## Materials and Methods  
To confirm the pathogenicity of _Streptococcus parauberis_ against starry flounder, an in vivo experiment was carried out following the guidelines of the National Institute of Fisheries Science, of Korea. The fish were obtained from a fish farm in Jeju Island, Korea and were acclimated in a fish tank before the experiment. Fish without any physical malformations or abnormal swimming behavior were used in this study. A total of 100 fish (\(720\pm 25\) g) were kept for 4 weeks (\(17\pm 0.5\)\({}^{\circ}\)C) and fed daily with compound fish feed. The fish were then divided into two groups (50 heads per group) and the pathogenicity experiments were duplicated. The _Streptococcus parauberis_ was prepared in suspension at a concentration of \(1\times 10^{9}\) cfu/mL, and 100 \(\upmu\)L of the suspension was intraperitoneally used to each fish. Before injection, the fish were anesthetized to MS-222 (250 mg/L) for 20 min and washed for sedation. The FKC was obtained by treating _Streptococcus parauberis_ in 1% formalin solution. Then, the FKC was suspended in phosphate buffered saline (PBS) to have an optical density (O.D.) of 0.1 for further treatment. The kaolinite (KA, EP grade) was purchased from Fisher Chemical, Fisher Scientific (Loughborough, UK). Another ingredient, layered double hydroxide (LDH) was synthesized to produce a size and morphology of LDH similar to KA. Typically, mixed metal solution containing Mg(NO\({}_{3}\))\({}_{2}\) 6H\({}_{2}\)O (0.3 M) and Al(NO\({}_{3}\))\({}_{3}\) 9H\({}_{2}\)O (0.15 M) was titrated with alkaline solution (0.5 M NaOH and 0.5 M NaHCO\({}_{3}\)) up to pH 9.5. Then the white suspension was subjected to hydrothermal treatment at 150 \({}^{\circ}\)C for 24 h. Finally, the precipitates were obtained through centrifugation, and were washed with deionized water and lyophilized. To obtain the FKC + clay mixture, FKC suspension (OD = 0.1) and an equivalent volume of aqueous clay suspension (1 mg/mL) were mixed and gently stirred under room temperature for 1 h. Next, the agglomeration or dispersion of FKC in the presence of clay particles was investigated by either measuring the hydrodynamic radius (dynamic light scattering measurement by ELSZ-1000, Otsuka, Kyoto, Japan) or by observing via scanning electron microscopy (FE-SEM, FEI Quanta FEG250, Hillsboro, OR, USA). For the SEM specimen, FKC or FKC + clay suspension were drop-cast on a piece of silicon wafer (\(\sim\)0.5 mm \(\times\) 0.5 mm) that was pre-cleaned with piranha solution (sulfuric acid: hydrogen peroxide = 3:1). After drying the specimen at room temperature, the specimen was coated with Pt/Pd sputtering (60 s) and was subjected to SEM measurement under 30 kV of accelerating voltage. To begin, the alginate was obtained from local seaweed. Typically, 5 g of dried seaweed was treated with 50 mL of 0.4% HCl and was washed with deionized water. Then, the precipitate was treated with 125 mL of 0.4% NaOH, and the solution was heated-up to 60 \({}^{\circ}\)C for 2.5 h. After the solution had cooled down, 150 mL of deionized water were added for dilution. Furthermore, the solution was separated by filtration and was treated with a small amount of 1 M HCl for gelation. The alginate gel was then separated by filtration, and 0.4% NaOH (200 mL) was added for neutralization. The final product was washed with 200 mL of EtOH then was then dried at 60 \({}^{\circ}\)C for 24 h.  
To conduct a quantitative analysis of the FKC, fluorescent dye, fluorescein isothiamate (FITC) (Sigma-Aldrich, Co. Inc., St. Louis, MO, USA, CAS No. 27072-45-3) was labelled on FKC. First, 1 mL of FKC suspension (OD = 0.1) was mixed with 1 mL of FITC solution (20 ppm). The mixture was vigorously stirred to induce thiourea bond between the amine terminal of the FKC surface and the isothiamate group of FITC. A reaction was carried out under dark conditions to avoid photodegradation. After 3 h of reaction, the FITC labelled FKC was washed with PBS and was collected via centrifugation.