Mannanase enzyme and corresp. DNA - are produced in recombinant yeast or fungi; used for hydrolysis of manno-polymers, esp. in bleaching lignocellulose pulps

摘要

DNA (I) encoding a Trichoderma enzyme having mannanase (MN) activity is new, which when transferred into a yeast or fungus strain induces that strain to produce MN. Also new are (a) a vector contg. (I), (b) a recombinant yeast or fungus strain contg. (I), (c) a process for producing a MN or enzyme mixt. by (i) treating a T. reesei culture medium with bentonite, (ii) subjecting the medium to first cation exchange then to anion exchange at pH 7-7.5, (iii) collecting the eluates and purifying by hydrophobic interaction chromatography, and (iv) opt. subjecting the prod. to additional purificn., and (d) an enzyme prepn. contg. at least 1 MN produced by Trichoderma with MN activity and an isoelectric point (pI) of about 3.8, 4.1, 4.5, 5.4 or 6.5, as determined by isoelectric focusing. Pref. (I) hybridises to the insert of vector pMAN1 (in specification), and the yeast is pref. Saccharomyces cerevisiae or Trichoderma species. In hydrolysis, the glucomannans of cellulose pulp are hydrolysed by MN and pref. of at least 1 xylan. The MN treatment (pref. with xylanase) is carried out before bleaching (chlorine-free or peroxide) of sulphite pulp.