Structures of Gram-Negative Cell Walls and Their Derived Membrane Vesicles

Gram-negative cell walls are strong enough to withstand ;3 atm of turgor pressure (40), tough enough to endure extreme temperatures and pHs (e.g., Thiobacillus ferrooxidans grows at ap H of’1.5) and elastic enough to be capable of expanding several times their normal surface area (41). Strong, tough, and elasti c...t hegram-negative cell wall is a remarkable structure which protects the contents of the cell and which has stood the test of time for many, many years. Presumably, these three descriptive traits, have much to do with the tremendous success gram-negative bacteria have had as a life-form on our planet; members of the domain Bacteria inhabit almost all imaginable habitats except those excruciatingly extreme environments in which (some) members of the domain Archaea thrive. Molecular biological methods have not yet given scientists a precise historical record of the origin of gram-negative bacteria, but ancient stromatolites containing fossilized remains of cyanobacterium-like prokaryotes date back to the Archean eon. Over such extraordinary periods of time (much of it when no other life existed), we can imagine that random mutation, selection, and the slowly but ever-changing global