抄録
Currently, there is no suitable method for screening thermophilic bacteria for dextranases (E.C. 3.2.1.11). Here we report a procedure suitable for the identification of anaerobes grown at high temperatures (55-68°C). Water samples to be screened are inoculated into liquid medium containing Blue Dextran. Anaerobic thermophiles containing an active dextranase can be identified visually by a change in color of the medium from blue to yellow. The method may be quantified by extracting the cell-free supernatant into 70% ethanol and measuring absorbance at 420nm. Production of the yellow chromophore requires actively growing cells producing an endodextranase. Some 150 thermophiles were screened. A selection of 30 anaerobic thermophiles were ranked with respect to their dextranase activity. This method allowed the identification of organisms producing a new class of enzyme, amylodextranase, which hydrolyses both starch and dextran.
