Preparation and characterization of alginate–gelatin microencapsulated Bacillus subtilis SL-13 by emulsification/internal gelation

Abstract

Gelatin was blended with sodium alginate (NaALG) to obtain a novel microbial fungicide, and dispersed micron Bacillus subtilis SL-13 microspheres prepared by emulsification/internal gelation method. Microscopic examination revealed that microcapsules were nearly spherical in shape. Fourier transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffraction confirmed that the electrostatic interaction was occurred when gelatin added into NaALG. The maximum encapsulation efficiency was 93.44% at a gelatin concentration of 1.5%. Particle size, swelling, and biodegradation of beads increased with gelatin content increase. Furthermore, the viability of encapsulated SL-13 could be preserved at more than 10⁸ CFU/mL after 120 d storage at 25 °C. The number of viable cells released from microcapsules presented an initial rapid increase followed by a gradual increase, and reached the maximum as 10¹⁰ CFU/mL on day 35. Thus, it is feasible to prepare uniform, rounded shape, and well-dispersed micron microcapsules of SL-13 via emulsification/internal gelation using NaALG and gelatin composites. This encapsulation strategy could be considered as a potential alternative to future applications in the agricultural industry.

Keywords:

• microcapsule
• Bacillus subtilis SL-13
• sodium alginate
• gelatin
• emulsification internal gelation

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was financially supported by the National Natural Science Foundation of China [31260022]; Science and Technology Fund Projects of Shihezi University [2013ZRKXJQ01].