Abstract:Low temperature is an important method to ensure the quality and safety of aquatic products, but some cold tolerant bacteria can still survive and proliferate in the low temperature environment, and eventually lead to deterioration of aquatic products. In order to understand the effects of temperature on the growth kinetic parameters and membrane physicochemical properties of Shewanella putrefaciens, which is a typical cold resistant microorganism found in aquatic products, the growth curve and growth kinetic parameters of Shewanella putrefaciens DSM6067 strain, as well as the fatty acid composition, protein content, fluidity, and microstructure of its cell membrane were studied. It was found that the lag phase of the strain cultured at 30 ℃, 10 ℃, and 4 ℃ were 3.35 h, 25.94 h and 122.03 h respectively. Although the growth rate of Shewanella putrefaciens was slower in low temperature environment, it could still proliferate continually. According to the fatty acids compositions of cell membrane at the mid of exponential phase, the total contents of unsaturated fatty acids in bacteria cultured at 4 ℃ was 51.04%, while that of strains cultured at 30 ℃ was as low as 43.36%. Among them, the monounsaturated fatty acid (palmitic acid) C16:1 increased the most significantly from 26.62% at 30 ℃ to 46.66% at 4 ℃. The protein content of membrane also increased slightly as the temperature decreased. The fluidity of cell membrane was low initially when the strain was incubated at low temperature, but increased in the latter culture period. The TEM results showed that smoother cell membrane, smaller vacuolation and bigger cell size in strains cultured at low temperatures. The changes of physic-chemical properties should be responsible for Shewanella putrefaciens strains to survive and grow at low temperatures.