The present invention relates to a Streptomyces mutant strain in which a -agarase DagA enzyme is over-expressed and a method for developing the strain. In addition, the present invention relates to a method for producing neoagarohexaose or neoagarotetraose in vivo by using the Streptomyces mutant strain.

The present invention provides Streptomyces coelicolor strain A3(2)_M22-2C43 obtained by inducing a point mutation in the base sequence of the DagB gene in a wild-type Streptomyces coelicolor strain A3(2) by UV radiation. Since the Streptomyces coelicolor strain A3(2)_M22-2C43 according to the present invention expresses a DagB mutant enzyme expressing little or no DagB beta-agarase or exhibiting little or no beta-agarase activity, there is no need for separate isolation and purification of DagA enzymes from culture fluid, and the culture fluid of the Streptomyces coelicolor strain A3(2)_M22-2C43 or supernatant thereof may be used to produce, from agar or agarose, neoagarose oligosaccharides with a higher content of neoagarotetraose or neoagarohexaose than that of neoagarobiose.

The present disclosure relates to an enzyme complex of arabinose isomerase, agarase and 3,6-anhydro galactosidase and a method for producing tagatose by degrading agar using the same. By using the enzyme complex according to the present disclosure, agar obtained from marine biomass can be degraded effectively and useful physiologically active substances such as tagatose can be obtained effectively therefrom.

The present invention relates to a method for producing marine algae-derived agarotriose, and a use thereof as a prebiotic. More specifically, the present invention investigates the characteristics of agarotriose as a prebiotic which is selectively metabolized by probiotic microorganisms, thereby enabling agarotriose to be used as an anti-cancer or anti-inflammatory agent in the fields of food and pharmaceuticals, and enabling agarotriose to be obtained at high yield through efficient purification with minimal loss after enzymatic hydrolysis of a red algae-derived polysaccharide without pre-treatment.

The present invention provides a -agarase, a composition containing the same and applications thereof. The present -agarase provides the field a novel alternative and is favorable for the industrial utilities of the hydrolysis products of agarose. Furthermore, the present agarase is particularly modified for heterologous production by prokaryotic expression systems, and thereby is favorable for commercial use.

The present invention relates to an expansin-agarase enzyme complex and a method of degrading agar by using the same. The use of the enzyme complex according to the present invention can efficiently degrade agar obtained from marine biomass, and thus can efficiently provide not only galactose or glucose necessary for ethanol production, but also useful biologically active substances, such as diose, triose, and oligosaccharides.

The present invention relates to a novel method for purifying 3,6-anhydro-L-galactose by using microorganisms and provides an effect of improving the production yield of 3,6-anhydro-L-galactose by using microorganisms during purification after enzymatic hydrolysis of agarose or agar.

The present invention relates to a heat-resistant agarase and a monosaccharide production method using same. More particularly, in the present invention, a heat-resistant agarase may be used to produce galactose and 3,6-anhydro-L-galactose at high yield by efficiently breaking down agarose or agar without a chemical pretreatment, a neutralization process, or an agarotriose hydrolase treatment process.

Disclosed are an agarase mutant with improved thermal stability and application thereof, belonging to the fields of genetic engineering technology and enzyme engineering. The present disclosure provides an agarase mutant, which is obtained by mutating the amino acid at the 86.sup.th site, the 373.sup.rd site, the 374.sup.th site, the 496.sup.th site, the 507.sup.th site, or the 747.sup.th site of agarase with an amino acid sequence as shown in SEQ ID NO.1. The agarase mutant provided by the present disclosure improves the thermal stability and the hydrolytic activity of the agarase. Compared with the wild type enzyme, the mutant enzyme shows excellent heat resistance and can be industrially used at a relatively high temperature, so that the utilization rate of agar raw materials and the yield of oligosaccharides from agar are improved, and the mutant enzyme has a good industrial application prospect.

Provided in the present invention is a composition having a novel use and containing a neoagarooligosaccharide mixture as an active ingredient. According to the present invention, a neoagarooligosaccharide mixture, which is the active ingredient of the composition according to the present invention, and the like can reduce the expression of RANKL, which is an osteoclast inducer, and effectively inhibit the differentiation of mononuclear cells into osteoclasts. Therefore, the composition according to the present invention can be used as a medicine or functional food for preventing, alleviating, or treating arthritis (especially rheumatoid arthritis) or osteoporosis.