The genes encoding resistance to four different antibiotics (erythromy
cin, kanamycin, tetracycline and spectinomycin) were cloned in the pol
ylinker of various Escherichia coli plasmid vectors. These cassettes c
an be inserted into cloned Bacillus subtilis (Bs) genes and used to cr
eate tagged chromosomal disruptions after recombination into Bs and se
lection in the presence of the appropriate antibiotic.