Characteristics of Bacillus subtilis and Bacillus licheniformis Consortium as Probiotics for Late-Phase Laying Hens

This study was carried out to characterize the consortium of Bacillus (B.) subtilis and B. licheniformis as potential probiotic supplements for late-phase laying hens by characteristics of their antimicrobial, protease, and lipase activities.Both bacteria were tested for their resistance to acidic conditions and bile salts to ensure the suitability of both bacteria as probiotics.The results of resistance tests to acid pH and bile salt indicate that B. subtilis and B. licheniformis are suitable as probiotics for laying hens.A Complete Randomized Design experimental design having three treatments and six replications was used during current study.The treatments included T1=1 B. subtilis : 1 B. licheniformis; T2=1 B. subtilis: 2 B. licheniformis; T3=2 B. subtilis : 1 B. licheniformis.The study used the agar well diffusion method to assess antimicrobial activity, lipase activity using the titrimetric method, and protease activity using the enzymatic method.Statistical analysis showed a significant difference (P<0.05) in the inhibition zones against E. coli, S. aureus, and S. typhimurium, as well as in protease and lipase activities.The results showed that the T1 consortium have excellent antimicrobial activity.Although the enzyme activity in T1 was not the highest, the difference was minimal compared to the other treatments.This study found the optimal ratio of B. subtilis and B. licheniformis (1:1) as a potential probiotic for late-phase laying hens, contributing to improved digestive health and function.