title: Purification and functional characterization of endo-beta-mannanase MAN5 and its application in oligosaccharide production from konjac flour.
abstract: MAN5, the main extracellular saccharide hydrolase from Bacillus sp. MSJ-5, is an endo-beta-mannanase with a demand of at least five sugar moieties for effective cleavage. It has a pH optimum of 5.5 and a temperature optimum of 50 degrees C and is stable at pH 5-9 or below 65 degrees C. MAN5 has a very high ability to hydrolyze konjac flour, 10 U/mg of which could completely liquefy konjac flour gum in 10 min at 50 degrees C. HPLC analysis showed that most glucomannan in the konjac flour was hydrolyzed into a large amount of oligosaccharides with DP of 2-6 and a very small amount of monosaccharide. With the culture supernatant as enzyme source, the optimum condition to prepare oligosaccharides from konjac flour was obtained as 10 mg/ml konjac flour incubated with 10 U/mg enzyme at 50 degrees C for 24 h. With this condition, more than 90% polysaccharides in the konjac flour solution were hydrolyzed into oligosaccharides and a little monosaccharide (2.98% of the oligosaccharides). Konjac flour is an underutilized agricultural material with low commercial value in China. With MAN5, konjac flour can be utilized to generate high value-added oligosaccharides. The high effectiveness and cheapness of this technique indicates its potential in industry.
authors.affiliation: Shandong University, Jinan, People's Republic of China.
authors.forename: Min
authors.initials: M
authors.lastname: Zhang
authors.forename: Xiu-Lan
authors.initials: XL
authors.lastname: Chen
authors.forename: Zhi-Hua
authors.initials: ZH
authors.lastname: Zhang
authors.forename: Cai-Yun
authors.initials: CY
authors.lastname: Sun
authors.forename: Lei-Lei
authors.initials: LL
authors.lastname: Chen
authors.forename: Hai-Lun
authors.initials: HL
authors.lastname: He
authors.forename: Bai-Cheng
authors.initials: BC
authors.lastname: Zhou
authors.forename: Yu-Zhong
authors.initials: YZ
authors.lastname: Zhang
mesh_terms: D031056:Amorphophallus / Q000378:metabolism*; D001407:Bacillus / Q000737:chemistry / Q000145:classification / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D004795:Enzyme Stability; D005433:Flour / Q000032:analysis / Q000382:microbiology; D009844:Oligosaccharides / Q000378:metabolism*; D010802:Phylogeny; D044902:beta-Mannosidase / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D009844:Oligosaccharides; D044902:beta-Mannosidase