• Title, Summary, Keyword: levanbiose

Search Result 2, Processing Time 0.047 seconds

Isolation and Cultivation of Microorganism Producing Levanbiose from Levan (Levan으로부터 Levanbiose를 생산하는 미생물의 분리 및 배양)

  • 이태호;강은정;강수경
    • Journal of the Korean Society of Food Science and Nutrition
    • /
    • v.27 no.3
    • /
    • pp.441-447
    • /
    • 1998
  • A bacterial strain No. 43 was isolated from soil samples as a levan-assimiating microorganism producing an extracellular levanase and hydrolying levan to levanbiose. According to the taxonomic characteristics of its morphological and physiological properties, the strain was idenified as Pseudomonas sp. No. 43. The optimum culura medium was composed of 10g levan, 5g(NH4)2SO4, 3g NH4Cl, 3g polypepton, 1g K2HPO4, 0.5gMgSO4.7H2O, and 0.2g MnCl2.4H2O per liter. The cultivation for levanase was carried out in pH 7.0 at 4$0^{\circ}C$ for 28hr. The reaction product was a kind of oligosaccharide and it was purified by chilled ethanol precipitation and gel filtration for evalluation of degree of polymerization (DP). The purified product was determined as levanbiose of MW 342 and DP2 by HPLC and FAB-MS.

  • PDF

Probing the Critical Residues for Intramolecular Fructosyl Transfer Reaction of a Levan Fructotransferase

  • Moon, Keum-Ok;Choi, Kyoung-Hwa;Kang, Ho-Young;Oh, Jeong-Il;Jang, Se-Bok;Park, Cheon-Seok;Lee, Jong-Hoon;Cha, Jae-Ho
    • Journal of Microbiology and Biotechnology
    • /
    • v.18 no.6
    • /
    • pp.1064-1069
    • /
    • 2008
  • Levan fructotransferase (LFTase) preferentially catalyzes the transfructosylation reaction in addition to levan hydrolysis, whereas other levan-degrading enzymes hydrolyze levan into a levan-oligosaccharide and fructose. Based on sequence comparisons and enzymatic properties, the fructosyl transfer activity of LFTase is proposed to have evolved from levanase. In order to probe the residues that are critical to the intramolecular fructosyl transfer reaction of the Microbacterium sp. AL-210 LFTase, an error-prone PCR mutagenesis process was carried out, and the mutants that led to a shift in activity from transfructosylation towards hydrolysis of levan were screened by the DNS method. After two rounds of mutagenesis, TLC and HPLC analyses of the reaction products by the selected mutants revealed two major products; one is a di-D-fructose-2,6':6,2'-dianhydride (DFAIV) and the other is a levanbiose. The newly detected levanbiose corresponds to the reaction product from LFTase lacking transferring activity. Two mutants (2-F8 and 2-G9) showed a high yield of levanbiose (38-40%) compared with the wild-type enzyme, and thus behaved as levanases. Sequence analysis of the individual mutants responsible for the enhanced hydrolytic activity indicated that Asn-85 was highly involved in the transfructosylation activity of LFTase.