title: Enhanced inulinase production in solid state fermentation by a mutant of the marine yeast Pichia guilliermondii using surface response methodology and inulin hydrolysis.
abstract: In order to isolate inulinase overproducers of the marine yeast Pichia guilliermondii, strain 1, cells were mutated by using UV light and LiCl(2). One mutant (M-30) with enhanced inulinase production was obtained. Response surface methodology (RSM) was used to optimize the medium compositions and cultivation conditions for inulinase production by the mutant in solid-state fermentation. The initial moisture, inoculum, the amount ratio of wheat bran to rice bran, temperature, pH for the maximum inulinase production by the mutant M-30 were found to be 60.5%, 2.5%, 0.42, 30 degrees C and 6.50, respectively. Under the optimized conditions, 455.9 U/grams of dry substrate (gds) of inulinase activity was reached in the solid state fermentation culture of the mutant M-30 whereas the predicted maximum inulinase activity of 459.2 U/gds was derived from RSM regression. Under the same conditions, its parent strain only produced 291.0 U/gds of inulinase activity. This is the highest inulinase activity produced by the yeast strains reported so far.
authors.affiliation: UNESCO Chinese Center of Marine Biotechnology, Ocean University of China, Yushan Road, No. 5, Qingdao, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Guo
authors.forename: Fang
authors.initials: F
authors.lastname: Gong
authors.forename: Zhenming
authors.initials: Z
authors.lastname: Chi
authors.forename: Jun
authors.initials: J
authors.lastname: Sheng
authors.forename: Jing
authors.initials: J
authors.lastname: Li
mesh_terms: D003470:Culture Media / Q000378:metabolism; D046508:Culture Techniques; D005285:Fermentation; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000235:genetics / Q000378:metabolism*; D006868:Hydrolysis; D007328:Insulin / Q000378:metabolism*; D018020:Lithium Compounds / Q000737:chemistry; D016296:Mutagenesis; D009154:Mutation; D010843:Pichia / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification / Q000528:radiation effects; D012623:Seawater / Q000382:microbiology*; D014466:Ultraviolet Rays
chemical_list: D003470:Culture Media; D005656:Fungal Proteins; D007328:Insulin; D018020:Lithium Compounds; D006026:Glycoside Hydrolases; C023086:inulinase