Abstract
Shewanella putrefaciens is a well-known specific spoilage organism (SSO) and cold-tolerant microorganism in refrigerated fresh marine fish. Cold-adapted mechanism includes increased fluidity of lipid membranes by the ability to finely adjust lipids composition. In the present study, the lipid profile of S. putrefaciens cultivated at 30, 20, 10, 4, and 0 °C was explored using ultra-high-pressure liquid chromatography/electrospray ionization tandem mass spectrometry (UHPLC-ESI-MS/MS) to discuss the effect of lipid composition on cold-adapted tolerance. Lipidomic analysis detected a total of 27 lipid classes and 606 lipid molecular species in S. putrefaciens cultivated at 30, 20, 10, 4, and 0 °C. S. putrefaciens cultivated at 30 °C (SP-30) had significantly higher content of glycerolipids, sphingolipids, saccharolipids, and fatty acids compared with that at 0 °C (SP-0); however, the lower content of phospholipids (13.97%) was also found in SP-30. PE (30:0), PE (15:0/15:0), PE (31:0), PA (33:1), PE (32:1), PE (33:1), PE (25:0), PC (22:0), PE (29:0), PE (34:1), dMePE (15:0/16:1), PE (31:1), dMePE (15:1/15:0), PG (34:2), and PC (11:0/11:0) were identified as the most abundant lipid molecular species in S. putrefaciens cultivated at 30, 20, 10, 4, and 0 °C. The increase of PG content contributes to the construction of membrane lipid bilayer and successfully maintains membrane integrity under cold stress. S. putrefaciens cultivated at low temperature significantly increased the total unsaturated liquid contents but decreased the content of saturated liquid contents.
Highlights
Bacterial cell membranes are mainly composed of glycerolipids such as phospholipids (PL) and glycolipids (GL), which play an important role in membrane properties and functions [1]
Lipid Search 4.1.30 was employed in order to process ultra-high-pressure liquid chromatography/electrospray ionization tandem mass spectrometry (UHPLC-ESI-MS/MS)
Under the optimal temperature, SP-30 had significantly higher content of glycerolipids, sphingolipids, and saccharolipids compared with SP-0; the lower content of phospholipids (13.97%) was found in SP-30
Summary
Bacterial cell membranes are mainly composed of glycerolipids such as phospholipids (PL) and glycolipids (GL), which play an important role in membrane properties and functions [1]. Some researchers mainly focused on the fatty acids composition of the bacterial cell membrane instead of the lipids [4,5]. Molecules 2019, 24, 4609 from Han and Gross [8] According to these authors, the aim of lipidomics is “the full characterization of lipid molecular species and of their biological roles with respect to expression of proteins involved in lipid metabolism and function” [9]. Some methods based on mass spectrometry (MS) have been used for the detailed analysis of bacterial cell membranes lipidomics, including directly analyzing lipid extracts by matrix-assisted laser desorption ionization (MALDI) [15,16], liquid chromatography (LC) [17], and electrospray ionization (ESI) [16,18,19] coupled to MS. The introduction of UHPLC coupled to tandem MS (UHPLC-MS/MS) allows rapid and effective separation of individual lipid species and has been become a powerful tool for analyzing lipid classes in bacteria [20]
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