The present invention relates to a novel bacterium Yersinia entomophaga MH96 as deposited at DSMZ on 4 May 2006 and designated accession no. DSM 18238. The present invention also relates to substances obtained or derived from Yersinia entomophaga MH96, which retain biopesticide activity. Methods for protecting a plant from pest infestation which include applying to the plant or its environment an effective amount of Yersinia entomophaga MH96 or a product delivered from the bacterium are also described.