Fermenters sampling

GUr-probe, /. fermentation sample or t t. -produkt, n. fermentation product, -prozess, m. fermentation (process), -raum, m. fermenting room. 

Holm KA. Automated determination of microbial peroxidase activity in fermentation samples using hydrogen peroxide as the substrate and 2,2 -azino-bis(3-ethylbenzothiazoUne-6-sulfo-nate) as the electron donor in a flow-injection system. Analyst 1995 120 2101-2105. 

A rapid quantitative method for the determination of gibberellic acid is based on the conversion of gibberellic acid to gibberellenic acid, followed by measurement of the absorption of the latter compound at 254 ny. The method has been shown to be specific for gibberellic acid and tolerant of the presence of other known impurities and decomposition products. It has been successfully applied to a wide range of fermentation samples. 

In fermentation samples, owing to the partial overlap of arabinose, xylitol, and arabitol, in the column Aminex HPX-87H, those components were also analyzed using a Sugar-Pak I column (Waters) operating at 90°C in a Merck-Hitachi HPLC system (Merck) equipped with an RI detector (L-7490 Merck). The mobile phase was 50 mg/L of calcium EDTA at a flow rate of 0.5 mL/min. 

N. George, M. Kuppusamy, and K. Balaraman, Optimization of HPLC conditions for the determination of cyclosporins A, B, and C in fermentation samples, J. Chromatogr., 604r285 (1992). 

On-line MIR ZnSe ATR analysis of microbial cultures has been used primarily for non-invasive monitoring of alcoholic or lactic fermentations. Alberti et al. [76] reported the use of a ZnSe cylindrical ATR crystal to monitor accurately substrate and product concentrations from a fed-batch fermentation of Saccharomyces cerevisiae. Picque et al. [77] also used a ZnSe ATR cell for monitoring fermentations and found that whereas NIR spectra obtained from alcoholic or lactic fermentation samples contained no peaks or zones whose absorbance varied significantly, both transmission and ATR MIR could be used successfully to measure products. Fayolle et al. [78] have employed MIR for online analysis of substrate, major metabolites and lactic acid bacteria in a fermentation process (using a germanium window flow-through cell), and... 

Fig. 4.4 Effect of alcoholic fermentation and yeast strain on the concentration of glycoside-derived volatile compounds and of different classes of glycosidic precursors during the fermentation of a model grape juice containing Muscat glycosides. The control refers to a non-fermented sample kept under the same conditions utilized for fermentation, which accounts for add catalysed hydrolysis of glycosides (adapted from Ugliano 2006)...

To identify the substrates obtained from starch and to confirm that the substrates were available for H2 production in BCI, soluble starch (4.05 g/f) was fed to a pure culture of V. fluvialis T-522 (Fig. 3A). The fermentate, sampled after approx. 120 h, contained a large amount of acetic acid (approx. 400 mg//) as the major metabolite, and approx. 100 mg// ethanol as the by-product. These results suggest that acetic acid and ethanol might be the major substrates for H2 production by strain A-501 in BCI. Subsequently, the fermentate was fed to a pure culture of strain A-501 (Fig. 3B). As shown in Fig. 3B, the concentrations... 

Figure 2. Viscosities of fermenter sample of laboratory-produced glucan after various treatments blend, 60 s at low speed of blender heat, to 90°C for 30 min neutralize, to pH 6.5—7.0. Numbers refer to viscosities in centipoise, measured at 60 rpm Brookfield LVT, spindle No. 3,T = 25° 1 °C.

Lactamase has been coimmobilized with the pH indicator bro-mocresol green on a transparent cellulose membrane in a flow-through device (Lowe and Goldfinch, 1983). This reagentless system responded linearly to penicillin in the range 0.5-10 mmol/1. With fermentation samples, however, disturbances caused by varying pH values and buffer capacities of the samples have to be expected. 

Weise et al. (1987) proposed saturating food and fermentation samples by bubbling with air directly in the reaction vessel of a modified automated sampler. During the oxygenation, hydrolysis of the analytes sucrose, glucosinolate, or starch was performed. Up to 60 samples per hour could be analyzed automatically with good precision. 

Cell-free Experiments. Cell-free extracts were prepared from fermentation samples (12 mL) by centrifugation (2700g for 10 minutes) of the clarified supernatant. Tannin (15 mg) and enriched anthocyanin (400 xL, adjusted to pH... 

As several biologically active molecules may be unstable to extreme pH values, it is also important to carry out a pH-stability study. In such a study, the fermentation sample is adjusted to several pH values (for example 2,4,9,11) for various lengths of time (for example 30 min, 3 h, 24 h). At the end of the time interval, the solution is adjusted back to pH 7.0 and the sample bioassayed. The pH-stability profile will often dictate the type of separation to be performed and hence the resin to be used. 

Time-dependent offline sampling of 1 ml aliquots was performed aseptically during fermentations. Samples were mixed immediately before dilution in deionized water, and then subjected to duplicate absorbance determination in a spectrophotometer at 600 nm. Diluted cell-free medium was used to establish background readings and set zero absorbance levels. Values were averaged and corrected for dilution. Protein concentration in cell-free extracts was determined by Bradford method [21], using bovine serum albumin as a standard. 

I. Schneider, Determination of Penicillin V in Fermentation Samples by Flow Injection Analysis. Anal. Chim. Acta, 166 (1984) 293. 

K. A. Holm, Spectrophotometric Flow-Injection Determination of Cello-biose Dehydrogenase Activity in Fermentation Samples with 2,6-Di-chlorophenolindophenol. Anal. Chim. Acta, 188 (1986) 285. 

Glucose measurements in urine and fermentation samples by means of GOD electrodes based on hydrogen peroxide detection usually suffer from interferences by anodically ox-idizable compounds. These can be oxidized in the measuring solution by reaction with hexa-cyanoferrate(III). However, the hexacyanoferrate(lI) ion formed is also oxidizable at an electrode potential of +600 mV. In order to prevent the hexacyanoferrate(II) from reaching the electrode, laccase has been co-immobilized with GOD in the sensor membrane [352]. Thus, the mediator is reoxidized in a laccase-catalyzed reaction with consumption of oxygen. The system is capable of shielding the electrode from ascorbic acid at concentrations up to 2 mmol/L. 

The glucose concentration of the fermentation samples was measured by the DNSA (dinitrosalicylic acid) method ( ) using glucose as a stemdard. Samples were diluted to contain less than 1 g/1 glucose. 

Diffuse reflectance absorbance infra-red spectroscopy provides an alternative rapid, automated, quantitative approach which yields more detailed information about chemical characteristics than, for example, the UV absorbance spectrum typically used in HPLC analysis. The method can also be employed non-invasively on unprocessed fermentation samples. 

Stewart, J. S., Dowhanick, T. M. (1996). Rapid detection of lactic acid bacteria in fermenter samples using a nested polymerase chain reaction. Journal of the American Society of Brewing Chemists, 54, 78-84. 

Bell [526] analyzed transition metals together with magnesium and calcium utilizing ion pair chromatography on a chemically bonded reversed-phase column, which can be combined with both nonsuppressed conductivity detection and photometric detection after derivatization with PAR. Because Bell used predominantly ashed fermentation samples, his chromatograms are free of interferences. Simultaneous separations of alkali and alkaline-earth metals in methanotropic bacterial cultures and other media on surface-sulfonated... 

NIR is widely used for rapid and nondestructive analysis in industries such as agriculture, food, pharmaceuticals, textiles, cosmetics, and polymer production. NIR has several advantages. In addition to nondestructive and rapid analysis, several components can be assayed simultaneously. The sample is supplied to the photometer without pretreatment. Both dry and wet materials can be accepted as a sample. Therefore, both aqueous and solid fermented samples can be accepted. NIR is an assay technique with high precision, and on-line measurement is available with fiber optics. These characteristics of NIR are an excellent match for the requirements of monitoring systems for the fermentation process. NIR will be increasingly apt for fermentation process monitoring. 

However, several significant problems must be resolved. The fermentation sample contains various constituents such as proteins, lipids, and sugars. These compounds easily attach on the surface of a probe and a cuvette and cause the problem of shift of the optical density. It becomes a problem when the cell density increases to a hundred times with development of the fermentation. The increase causes the shift of the baseline of the NIR spectrum. Furthermore, the attachment of the bubbles generated by the fermentation on the surface of a probe and a cuvette also causes shift of the optical value measured. These problems should be studied as soon as possible to make sure the bright future of NIR in fermentation engineering. 

---