PH influences intracellular reaction network of beta-lactamase producing Bacillus licheniformis

Effects of pH on metabolic flux distributions in P-lactamase producing Bacillus licheniformis were investigated using metabolic flux analysis, at pH(C) = 6.5, 7.0 and 7.5 controlled-pH conditions. The bioprocess was divided into three periods: Period I (0 < t < 6 h) is the growth phase where beta-lactamase synthesis starts; Period II (6 < t < 8 h) is the transition phase; Period III (8 < t < 12 h) is the stationary phase for the cell-growth where beta-lactamase synthesis increases. The central pathways were active for the growth and beta-lactamase synthesis throughout the bioprocess at all the conditions. In Period I, the fiuxes through the by-products were the highest at pHC = 7.0 while the lowest at pH(C) = 7.5; however, there was no significant difference between the beta-lactamase synthesis fluxes. On the other hand, in Period III the by-product and lactamase fluxes were the highest at pH(C) = 7.5 and 7.0, respectively. Based on the intracellular-reaction-network fluxes to increase beta-lactamase production further the following pH operation strategy is proposed: initial pH of the fermentation medium should be set to pH = 7.5, and pH of the medium can be let to decrease until pH = 7.0; thereafter, controlled at pH(C) = 7.0 until the end of the bioprocess.


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Çalık, Pınar; Calik, G; Ozdamar, TH (Elsevier BV, 2003-02-01)
The influence of controlled- and uncontrolled-pH conditions together with the initial pH on the product and by-product distributions and oxygen transfer characteristics, whereupon the process rate limitations in relation to the intracellular reaction rates were investigated in serine alkaline protease (SAP) fermentation process by recombinant Bacillus licheniformis carrying pHV1431::subC on a defined medium with the sole carbon source glucose in the pH range of 6.80-7.25 in batch bioreactors. Although the s...
Metabolic engineering of aromatic group amino acid pathway in Bacillus subtilis for L-phenylalanine production
Ozcelik, IS; Çalık, Pınar; Calik, G; Ozdamar, TH (Elsevier BV, 2004-11-01)
Metabolic control sites in the aromatic group amino acid pathway (AAAP) of Bacillus subtilis for L-Phenylalanine (Phe) overproduction were determined; and aiming pathway flux amplification, by cloning the flux controlling gene aroH to a multi-copy plasmid, the impact of single gene cloning on pathway flux distributions were investigated. The branch-point metabolites E4P and PEP+E4P supplied in vitro, enhanced Phe production and well defined perturbations were achieved on the AAAP reactions. The intracellula...
Bioreaction network flux analysis for human protein producing Bacillus subtilis based on genome-scale model
ÖZDAMAR, HASAN TUNÇER; Senturk, Birguel; YILMAZ, OĞUZ; KOCABAŞ, PINAR; Calik, Guezide; Çalık, Pınar (Elsevier BV, 2010-01-01)
To interpret the effect of human protein gene, e.g., human growth hormone gene hGH, on the intracellular bioreaction network of Bacillus subtilis, the intracellular reaction fluxes were calculated by solving the mass-balance-based genome-scale mathematical model, at pseudo-steady state by using bioreactor data. The bioreaction network consists of 1340 reactions including 990 metabolites. Reaction fluxes in B. subtilis carrying pMK4::pre(subC)::hGH (rBsHGH) and B. subtilis carrying merely pMK4 (rBsP) were ca...
Effect of Midsynthesis Addition of Silica to the Synthesis Medium on the Properties of MFI-Type Zeolite Membranes
Soydas, Belma; Kalıpçılar, Halil; Culfaz, Ali (American Chemical Society (ACS), 2010-06-02)
Thin zeolite membranes of MFI type were prepared on alpha-Al2O3 supports by midsynthesis addition of silica in a recirculating flow system at 95 degrees C The synthesis was started with the batch composition of 80SiO(2): 30TPAOH:1500H(2)O which was changed to 80SiO(2)center dot 9TPAOH:1500H(2)O by addition of silica Mkt 24, 48, or 72 h Compared to synthesis at constant composition. it is possible to affect the rates of nucleation and crystal growth to obtain membranes with better quality by changing the ove...
Pre-ozonation of aqueous azo dye (Acid Red-151) followed by activated sludge process
Gokcen, Fulya; Ozbelge, Tulay A. (Elsevier BV, 2006-10-15)
In this study, the efficiency of the integrated process was investigated in which the pre-ozonation step was followed by activated sludge process (ASP) in treating the aqueous Acid Red-151 (AR 151) solutions. The percent dye removal in the integrated process was found to be 47% for a pre-ozonation time of 30 min, instead of 25% in the singly ASP without pre-ozonation. The treatment efficiency of this process could be higher if the pre-ozonation time of 120 min yielding maximum enhancement of biodegradabilit...
Citation Formats
P. Çalık, “PH influences intracellular reaction network of beta-lactamase producing Bacillus licheniformis,” CHEMICAL ENGINEERING SCIENCE, pp. 5206–5211, 2007, Accessed: 00, 2020. [Online]. Available: