Up until this point you might think sugars are the only substrates that bacteria can grow on. Nothing could be farther from the truth. Bacteria are capable of growth on fatty acids and lipids. Lipids are large molecules and cannot be transported across the membrane. A class of extracellular enzymes called lipases are responsible for the breakdown of lipids.
Lipases attack the bond between the glycerol molecule oxygen and the fatty acid.
Phospholipids are attacked by phospholipases . There are four classes of phospholipases given different names depending upon the bond they cleave. Phospholipases are not particular about their substrate and will attack a glycerol ester linkage containing any length fatty acid attached to it. The result of this digestion is a hydrophillic head molecule, glycerol and fatty acids of various chain lengths. The head can be one of several small organic molecules that are funneled into the TCA cycle by one or two reactions that we won't cover here.