Abstract: Aspergillus oryzae strains were screened to produce koji for fish sauce fermentation, and cultivated conditions of :5 fish sauce koji with single and mixing strains were also studied in this test. The result is that the highest protease activity is As1 strain; the optimal fermentation process is that the cultivate temperature is 28℃, the water content is 52%, bran: bean cake of medium is 3:1; Cultivate temperature has the most effect on protease, then the water content, the least effect is medium component. The protease activity of koji mixed Aspergillus oryzae with Bacillus subtilis was higher than that of single strain, it appears potential perspective in the fermentation of fish sauce.

Key words: fish sauce, koji, aspergillus oryzae