Bioprocess Parameters and Oxygen Transfer Characteristics in β-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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- "Experimental designs to produce natural colorants It is known that metabolite production by microorganisms is largely influenced by the medium compounds, such as carbon and nitrogen sources, physicochemical factors , such as pH, temperature, inoculum size, stirring intensity and incubation time (Oh et al., 2000; Celik and Calik, 2004; Mapari et al., 2005). In previous work (Santos- Ebinuma et al., 2013b) different carbon (glucose, fructose, sucrose, maltose and starch) and nitrogen (malt extract, ammonium sulfate, peptone, yeast extract and tryptone) sources was evaluated in order to produce natural colorants by submerged culture of P. purpurogenum and sucrose and yeast extract were the more suitable sources. "
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 08/2014; 45(2):731-42. DOI:10.1590/S1517-83822014000200049 · 0.45 Impact Factor
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- "These enzymes are widely used not only in chemical and medical industries but also in food and basic biological sciences . It is well known that extracellular protease production in microorganisms was greatly influenced by medium components, especially carbon and nitrogen sources, physical factors, such as pH, temperature, inoculum size, orbital agitation speed and incubation time  . "
ABSTRACT: Culture conditions (pH, time, temperature, inoculum size, orbital agitation speed and substrate concentration) for an extracellular collagenase produced by Candida albicans URM3622 were studied using three experimental designs (one 26−2 fractionary factorial and two 23 full factorial). The analysis of the 26−2 fractionary design data indicated that agitation speed and substrate concentration had the most significant effect on collagenase production. Based on these results, two successive 23 full factorial design experiments were run in which the effects of substrate concentration, orbital agitation speed and pH were further studied. These two sets of experiments showed that all variables chosen were significant for the enzyme production, with the maximum collagenolytic activity of 6.8 ± 0.4 U achieved at pH 7.0 with an orbital agitation speed of 160 rpm and 2% substrate concentration. Maximum collagenolytic activity was observed at pH 8.2 and 45 °C. The collagenase was stable within a pH range of 7.2–8.2 and over a temperature range of 28–45 °C. These results clearly indicate that C. albicans URM3622 is a potential resource for collagenase production and could be of interest for pharmaceutical, cosmetic and food industry.Biochemical Engineering Journal 03/2009; 43(3-43):315-320. DOI:10.1016/j.bej.2008.10.014 · 2.37 Impact Factor
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- "The effect of oxygen transfer has been studied in different biosystems (Çelik and Çalik, 2004; Elibol and Ozer, 2000; Tang and Zhong, 2003), but in acetic fermentation the effects of oxygen concentration have only been considered in the context of bacterial growth (Park et al., 1991; Romero et al., 1994). However, it is well known that a failure in oxygen supply can dramatically reduce cell population viability (Drysdale and Fleet, 1989; Muraoka et al., 1982). "
ABSTRACT: The production of vinegar in an aerated-stirred reactor was modelled using a hybrid approach. The growth rate was modelled according to the total biomass specific growth rate, μgν, which represents the growth of an active biophase and the fraction of cells which are growing. A quadratic model based on the process variables, i.e. hydrostatic pressure, ethanol concentration, aeration, agitation and temperature, was developed for μgν and the substrate and product kinetics were related mechanistically to the growth rate, including the kinetics of acetoin and ethyl acetate production. This model was coupled with the models for oxygen transfer and gas–liquid transfer, reported in a previous study, and the prediction capacity of the system of equations was validated by simulating semi-continuous and continuous real processes developed in a pilot fermentor.Journal of Food Engineering 03/2009; 91(2):183-196. DOI:10.1016/j.jfoodeng.2008.08.028 · 2.58 Impact Factor