1993. Extra-and intracellular lipases from a thermophilic Rhizopus oryzae and factors affecting their production. Can. J. Microbiol. 39: 978-981.A thermophilic Rhizopus oryzae was isolated, and parameters affecting its production of extra-and intra-cellular lipases were investigated. All carbon sources tested with the exception of sucrose generally inhibited the production of extracellular lipase, but enhanced the production of intracellular lipase. Peptone was the best substrate for extracellular enzyme production, but for intracellular lipase production other substrates such as tryptone, tryptic soy digest, polypeptone, and corn steep liquor gave comparable results. Among lipid substrates, glycerol was the only stimulator of extracellular enzyme production, whereas olive oil, triolein, and oleic acid had very positive effects on intracellular enzyme production. Shaking enhanced the production of both types of enzymes; the temperature optima were 45 and 37°C for extra-and intra-cellular lipases, respectively. A pH of 5.0 was optimal for production of both enzymes. intracellular lipases from a thermophilic Rhizopus oryzae and factors affecting their production. Can. J. Microbiol. 39 : 978-98 1.Nous avons isole une souche de Rhizopus oryzae et etudit les parametres qui peuvent influencer la production de ses lipases extra-et intra-cellulaires. A ['exception du sucrose, chacune des sources de carbone verifiees inhibaient generalement la lipase extracellulaire mais favorisait la production de la lipase intracellulaire. Les peptones etaient le meilleur substrat pour la production de I'enzyme extracellulaire mais pour la lipase intracellulaire d'autres substrats comme la tryptone, les polypeptones, le produit de digestion du soja par la trypsine et une infusion de m a~s ont donne des resultats comparables. Parmi les substrats lipidiques, seule le glycerol stimulait la production de I'enzyme extracellulaire alors que I'huile d'olive, la trioleine et I'acide oleique avaient un effet t r b positif sur la production de I'enzyme intracellulaire. L'agitation favorise la production des deux types d'enzymes. La temperature optimale est de 45°C pour la lipase extracellulaire et de 37°C pour la lipase intracellulaire. Un pH de 5.0 est optimal pour la production des deux enzymes.

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The characteristics of the membrane-bound lipase from a thermophilic Rhizopus oryzae were studied. The pH and temperature optima for lipase activity were at 7.0 and 37°C, respectively. The enzyme was stable and acidic conditions, retaining more than 80% of its initial activity at pH 4.0 after 30 min incubation. It was stable up to 50°C with 70% of initial activity retained after 3 h incubation. The enzyme is 1,3 specific and exhibits substrate preference. Monoacid triglyceride substrates were hydrolyzed better than methyl esters, polyoxysorbitan and sorbitan substrates.Paper no. J8834 in JAOCS 76, 171-174 (February 1999).