[Objective] To investigate the influencing factors of Bacillus contamination in raw milk and analyze the reasons for the different forms of Bacillus.[Method] The species of Bacillus in raw milk were determined by matrix-assisted laser desorption ionization time-of-flight mass spectrometry（MALDI-TOF-MS）.[Result] In this study, 8 strains of Brevibacillus and 2 strains of Paenibacillus were isolated,among which there were 2 types of colony and morphology of Brevibacillus invocatus,and the long rod or filamentous form belonged to the special morphology of Brevibacillus invocatus.[Conclusion] The morphology of colonies changed regularly with the passage times and culture time,but there was no obvious pattern. The main factors of Bacillus contamination were related to the disinfection of cow bed,milkers’hands,wiping towels and equipments in the milk area. This study provided new morphological insights for the prevention and control of Bacillus and provided theoretical basis for related prevention and control.

Bacillus  /  morphological change  /  raw milk  /  MALDI-TOF-MS