The editorial on extinction was both interesting and timely, especially the reference to three microbial pathogens, viz. Mycobacterium leprae - the causative agent of obviously the most stigmatized disease in human history, Helicobacter pylori - the causative agent of peptic ulcers, and the poxvirus - microbial agent that killed more humans than all the wars put together. Even though microbes are all-pervasive, profoundly affecting humans, animals, plants and the environment, and span the longest history of evolution (more than 3 billion years) among living beings, the principles relating to their evolution (diversification, extinction) are the least understood. It is only in the last decade that we have beenable to gauge, with any reasonable accuracy, the magnitude of the diversity of extant microbes. Obviously, the reference here is to the diversity of non-culturable microbes. As regards their nature, all explanations apart, we have no idea if these represent microbes on the verge of extinction. The possible eradication (extinction) of H, pylori due to chemotherapy and its effect on the human host cited by Balaram, is only illustrative.
展开▼
