Self-floating Capsule of Algicidal Bacteria Bacillus sp. HL and its Performance in the Dissolution of Microcystis Aeruginosa

Algicidal bacteria is known as efficient and environmentally friendly in treating Microcystis aeruginosa ( M. aeruginosa ). However, the practical application of algicidal bacteria in the natural water is limited by the interference of external factors and the low reuse capability. In this study, a biodegradation capsule for M. aeruginosa is prepared by biocompatible sodium alginate (SA) compositing with eco-friendly ethyl cellulose (EC). Bacterial strain HL was immobilized and the capsule was obtained under optimal usage concentrations of SA, Calcium chloride (CaCl 2 ) and EC at 2%, 3% and 3%. It has been observed that capsules immobilizing bacteria HL shows considerable advantages over traditional bio-treatment systems (free-living bacteria) and good reusability performance. A better dissolution rate of 77.67% ± 1.14% on the 7th day was obtained with the embedding of algicidal bacteria at 50 mL, which enhanced algae dissolution rate by 11.05% compared with free-living bacteria, and the dissolution rate for M. aeruginosa still reaches 68.57% ± 2.88% after three times repetitive use. Algicidal bacteria capsules were examined on the fluorescence and antioxidant system of M. aeruginosa . It was indicated that photosynthetic mechanisms of M. aeruginosa were destroyed, superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) were all significantly induced as antioxidant response, and malondialdehyde (MDA) content increased. Overall, capsules prepared in this study can provide a desirable environment for algicidal bacteria HL and ensure algicidal bacteria to in-situ work well in the inhibition of algae.