Bioprocess parameters and oxygen transfer characteristics in beta-lactamase production by Bacillus species.
ABSTRACT After screening potential beta-lactamase producers in a medium containing penicillin G, an inducible (Bacillus subtilis NRS 1125) and a constitutive (Bacillus licheniformis 749/C ATCC 25972) beta-lactamase producer were selected. As the highest enzyme activity was obtained with B. licheniformis 749/C, the effects of the concentration of carbon sources, i.e., glucose, fructose, sucrose, citric acid, and glycerol, and nitrogen sources, i.e., (NH(4))(2)HPO(4), NH(4)Cl, yeast extract, casamino acids and peptone, pH, and temperature on beta-lactamase production were investigated with B. licheniformis 749/C in laboratory scale bioreactors. Among the investigated media, the highest volumetric activity was obtained as 270 U cm(-)(3) in the medium containing 10.0 kg m(-)(3) glucose, 1.18 kg m(-)(3) (NH(4))(2)HPO(4), 8.0 kg m(-)(3) yeast extract, and the salt solution at 32 degrees C and pH(0) = 6.0. By using the designed medium, fermentation and oxygen transfer characteristics of the bioprocess were investigated at V = 3.0 dm(3) bioreactor systems with a V(R) = 1.65 dm(3) working volume at Q(O)/V(R) = 0.5 vvm and N = 500 min(-1). At the beginning of the process the Damköhler number was <1, indicating that the process was at biochemical reaction limited condition; at t = 2-5 h both mass-transfer and biochemical reaction resistances were effective; and at t = 6-10 h (Da >1) the bioprocess was at mass transfer limited condition. Overall oxygen transfer coefficients (K(L)a) varied between 0.01 and 0.03 s(-)(1), enhancement factor (K(L)a/K(L)a(O)) varied between 1.2 and 2.3, and volumetric oxygen uptake rate varied between 0.001 and 0.003 mol m(-)(3) s(-)(1) throughout the bioprocess. The specific oxygen uptake and the specific substrate consumption rates were the highest at t = 2 h and then decreased with the cultivation. The maximum yield of cells on substrate and the maximum yield of cells on oxygen values were obtained, respectively, as Y(X/S) = 0.34 and Y(X/O) = 1.40, at t = 5 h, whereas the highest yield of substrate on oxygen was obtained as Y(S/O) = 6.94 at t = 3.5 h. The rate of oxygen consumption for maintenance and the rate of substrate consumption for maintenance values were found, respectively, as m(O) = 0.13 kg kg(-)(1) h(-)(1) and m(S) = 3.02 kg kg(-)(1) h(-)(1).
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ABSTRACT: Purpose: The aim of the present study was to investigate the most suitable value of volumetric mass transfer coefficient for the maximum yield of alkaline protease by B. licheniformis UV-9. Material and Methods: The effects of various aeration (0.5 to 2.5vvm) and agitation rates (300-700 rpm) on cell growth, glucose consumption and protease production by B. licheniformis UV-9 were studied in a 2 L stirred tank bioreactor. Volumetric mass transfer coefficient values were measured by dynamics gassing-out techniques at each aeration and agitation rate. Results and Conclusion: Maximum cell biomass (3.41 g/L) and protease yield (1270.20 PU/mL) were obtained at aeration rate of 2 vvm and agitation speed of 500 rpm. Volumetric mass transfer coefficient and oxygen transfer rate were found to be highly dependent on aeration and agitation rates. Their volumes in the fermented broth increased with the increase of aeration and/or agitation rates. However, the values of kinetic parameters were found maximum at 72 h-1 of volumetric mass transfer coefficient and 3.90 mol m-3 h-1 of oxygen transfer rate, corresponding to 2 vvm and 500 rpm. This correlation of volumetric mass transfer coefficient and yield coefficients would be used as an instructive tool in scale up process of protease production.Turkish Journal of Biochemistry 01/2009; 34(2):89-96.
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ABSTRACT: Safety issues related to the employment of synthetic colorants in different industrial segments have increased the interest in the production of colorants from natural sources, such as microorganisms. Improved cultivation technologies have allowed the use of microorganisms as an alternative source of natural colorants. The objective of this work was to evaluate the influence of some factors on natural colorants production by a recently isolated from Amazon Forest, Penicillium purpurogenum DPUA 1275 employing statistical tools. To this purpose the following variables: orbital stirring speed, pH, temperature, sucrose and yeast extract concentrations and incubation time were studied through two fractional factorial, one full factorial and a central composite factorial designs. The regression analysis pointed out that sucrose and yeast extract concentrations were the variables that influenced more in colorants production. Under the best conditions (yeast extract concentration around 10 g/L and sucrose concentration of 50 g/L) an increase of 10, 33 and 23% respectively to yellow, orange and red colorants absorbance was achieved. These results show that P. purpurogenum is an alternative colorants producer and the production of these biocompounds can be improved employing statistical tool.Brazilian journal of microbiology : [publication of the Brazilian Society for Microbiology]. 01/2014; 45(2):731-42.