Identification and Characterization of Bacillus megaterium as Probiotic Bacteria in Poultry Feed

Abstract

The present study was planned to identify the Bacillus probiotic characteristics from a strain knows as Bacillus spp. in with the aim of use as a probiotic candidate in broiler chickens feed. The strain was identified phenotypically and evaluated for their viability through total plate count method, colony morphology, catalase test, hemolysis activity, pH (2 and 3) and bile salts (0.3% w/v) tolerance under simulated gastrointestinal tract (GIT) conditions, rate of survivability (%), spores resistance at high temperature and antibiotics susceptibility tests. Registered under the code IBNA 66, the strain was identified by API 50CHB (ID 99.9%) and ABIS online (91.8% similarity) as Bacillus megaterium. The strain presented a viable count of 3 x 1011 CFU/mL after 22±2h of incubation at 37°C, 120 rpm with positive catalase, and non-hemolytic activity results. Also, Bacillus megaterium showed a significant resistance and survivability at pH 2 (P <0.0001, 62.09%) and pH 3 (P <0.0001, 77.53%), bile salts (P <0.0001, 84.27%), with a high ability to produce spores (after 120 min. at 80°C show 9.47 Log CFU/mL, P <0.0001). The antibiotic susceptibility test showed 100.00% resistance of strain to oxacillin (1 μg/mL), with multiple antibiotic resistance indices above 0.5. In conclusion, Bacillus megaterium can be an ideal probiotic candidate that can potentially be formulated and applied in the poultry feed for improving performance and modulated GIT microflora.

Keywords

• gastrointestinal resistance
• in vitro properties
• probiotic