Streptomyces cericolor mutant strain, method for producing beta agarase using the same and method for producing NGNO oligosaccharide

摘要

In the present invention, the base sequence of the DagB gene present in the wild-type Streptomyces coelicor A3 (2) strain is point-mutated by UV irradiation, and the Streptomyces coelicor A3 (2) _M22- A 2C43 strain is provided. The Streptomyces coelicol A3 (2) _M22-2C43 strain according to the present invention expresses a DagB mutant enzyme that hardly expresses DagB beta-agarase or has little beta-agarase activity. It is not necessary to separately purify the DagA enzyme from the agar or agarose using the culture solution of the Streptomyces coelicol A3 (2) _M22-2C43 strain or the supernatant thereof. It is possible to produce a neo-agarooligosaccharide having a relatively high content of neoagarotetraose or neoagarohexaose from neoagarobiose).