Screening of aPlanococcusbacterium producing a cold‐adapted protease and its application in low‐salt fish sauce fermentation

A strain of bacteria isolated from a traditional fermented shrimp paste showed high protease activity at low-temperature (15°C). The strain was identified as Planococcus maritimus and named Planococcus maritimus XJ2. P. maritimus XJ2 grows well in a low-temperature, low-salt, and alkaline environment. The protease produced by P. maritimus XJ2 exhibited the highest enzyme activity at 40°C, pH 9.0 and showed salt tolerance. The amino acid nitrogen content of low-salt fish sauce inoculated with P. maritimus XJ2 was 1.28 ± 0.04 g/100 ml, which was significantly higher than that of the control without P. maritimus XJ2 (0.89 ± 0.02 g/100 ml, p < .01). The amounts of key desirable volatiles, such as alcohols, ketones, acids, esters, and pyrazine were higher in P. maritimus XJ2 than in the control (p < .05). P. maritimus XJ2 could be used as a starter culture for low-salt fish sauce incubated at 21°C. Practical applications The bacteria identified in this study has a good capacity to ferment the fish for good quality of fish sauce. A new method for the rapid fermentation of low-salt fish sauce and the improvement of its flavor by using Planococcus maritimus XJ2 is established. The procedure can help people to produce fish sauce in a shorter time, which will promote the development of fish sauce industry. Therefore, the starter and the method have good practical application in fish sauce produce.