Isolation of a dextranase constitutive mutant of Lipomyces starkeyi and its use for the production of clinical size dextran.
A derepressed and partially constitutive mutant for dextranase of Lipomyces starkeyi was selected after ethyl methane sulphonate mutagenesis by zone clearance on blue dextran agar plates. The mutant produced dextranase when grown on glucose, fructose and sucrose as well as on dextran, and more enzyme was produced by the mutant than by the parental strain when grown on 1% dextran. The pH and temperature optima for the mutant dextranase were 5.5 and 55 degrees C, respectively. Dextranase produced on sucrose produced more isomaltose and less glucose after dextran hydrolysis than the equivalent enzyme produced on dextran. The clinical size dextran (average mol. wt of 75,000 +/- 25,000) yield of mixed culture fermentation with the mutant and Leuconostoc mesenteroides was 94% of the total dextran produced.
Kim
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Department of Microbiology, Louisiana State University, Baton Rouge, USA.
Day
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D003910:Dextranase / Q000737:chemistry / Q000378:metabolism*; D005285:Fermentation; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D009154:Mutation; D013696:Temperature; D015003:Yeasts / Q000201:enzymology* / Q000302:isolation & purification
D003910:Dextranase