Preparation, characterization and cell viability of encapsulated Trichoderma asperellum in alginate beads.

Aim: The encapsulation of Trichoderma asperellum BRM-29104 using Ca-alginate matrix was evaluated. Methods: Intact and freeze-dried beads containing submerged conidia and microsclerotia (MS) of T. asperellum grown in liquid culture were prepared and characterised. Beads were stored at 8, 25, and 35 degrees C over 120 days. Results: The mean sizes of beads before and after freeze-drying were 2.5 +/- 0.2 mm and 1.5 x 1.1 mm (+/- 0.1 mm), respectively. Freeze-dried beads stored at 8 degrees C were more effective in maintaining conidia concentration, while MS concentrations yielded 10(2) MS/g for both beads at 8 and 25 degrees C. The concentration of viable cells in freeze-dried beads stored at 8 degrees C attained 3.0 x 10(8) CFU/g after 120 days. FIRT analysis showed an interaction between the alginate and the cell wall of the fungus. Conclusion: These findings support the use of alginate beads followed by freeze drying and cold storage for maintenance of viability of T. asperellum.