SUMMARY: L-Alanine-initiated germination of spores of Bacillus cereus was potentiated by the following structural analogues of alanine: O-carbamyl-D-serine (OCDS), D-cycloserine (DCS), β-alanylhydroxamic acid (βAHA) and glycyl hydroxamic acid (GHA); but not by D-α-alanyl-hydroxamic acid (DAHA). Potentiation of germination resulted from inhibition of alanine racemase in the spores with consequent suppression of the formation of D-alanine, an inhibitor of L-alanine-initiated germination. OCDS was the most effective potentiator of germination and inhibitor of racemase. βAHA and GHA were more effective potentiators of germination than could be explained solely by their weak inhibition of the racemase. The extra effectiveness was associated with slow binding of the analogues to the spores, and possibly also with formation of hydroxylamine which also inhibited alanine racemase and potentiated L-alanine-initiated germination. Germination initiated by ribosides and amino acids other than L-alanine was not strongly potentiated by OCDS, arguing against a role for L-alanine as an intermediate. However, germination initiated by adenosine+D-alanine was strongly inhibited by OCDS, which argues for the role of D-alanine being to supply the L-isomer by racemization. Antibacterial activities of the analogues did not mirror their activities as potentiators of germination.