Christian Bouillanne

Isolation and characterization of exocellular polysaccharide produced byLactobacillus bulgaricus

SummaryLactobacillus bulgaricus strains grown on skim milk produce a viscosifying exocellular watersoluble heteropolysaccharide composed of galactose, glucose and rhamnose in an approximately molar ratio of 4:1:1. The molecular weight is approximately 500.000.

Exocellular polysaccharide production byStreptococcus thermophilus

SummaryStreptococcus thermophilus strains grown on skim milk produce exocellular polysaccharide, essentially composed of galactose and glucose. Small amounts of xylose, arabinose, rhamnose and mannose are identified also. A relationship exists between viscosity of the culture medium and the amount of polymer produced. However, the thickness producing trait in the strains studied is highly unstable.

Influence of temperature, pH and dissolved oxygen on growth of Brevibacterium linens in a fermentor

SummaryThe effects of temperature (20°, 25°, 30° C), pH (7.5, 8.0, 8.5) and dissolved oxygen (40%, 45%, 50%, 55%, 60% of concentration in air-saturated medium) on the growth of Brevibacterium linens were studied with cultures on sodium l-lactate and casamino acids in a regulated fermentor, using a factorial design methodology and an analysis of variance programme. The effect on growth rates was very striking: an extremely significant quadratic effect of oxygen, a marked negative effect of pH and a great negative interaction between pH and temperature were observed. Growth, transition from cocci to rods and pigmentation were inhibited by dissolved oxygen levels of 40% and 60%, while the level 50% produced higher absorbance values and growth rates.

Etude de quelques caractères de souches de Streptococcus thermophilus utilisées en fabrication de yoghourt et proposition d'une méthode de classement

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d’enseignement et de recherche français ou étrangers, des laboratoires publics ou privés. Etude de quelques caractères de souches de Streptococcus thermophilus utilisées en fabrication de yoghourt et proposition d’une méthode de classement C. Bouillanne, M. J. Desmazeaud, Michèle Landon, J.J. Gratadoux, M. Fourier

Studies on Brevibacterium linens metabolism in fermentor

SummaryGrowth and metabolism of Brevibacterium linens were studied in a fermentor regulated for fixed levels of pH (7.5 to 8.5), temperature (20–30° C) and dissolved oxygen (40%–60% of air saturated medium). The curves of disappearance of l-lactate and amino acids were invariable, indicating that phenylalanine, tyrosine, arginine, proline, glutamic acid and histidine are growth-limiting nutrients. Ornithine appeared at the beginning of cultures when oxygen consumption was low. Ammonia was produced, but large quantities were observed only when amino acid concentrations were higher than that of the carbon source. When the latter was low, the ammonia produced was consumed before a number of amino acids as an easily assimilable nitrogen source. Whether alkali or acid was consumed to maintain constant pH depended on the pH of the medium and on maximal growth rates.