2.2. Bacterial strains
Three potential bacterial strains viz. B. coagulans (MTCC 9872), B.
licheniformis (MTCC 6824) and P. polymyxa (MTCC 122) were procured
from the Indian Institute of Microbial Technology (IMTech),
Chandigarh, India. The bacteria B. coagulans and P. polymyxa were
revived in nutrient broth and B. licheniformis in Zobell marine broth
for 48 h at 37 C. To confirm the purity of strains, colonies were
identified on the basis of their morphological, Gram's staining and
biochemical characteristic using bacterial identification kits
(HiMedia, India). Cell density was calculated spectrophotometrically
at OD600 and values were correlated with colony forming unit
(CFU) counts using serial dilution and spread plating on their
respective agar. The quantified bacteria were centrifuged and suspensions
were made with phosphate buffered saline (PBS, pH 7.5).
The suspended form was used for feed preparation as required.