Abstract: 【Objective】 The aim of this experiment was to screen Bacillus with high enzyme activity and antibacterial properties from chicken intestines,and determine its probiotic properties,so as to provide high-quality strains for the development of poultry microecological preparations,promote the healthy development of poultry industry. 【Method】 Strains were screened from intestinal contents and mucous membrane of White-feathered broilers,and high-quality Bacillus was selected by morphological observation,enzyme-producing activity and bacteriological inhibition.The colony morphology, in vitro growth characteristics,tolerance,intestinal adhesion and drug sensitivity of the isolates were further determined to evaluate their basic probiotic properties.The species types of the isolates were identified by physiological,biochemical and molecular biological tests. 【Result】 9 strains were isolated and purified,which were named P1-P9.Morphological identification showed that 7 strains were Gram-positive and 2 strains were Gram-negative.The optimal strain P2 was selected by enzymic activity and bacteriostatic characteristics.The diameter of transparent circle of protease,cellulase,amylase and lipase of the isolate P2 were 46.86,41.52,20.70 and 14.47 mm,respectively.The inhibition zone diameter against Escherichia coli, Staphylococcus aureus and Salmonella Pullorum were 14.77,24.05 and 19.19 mm,respectively.The colony form of the isolate P2 was round,milky white,and the surface was wrinkled and convex,opaque,and had a sense of viscosity.It was a short rod-like bacterium,with a single bacterium size of (1.46±0.07) μm×(0.81±0.03) μm.The isolate P2 had good growth performance,strong tolerance to strong acids and bile salts,and certain intestinal adhesion with a adhesion capacity of 146.52 CFU/cell.The results of drug sensitivity test showed that P2 was sensitive to gentamicin,kanamycin,clindamycin,vancomycin,ampicillin,streptomycin,chloramphenicol and erythromycin.Physiological,biochemical and molecular biological identification results showed that the isolate P2 was Bacillus siamensis,and named CPU-B1. 【Conclusion】 In this study,a strain of Bacillus siamensis CPU-B1 from chicken was screened,which had strong enzyme production activity,strong antibacterial properties,excellent growth characteristics,tolerance and intestinal adhesion,and could be further developed as a microecological preparation for poultry industry.

Key words: Bacillus; isolation and identification; enzyme-producing activity; bacteriostatic property