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J Labadie

Publications and source records attributed to J Labadie.

5 recordsLinked to original sources

[Induction and repression of the collagenase synthesis in Acinetobacter sp].

The synthesis of collagenase in Acinetobacter sp. was found to be inducible by denatured collagen and by its high molecular weight fragments. The presence in the inducer of part of the tertiary structure appear to be indispensable. On the other hand, an addition of Casamino acids, meat protein hydrolysate, or a mixture of amino acids with a similar composition to gelatin does not stimulate collagenase synthesis. Enzyme production was severely repressed in the early phase of growth by glucose, arabinose, and ribose, single amino acids, proline, hydroxyproline, alanine, glutamic acid or casein acid hydrolysate. A mechanism of repression similar to catabolite repression was involved in the phenomenon caused by carbohydrates. However, the fact that cyclic adenosine 3'5-monophosphate did not overcome the repression caused by amino acids or Casamino acids, in contrast to classical catabolite repression, suggests that these two forms of repression may be distinct.

Acinetobacter

[Purification and physico-chemical properties of collagenase synthesized by a bacterium of the type Acinetobacter sp].

The Acinetobacter spec collagenase has been almost completely purified. This enzyme is a true collagenase the activity of which is high on collagen. The enzyme is active on insoluble collagen, gelatin and the synthetic Pz-peptide, but has no proteolytic activity on casein or bovine serum-albumin. The collagenase was obtained on a simple medium with gelatin and yeast extract. The enzyme was purified by (NH4)2SO4 precipitation. DEAE cellulose column chromatography, Sephadex G 200 gel-filtration. The molecular weight of the enzyme was found to be 102 000 daltons, and its isoelectric point was found to be 7,7 +/- 0,2. The optimum pH and temperature for insoluble collagen hydrolysis were 7.6 and 37 degrees C, respectively; so, this collagenase corresponds to true collagenase. Hydrolysis of Pz-peptide is activated by Ca2+ and inhibited by metal ions (Cu2+, Fe3+, Zn2+, Pb2+, Hg2+). EDTA and o-phenanthroline induced a very significant reduction in enzyme activity. Iodoacetate and p-CMB induced a slight reduction in enzyme activity only at high concentrations (10-2M). The collagenase is most stable for temperatures less than or equal to 50 degrees C.

Acinetobacter

Development of listeria monocytogenes in monoxenic and polyxenic beef minces.

The objective of this study was to determine the multiplication possibilities of Listeria monocytogenes in beef minces with a defined microflora (gnotoxenic). Selective counts were made for each species and each bacterial association for a period of 17 days after inoculation of the axenic meat. The concentration of L. monocytogenes did not increase, but remained constant in monoxenic meats. Associated with Lactobacillus plantarum, the number of Listeria tended to decrease. Conversely, in association with P. fluorescens, L. monocytogenes definitely multiplied, especially in polyxenic meats, the microflora of which is similar to that of conventional meats. Consequently, it seems that meat might constitute a source of L. monocytogenes infection.

Food Contamination

Blood poisonings at slaughter and their consequences.

Contamination of pig blood by Str. faecium and P. fluorescens realized either through the bleeding knife or through intravenous injection. Bacterial counts made in the organs and muscles showed a large contamination of the organs and a smaller contamination of the muscles. In the case where Str. faecium and P. fluorescens were injected into the blood circulation, only Str. faecium could be re-isolated in muscles and organs. Study of the bactericidal activity of total blood and plasma showed a marked antimicrobial activity against P. fluorescens and a slightly activity against Str. faecium.

Abattoirs

[Attachment of a collagenolytic strain to its substrate (author's transl)].

The bacterial collagenolytic strain Acinetobacter sp. CRZV2 adheres to insoluble collagen fibers when this substrate is introduced into the growth medium. This attachment occurs during the exponential growth. Proteolytic enzymes such as pronase and trypsine activate the adherence of bacterial cells to collagen fibers.

Acinetobacter