Enzymatic desulfation of the red seaweeds agar by Marinomonas arylsulfatase

Abstract

Agar and sulfated galactans were isolated from the red seaweeds Gracilariopsis lemaneiformis and Gelidium amansii. A previously purified arylsulfatase from Marinomonas sp. FW-1 was used to remove sulfate groups in agar and sulfated galactans. After enzymatic desulfation, the sulfate content decreased to about 0.16% and gel strength increased about two folds. Moreover, there was no difference between the DNA electrophoresis spectrum on the gel of the arylsulfatase-treated agar and that of the commercial agarose. In order to reveal the desulfation ratio and site, chemical and structural identification of sulfated galactan were carried out. G. amansii sulfated galactan with 7.4% sulfated content was composed of galactose and 3,6-anhydro-l-galactose. Meanwhile, G. lemaneiformis sulfated galactan with 8.5% sulfated content was composed of galactose, 3,6-anhydro-l-galactose, 2-O-methyl-3,6-anhydro-l-galactose and xylose. Data from C NMR, FT-IR, GC-MS provided evidence of sulfate groups at C-4 and C-6 of d-galactose and C-6 of l-galactose both in GRAP and GEAP. Data from GC-MS revealed that desulfation was carried out by the arylsulfatase at the sulfate bonds at C-4 and C-6 of d-galactose and C-6 of l-galactose, with a desulfation ratio of 83.4% and 86.0% against GEAP and GRAP, respectively.

Convenient Agarose Preparation with Hydrogen Peroxide and Desulfation Process Analysis

“…Although alkali treatment and organic reagent treatment can achieve the purpose of desulfation, the sulfate content of the final samples obtained by these two methods was much higher than the standard of agarose. Enzymatic treatment is a desulfation method that has emerged in recent years [ 17 ]. Table 1 shows that the sulfate content of this method can be reduced to less than 0.20%, and the desulfation rate can exceed 85%.…”

“…Considering that the infrared spectrum detection line cannot detect sulfate at different positions in raw agar, to increase the sulfate content, we used Wang’s method to extract the sulfated galactan with a higher sulfate content from the raw agar. The spectra of the samples before and after the modification are shown in Figure 4 d. The position of the sulfate group of agar-type polysaccharide was identified by the bands at 800–850 cm −1 [ 17 ]. The absence of the band at 850 cm −1 of modified sulfated galactan indicates that the sulfate groups of C-4 of D-galactose were eliminated.…”

“…However, the above methods cannot meet the requirements of agarose because of the high sulfate content (above 1.0%) after treatment. In recent years, more environmentally friendly methods have emerged for the removal of sulfate from agar, such as the use of enzymes [ 16 , 17 ]. Enzymatic desulfation can significantly improve the quality of agar and reduce sulfate content to less than 0.2%.…”

Structural Diversity in Galactans From Red Seaweeds and Its Influence on Rheological Properties

“…Water soluble agarans obtained after removal of agarose from Gracilariopsis lemaneiformis (as Gracilaria lemaneiformis) and Gelidium amansii showed considerable amounts of G-L6S (16.2 and 15%, respectively). In addition, for G. lemaneiformis, no methylated derivatives were found and only small amounts of G6S and G4S were detected, while for G. amansii, these galactose derivatives were present in minor quantities, but also minor amounts of GP and LA2M were detected (Wang et al, 2016).…”

Optimisation of Lactose Hydrolysis by Combining Solids and ß-Galactosidase Concentrations in Whey Permeates

“…Means followed by the same letter do not differ significantly by Tukey's test (p > 0.05). follows: invertase (ß-fructofuranosidase (EC.3.2.1.26)) hydrolyses sucrose into glucose and fructose (Soares et al, 2019); arylsulfatase (E.C.3.1.6.1) hydrolyses arylsulfate esters into aryl-compounds and inorganic sulphates (Wang et al, 2016); glucoamylase (g-amylase (EC 3.2.1.3)) hydrolyses a-1-4, a-1-6 glycosidic bonds in starch and malto-oligosaccharides (Meng et al, 2018); lipases (triacylglycerol hydrolases (E.C. 3.1.1.3)) hydrolyse many reactions such as hydrolysis or synthesis of esters, esterifications, aminations, alcoholysis, and others (Rios et al, 2018).…”