Fig. 2.

Newly created deletions are fully supplementable and strongly selectable. LO9771 carries seven selectable markers. When minimal medium is supplemented for all seven markers, growth is essentially the same as the parental strain LO4389. Selections against the four newly created deletions are shown. Omission of biotin selects against the biA deletion, omission of p-aminobenzoic acid selects against the pabaA deletion, omission of lysine selects against the lysB mutation and omission of choline selects against the choA deletion. In the absence of each of these supplements, the growth of the strain is strongly inhibited. For simplicity only the seven-marker strain is shown but similar results were obtained with strains carrying fewer markers.