FIG S1 Protein sequence alignment of AgaO and characterized GH50 β-agarases. Amino acid residues with homology ≥ 75% are shaded in black

frames. Two glutamine residues that constitute the highly conserved catalytic motif of GH50 β-agarases are indicated by star. Agarases and their resources

are BAE97587, AgaE-1 of Alteromonas sp. E-1; 4BQ4_A, Aga50D of Saccharophagus degradans 2-40; AHC72907, Aga21 of Pseudoalteromonas sp. NJ21;

AGT98631, AgaB1 of Thalassotalea agarivorans; AHM94172, AgWH50C of Agarivorans gilvus; ABD80438, Aga50A of Saccharophagus degradans 2-40;

CAB61811, AgaB of Streptomyces coelicolor A3(2); ADM25828, Aga41A of Vibrio sp. CN41; AFP32918, AgWH50A of Agarivorans gilvus; ADY17919,

HZ2 of Agarivorans sp. HZ105; ABM90422, AgaD02 of Agarivorans sp. QM38; BAA04744, AgaB of Vibrio sp.; BAG71428, AgaE of Vibrio sp. PO-303;

BAA03541, AgaA of Vibrio sp. JT0107; ABK97391, AgaE11 of Agarivorans sp. JA-1; ACU52709, AgrA of Agarivorans sp. AG17; BAG71427, AgaB of

Vibrio sp. PO-303; ADY17918, HZ1 of Agarivorans sp. HZ105; BAD99519, AgaA11 of Agarivorans sp. JAMB-A11; and AME16507, AgaO of

Flammeovirga sp. MY04.

FIG S2 SDS-PAGE analysis of the expression and purification of the recombinant agarase rAgaO. M, standard protein molecular weight markers. Lane

1, the induced cell lysate of the E. coli strain containing the control plasmid pBAD/gIII A; Lane 2, the induced cell lysate of the E. coli strain harbouring the

recombinant plasmid pBAgaO; Lane 3, soluble protein fractions of the induced cell lysate; Lane 4, the rAgaO protein purified from the soluble protein

fractions by Ni2+ affinity chromatography.