title: [Polygalacturonase enzyme production from bacterial isolated from raw milk and green and black olives].
abstract: 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 x mL(-1)) and Leuconostoc sp. LLn1 (0.16 U x mL(-1)), which had a more active polygalacturonase 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 x L(-1) (Rhodotorula sp. ONRh9) and 5 g x 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 x 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 x mL(-1)) and 24 h (DO, 3.90; PG, 0.27 U x mL(-1)) of culture. With uncontrolled initial pH, the cultures produced maximum biomass and polygalacturonase after 20 h (DO, 3.30; PG, 0.26 U x mL(-1)) for Rhodotorula sp. ONRh9 and 10 h (DO, 2.84; PG, 0.17 U x mL(-1)) for Leuconostoc sp. LLn1.
authors.affiliation: Laboratoire de génie microbiologique et applications, Département des sciences de la nature et de la vie, Université de Mentouri, Algérie. faridabekhouche@yahoo.fr
authors.forename: Farida
authors.initials: F
authors.lastname: Bekhouche
authors.forename: Estelle
authors.initials: E
authors.lastname: Bonnin
authors.forename: Abderrahmane
authors.initials: A
authors.lastname: Boulahrouf
authors.forename: Jean Yves
authors.initials: JY
authors.lastname: Leveau
mesh_terms: D000818:Animals; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007934:Leuconostoc / Q000201:enzymology*; D008892:Milk / Q000382:microbiology*; D031658:Olea / Q000382:microbiology*; D011096:Polygalacturonase / Q000096:biosynthesis*; D012248:Rhodotorula / Q000201:enzymology*
chemical_list: D011096:Polygalacturonase