An Update on Bacterial Aging

The aging of bacteria has been a topic of interest in the years since its discovery; firstly, it overturns the long-held assumption that bacteria are essentially immortal, and secondly it provides insight into the very early evolutionary origins of aging. Here is a recent update: "Evidence for aging in symmetrically dividing bacteria such as Escherichia coli has historically been conflicting. Early work found weak or no evidence. More recent studies found convincing evidence, but negative results are still encountered. Because bacterial aging is believed to result from non-genetic (e.g. oxidative) damage, we tested the possibility that the negative outcomes resulted from the lack of an extrinsic damage agent. We found that streptomycin, which produces mistranslated proteins that are more vulnerable to oxidation, was able to induce both damage and aging in bacterial populations. A dosage effect relating the level of damage to the concentration of streptomycin was observed. Our results explain the previous inconsistencies because all studies that failed to find evidence for bacterial aging did not use a damage agent. However, all studies that succeeded in finding evidence utilized fluorescent proteins as a visual marker. We suggest that aging in those studies was induced by the harmful effects of an extrinsic factor, such as of the proteins themselves or the excitation light. Thus, all of the previous studies can be reconciled and bacterial aging is a real phenomenon. However, the study and observation of bacterial aging requires the addition of an extrinsic damage agent."

Link: http://www.ncbi.nlm.nih.gov/pubmed/22422756

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