Temperature dependency of the production of iturin A and surfactin by a dual producer, Bacillus subtilis RB14, in the solid-state fermentation of okara was investigated. The optimal temperature for burin A was 25 degrees C, while that for surfactin was 37 degrees C, in spite of their dependency on a common gene, lpa-14. When the effect of temperature on the relative ratios of the amount of the five homologues of iturin A to the total iturin A produced by RB14 was investigated, only the ratios of homologues having beta-amino acid residues with normal aliphatic chains were affected and the ratio of the homologue with longer normal (C-16-) chain increased as the temperature was increased.