Fuente: WIPO "tomato" Disclosed herein is a strain of Bacillus infantis deposited under number CECT 30759. Also, a microbial composition and process for the preparation thereof. Particularly, a microbial composition based on Bacillus infantis strain used as plant growth promotion bacteria (PGPB), more specifically as a biological fixing nitrogen. In addition, the present invention discloses a method for reducing the total amount of nitrogen fertilizer required by crop.