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Production d'enzyme polygalacturonase par des souches microbiennes isolées du lait cru et des olives noires et vertes

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Forty microbial strains isolated from raw milk samples and black and green olives were grown in MP5 (mineral pectin 5) medium containing 0.5% lemon pectin. All strains synthesized an extracellular polygalacturonase. Rhodotorula sp. ONRh9 (0.44 U·mL–1) and Leuconostoc sp. LLn1 (0.16 U·mL–1), which had a more active poly galacturonase in MP5 medium, were studied in MAPG5 medium containing polygalacturonic acid. Highest biomass and polygalacturonase production by these two strains were observed for polygalacturonic acid concentrations of 10 g·L–1 (Rhodotorula sp. ONRh9) and 5 g·L–1 (Leuconostoc sp. LLn1) and for initial pH values of 6 (Rhodotorula sp. ONRh9) and 5.5 (Leuconostoc sp. LLn1). The two strains grown in fermenters in MAPG5 medium generated the following results: with controlled initial pH, Rhodotorula sp. produced maximum biomass (DO) and polygalacturonase (PG) after 20 h (DO, 3.86; PG, 0.24 U·mL–1) of growth, and this level was sustained until the end of the culture; Leuconostoc sp. LLn1 synthesized more cells and polygalacturonase between 4 h (DO, 1.80; PG, 0.17 U·mL–1) and 24 h (DO, 3.90; PG, 0.27 U·mL–1) of culture. With uncontrolled initial pH, the cultures produced maximum biomass and poly galacturonase after 20 h (DO, 3.30; PG, 0.26 U·mL–1) for Rhodotorula sp. ONRh9 and 10 h (DO, 2.84; PG, 0.17 U·mL–1) for Leuconostoc sp. LLn1.Key words: Leuconostoc, Rhodotorula, polygalacturonic acid, polygalacturonase, cell growth.[Journal translation]

Quarante souches microbiennes, isolées à partir d'échantillons de lait cru et d'olives noires et vertes, furent cultivées dans le milieu MP5 (« mineral pectin 5 medium ») à 0,5 % de pectine de citron. L'ensemble des souches synthétisait une polygalacturonase extracellulaire. Rhodotorula sp. ONRh9 (0,44 U·mL–1) et Leuconostoc sp. LLn1 (0,16 U·mL–1), possédant une polygalacturonase plus active dans le milieu MP5, furent étudiées dans le milieu MAPG5 contenant de l'acide polygalacturonique. Les productions de croissance et de polygalacturonase maximales, obtenues par ces deux souches, furent observées pour des concentrations en acide polygalacturonique égales à 10 g·L–1 (Rhodotorula sp. ONRh9) et 5 g·L–1 (Leuconostoc sp. LLn1) et pour des valeurs de pH initiaux équivalents à 6 (Rhodotorula sp. ONRh9) et 5,5 (Leuconostoc sp. LLn1). Les deux souches cultivées en fermenteur dans le milieu MAPG5 donnèrent les résultats suivants : avec le pH initial contrôlé, Rhodotorula sp. ONRh9 produisait un maximum de cellule (DO) et de polygalacturonase (PG) après 20 h (DO, 3,86; PG, 0,24 U·mL–1) de cultures, et ce niveau fut maintenu jusqu'à la fin de la culture. Leuconostoc sp. LLn1 synthétisa plus de cellules et de polygalacturonase entre 4 h (DO, 1,80; PG, 0,17 U·mL–1) et 24 h (DO, 3,90; PG, 0,27 U·mL–1) de culture. Avec le pH initial non contrôlé, les cultures produisaient des cellules et une polygalacturonase maximales après 20 h (DO, 3,30; PG, 0,26 U·mL–1) pour Rhodotorula sp. ONRh9 et 10 h (DO, 2,84; PG, 0,17 U·mL–1) pour Leuconostoc sp.Mots clés : Leuconostoc, Rhodotorula, acide polygalacturonique, polygalacturonase, croissance cellulaire.

Document Type: Research Article

Publication date: July 1, 2006

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  • Published since 1954, this monthly journal contains new research in the field of microbiology including applied microbiology and biotechnology; microbial structure and function; fungi and other eucaryotic protists; infection and immunity; microbial ecology; physiology, metabolism and enzymology; and virology, genetics, and molecular biology. It also publishes review articles and notes on an occasional basis, contributed by recognized scientists worldwide.
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