Monitoring of glucose in fermentation processes using a commercial glucose analyser

Summary A commercial glucose analyzer, originally designed for monitoring of blood glucose in patients, was tested for use in fermentation processes. The system operates in such a way that the measured value is updated every 90 seconds. The measuring range of the system is 0–5 g glucose/l and the accuracy is ±7%. The response time was found to be approximately 6 min. The system was used to follow fermentations with two different microorganisms, Saccharomyces cerevisiae and Escherichia coli in media containing up to 5 g/l of glucose. The performance was fully satisfactory and the values had a very good correlation with off-line analyses.     

End products and fermentation balances for lactic streptococci grown aerobically on low concentrations of glucose.

Maximum acetate produced aerobically by Streptococcus diacetilactis and Streptococcus cremoris was 14% of 1 to 7 mumol of glucose/ml in a partially defined medium that contained lipoic acid. Y (glucose) values were 35.3 (S. diacetilactis) and 31.4 (S. cremoris) with low concentrations (1 to 7 mumol/ml) of glucose in the medium and 21 (S. diacetilactis) with higher concentrations (6 to 15 mumol/ml). Y (adenosine 5'-triphosphate) values for the bacteria, determined by taking into account the end products produced, were 15.6 and 13.9 for S. diacetilactis and S. cremoris, respectively, in the partially defined medium containing 1 to 7 mumol of glucose/ml and higher (21.5 and 18.9, respectively) in a complex medium that contained 2 mumol of glucose/ml. Addition of citrate in addition to glucose did not result in higher molar growth yields.     

Power requirement in non-newtonian fermentation broth

Power requirements in the agitation of non-Newtonian fermentation broths with and without aeration were measured by a strain gage-type dynamometer. Broth from the production of gluc-amylase by Endomyces species and carboxymethyl cellulose solutions were used as non-Newtonian fluids. In gas–liquid agitation systems, the correlation between P_g and P₀² ND³/Q^0.56 observed by Michel and Miller was found to be applicable to non-Newtonian fluids in laminar and transition regions. This was particularly true for fluids with apparent viscosities larger than 300 cp. The impeller diameter and impeller blade width had considerable effects on power consumption in a nongassed system. It was suggested, therefore, that P_g/P₀ should be correlated by a dimensionless term involving some impeller-size factors.     

Rapid estimation of glucose and amylase in fermentation culture broth with test strips by reflectance photometry

Summary The applicability of clinical multilayer test strips based on dry reagent chemistries for the quantitative analysis of fermentation media constituents was evaluated. For glucose and amylase determinations a significant correlation to conventional wet chemical methods was obtained. Bacterial biomass in the range of 0.5–5 g/l has no interfering effect. It is a rapid and cost-effective method for fermentation process monitoring and control.     

On-line evaluation of fermentation broth colour

Summary A novel method for evaluating pigment production during fermentation ofMonascus ruber has been developed and consists of reflectance measurement with a 10° observer under an artificial illuminant. A spectrophotometer was adapted to measure pigmentation during culture in a bioreactor. The lightness parameter L was the most useful information delivered by this sensor. An absorbency over 30 units at 480nm on batch cultures was estimated on-line without dilution. member of the GR Automatique - SARTA - CNRS     

黄原胶发酵液纯化精制研究

溶剂法直接提取的黄原胶产品含有大量菌体蛋白和色素杂质,总氮含量高、透明度差、色泽暗深。通过中性蛋白酶处理发酵液,使成品含氮量下降５６．５％;通过Ｎａ２ＳＯ３漂白液,使产品色泽大为改善。实验得出最佳酶解条件：发酵液稀释１倍,温度４４℃、ｐＨ７,加酶量１００ｕ／ｇ发酵液,作用时间２．５ｈ;最佳Ｎａ２ＳＯ３漂白条件：温度２０￣３０℃,ｐＨ５￣６,Ｎａ２ＳＯ３用量为１％（ｗ／ｗ）,作用时间１￣１．５ｈ。     

HPLC-ELSD法测定发酵液中L-精氨酸含量

建立了一种快速、准确的高效液相色谱-蒸发光散射检测法(HPLC-ELSD)测定发酵液中L-精氨酸含量。采用Prevail C18色谱柱(C18 5μm,250×4.6 mm,Alltech),以5 mmol.L-1七氟丁酸(三氟乙酸调pH至1.0)和乙腈为流动相,采用梯度洗脱,总流速为1.0 mL/min。ELSD参数:漂移管温度为117.0℃,载气流速为3.2 L/min。L-精氨酸等氨基酸的回收率为96%~104%。能够快速、精确测定发酵样品中目的产物L-精氨酸与其它氨基酸含量。     

Downstream processing of pullulan from fermentation broth

pullulan, a water soluble extracellular polysaccharide, was produced by downstream fermentation employing the strain Aureobasidium pullulans. To obtain pure biopolymer from the fermentation broth, it is necessary to harvest cells, heat the broth, remove the melanin pigments co-produced during fermentation, concentration, precipitate and dry. Centrifugation of the fermentation broth at 10,000 rpm for 15 min gave cell pellets that were discarded and a green–black supernatant containing melanin pigment was subjected to the heat treatment at 80 °C for 20 min in order to remove the protein in the fermentation broth. The supernatant was demelanized by oxidation with hydrogen peroxide, concentrated under vacuum, precipitated with ethanol and dried at 60 °C for 30 min. This procedure produced high purity pullulan that was comparable in color and texture to the commercial samples.     

Purification during crossflow electromicrofiltration of fermentation broth

The present study was to investigate the purification of a fermentation broth by an electromicrofiltration membrane. Microfiltration runs with a crude and a centrifuged broth, with solution of particles recovered from centrifugation and with permeates from microfiltration experiments were thus compared.Microfiltration performances were governed by colloids and small particles that induced sharp initial flux declines. For these results, the evolution of the overall membrane resistance was increased by 80% in comparison with the electromicrofiltration membrane. The main focus of this study was set on the enhancement of the filtrate flux by an electric field. This pressure electrofiltration leads to a drastic improvement of the filtration by 100% and the filtration time was thereby reduced. Pressure electrofiltration serves as an interesting alternative to the cross-flow filtration and it effectively separates advantageous constituents such as amino acids and biopolymers from a fermentation broth. They were equally maintained during the microelectrofiltration, although they were significantly reduced by 45% by the microfiltration without the application of an electric field. Accordingly, since the electrofiltration membrane was provided more permeability, this study experimentally demonstrates that the permeability inside a membrane can be controlled using an electric field.     

Recovery of succinic acid from fermentation broth

Succinic acid is of high interest as bio-feedstock for the chemical industry. It is a precursor for a variety of many other chemicals, e.g. 1,4-butandiol, tetrahydrofuran, biodegradable polymers and fumaric acid. Besides optimized production strains and fermentation processes it is indispensable to develop cost-saving and energy-effective downstream processes to compete with the current petrochemical production process. Various methods such as precipitation, sorption and ion exchange, electrodialysis, and liquid–liquid extraction have been investigated for the recovery of succinic acid from fermentation broth and are reviewed critically here.     

Sugaring-out extraction of acetoin from fermentation broth by coupling with fermentation

Bioprocess and Biosystems Engineering - Acetoin is a natural flavor and an important bio-based chemical which could be separated from fermentation broth by solvent extraction, salting-out...     

发酵法生产葡萄糖酸钠过程中参数检测

主要研究了发酵法生产葡萄糖酸钠过程中的各参数的变化规律,通过在线监测和离线分析检测,得出各参数的变化规律:各参数的变化均与黑曲霉的生长周期有关;发酵初期(0~5 h)各参数维持恒定;发酵期(5~16 h)溶氧、残糖质量浓度分别快速降低至30%、15 g/L;酶活、葡萄糖酸钠含量快速上涨至500 U/mL、18 g/L;发酵中后期(16~20 h)维持阶段,各参数缓慢变化;发酵结束后溶氧回升。各参数的变化规律与黑曲霉生长周期的关系研究为工厂进一步优化发酵工艺、缩短发酵周期提供原始的理论依据。     

Cross-flow membrane microfiltration of a bacteriol fermentation broth

Although cross-flow membrane filtration is a very attractive option for harvesting cells and recovering enzymes from cell homogenates, the process is not without its problems. Foremost of these is the deposit of dissolved and suspended solutes onto the membrane surface during operation. The formation of these dense and sometimes compressive sublayers (often called cakes) offers additional resistance to axial and permeate flows and often affects the retention characteristics of the process. In view of the complex nature of the sublayer formation process and its sensitivity to cross-flow velocity, this investigation was undertaken to determine the main factors responsible for the decline in performance during the harvesting of B. polymyxa broth by membrane microfiltration. System parameters varied include axial flow rate, concentration of cells, proteins and other components in the feed, membrane materials (ceramic, polypropylene, and stainless steel), and cleaning methods. To help explain the observed results, a new mass transport model-the solids flux model-based on the assumptions that back migration of particles from the sublayer or membrane surface is negligible and that particles that reach the solid-solution interface attach (stick) completely, is tested. Using a variety of diagnostic methods, magnesium ammonium phosphate precipitate is formed during steam sterilization of the medium and is implicated as the major foulant in this study.     

Characterization of peptidyl-nucleoside antifungal antibiotics from fermentation broth

Summary Characterization of sinefungin related antifungal antibiotics from fermentation broth was accomplished by coupling photodiode array (PDA) detection to high performance liquid chromatography (HPLC). From the combined HPLC-PDA evaluation of broth filtrate, we detected five sinefungin related components. Fast atom bombardment (FAB) mass spectroscopic evaluations, mass-analysed ion kinetic energy spectra (MIKES) and collision activated (CA) MIKES of these components confirmed their respective identities. Our findings from the combination of HPLC photodiode array acquisition and FAB-mass spectrometry suggest we have detected the presence of a previously unreported sinefungin analogue.     

Nutrition and broth alterations in the lactic acid fermentation

In order to optimize the thermophilic lactic acid fermentation on saccharose as the sole carbon source and improve the effectiveness of the process, alternative nitrogen sources were tested and a minimal broth composition was found. Of the alternative nitrogen sources, whey protein hydrolyzate (WPH) was the best; the broth composition was reduced from seven down to three items. Application of ammonium as a neutralizing agent instead of sodium hydroxide brought an important positive change.     

Azocasein assay for alkaline protease in complex fermentation broth

Summary An azocasein assay has been developed for determination of alkaline protease in fermentation broth from a complex substrate containing ca. 50 g/l protein which to a high degree interferes with azocasein. Methods described in the literature have been found inaccurate as results deviate ca. 50% from true activity, so one of the methods is modified in order to eliminate interference. Proportionality between the relative azocasein concentration and the deviation from true activity is found. An azocasein concentration of 350 mg azocasein per ml sample gives satisfactory results with an accuracy of ±5%. Application of a standard addition method also improves the accuracy, but is laborious and less precise.Abbreviations a true enzyme activity - a _s activity determined from standard curve - AU Anson unit - c _A/T relative azocasein concentration (mg azocasein per mg total protein) - r ratio between measured and true enzyme activity - RD relative deviation from true value (%) - RSD relative standard deviation (%) - TCA trichloroacetic acid     

酶法测定甲醇酵母发酵液中甲醇浓度

用醇氧化酶－过氧化氢酶联合的酶促反应法,测定甲醇酵母发酵诱导阶段变化的发酵液中甲醇浓度,建立一种能够快速测定发酵液中甲醇浓度的方法,测定的最佳浓度范围是0．5－5％。     

Bioassay for the rapid detection of bacteriocins in fermentation broth

A bioassay for the rapid detection of bacteriocins by detecting efflux of K⁺ ions from a bacteriocin-sensitive indicator strain was developed. There was a rapid increase in concentration of K⁺ in the medium from approximately 1.6 to 9.5 mM when the crude bacteriocin was added to the sensitive strain. A bacteriocin activity of 8.25 AU ml^–1 produced the lowest detectable concentration of K⁺ (0.179 mM) and the smallest inhibition zone (0.4 mm). The smallest cell dry mass of the indicator strain capable of releasing a detectable level of K⁺ (0.102 mM) was 0.76 mg. Detection of the bacteriocin by measuring the efflux of K⁺ compares well with the conventional agar well diffusion assay. Low activities of bacteriocin and low amounts of the sensitive indicator strain biomass can be used with this bioassay.