Thermophilic and alkalophilic xylanases from several Dictyoglomus isolates

• Published in: Applied microbiology and biotechnology 1992-10, Vol.38 (1), p.23-27
• Main Authors: MATHRANI, I. M, KIÆR AHRING, B
• Format: Article
• Language: English
• Subjects: activity; anaerobic bacteria; batch culture; Biological and medical sciences; Biology of microorganisms of confirmed or potential industrial interest; Biotechnology; Dictyoglomus; Fundamental and applied biological sciences. Psychology; heat tolerance; Mission oriented research; Physiology and metabolism; purification; thermophilic bacteria; xylan endo-1,3- beta -xylosidase
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/bf00169413

Supernatant xylanases from three thermophilic and strictly anaerobic Dictyoglomus strains isolated from very different environments were examined: the type species, D. thermophilum super(T), from a hot-spring in Japan; strain B1, a recently described strictly xylan-utilizing Dictyoglomus) from a paper-pulp factory in Finland; and strain B4a, isolated from a thermal pool on Iceland. The highest enzymatic activity observed from batch-culture supernatant with 4 g/l of beech xylan as growth substrate was 3.8 x 10 super(-6) kat/l. The K sub(m) for the xylanases of strain B1 was 4.7 g beech xylan/l. The xylanases of all the isolates had a broad range of activity with respect to pH, showing good activity from pH 5.5 to near 9.0. The xylanases from the three isolates had a very high temperature optimum of 80 degree C, maximum temperature for extended activity between 80 and 90 degree C, and a thermal half-life of over 1 h at 90 degree C for strain B1. The application of thermophilic alkalophilic xylanases to paper pulping was discussed.