15A-21 |
Production of arylsulfatase to improve physical properties of agar |
D. S. BYUN, Faculty of Food Science and Biotechnology, Pukyong National University, 599-1, Daeyeon-Dong, Nam-Gu, Pusan, 608-737, South Korea, D. S. Kim, Faculty of Food Science and Biotechnology, PNU, 599-1, Daeyeon-Dong, Nam-Gu, Pusan, 608-737, South Korea, M. J. Oh, Fish Pathlogy, Yosu National University, 96-1, Dundeuk-Dong, Yosu-si, Chunnam, 550-749, South Korea, J. S. Godber, Food Science, Louisiana State University and Agricultural Station, Food Science Bldg, Baton Rouge, LA LA 70803, and H. R. Kim, Faculty ofFood Science and Biotechnology, Pukyong National University, 599, Daeyen-Dong, Nam-Gu, Pusan, 608-737, South Korea. Agar is composed of about 70% of agarose and about 30% of agaropectin which has sulfate groups in its molecule. Low proportion of agaropectin in agar improves physical properties of agar, such as gel strength, gelling temperature, and electroendosmosis. Enzymatic hydrolysis of sulfate groups in agaropectin results in improvement of the physical properties of agar with little waste water. The isolated Sphingomonas sp. nov. from the South coast in Korea produced arylsulfatase and reaction conditions of the enzyme were established using agar as a substrate. Our objective was to identify arylsulfatase producing microorganism and establish a fermentation condition for arylsulfatase production, and an optimum reaction conditions to reduce sulfate level in agar. Identification of the microorganism was conducted by cellular lipid and fatty acid composition, Biolog analysis, and 16S rRNA gene sequence. Fermentation conditions for the production of arylsulfatase were determined with a 7L Lab-scale fermentor. Reaction conditions for the removal of sulfate group in agaropectin were determined by sulfate assay. Complete 16S rRNA gene sequence aligned with other Sphingomonas 16S rRNA gene sequence, levels of sequence similarity and a phylogenetic dendrogram were constructed. 16S rRNA sequence of the bacteria was closely related to Sphingomonas xenophaga (96.35% similarity), which showed the bacteria was identified as a new species. Medium conditions for the production of arylsulfatase were determined to be 1.4% tryptone, 0.25% glucose, 0.25% K2HPO4, 0.25% NaCl, and 0.012% MgSO4 and fermentation conditions were for 72 hr fermentation at pH 7.0 and 25oC. With the reaction of agar with arylsulfatase in the ratio of 1: 10-6 (w/w) for 2 hr at 45oC, gel strength increased to 2.3-fold and 97% (p<0.01) of sulfate in agaropectin was removed. These results suggest that arylsulfatase is a good candidate for improving physical properties of agar for food additives. Also, the enzyme could be applicable to the production of value-added products such as electrophoresis grade agarose, immunodifusion, and isoelectrofucusing.
Session 15A, Biotechnology
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