Continuous cultivation of Clostridium thermobutyricum in a rotary fermentor system

The growth behavior of Clostridium thermobutyricum JW171K and its production of butyric acid were investigated under continuous cultivation in a recently developed rotary fermentor. Using low dilution rates (up to 40 times the shortest doubling time), the continuous culture conditions caused metabolic shifts from butyrate formation to the production of acetate. Using an 18-h volumetric retention time, no true steady state in butyrate formation was achieved after 22 days, although the optical density was stable. Acetate and butyrate were formed in an oscillatory mode with an alternating predominance between these two products, indicating an oscillation between the less exergonic acetate-forming but higher ATP (4ATP mol⁻¹ glucose) forming mode, and the more exergonic butyrate and 3ATP mol⁻¹ glucose forming mode. During the continuous culture drastic changes in cell morphology occurred and, at the lower dilution rates, long, granulose-containing, filamentous cells with rounded protuberances and swellings were observed. A maximal butyrate concentration of 18.4 g L⁻¹ and a productivity of about 2.4 g L⁻¹ per h (at 25–27 mM concentration in the broth) were obtained. Journal of Industrial Microbiology & Biotechnology (2000) 24, 7–13. Received 26 April 1999/ Accepted in revised form 16 August 1999     

The production of mycobacterial antigens by homogeneous culture in a fermentor

Mycobacterium bovis strain BCG, substrain 1173P2, has been grown in homogeneous culture in classical synthetic Sauton medium without supplementary ingredients. The culture conditions are described. The protein release in the culture medium and the tuberculin yield after 2% trichloroacetic acid precipitation were significantly improved. The antigenicity of the tuberculin has been successfully assayed on specifically sensitized guinea-pigs. It is concluded that homogeneous mycobacterium culture in a fermentor using synthetic medium is a suitable method for the large scale production of antigen.     

Continuous production of extracellular protease by Bacillus subtilis in a two-stage fermentor

Growth and protease production of Bacillus subtilis in semisynthetic and synthetic media were studied in batch culture and in a two-stage, laboratory scale, continuous fermentor. The amount, of extracellular protease production was measured under specific growth conditions in both stages of the ferment or. At the dilution rates employed, the cells in the first stage of the ferment or produced negligible quantities of protease, and the culture primarily functioned as a continuous inoculum for the second stage of the fermentor. The culture effluent from the second stage of the fermentor contained extracellular protease, on the average, equal to 60 per cent, of the activity that had been found in the supernatant of a 48-hr batch culture grown in a medium having the same composition as that in the continuous fermentor. Extracellular protease was produced in semisynthetic medium by B. subtilis in the two-stage fermentor for as long as 20 days without culture degeneration. Additional studies indicated that continuous protease production could also be achieved in a synthetic medium. The RNA/ protein ratios of cells grown in semisynthetic medium in batch culture and in each stage of the two-stage fermentor were examined. There was a positive correlation between the amount of protease produced by the cells and their RNA/ protein ratio. Techniques employed for continuous production of protease by B. subtilis and the potential use of the method for investigating the control of secondary metabolite synthesis are discussed.     

Continuous production of ethanol by yeast "immobilized" in a membrane-contained fermentor

A dialysate-feed, immobilized-cell dialysis continuous fermentation system was investigated as a method of relieving product inhibition in the conversion of glucose to ethanol by cells of Saccharomyces cerevisiae ATCC 4126. The substrate was fed into a continuous dialysate circuit and then into a batch fermentor circuit via diffusion through the microporous membranes of an intermediate dialyzer. Simultaneously, product was withdrawn from the fermentor circuit through the dialyzer membranes into the dialysate circuit and out in the effluent. Since the fermentor was operated without an effluent, the cells essentially were immobilized and converted substrate to product by maintenance metabolism. Contrary to prior results with this novel system for the continuous fermentation of lactose to lactate by lactobacillus cells, a steady state of yeast cells in the fermentor did not occur initially but was obtained by the depletion of medium nitrogen and the prevention of cell breakage, although the substrate and product concentrations then became unsteady. The inherent advantages of the system was offset in the ethanol fermentation by relatively low productivity, which appeared to be limited by membrane permeability.     

Continuous production of monoclonal antibody with immobilized hybridoma cells in an expanded bed fermentor

Summary Continuous production of monoclonal antibody was achieved in serum-free medium by hybridoma cells immobilized by calcium alginate. The cells were cultivated in an expanded bed fermentor under mild flow conditions which reduced destruction of the immobilized gel particles. Monoclonal antibody was produced continuously for more than 40 days.     

球孢白僵菌固态罐发酵产孢培养的研究

建立了一套两升圆柱体玻璃发酵罐的固态通风培养装置及通风系统。以球孢白僵菌Bb371为生产菌,培养基220g(82％麸皮 4．5％黄豆粉 4．5％玉米粉 9％稻壳)作为生产原料,接种30ml,23℃培养温度下,分阶段调节通风量和空气湿度,培养5d,产孢量可达到116亿／g干培养基。     

Recombinant production of anti-HIV protein, griffithsin, by auto-induction in a fermentor culture

Griffithsin (GRFT) is a novel anti-HIV protein isolated from the red alga Griffithia sp. The potent anti-viral activity of GRFT against both laboratory and primary isolates of HIV at picomolar concentrations makes this protein an attractive candidate microbicide to prevent sexual transmission of HIV. Here, we describe the recombinant production and purification of a biologically active hexa-histidine-tagged GRFT (His-GRFT) from Escherichia coli. To facilitate a large-scale production of recombinant His-GRFT, we tested different expression conditions to optimize the expression in the cytoplasm of E. coli to increase the overall production of soluble His-GRFT. Attempts to express His-GRFT in shake flask cultures resulted in a modest yield of soluble His-GRFT, with a large accumulation of the protein in inclusion bodies. The use of a fermenter and of a rich, auto-inducing medium allowed the total amount of His-GRFT per liter to be increased by about 45-fold, with approximately 70% of the protein expressed in the soluble fraction. N-terminal sequencing and MALDI-TOF analyses of the recombinant His-GRFT confirmed that the initial methionine residue was cleaved off. Recombinant His-GRFT showed equivalent activity with natural GRFT, both in respect to gp120-binding characteristics as well as anti-HIV activity. Size-exclusion chromatography analysis showed that both native GRFT and recombinant His-GRFT existed as homodimers in solution. The expression system described in this work provides a basis for the mass production of GRFT to allow further studies of the protein and investigation of therapeutic and preventive strategies against HIV.     

Continuous culture of photobacterium

The design and performance characteristics of a small volume (20 ml) continuous culture device for the cultivation of luminous bacteria are described. This simply constructed device can be used to supply luminescent bacteria with constant properties for either laboratory use or the assay of environmental pollutants. Furthermore, bacteria can be deployed to make sensitive (<1 nM) oxygen measurements. The culture device may be configured, alone or in combination, as a chemostat, turbidostat or a "bioluminostat" where bacterial bioluminescence becomes the controlling variable. Over extended periods (>1 week) it was possible to maintain steady-state luminescence within 5% of a pre-set value, although occasionally a non-bioluminescent "mutant" became dominant; in this case light emission was irreversibly lost. A secondary chamber provided additional flexibility and easy manipulation of the cultivated bacteria for testing. The continuous culture system is also suitable for the growth of recombinant microorganisms that either constitutively express luciferase, or do so in response to stress promoter activity. The non-standard control methodologies reported may have important research and industrial applications, for example in providing immediate process control or as an inferential method to optimize biomass: product yield ratios.     

Continuous culture of Thiorhodaceae

Summary In sulfide limited continuous culture of a marine isolate of Chromatium vinosum, sulfide was undetectable in steady states below dilution rates of 0.06h^-1, that is 1/2 of the maximum specific growth rate. In the same range, sulfur is assumed to attain the role of the growth rate limiting substrate. Furthermore, it could be shown that the rate of sulfur oxidation is a function of the surface area of the sulfur globules rather than of the sulfur concentration. In completely filled chemostats, steady states were obtainable only at dilution rates not exceeding 0.09 h^-1. In the presence of a nitrogen flushed gas phase, steady states were obtained at dilution rates approaching the maximum specific growth rate (0.12h^-1). This phenomenon is ascribed to the particular sulfide tolerance of our strain of Chromatium vinosum. The saturation constant and the inhibition constant (lowest, respectively highest total sulfide concentration at which the specific growth rate is equal to one-half of the maximum specific growth rate in the absence of inhibition) were 0.007 mM and 0.85 mM, respectively.The ecological significance of the data is discussed.Contribution No. 2406 from the Woods Hole Oceanographic Institution.     

Continuous high rate production of ethanol by Zymomonas mobilis in an attached film expanded bed fermentor

Summary Experiments were conducted with Zymomonas mobilis in an attached film expanded bed (AFEB) fermentor at different dilution rates, using a feed glucose concentration of 100 gm/l. Vermiculite was used as the bed material for attachment of the bacterial film. Ethanol volumetric productivities were maximum at a dilution rate of 3.6hr^-1. The productivities were 105 gm/l-hr and 210 gm/l-hr based on total fermentor volume and bed volume, respectively.     

Effect of volume of culture medium on enhanced citric acid productivity by a mutant culture of Aspergillus niger in stirred fermentor

AIMS: The present study deals with the effect of volume of culture medium on enhanced citric acid productivity by a mutant culture of Aspergillus niger. METHODS AND RESULTS: A laboratory scale stirred fermentor of 15-l capacity was employed for all microbial cultivations. Blackstrap molasses, a by-product of sugar industries is easily and abundantly available for its exploitation as a carbon source in fermentation processes. The parental culture of A. niger was improved by mutation using ultraviolet radiations and N-methyl N-nitro N-nitroso guanidine, i.e. mutagen MNNG. Six MUV and eight MNNG-treated mutant strains were isolated after extensive screening and optimization. Mutant strain of A. niger MNNG-2 showed enhanced citric productivity (87.60 g l-1) over the parental strain BTL-45 (19.53 g l-1) and other mutant derivatives (49.85 g l-1 citric acid in case of mutant MUV-5 and 76.82 g l-1 in case of mutant MNNG-7). The optimal sugar level was found to be 150 g l-1 (optimum volume of the medium, 60%) after 6 days of inoculation, which is economically significant. Specific productivity of the mutant culture MNNG-2 (qp = 0.057 g/g cells h-1) was several folds higher than other strains. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of the present study are of commercial level. All kinetic parameters including yield coefficients and volumetric rates revealed the hyper-producibility of citric acid by mutant MNNG-2 using blackstrap molasses as the basal medium in stirred fermentor.     

Enhanced catalase synthesis by a novel combined system of photocatalytic reactor and fermentor

A novel combined system of a photocatalytic reactor, with UV and titanium dioxide as photocatalyst, and a fermentor with Bacillus sp. F26 as catalase producer was developed. Production of catalase was enhanced by 14% to 18.5 U ml⁻¹ without affecting cell growth.Nomenclature q_s: specific glucose consumption rate; μ: specific growth rate; q_p: specific CAT production rate     

Vortex behavior in the waldhof fermentor

This is the first part of a systematic study on the mechanisms of the Waldhof fermentor. When an agitator is rotating in a liquid, a vortex will develop on the surface. Air is dispersed into the liquid when the vortex is deep enough to reach the agitator. This is the basic mechanism of air dispersion in a Waldhof fermentor. In this work, experimental results, empirical correlations, and theoretical equations were obtained to relate the vortex depth to a number of physical factors including agitator diameter, agitator speed, tank diameter, liquid depth, liquid viscosity, and so on. The vortex depth was found a function of both Reynolds number and Froude Number.     

Continuous synchronous culture of Tetrahymena pyroformis

Tetrahymena was continuously cultivated in a series of stirred tank reactors with recycle. By holding part of the reactor train at a higher temperature than the remainder a synchronizing influence was introduced into the cells' environment. The system resulted in division occurring preferentially in a small contiguous group of the reactors, this effect being observed in both the number of cells found in each reactor and also their size distribution.