Xanthanase enzyme and its production.

摘要

A process for the production of a xanthan gum depolymerising enzyme (hereinafter termed <>) which comprises culturing Corynebacterium strain 20/122 (deposited with NCIB under accession number 11535) under aerobic conditions in a liquid growth medium comprising assimilable sources of nitrogen and essential mineral salts and, as the sole carbon source, xanthan gum, separating the bacterial cells from the reaction mass and recovering the xanthanase from the resultant spent growth medium. Also the xanthanase enzyme produced by the foregoing process, which enzyme has been characterised by the reaction products derived from the enzymic depolymerisation of deacetylated xanthan gum. There are 4 major products, which have Rf values of 0.55, 0.50, 014 and 0.05 when resolved by chromatography on cellulose thin layer plates using, as solvent, ethyl acetate-pyridine-glacial acetic acid-water (5 : 5 : 1 : 3 by volume), and detected with standard silver nitrate-sodium hydroxide spray reagent. The four were further identified by sugar analysis as being, in order of decreasing Rf value, mannose, mannose ketal-linked to pyruvate, an oligosaccharide containing glucose, mannose and uronic acid in the proportions 1.0 : 0.5 : 0.34 respectively, and an oligosaccharide containing glucose, mannose and uronic acid in the proportions 1.0 : 0.84 : 0.55. Also a process for the depolymerisation of xanthan gum or carboxymethyl cellulose (CMC), in which an aqueous solution of the gum or CMC is reacted with the xanthanase produced as defined above at a temperature between 25 DEG C and 70 DEG C, preferably 30 DEG C, and a pH between 5 and 7, preferably pH 5.6.