Fermentation optimization and enzyme characterization of a new ι-Carrageenase from Pseudoalteromonas carrageenovora ASY5

Background: A new iota-carrageenase-producing strain was screened from mangroves and authenticated as Pseudoalteromonas carrageenovora ASY5 in our laboratory. The potential application of this new strain was evaluated. Results: Medium compositions and culturing conditions in shaking flask fermentation were firstly optimized by single-factor experiment. iota-Carrageenase activity increased from 0.34 U/mL to 1.08 U/mL after test optimization. Optimal fermentation conditions were 20 degrees C, pH 7.0, incubation time of 40 h, 15 g/L NaCl, 1.5% (w/v) yeast extract as nitrogen source, and 0.9% (w/v) iota-carrageenan as carbon source. Then, the crude iota-carrageenase was characterized. The optimum temperature and pH of the iota-carrageenase were 40 degrees C and 8.0, respectively. The enzymatic activity at 35-40 degrees C for 45 min retained more than 40% of the maximum activity. Meanwhile, The iota-carrageenase was inhibited by the addition of 1 mmol/L Cd2+ and Fe3+ but increased by the addition of 1 mmol/L Ag+, Ba2+, Ca2+, Co2+, Mn2+, Zn2+, Fe2+, and Al3+. The structure of oligosaccharides derived from iota-carrageenan was detected using electrospray ionization mass spectrometry (ESI-MS). The iota-carrageenase degraded iota-carrageenan, yielding disaccharides and tetrasaccharides as main products. Conclusions: The discovery and study of new iota-carrageenases are beneficial not only for the production of iota-carrageenan oligosaccharides but also for the further utilization in industrial production. (C) 2017 Pontificia Universidad Catolica de Valparaiso. Production and hosting by Elsevier B.V. All rights reserved.