Isolation of Protease-productive Bacteria from Fish Sauces Collected in Vietnam

We isolated protease-productive bacteria from fish sauces collected in Vietnam and investigated their characteristics. Bacteria were detected from all the fish sauces on the low saline agar medium including 2.5% sodium chloride, and viable cell counts in the fish sauces were 1.0×102 to 1.4×106 cfu/ml. On the other hand, high halophilic bacteria which grow well on the high saline agar medium including 20% sodium chloride, were not found in all the fish sauces. Nine strains of protease-productive bacteria were picked out of the isolates of bacteria which grew on the low saline agar medium, and five of them were coccus and four were bacillus. All the strains of coccus producing protease were identified with Staphylococcus xylosus, and had a high halotolerant and did not have high protease productivity. All the strains of bacillus producing protease were identified with Bacillus, and their characteristics came closest to Bacillus firmus. Therefore, DNA homology of the strain of bacillus with B. firmus IFO 3330 was measured. Consequetly, it was confirmed that the strains of bacillus were not B. firmus. These strains had high halotolerant and high protease productivity, so it was suggested that they were involved in the maturing of the fish sauces.