Are Germs Good Bugs Gone Bad?
The Case of Anthrax 05/01/2003 Now that the anthrax genome has been decoded, scientists are surprised that most of it looks like another milder bacterium, Bacillus cereus. Only about 3% of their genomes are significantly different. In addition, the pathogenic genes are not in the nucleus, but in plasmids (smaller, circular strands of DNA in the cytoplasm). They give the appearance of having been imported by horizontal gene transfer. One of the papers in Nature suggests that both bacteria acquired toxic elements from soil bacteria in this manner, and Other major differences between B. anthracis and B. cereus may have been effected through altered gene expression rather than loss or gain of genes. Some are wondering if anthrax acquired its toxicity recently. One team asks, Findings from this genome sequence analysis raise further questions about the biology of B. anthracis; for instance, what are the roles of putative virulence genes in close relatives of B. anthracis that do not cause a
