The bacterium was cultured and prepared as a stock suspension of endospores according to the method described by Chumthong et al. (2008). Formulations of alginate microcapsules were prepared, either with or without endospores of B. megaterium using an ionotropic gelation method (Elc¸in 1995), that mixed a 4 % (w/v) sodium alginate (Alg) solution with a bacterial endospore suspension. The final 1, 1.5 or 2 % (w/v) sodium alginate solutions thus obtained were used in the experiment. The alginate-bacterium mixture (50 ml) was magnetically stirred for an hour then extruded through an air-brush injector (Badger Model 150TM, Badger Air-Brush Co., USA) into CaCl2 (0.5 M, 100 ml) (at a pressure of 1 psi and a distance of 5 cm), thus forming microcapsules. The calcium alginate microcapsules were washed with sterile saline and stored in sterile glass containers at room temperature (28 ± 2 C).