Characterization of bioactive porphyran oligosaccharides produced using porphyranase from Bacillus sp. NIOA284

Abstract

Macroalgae associated bacteria are the major source of polysaccharide hydrolyzing enzymes for efficient bioutilisation of macroalgal biomass. In this study, extracellular porphyranase, PB1 isolated from a macroalgae associated bacterium, Bacillus sp. NIOA284 was purified and characterized for hydrolysis of porphyran into porphyran oligosaccharides. The enzyme, PB1 showed the highest activity at the optimum conditions; the temperature of 35 oC, pH 7 and 0.4 NaCl with 10 mM CoCl2. The structural characterization of the enzymatically produced POS using NMR spectroscopy and HRMS spectrometry showed that the enzyme acted on porphyran as ?-porphyranase and produced di, tri and tetra saccharides. The bioactive potential of POS was determined based on its radical scavenging and prebiotic activity. Results show that POS exhibited higher antioxidant activity than parent porphyran and fructooligosaccharides. It was also capable to proliferate the beneficial gut bacterium Lactobacillus acidophilus and L. bulgaricus, it recorded a prebiotic activity score equivalent to model prebiotic compound fructooligosaccharides. Results show that the enzymatically produced POS has combined antioxidant and prebiotic activity. This highlights the significance of macroalgae associated bacteria as a source of enzymes capable of hydrolyzing polysaccharides into simple bioactive oligosaccharides for efficient management of chronic disorders caused due to oxidative stress.