Aromatic amino acid synthesis performance of bacillus acidocaldarius

Kocabaş, Pınar
In this study, the effects of bioprocess operation parameters on aromatic amino acid synthesis performance of Bacillus acidocaldarius were investigated. Firstly, in laboratory scale shake-bioreactors, a defined medium was designed in terms of its carbon and nitrogen sources, to achieve the highest cell concentration. Thereafter, the effects of bioprocess operation parameters, i.e., pH and temperature were investigated; and the optimum medium contained (kg m-3): fructose, 8; (NH4)2HPO4, 5; CaCl2, 0.2; KH2PO4, 2; NaH2PO4.2H2O, 7.318; Na2HPO4, 0.0438; Mg(CH3COO)2.4H2O, 87₉10-3 ; 1 , MgSO4.7H2O; 2₉10-3, FeSO4.7H2O; 2₉10-3, ZnSO4.7H2O; 15 ₉10-5, MnSO4.H2O; 2₉10-5, CuSO4.5H2O with pH0 =5, T=55?C, N=175 min-1. In this medium, the bacteria produced L-tryptophan at the highest concentration of 0.204 kg m-3 and L-phenylalanine at a maximum concentration of 0.0106 kg m-3 with no L-tyrosine production. Finally the fermentation and oxygen transfer characteristics of the bioprocess were investigated in 3.0 dm3 pilot scale bioreactors. The effects of oxygen transfer were investigated at four different conditions at the parameters air inlet rates of QO/VR =0.2, and 0.5 vvm, and agitation rates of N= 250, 500, 750 min-1. The effect of pH was investigated at pH=5 uncontrolled and controlled operations. The variations in cell, fructose, amino acid and organic acid concentrations with the cultivation time; and using the dynamic method, the oxygen uptake rate and the liquid phase mass transfer coefficient values throughout the growth phase of the bioprocess; the yield and maintenance coefficients were determined. The aromatic amino acids produced at the highest and the least amount and frequency were L-tryptophan and L-tyrosine, respectively. The highest L-tryptophan production, 0.32 kg m-3 in 17 hour was at 0.2 vvm and 500 min-1. Among all operations, the highest L-tryptophan was


KOCABIVIK, S; PERLIN, MH (Elsevier BV, 1994-01-01)
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Özdoğan, Nizamettin; Özdoğan, Nizamettin; Department of Biochemistry (2007)
This study was designed to investigate the cytotoxic and antioxidative properties of Aesculus hippocastanum L. (A. hippocastanum) bark extracts. Dried and powdered barks were extracted in ethanol, methanol, water and ethylacetate at a ratio of 1:6 (w/v). Antioxidative capacity of each extract (ethanol, methanol, water and ethylacetate) were determined by their ability to scavenge 1, 1 -diphenyl-2-picryl-hydrazyl radical (DPPH). Effective concentration (EC50) values were calculated as 0.010 mg/mL 0.011 mg/mL...
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In the polyol pathway, Aldose reductase (AR) is an important enzyme in reduction of aldehydes and aldosugars to their suitable alcohols. AR, using NADPH as a coenzyme, has a molecular weight of 37 000 dalton. AR in its activated form, known to increase the sorbitol accumulation in lens, is responsible for the cataract formation in diabetis diseases. Therefore, the inhibition of aldose reductase is important to prevent the incedence of cataract formation in diabetus mellitus. In the treatment of diabetis dep...
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Interactions of simvastatin with zwitterionic dipalmitoyl phosphotidylcholine (DPPC) multilamellar liposomes were investigated as a function of temperature and simvastatin concentration. And acyl chain length effect on the simvastatin-model membrane interactions was monitored with DPPC and dimyristoyl phosphotidylcholine (DMPC) lipids. All studies were carried out by two non-invasive techniques, namely Fourier transform infrared (FTIR) spectroscopy, and differential scanning calorimetry (DSC). The results s...
Citation Formats
P. Kocabaş, “Aromatic amino acid synthesis performance of bacillus acidocaldarius,” M.S. - Master of Science, Middle East Technical University, 2004.