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J Boudrant

Publications and source records attributed to J Boudrant.

7 recordsLinked to original sources
PubMed1991

Metabolic roles of peptone and yeast extract for the culture of a recombinant strain of Escherichia coli.

The influence of complex compounds on the growth of a recombinant strain of Escherichia coli containing the gene encoding glyceraldehyde 3-phosphate dehydrogenase, as well as the production of this enzyme have been studied. Batchwise cultures led to an accumulation of acetate, which was not utilized in a yeast extract-free medium. After glucose exhaustion, growth stopped and enzyme activity decreased. Whereas yeast extract allowed acetate assimilation and growth, peptone stabilized the enzymatic activity. The addition of both compounds resulted in optimal performances for enzyme production.

Culture Media↗
PubMed1990

Microbial processes for ascorbic acid biosynthesis: a review.

L-Ascorbic acid is an important product currently made using the Reichstein process, which is mainly chemical. Recently, bacteria have been identified that are able to transform in a very efficient way glucose to 2,5-keto-D-gluconic acid and this product to 2-keto-L-idonic acid, precursor of L-ascorbic acid. When the corresponding strains are used together, it is possible to get 2-keto-L-idonic acid directly from glucose. Moreover, new strains have been constructed by introducing a gene from a strain responsible for the second step into a strain responsible for the first step. By using one of the new strains, the transformation can be performed in a single step with only one strain. However, the classical process still remains the most competitive.

Acetobacter↗
PubMed1979

Process characteristics of cell lysis mutants of Saccharomyces cerevisiae.

Several temperature-sensitive lysis mutants of Saccharomyces cerevisiae were selected according to their ability to release alkaline phosphatase when incubated at a nonpermissive temperature. For two mutants, cell lysis and release of alkaline phosphatase reached a maximum when cells in the logarithmic growth phase were shifted to the nonpermissive temperature. Morphological changes, as well as changes in macromolecular composition of the cells, were observed. Growth is necessary and oxygen is important for the expression of cell lysis at the nonpermissive temperature.

Alkaline Phosphatase↗
PubMed1976

Continuous Proteolysis with a stabilized stabilized protease. I. Chemical stabilization of an alkaline protease.

Due to the loss of enzymatic activity as a function of time, an alkaline protease, selected for the continuous preparation of protein hydrolysates (J. Boudrant and C. Cheftel, Biotechnol. Bioeng., 18,1735, 1976), was chemically stabilized by a simple treatment with glutaraldehyde. Two fractions, soluble and insoluble, were obtained. The activities of these two fractions were measured with casein and N-benzoyl-L-arginine ethyl ester (BAEE) as a function of glutaraldehyde concentration used. It was noted that the insoluble fraction was practically inactive with the first substrate and that the heat stability of the soluble form was likewise enhanced. Molecular weights of these two forms were unchanged, but the uv-spectrum of the soluble form was modified. From amino acid analysis, it appears that this treatment mainly provokes a decrease in lysine content.

Aldehydes↗
PubMed1976

Continuous proteolysis with a stabilized protease. II. Continuous experiments.

Batch proteolysis experiments were performed in order to choose a protein-protease system to prepare a correct hydrolysate suitable for the enrichment of soft-drinks. The system eventually studied was casein-Alcalase. Comparative batch and continuous proteolysis of casein by Alcalase showed that the reaction, which does not exactly follow first order kinetics with respect to the substrate concentration, is inhibited by the reaction products. Furthermore, experiments were done in order to determine the reaction conditions (pH8.8 in the reactor, casein concentration 5%, 40 degrees C). Determining the molecular weight of Alcalase (43,000) suggested the choice of ultrafiltration membrane PM 30. Sutdies of continuous proteolysis with the chemically stabilized enzyme retained by the ultrafiltration reactor showed that protease reuse for seven days at 40 degrees C is possible and that the growth of microorganisms is practically inhibited under these conditions. Gel chromatography showed the molecular weight.range of the peptides to be less than 2,000. Triangular taste tests showed that the threshold identification concentration of the dry hydrolysate in orange juice is about 0.65%.

Beverages↗
PubMed1975

[Application of the theory of oxygen transfer: determination of the Michaelis constant of glucose oxidase with respect to oxygen].

The oxidation of beta-D-glucose with glucose oxidase generally requires oxygen, which, under normal conditions is present at low concentrations in the reaction medium. Experiments show that glucose oxidase is no longer saturated by oxygen at enzyme concentrations greater than 0.4 mg.ml1. This is due to the decrease in the oxygen concentration of the solution. The value of the oxygen mass transfer coefficients and dissolved oxygen concentrations are determined. These dissolved oxygen concentrations are found to correlate with direct measurements with an oxygen electrode. From this, the Michaelis constant of glucose oxidase for oxygen is calculated. These experiments also show that oxygen is a limiting factor for this reaction.

Aspergillus niger↗