Cell dry weight

Recently, recombinant biocatalysts obtained using Escherichia coli cells were designed for this process. The overexpression of all enzymes required for the process, namely, hydantoinase, carbamoylase, and hydantoin racemase from Arthrobacter sp. DSM 9771 was achieved. These cells were used for production of a-amino acids at the concentration of above 50 g 1 dry cell weight [37]. This is an excellent example presenting the power of biocatalysis with respect to classical catalysis, since a simultaneous use of three different biocatalysts originated from one microorganism can be easily achieved. 

Fig. 2. Whole cell biocatalytic reactions for four types of recombinant whole cell systems. Bioconversion reactions were performed in resting cell condition. All data were based on unit cell concentration (1 mg-dry cell weight ml ). Each value and error bar represents the mean of two independent experiments and its standard deviation.

Section 5.3.2.3) combined with over-expression of IPPI resulted in enhanced astaxanthin accnmnlation to 1.4 mg/g dry cell weight (DCW). Further increases to 45 mg/g DCW were obtained by random mutagenesis of GGPPS, perhaps by altering enzyme response to substrate-level feedback inhibition. 

When the whole-cell reaction was carried out in the presence of 0.1-3 M 1,3-dihydroxybenzene and 3M KHCO3, the molar conversion ratio of 1,3-dihydroxybenzene always reached 45-50% (Fig. 6). The high concentration of 1,3-dihydroxybenzene was not inhibitory on 2,6-dihydroxybenzoate decarboxylase. When 3M 1,3-dihydroxybenzene was incubated with the whole cells of Pandoraea sp. 12B-2 (43.9 mg as dry cell weight) in the presence of 3M KHCO3, 220mgmr of 2,6-dihydroxybenzoate (1.42 M) accumulated after 120 h incubation, with a conversion ratio of 48%. During the carboxylation of 1,3-dihydroxybenzene, no other product except for 2,6-dihydroxybenzoate was formed. 

Carboxylation of 20-300 mM 1,2-dihydroxybenzene was carried out using 36.9 mg (as dry cell weight) of whole cells in the presence of 3M KHCO3 in 1 ml of the reaction mixture. The molar conversion yields were almost the same using 20, 100, and 200 mM 1,2-dihydroxybenzene (approximately 25%) as shown in Fig. 7. 

Lycopene is a carotenoid with anticancer properties. To improve the production of lycopene by increasing the IPP flux in an engineered E. coli, the dxs gene was overexpressed and enhanced lycopene production was obtained [45]. In another example, the native promoters of DXP pathway genes in the E. coli chromosome were replaced with the strong bacteriophage T5 promoter (PTs), and the increase in isoprenoid precursors resulted in improved /3-carotene production (with a titer of 6 mg/g dry cell weight) [44]. 

Take 0.1 m potassium phosphate buffer (640 mL) and add resting cell suspension (40 mL, containing 2 g dry cell weight) into a 1.5 L vessel or a fermentor (reactor with temperature control, impeller and addition port to add substrate periodically). 

Shaker flasks Laminaria japonica (kelp) Plasminogen activator protein Gao et al., 2005 56 pg/g dry cell weight Illuminated bubble column bubble reactor... 

Food yeast, molasses-grown, is dried to about 5% moisture and has the same chemical composition as bakers yeast. In terms of micrograms per gram of yeast, the vitamin content is 165 thiamine 100 riboflavin 590 niacin 20 pyridoxine 13 folacin 100 pantothenic acid 0.6 biotin 160 para-ainiiiobeuzoie acid 2710 choline and 3000 inositol. YeasL crude protein contains 80% amino acids 12% nucleic acids and 8% ammonia. The latter components lower the true protein content to 40% of the dry cell weight. 

First, let us define the terminologies we use for microbial growth. If we mention the cell concentration without any specification, it can have many different meanings. It can be the number of cells, the wet cell weight, or the dry cell weight per unit volume. In this text, the following nomenclature is adopted ... 

Cx Cell concentration, dry cell weight per unit volume CN Cell number density, number of cells per unit volume p Cell density, wet cell weight per unit volume of cell mass Accordingly, the growth rate can be defined in several different ways, such as ... 

As cells in a fermenter cannot be counted easily, it is more convenient to employ cell density X, expressed as dry cell weight (dew) per volume [g IT1], as the dependent variable [Eq. (8.4)], which yields Eqs. (8.5a) and (8.5b) upon integration with the inoculum. 

Metabolic flux this is defined as the amount of the unit of interest, usually the mass of a metabolite in moles (often micromoles, rather) per unit time per unit area or volume, or often grams dry cell weight (dew) [pmol (h g dew)-1] passing between components A and B of the metabolic system. A metabolic rate is equivalent dimensionally to a specific reaction rate. Metabolic flux is the basic unit of observation and modeling in metabolic engineering. 

All reactions contained 50 mM Tris-HCl pH 7.4 buffer and 2 mg/ml of penicillin G. Dry cell weight 13 mg/ml. A 1-ml sample from each reaction was taken after 2 hr and centrifuged (14,000 X g, 5 min). The supernatants were transferred to new tubes and 200 pi were used in the bioassay. Source. Ref. 14. 

A set of alcoholic fermentations experiments was conducted in order to verify the performance of the model-based substrate sensor. Diluted molasses was used in the experiments as feed substrate and bread yeast, Saccharomyces cerevisiae, as inoculum. The operational conditions and kinetic parameters used are given in Table 1 for two different experiments (tests 1 and 2), and values of ethanol and biomass concentrations were also determined off-line using gas chromatography (CG) and dry cell weight standard (7) methods, respectively. 

The culture supernatant was used for determination of glucose concentration by the dinitrosalicylic acid method (11) and pH measurement. Cell growth was monitored by the determination of optical density (OD) at 600 nm in a spectrophotometer (Shimadzu-UV 1601). One OD600 unity was found to be equivalent to 0.46 mg dry cell weight (DCW). Asparaginase II activity was assayed using fresh cells as previously described (3,4). 

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