A new high-alkaline alginate lyase from a deep-sea bacterium Agarivorans sp.
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A high-alkaline, salt-activated alginate lyase is produced by Agarivorans sp. JAM-A1m from a deep-sea sediment off Cape Nomamisaki on Kyushu Island, Japan. Purified to homogeneity, as judged by SDS-PAGE, the enzyme (A1m) had a molecular mass of approximately 31 kDa. The optimal pH was around 10 in glycine–NaOH buffer, and the activity was increased to 1.8 times by adding 0.2 M NaCl. However, when the optimal pH in the presence of 0.2 M NaCl was shifted to pH 9.0, the activity was more than 10 times compared with that at pH 9 in the absence of NaCl. A1m showed the optimal temperature at around 30°C and was stable to incubation between pH 6 and 9. The enzyme degraded favorably mannuronate–guluronate and guluronate-rich fragments in alginate. Shotgun cloning and sequencing of the gene for A1m revealed a 930-bp open reading frame, which encoded a mature enzyme of 289 amino acids (32,295 Da) belonging to polysaccharide lyase family 7. The deduced amino acid sequence showed the highest similarity to that of a Klebsiella enzyme, with only 54% identity.
KeywordsAlginate lyase PL family 7 Alkaline enzyme Deep sea Agarivorans
We are grateful to the captain and crew of the R/V Natushima and the ROV Hyper Dolphin operation team, for their technical support in sampling. We also thank the chief scientist, Prof. K. Kubokawa of the Ocean Research Institute, University of Tokyo, as well as all scientists aboard the NT05-12 cruise. We thank Dr. S. Aihara and Dr. H. Minegishi of Bio-Nano Electronics Research Center, Toyo University, for the IR spectra.
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