For the Bus
A318/319/320/321 - FCOM 3.01.28 pag. 2 - on top
MINIMUM FUEL QUANTITY FOR TAKE OFF : 1500 kg (3307 lb)
A330 - FCOM 3.01.28 pag. 1 - bottom
MINIMUM FUEL QUANTITY FOR TAKE OFF : 5200 kg (11460 lb)
According those minimum requirements the minimum weight would be aircraft empty weight, plus minimum crew weight, plus the above figure.