Involved in degradation of fumonisin B1. Catalyzes the hydrolysis of fumonisin B1 (FB1) to aminopentol (HFB1). fumonisin B1 + 2 H2O = (2S,3S,5R,10R,12S,14S,15R,16R)-2-amino-12,16-dimethylicosane-3,5,10,14,15-pentol + 2 H(+) + 2 tricarballylate Belongs to the type-B carboxylesterase/lipase family.