This invention proposes a method for preparing selenomethionine, comprising the following steps: S1. Inoculating
selenium-resistant
Bacillus subtilis into a culture medium containing
sodium selenite for activation, and selecting seed culture in the
logarithmic growth phase; S2. Inoculating the seed culture into a
fermentation medium, providing carbon and
nitrogen sources for
cell proliferation in the early stage of
fermentation, and adding
inorganic selenium source and exogenous
methionine precursor in the middle and late stages of
fermentation, while adjusting dissolved
oxygen and pH to reduce
inorganic selenium into selenomethionine within the cells; S3. After fermentation, subjecting the
fermentation broth to
cell disruption,
solid-liquid separation, and
drying to obtain a product rich in selenomethionine. This preparation method, through staged fermentation, balances
cell growth and
selenium conversion efficiency, achieving efficient synthesis of selenomethionine from
Bacillus subtilis. The product contains
selenium primarily in the form of selenomethionine, with a high proportion of organic selenium. The strains used are highly safe, the process is mature, and the application value is significantly improved, making it suitable for industrial-scale production.