions, the specific growth rate increased steadily up to 0.28 hour−1with decreasing population levels.Incidence of mutants was governed by the dilution rate and could also be reduced by various chelating substances.In continuous growth combined with continuous dialysis, population levels were approximately twice those obtained in continuous growth without dialysis. The effect of dialysis appears to be the continuous removal of growth-limiting metabolic products.

E-beam irradiation affects the maximum specific growth rate ofBacillus cereus

2012 ◽  
Vol 48 (2) ◽  
pp. 382-386 ◽  
Author(s):  
Juan Aguirre ◽  
Mª Rosa Rodríguez ◽  
Rodrigo González ◽  
Gonzalo García de Fernando
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Specific Growth ◽  
Maximum Specific Growth Rate ◽  
Beam Irradiation ◽  
Ofbacillus Cereus

Maximum specific growth rate of anammox bacteria revisited

2017 ◽  
Vol 116 ◽  
pp. 296-303 ◽  
Author(s):  
Lei Zhang ◽  
Yuko Narita ◽  
Lin Gao ◽  
Muhammad Ali ◽  
Mamoru Oshiki ◽  
...  
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Specific Growth ◽  
Maximum Specific Growth Rate ◽  
Anammox Bacteria

Evolution of Escherichia coli During Growth in a Constant Environment

Genetics ◽  
1987 ◽  
Vol 116 (3) ◽  
pp. 349-358
Author(s):  
Robert B Helling ◽  
Christopher N Vargas ◽  
Julian Adams
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Specific Growth Rate ◽  
Continuous Culture ◽  
Specific Growth ◽  
Maximum Specific Growth Rate ◽  
Constant Environment ◽  
Single Clone ◽  
Mixed Populations

ABSTRACT Populations of Escherichia coli, initiated with a single clone and maintained for long periods in glucose-limited continuous culture, developed extensive polymorphisms. In one population, examined after 765 generations, two majority and two minority types were identified. Stable mixed populations were reestablished from the isolated strains. Factors involved in the development of this polymorphism included differences in the maximum specific growth rate and in the transport of glucose, and excretion of metabolites by some clones which were utilized by minority clones.

scholarly journals Anaplerotic reactions active during growth of Saccharomyces cerevisiae on glycerol

2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Joeline Xiberras ◽  
Mathias Klein ◽  
Celina Prosch ◽  
Zahabiya Malubhoy ◽  
Elke Nevoigt
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Growth Rate ◽  
Specific Growth Rate ◽  
Pyruvate Carboxylase ◽  
Reference Strain ◽  
Specific Growth ◽  
Glyoxylate Cycle ◽  
Maximum Specific Growth Rate ◽  
The Glyoxylate Cycle ◽  
Anaplerotic Reactions

ABSTRACT Anaplerotic reactions replenish TCA cycle intermediates during growth. In Saccharomyces cerevisiae, pyruvate carboxylase and the glyoxylate cycle have been experimentally identified to be the main anaplerotic routes during growth on glucose (C6) and ethanol (C2), respectively. The current study investigates the importance of the two isoenzymes of pyruvate carboxylase (PYC1 and PYC2) and one of the key enzymes of the glyoxylate cycle (ICL1) for growth on glycerol (C3) as a sole carbon source. As the wild-type strains of the CEN.PK family are unable to grow in pure synthetic glycerol medium, a reverse engineered derivative showing a maximum specific growth rate of 0.14 h−1 was used as the reference strain. While the deletion of PYC1 reduced the maximum specific growth rate by about 38%, the deletion of PYC2 had no significant impact, neither in the reference strain nor in the pyc1Δ mutant. The deletion of ICL1 only marginally reduced growth of the reference strain but further decreased the growth rate of the pyc1 deletion strain by 20%. Interestingly, the triple deletion (pyc1Δ pyc2Δ icl1Δ) did not show any growth. Therefore, both the pyruvate carboxylase and the glyoxylate cycle are involved in anaplerosis during growth on glycerol.

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