Lipid extraction from bacterial pellet
The CLA analysis for bacterial pellet samples was modified from
Coakley and others (2003), where 60 μL of internal standard (6.49
mg/mL heptadecanoic acid in hexane)were added to the pellet suspended
in 1 mL buffered saline solution (0.137 mol/L NaCl, 7.0
mmol/L K2HPO4, and 2.5 mmol/L KH2PO4). Then 2 mL of isopropanol
were added and vortexed 60 s followed by the incorporation
of 1.5 mL of hexane. The mixture was shaken vigorously for 3
min and centrifuged 5 min at 2000 × g at 2 to 4 ◦C. The upper layer
was recovered and dried under nitrogen gas at 70 ◦C for 10 min in
the Zymark evaporator. The sample was dissolved in 500 μL hexane,
transferred to a microtube, and 100 μL 1N methanolic sodium hydroxidewere
added and vortexed for 1 min. The mixture was held 15
min in a 70 ◦C bath. Then, fatty acid methyl esters were prepared.