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Query: UMLS:C0085631 (agitation)
 12,064 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The time of appearance and the quantity of toxin produced by the Hall strain of Clostridium botulinum type A were examined under various conditions. A 70-liter fermentor and a complex medium consisting of 2% casein hydrolysate and 1% yeast extract plus an appropriate concentration of glucose were employed. Optimal conditions for toxin production were as follows: a nitrogen overlay at a rate of 5 liters/min, an agitation rate of 50 rpm, a temperature of 35 degrees C, and an initial glucose concentration of 1.0% with the pH uncontrolled. Under these conditions, the maximum toxin concentration (6.3 x 10(5) mouse median lethal doses/ml) was attained within 24 h. Cell lysis was apparently not required to obtain maximum toxin concentrations under the fermentation conditions described.
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PMID:Toxin production by Clostridium botulinum type A under various fermentation conditions. 4 75

The problems related to the use of serum in cell culture are reviewed. The possibility of substituting the serum with peptones has already been shown. Different peptones have been tested: one of the best is a peptone obtained from meat and casein pepsin pancreatically digested. BHK 21/13 cells were cultivated in serum-free media for 35 passages. The 0.81 cultures without automatic pH control had a cycle length of 3 days; starting with concentrations of 0.4 X 10(6) cells/ml, concentrations higher than 3 X 10(6) cells/ml were often obtained. We did not obtain satisfactory results when the volume of cultivation was increased to more than 6 1, perhaps because of different requirements for agitation, pH, O2. It is also necessary to check whether the results obtained up to now are consistent with reference to the source of reagents and cell strain used. The absence of serum in the medium did not influence virus replication when infectivity and complement fixation titers were tested.
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PMID:New media and their advantages in the production of suspended cells and foot--and--mouth disease virus. 19 93

We investigated the kinetics of production of the hepatocyte stimulating factor (HSF) by peritoneal exudate- and peripheral circulating blood-polymorphonuclear leukocytes (PMNLs). Effects of the HSFs on alpha-2-macroglobulin (a2M) synthesis and a2M specific gene expression in primary cultured adult rat hepatocytes were also examined. Peritoneal exudate-PMNLs were collected 3 hr after the injection of alkaline-denatured casein into the peritoneal cavity of rats. Secretion of HSF into the culture medium began within 15 min after the start of incubation and practically a full secretion was noted within 3 hr. Lipopolysaccharide or other agents were not required to induce HSF from the PMNLs. Inhibitors of protein or DNA synthesis, cycloheximide, actinomycin D or puromycin, did not inhibit the secretion of HSF by rat PMNLs thereby suggesting that preformed and pooled HSF in the PMNLs was secreted during incubation. Peripheral circulating blood-PMNLs collected from a healthy man did not secrete HSF, in the absence of stimulation but did secrete HSF after vigorous agitation during incubation at 37 degrees C. The PMNL-HSF induced the synthesis of a2M and the accumulation of a2M mRNA in primary cultured rat hepatocytes. However, the effect was evident only with dexamethasone present in the culture medium. Furthermore, the effects of the PMNL-HSFs on a2M and albumin protein synthesis were reciprocal: The PMNL-HSF induced a2M synthesis, whereas it suppressed albumin synthesis.
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PMID:Induction of polymorphonuclear leukocyte-derived hepatocyte stimulating factor and effects on alpha 2-macroglobulin synthesis. 248 50

Glass, rubber and stainless steel surfaces were exposed to various types of bacteria in the presence of milk and a number of milk components under both static and agitated incubation conditions. Numbers of bacteria attaching were enumerated by epifluorescence microscopy. Results were affected by the different bacterial types, the nature of the attachment surface and the substances in which the bacteria were suspended with a Moraxella-like species, stainless steel and lactose and non-casein protein solutions respectively resulting in greatest numbers of cells attaching. Agitation had no marked influence on attachment.
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PMID:The influence of milk and milk components on the attachment of bacteria to farm dairy equipment surfaces. 406 51

In the course of screening amylase inhibitor producing, microorganisms, a strain identified as Streptomyces nigrifaciens NTU-3314 was found to have the highest inhibitor-producing ability among the other isolated strains. This strain was aerobically cultured at 30 degrees C in a 5l jar fermentor with a working volume of 2l. The optimum cultural medium consisted of defatted soybean flake 3.0%, potato starch 4.0%, casein 0.6%, sucrose 0.6%, serine 0.02% and NaCl 0.8% (pH 7.0). With an aeration rate of 1.5 vvm, an agitation speed of 300 rpm and an inoculum of 15% seed (previously grown in seed medium 3), the highest amount of inhibitor was obtained after 24 hours of cultivation. The amylase inhibitor produced had inhibitory effects on both alpha-amylase and glucoamylase, but not on beta-amylase, alpha-glucosidase, beta-glucosidase or dextranase. It was quite stable in 0.1M phosphate buffer (pH 7.0) and nearly 100% of its activity was retained even after boiling at 100 degrees C for 20 min.
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PMID:The microbial production of amylase inhibitor and its application. I. Isolation and cultivation of Streptomyces nigrifaciens NTU-3314. 608 1

To obtain high yields of toxin for the preparation of purified neurotoxoids, we examined the time of appearance and the quantity of toxin produced by the Bean strain of Clostridium botulinum type B under various conditions by using a fermentor system. The medium employed consisted of 2.0% casein hydrolylsate and 1.5% yeast extract plus an appropriate concentration of glucose. The maximum toxin concentration (4 x 10(5) to 5 x 10(5) mouse median lethal doses per ml) was attained within 48 h under the following fermentation conditions: an initial glucose concentration of 0.5 or 1.0%, a temperature of 35 degrees C, a nitrogen overlay at a rate of 5 liters/min, and an agitation rate of 50 rpm.
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PMID:Effect of fermentation conditions on toxin production by Clostridium botulinum type B. 700 3

Exposure of DNA to several proteins peroxidized by radiation-generated hydroxyl free radicals resulted in formation of crosslinks between the macromolecules, detected by retardation and broadening of DNA bands in agarose gels. This technique proved suitable for the study of crosslinking of DNA with peroxidized BSA, insulin, apotransferrin and alpha casein, but not with several other proteins, including histones. The crosslinking depended on the presence of intact hydroperoxide groups on the protein, on their number, and on the duration of the interaction with DNA. All DNA samples tested, pBR322, pGEM, lambda/HindIII and pUC18, formed crosslinks with the peroxidized BSA. Sodium chloride and formate prevented the crosslinking if present during incubation of the peroxidized protein and DNA, but had no effect once the crosslinks had formed. The gel shift of the crosslinked DNA was reversed by proteolysis, indicating that the DNA mobility change was due to attachment of protein and that the crosslinking did not induce DNA strand breaks. The metal chelators Desferal and neocuproine reduced the extent of the crosslinking, but did not prevent it. Scavengers of free radicals did not inhibit the crosslink formation. The DNA-protein complex was not disrupted by vigorous agitation, by filtration or by non-ionic detergents. These observations show that the crosslinking of DNA with proteins mediated by protein hydroperoxides is spontaneous and probably covalent, and that it may be assisted by transition metals. It is suggested that formation of such crosslinks in living organisms could account for some of the well-documented forms of biological damage induced by reactive oxygen species-induced oxidative stress.
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PMID:Crosslinking of DNA and proteins induced by protein hydroperoxides. 1005 32

In spite of the widespread use of proteins (casein, peptone, etc.) and protein fragments as a substrate for the proteolytic enzymes, a substrate prepared from dyes that adsorb onto appropriate materials, such as wool and cotton, are also used for enzyme activity determination. In the point of view of this thought, it was our aim to develop the substrates which are easily and economically obtainable and also environmentally safer for the frequently used proteolytic enzymes, such as subtilisin carlsberg, trypsin, chymotrypsin, and protease type XVI and, if possible, to prepare the specific substrate at least for one of these enzymes. For this aim, wool was dyed with natural dyes such as juglone, lawsone, berberine, and quercetin. The optimum pH, incubation time, and agitation rate were determinated. The results indicate that, of all the tested enzymes on wool-dye complex as an insoluble substrate, the most appropriate complex was found to be wool-lawsone complex.
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PMID:Dyeing of wool fibres with natural dyes: effect of proteolytic enzymes. 1670 32

The production optimization of alpha-amylase (E.C.3.2.1.1) from Aspergillus oryzae CBS 819.72 fungus, using a by-product of wheat grinding (gruel) as sole carbon source, was performed with statistical methodology based on three experimental designs. The optimisation of temperature, agitation and inoculum size was attempted using a Box-Behnken design under the response surface methodology. The screening of nineteen nutrients for their influence on alpha-amylase production was achieved using a Plackett-Burman design. KH(2)PO(4), urea, glycerol, (NH(4))(2)SO(4), CoCl(2), casein hydrolysate, soybean meal hydrolysate, MgSO(4) were selected based on their positive influence on enzyme formation. The optimized nutrients concentration was obtained using a Taguchi experimental design and the analysis of the data predicts a theoretical increase in the alpha-amylase expression of 73.2% (from 40.1 to 151.1 U/ml). These conditions were validated experimentally and revealed an enhanced alpha-amylase yield of 72.7%.
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PMID:Application of a statistical design to the optimization of parameters and culture medium for alpha-amylase production by Aspergillus oryzae CBS 819.72 grown on gruel (wheat grinding by-product). 1818 Jan 55

The effect of whey protein concentrate (WPC) and gum tragacanth (GT) as fat replacers on the chemical, physical, and microstructural properties of nonfat yogurt was investigated. The WPC (7.5, 15, and 20 g/L) and GT (0.25, 0.5, 0.75, and 1 g/L) were incorporated into the skim milk slowly at 40 to 45 degrees C with agitation. The yogurt mixes were pasteurized at 90 degrees C for 10 min, inoculated with 0.1% starter culture, and incubated at 42 degrees C to pH 4.6, then refrigerated overnight at 5 degrees C. A control nonfat yogurt and control full fat yogurt were prepared as described, but without addition of WPC and GT. Increasing amount of WPC led to the increase in total solids, total protein, acidity, and ash content, whereas GT did not affect chemical parameters. Increasing WPC caused a more compact structure consisting of robust casein particles and large aggregates. Firmness was increased and susceptibility to syneresis was decreased as WPC increased. No significant difference was observed for firmness and syneresis of yogurt fortified with GT up to 0.5 g/L compared with control nonfat yogurt. Increasing the amount of gum above 0.5 g/L produced softer gels with a greater tendency for syneresis than the ones prepared without it. Addition of GT led to the coarser and more open structure compared with control yogurt.
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PMID:Whey protein concentrate and gum tragacanth as fat replacers in nonfat yogurt: chemical, physical, and microstructural properties. 1856 11


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