Iota-carrageenan hydrolysis by Pseudoalteromonas carrageenovora IFO12985
Bernadette M. Henares, Erwin P. Enriquez, Fabian M. Dayrit and Nina Rosario L. Rojas*
Department of Chemistry, School of Science and Engineering
Ateno de Manila University, Loyola Heights, Diliman, Quezon City 1101, Philippines
corresponding author:This email address is being protected from spambots. You need JavaScript enabled to view it.
ABSTRACT
We report iota-carrageenan hydrolysis by Pseudoalteromonas carrageenovora IFO 12985. Kappa-carrageenase and lambda-carrageenase were previously isolated from this organism, but iota-carrageenase activity had not been reported in the literature. P. carrageenovora was grown in iota-carrageenan-based liquid medium. Using the zone of depression assay, transfer of aliquots of the culture to solid medium with 2% iota- and kappa-carrageenan showed extensive hydrolysis of iota-carrageenan. Analysis of the hydrolysates by C-13 Nuclear Magnetic Resonance spectroscopy confirmed degradation of the iota-carrageenan. Hydrolytic activity of P. carrageenovora grown in iota-carrageenan was compared with that of the same organism grown in kappa-carrageenan. Cell-free supernatants from each yielded subtle differences in hydrolytic profiles, but showed degradation patterns consistent with hydrolysis to fragments smaller than 1.4 kDa, corresponding to six or fewer monosaccharide units. Different protein expression bands on SDS-PAGE were also observed for the cell-free supernatants of P. carrageenovora grown in iota- versus kappa-carrageenan, with lower kappa-carrageenase expression observed in the organism grown in iota-carrageenan.
INTRODUCTION
Carrageenans are sulfated galactopyranose polysaccharides which are widely used in both food and non-food products as thickeners and stabilizers. They belong to the family of galactan polysaccharides that also include the agars, and are produced by red algae (Rhodophyta). Carrageenans are linear sulfated galactans with alternating 3-linked beta-D-galactopyranosyl residue and 4 –linked 3,6-anhydro-alpha-D-galactopyranosyl residues. . . . .
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