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1.
Kenneth M. Bischoff Siqing Liu Timothy D. Leathers Ronald E. Worthington Joseph O. Rich 《Biotechnology and bioengineering》2009,103(1):117-122
The emergence of antibiotic‐resistant bacteria may limit the effectiveness of antibiotics to treat bacterial contamination in fuel ethanol plants, and therefore, new antibacterial intervention methods and tools to test their application are needed. Using shake‐flask cultures of Saccharomyces cerevisiae grown on saccharified corn mash and strains of lactic acid bacteria isolated from a dry‐grind ethanol facility, a simple model to simulate bacterial contamination and infection was developed. Challenging the model with 108 CFU/mL Lactobacillus fermentum decreased ethanol yield by 27% and increased residual glucose from 6.2 to 45.5 g/L. The magnitude of the effect was proportional to the initial bacterial load, with 105 CFU/mL L. fermentum still producing an 8% decrease in ethanol and a 3.2‐fold increase in residual glucose. Infection was also dependent on the bacterial species used to challenge the fermentation, as neither L. delbrueckii ATCC 4797 nor L. amylovorus 0315‐7B produced a significant decrease in ethanol when inoculated at a density of 108 CFU/mL. In the shake‐flask model, treatment with 2 µg/mL virginiamycin mitigated the infection when challenged with a susceptible strain of L. fermentum (MIC for virginiamycin ≤2 ppm), but treatment was ineffective at treating infection by a resistant strain of L. fermentum (MIC = 16 ppm). The model may find application in developing new antibacterial agents and management practices for use in controlling contamination in the fuel ethanol industry. Biotechnol. Bioeng. 2009;103: 117–122. Published 2008 Wiley Periodicals, Inc. 相似文献
2.
Heléne Sundström Fredrik Wållberg Erika Ledung Bo Norrman Christopher J. Hewitt Sven-Olof Enfors 《Biotechnology letters》2005,26(19):1533-1539
In Escherichia coli fermentation processes, a drastic drop in viable cell count as measured by the number of colony forming units per ml (c.f.u. ml–1) is often observed. This phenomenon was investigated in a process for the production of the recombinant fusion protein, promegapoietin (PMP). After induction, the number of c.f.u. ml–1 dropped to 10% of its maximum though the biomass concentration continued to increase. Flow cytometric analysis of viability and intracellular concentration of PMP showed that almost all cells were alive and contributed to the production. Thus, the drop in the number of c.f.u. ml–1 probably reflects a loss of cell division capability rather than cell death. 相似文献
3.
4.
Srinivas Ramisetti Hyun Ah Kang Sang Ki Rhee Chul Ho Kim 《Biotechnology and Bioprocess Engineering》2003,8(3):183-186
The artificial gene coding for anticoagulant hirudin was placed under the control of theGAL10 promoter and expressed in the galactokinase-deficient strain (Δgal1) ofSaccharomyces cereivisiae, which uses galactose only as a gratuitous inducer in order to avoid its consumption. For efficient production of recombinant
hirudin, a carbon source other than galactose should be provided in the medium to support growth of the Δgal1 strain. Here we demonstrate the successful use of glucose in the fed-batch fermentation of the Δgal1 strain to achieve efficient production of recombinant hirudin, with a yield of up to 400 mg hirudin/L. 相似文献
5.
Bacterial contaminants ofHeliothis virescens (F.) influenced the development ofMicroplitis croceipes (Cresson). Among the four bacterial species studied, the most virulent wasPseudomonas maltophilia Hugh and Ryschenkow followed byBacillus subtilis (Ehrenberg) Cohn. Both bacteria caused severe mortality in all stages ofMicroplitis tested.Microplitis larvae were less susceptible toEscherichia coli (Migula) Castellani and Chalmers andLeuconostoc mesenteroides (Tsenkovskii) van Thieghem than toB. subtilis andP. maltophilia. AlthoughE. coli did not affect the number of cocoons produced, adult emergence was lower than in controls. Longevity of adultMicroplitis exposed to bacterially contaminated honey-water was greatly reduced in all bacterial treatments.
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6.
The optimization of culture conditions for the bacteriumPseudomonas aeruginosa BYK-2 KCTC 18012P, was performed to increase its rhamnolipid production. The optimum level for carbon, nitrogen sources,
temperature and pH, for rhamnolipid production in a flask, were identified as 25 g/L fish oil, 0.01% (w/v) urea, 25 and pH
7.0, respectively. Optimum conditions for batch culture, using a 7-L jar fermentor, were 200 rpm of agitation speed and a
2.0 L/min aeration rate. Under the optimum conditions, on fish oil for 216 h, the final cell and rhamnolipid concentrations
were 5.3 g/L and 17.0 g/L respectively. Fed-batch fermentation, with different feeding conditions, was carried out in order
to increase, cell growth and rhamnolipid production by thePseudomonas aeruginosa, BYK-2 KCTC 18012P. When 2.5 g of fish oil and 100 mL basal salts medium, containing 0.01% (w/v) urea, were fed intermittently
during the fermentation, the final cell and rhamnolipid concentrations at 264 h, were 6.1 and 22.7 g/L respectively. The fed-batch
culture resulted in a 1.2-fold increase in the dry cell mass and a 1.3-fold increase in rhamnolipid production, compared to
the production of the batch culture. The rhamnolipid production-substrate conversion factor (0.75 g/g) was higher than that
of the batch culture (0.68 g/g). 相似文献
7.
8.
Fed-batch fermentation of Lactobacillus lactis for hyper-production of l-lactic acid 总被引:8,自引:0,他引:8
A fed-batch fermentation of Lactobacillus lactis to produce l-lactic acid was developed in which the residual glucose concentration in the culture was used to control a continuous feeding strategy. Up to 210 g l-lactic acid l–1 (97% yield) was obtained. The maximal dry cell was 2.7 g l–1 and the average l-lactic acid productivity was 2.2 g l–1 h–1. 相似文献
9.
G. Amin S. Alotaibi Narmen A. Youssef W. D. Saleh 《World journal of microbiology & biotechnology》2008,24(11):2465-2471
In an attempt to develop a cost-effective process for bioinsecticide production by B. thuringiensis, the feeding regime during aerobic cultivation of the bacterium was investigated and optimized. The process was designed
as a two-stage process; a first stage of active growth, where glucose and other nutrients were adequately supplied to the
growing cells over 12 h, followed by a second stage of 2 h for spore formation and toxin release. In order to maximize spore
and toxin yield and productivity, different quantities of glucose and nutrients were fed separately to the growing cells in
four different fermentation runs. In all runs, glucose was converted to bacterial biomass during the first stage and subsequently
to spores and crystal protein during the second phase. The best results were obtained with a fermentation run supplied with
190 g glucose in 1500 ml. Up to 20.1 g of bacterial insecticides/l were recovered from fermentation broth with a glucose to
toxin conversion yield of 0.159 g/g. Also, a markedly high spore concentration of 2.31 × 1012 c.f.u./ml was obtained. The spore–crystal protein mixture obtained was tested for its insecticidal activity against three
of the most agronomically important pests. Among the bioinsecticide-treated insect pests, Egyptian cotton leafworm, Spodoptera littoralis was the most susceptible pest with the lowest LC50 of the bioinsecticides against its larval instar and the highest virulence against adults emerged later on from the surviving
larvae. 相似文献
10.
W. Borzani 《World journal of microbiology & biotechnology》1996,12(4):415-416
The efficiency of ethanol yield increased from 61% to 88% of the theoretical value as the filling-up time was approached in fed-batch fermentation with Saccharomyces cerevisiae. Temporary accumulation of ethanol within the yeast cells may explain the above variation.The author is with the Instituto Mauá de Tecnologia, Estrada das Lágrimas 2035, 09580-900. Sao Caetano Do Sul, SP, Brazil 相似文献
11.
Propionibacterium acidipropionici was grown in a fed-batch culture, fed with glucose or lactate, or mixtures of lactate and glucose. Lactate and glucose were always simultaneously consumed. As co-substrate, glucose modified the propionate:acetate molar ratio (P/A) and increased the fraction of carbon used for biomass production. A P/A of 7.63 was obtained with a lactate:glucose molar ratio of 4; a P/A value of 1.34 was obtained with lactate alone and 1.85 with glucose alone. The fraction of carbon recovered in biomass was 0.09 for glucose, 0.12 for lactate, and 0.21 for a lactate:glucose molar ratio of 4. 相似文献
12.
Kurtanjek Z 《Biotechnology and bioengineering》1991,37(9):814-823
Presented is a new simple method for multidimensional optimization of fed-batch fermentations based on the use of the orthogonal collocation technique. Considered is the problem of determination of optimal programs for fermentor temperature, substrate concentration in feed, feeding profile, and process duration. By reformulation of the state and control variables is obtained a nonsingular form of the optimization problem which has considerable advantage over the singular case since a complicated procedure for determination of switching times for feeding is avoided. The approximation of the state variables by Lagrange polynomials enables simple incorporation of split boundary conditions in the approximation, and the use of orthogonal collocations provides stability for integration of state and costate variables. The interpolation points are selected to obtain highest accuracy for approximation of the objective functional by the Radau-Lobatto formula. The control variables are determined by optimization of the Hamiltonian at the collocation points with the DFP method. Constraints are imposed on state and control variables.The method is applied for a homogeneous model of fermentation with volume, substrate, biomass, and product concentrations as the state variables. Computer study shows considerable simplicity of the method, its high accuracy for low order of approximation, and efficient convergence. 相似文献
13.
Hasan B. Coban Paul H. Patterson Ryan J. Elias 《Preparative biochemistry & biotechnology》2016,46(2):157-160
Phenylpyruvic acid is a deaminated form of phenylalanine and is used in various areas such as development of cheese and wine flavors, diagnosis of phenylketonuria, and to decrease excessive nitrogen accumulation in the manure of farm animals. However, reported phenylpyruvic acid fermentation studies in the literature have been usually performed at shake-flask scale with low production. In this study, phenylpyruvic acid production was evaluated in bench-top bioreactors by conducting fed-batch and continuous fermentation for the first time. As a result, maximum phenylpyruvic acid concentrations increased from 1350 mg/L (batch fermentation) to 2958 mg/L utilizing fed-batch fermentation. Furthermore, phenylpyruvic acid productivity was increased from 48 mg/L/hr (batch fermentation) to 104 and 259 mg/L/hr by conducting fed-batch and continuous fermentation, respectively. Overall, this study demonstrated that fed-batch and continuous fermentation significantly improved phenylpyruvic acid production in bench-scale bioreactor production. 相似文献
14.
Weiying Mao Renrui Pan David Freedman 《Journal of industrial microbiology & biotechnology》1992,11(1):1-6
Summary High production (9016 U/ml) of alkaline protease byBacillus licheniformis has been achieved. A 49% increase in production was achieved by the method used as compared with a batch process. By using a synthetic medium and a fed-batch operation controlled by the Advanced Fermentation Software (AFS) package, it was found that the keys to high production of protease are: (i) to maintain a low concentration of glucose (<0.43 g/l) in the medium; (ii) to control pH at a certain level (pH 6.50) in the culture; and (iii) to use rough type colonies as the starting culture. Our fed-batch fermentation process successfully simulates and surpasses ordinary batch fermentation processes. By using ammonium sulfate instead of soy bean flour as the only nitrogen source, an expected benefit was the elimination of unpleasant odors caused by natural organic nitrogenous components in the media. This would improve the industrial production environment. 相似文献
15.
Converti A Arni S Sato S de Carvalho JC Aquarone E 《Biotechnology and bioengineering》2003,84(1):88-95
Simplified modeling based on material balances for biomass, ethanol and substrate was used to describe the kinetics of fed-batch alcohol fermentation of sugarcane blackstrap molasses. Maintenance requirements were previously shown to be of particular significance in this system, owing to the use of massive inoculum to minimize inhibitions; therefore, they were taken into consideration for kinetic modeling. Average values of biomass and ethanol yields, productivities, and substrate consumption rates, calculated at the end of runs performed either at constant or exponentially varying flow rates, demonstrated that all of these parameters were influenced by the initial sugar-feeding rate, F(o)S(o). Under conditions of substrate shortage (F(o)S(o) = 300 g(S) h(-1)), the amount of carbon dioxide produced was higher than that corresponding to the stoichiometry of sucrose fermentation to ethanol, indicating that an appreciable fraction of the carbon source was likely consumed by respiration. Besides, the biomass yields either on substrate, Y(X/S), or ethanol, Y(X/E), as well as the product yield on substrate, Y(E/S), notably decreased. These results are in agreement with the relatively high specific rate of anaerobic substrate consumption for maintenance estimated for this system (m(a) (s) = 0.789 g(S) g(X) (-1) h(-1)), which was responsible for the consumption of more than 70% of the fed carbon source. The proposed equations derived from the Monod model proved to be a useful tool to easily predict the performance of this process. 相似文献
16.
The effect of treatment of Lactobacillus fermentum with several protein- and carbohydrate-modifying reagents on the bacterium's ability to flocculate Saccharomyces cerevisiae was investigated. The proteinaceous nature of the cell-surface components of L. fermentum which are responsible for floc formation was confirmed by inactivation of floc formation following photo-irradiation, with Methylene Blue or Rose Bengal as sensitizer, or acylation with acetic anhydride, maleic anhydride or acetylimidazole, and by the reaction of the components with nitrous acid, I2 and performic acid.The phenolic hydroxyl group of tyrosine and the indole group of tryptophan appear essential for flocculation. Proteinaceous components of the yeast cell surface and carbohydrate components on the bacterial cell surface were not required for flocculation but carbohydrate residues on the yeast surface were essential. 相似文献
17.
A cellular automata model to simulate penicillin fed-batch fermentation process (CAPFM) was established in this study, based
on a morphologically structured dynamic penicillin production model, that is in turn based on the growth mechanism of penicillin
producing microorganisms and the characteristics of penicillin fed-batch fermentation. CAPFM uses the three-dimensional cellular
automata as a growth space, and a Moore-type neighborhood as the cellular neighborhood. The transition rules of CAPFM are
designed based on mechanical and structural kinetic models of penicillin batch-fed fermentation processes. Every cell of CAPFM
represents a single or specific number of penicillin producing microorganisms, and has various state. The simulation experimental
results show that CAPFM replicates the evolutionary behavior of penicillin batch-fed fermentation processes described by the
structured penicillin production kinetic model accordingly.
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Translated from ACTA BIOPHYSICA, 2005, 21(2) [译自: 生物物理学报, 2005,21(2)] 相似文献
18.
A cellular automata model to simulate penicillin fed-batch fermentation process(CAPFM)was established in this study,based on a morphologically structured dynamic penicillin production model,that is in turn based on the growth mechanism of penicillin producing microorganisms and the characteristics of penicillin fed-batch fermentation.CAPFM uses the three-dimensional cellular automata as a growth space,and a Moore-type neighborhood as the cellular neighborhood.The transition roles of CAPFM are designed based on mechanical and structural kinetic models of penicillin batch-fed fermentation processes.Every cell of CAPFM represents a single or specific number of penicillin producing microorganisms,and has various state.The simulation experimental results show that CAPFM replicates the evolutionary behavior of penicillin batch-fed fermentation processes described by the structured penicillin production kinetic model accordingly. 相似文献
19.
Kim JH Han KC Koh YH Ryu YW Seo JH 《Journal of industrial microbiology & biotechnology》2002,29(1):16-19
Xylitol, a functional sweetener, was produced from xylose by biological conversion using Candida tropicalis ATCC 13803. Based on a two-substrate fermentation using glucose for cell growth and xylose for xylitol production, fed-batch
fermentations were undertaken to increase the final xylitol concentration. The effects of xylose and xylitol on xylitol production
rate were studied to determine the optimum concentrations for fed-batch fermentation. Xylose concentration in the medium (100
g l−1) and less than 200 g l−1 total xylose plus xylitol concentration were determined as optimum for maximum xylitol production rate and xylitol yield.
Increasing the concentrations of xylose and xylitol decreased the rate and yield of xylitol production and the specific cell
growth rate, probably because of an increase in osmotic stress that would interfere with xylose transport, xylitol flux to
secretion to cell metabolism. The feeding rate of xylose solution during the fed-batch mode of operation was determined by
using the mass balance equations and kinetic parameters involved in the equations in order to increase final xylitol concentration
without affecting xylitol and productivity. The optimized fed-batch fermentation resulted in 187 g l−1 xylitol concentration, 0.75 g xylitol g xylose−1 xylitol yield and 3.9 g xylitol l−1 h−1 volumetric productivity. Journal of Industrial Microbiology & Biotechnology (2002) 29, 16–19 doi:10.1038/sj.jim.7000257
Received 15 October 2001/ Accepted in revised form 30 March 2002 相似文献