Purification and Characterization of Agarase from Marine Bacteria Acinetobacter sp. PS12B and Its Use for Preparing Bioactive Hydrolysate from Agarophyte Red Seaweed Gracilaria verrucosa
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Acinetobacter strain PS12B was isolated from marine sediment and was found to be a good candidate to degrade agar and produce agarase enzyme. The extracellular agarase enzyme from strain PS12B was purified by ammonium sulfate precipitation followed by DEAE-cellulose ion-exchange chromatography. The specific activity of the crude enzyme which was 1.52 U increased to 45.76 U, after two-stage purification, with an enzyme yield of 9.76%. Purified enzyme had a molecular mass of 24 kDa. The optimum pH and temperature for activity of purified agarase were found to be 8.0 and 40 °C, respectively. The Km and Vmax values for agarase were 4.69 mg/ml and 0.5 μmol/min, respectively. Treatment with EDTA reduced the agarase activity by 58% at 5 mM concentration. The enzyme activity was stimulated by the presence of Fe2+, Mn2+, and Ca2+ ions while reducing reagents (β-mercaptoethanol and dithiothreitol, DTT) enhanced its activity by 30–40%. The purified agarase exhibited tolerance to both detergents and organic solvents. Major hydrolysis products of agar were DP4 and also a mixture of longer oligosaccharides DP6 and DP7. The enzyme hydrolysed seaweed (Gracilaria verrucosa) exhibited strong antioxidant activity in vitro. Successful hydrolysis of seaweed indicates the potential use of the enzyme to produce seaweed hydrolysate having health benefits as well as the industrial application like the production of biofuels.
KeywordsAcinetobacter Agarase Degree of polymerization (DP) Gracilaria verrucosa Oligosaccharide Antioxidant activity
The authors wish to thank the Director, CSIR-CFTRI for encouragement, and the facilities provided. First author thanks UGC, Govt. of India (Grant No. 1269/NET-June 2011) for the support in the form of fellowship.
Compliance with Ethical Standards
Conflict of Interest
The authors declare that they have no conflict of interest.
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