Microbiology, we will agree, is a vast subject where many important aspects are likely to evade one’s sight. Here’s an example—the formation of vesicles from the outer membrane of Gram-negative bacteria. This phenomenon, known as vesiculation, is widespread and noteworthy for enhancing our understanding of bacterial capabilities and for its potential applications. My guess is that many microbiologists, like myself until recently, have only a hazy notion of it.
Let me set this in context. Bacteria have evolved a panoply of tactics for communicating both socially and antisocially with most anyone, be they other bacteria or cells of their host. For this they deploy small molecules (active only above a critical threshold concentration, hence quorum sensing), they construct pili to translocate DNA, and they export proteins via more than a half dozen secretory systems. Each of these tactics requires its own mechanics and makes its own demand for energy. Secreting proteins freely into the environment is particularly wasteful of resources because few of the molecules are likely to reach their intended target. To improve the odds, some bacteria depend on making direct contact between donors and recipients before exporting. Others parcel out the molecules inside specialized delivery structures—the subject of this post.
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