53#, a strain of efficient alginate degrading bacteria, is isolated from rotted kelp using sodium alginate as the only carbon resource. Strain 53# is identified as Paenibacillus agaridevorans based on physiological characteristics and 16S rRNA sequencing. The optimaltion yield condition of strain 53# is identified at pH=8, T=25ºC, NaCl 15 g/L, and sodium alginate 15 g/L by orthogonal experiment and analysis, and the highest enzyme activity is 390.53±17.32 U/mL. Strain 53# has the advantages such as being cultivated easily, producing enzyme fast and having high enzyme activity. It can achieve a high efficiency for saccharification of alginate and thus has potential value to be utilized in the production of bioethanol from brown algae.

The adsorption of sodium dodecyl sulfonate (SDBS), tetradecyl pyridinechloride (TPC) and Triton X-100 (TX-100) onto the alumina powders at various pH was studied. The ξ-potential of the particles and the stability of the suspension in water were determined. The main results are as follows. (1) At suitable pH, the adsorption isotherms are LS type for SDBS and TPC. At higher concentration of surfactants, association on the surface occurs to form a close-packed monolayer. The orientation of hydrophilic group to water phase was inferred from values of adsorption limit, surface area and molecular dimensions. The sign of ξ-potential of alumina powder was opposite to the original one in lower concentration of SDBS or TPC, and the values of ξ-potential increased with increasing concentration. The stability of suspension of alumina powders is a function of SDBS or TPC concentration and displays an V-shaped curve with increasing concentration at lower concentration. (2) At pH 6.9 and higher concentration, monolayer on the surface of alumina was formed by adsorption of TX-100. In the monolayer the hydrophilic EO group interact with the hydroxy of surface and the hydrophilic group is in water phase. Then the stability of the suspension of alumina powders is lower than that of the suspension at lower concentration of TX-100.