Kinetic analyses of the effects of temperature and light intensity on growth, hydrogenm production and organic acid utilization by rhodobacter capsulatus

Sevinç, Pelin
Effects of temperature and light intensity on photofermentative hydrogen production by Rhodobacter capsulatus DSM1710 by use of acetic and lactic acids as substrates were studied. Experiments were conducted at 20, 30 and 38oC incubator temperatures under light intensities in the 1500 – 7000 lux range. pH of the medium and quantity of hydrogen forming together with quantity of biomass, and concentrations of acetic, lactic, formic, butyric and propionic acids in the medium were determined periodically. Growth took place and hydrogen was produced under all experimental conditions. Growth was found to increase with increase in temperature but to decrease with increase in light intensity. Total hydrogen produced increased with light intensity up to 6000 lux at 20oC, 5000 lux at 30oC and 3000 lux at 38oC and decreased beyond these values. Medium temperature of about 30oC was found to be optimum for cumulative hydrogen. pH was found to increase slightly and almost all of lactic acid and most of acetic acid was consumed while formic, butyric and propionic acids were first formed and then consumed in the experiments. Growth data fitted well to the logistic model and hydrogen production data fitted well to the Modified Gompertz Model. Lactic acid was found to be almost completely consumed by first order kinetics in early times. Consumption of acetic acid was found to follow zero order kinetics in the early times when lactic acid existed in the system but the order shifted to one later when most of lactic acid was consumed.


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Tamer, I.M.; Özilgen , Mustafa; Ungan, Suat (Elsevier BV, 1988-12)
The kinetics of riboflavin production by Saccharomyces cerevisiae and Saccharomyces carlsbergensis in synthetic media and wort were studied. The results indicated that riboflavin was produced by growing cells only. Riboflavin production rate was proportional to growth rate of the yeasts in the exponential phase. Riboflavin was depleted in the stationary phase. The depletion rate was expressed with a first-order kinetic expression in yeast concentration. The kinetics of substrate utilization and ethanol prod...
BOZOGLU, F; OZILGEN, M; BAKIR, U (Elsevier BV, 1987-09-01)
Survival kinetics of lactic acid starter cultures were modeled considering the microorganism and external medium interfacial area as the critical factors determining the resistance of the microorganisms to freeze-drying. Surviving fraction of the microorganisms increased with the increasing biomass concentration during freeze-drying, and this is attributed to the mutual shielding effect of the microorganisms against the severe conditions of the external medium. Survival of the microorganisms over the storag...
Molecular cloning and co-expression of Thermoplasma volcanium proteasome subunit genes
Kocabıyık, Semra; Zwickl, Peter; Ozdogan, Seda (Elsevier BV, 2010-10-01)
In this study we describe, the construction of a co-expression vector allowing simultaneous production of Thermoplasma volcanium 20S proteasome alpha- and beta-subunits in Escherichia coli. This heterologous expression system provided high level production of fully active 205 proteasome that can be purified easily by using a conventional two-step chromatographic technique. The recombinant proteasome was purified to homogeneity 12-fold with a specific activity of 26.5 U/mg. Sodium dodecyl sulfate-polyacrylam...
OZILGEN, M (Springer Science and Business Media LLC, 1988-12-01)
Large amounts of data indicated that most of the metabolic processes of the acidogenic (acid producing) and the solventogenic (solvent producing) fermentations were regulated by product accumulation. A simple unstructured model simulated microbial growth, product formation and substrate utilization in six different fermentations, where five different microorganisms produced various combinations of ten different products. Specific growth rates of these microorganisms decreased proportionally with overall pro...
Comparison of benzaldehyde lyase production capacity in recombinant Escherichia coli and recombinant Bacillus species
Kaya, Hande; Çalık, Pınar; Department of Chemical Engineering (2006)
In this study, the benzaldehyde lyase (BAL, EC production in E. coli BL21 (DE3) pLySs as intracellular and in Bacillus species as extracellular were investigated, and comparison of the production capacity of the enzyme in the developed recombinant microorganisms were compared. For this purpose, firstly, PCR amplified bal gene was cloned into pRSETA vector which is under the control of strong T7 promoter and expressed in E. coli BL21 (DE3) pLysS strain. With developed recombinant E. coli BL21 (DE3)...
Citation Formats
P. Sevinç, “Kinetic analyses of the effects of temperature and light intensity on growth, hydrogenm production and organic acid utilization by rhodobacter capsulatus,” M.S. - Master of Science, Middle East Technical University, 2010.