  By challenging E. coli with sublethal norfloxacin for 10 days, Henry Lee and
James Collins suggests the bacterial altruism leads to the population-wide
resistance. By detailedly analyzing experiment data, we suggest that bacterial
cooperation leads to population-wide resistance under norfloxacin pressure and
simultaneously propose the bacteria shield is the possible feedback mechanism
of less resistant bacteria. The bacteria shield is that the less resistant
bacteria sacrifice the large number of themselves to consume norfloxacin and
then to relieve the norfloxacin burden from highly resistant bacteria. Thus,
due to highly resistant bacteria and less resistant bacteria extracted from the
same bacteria population, bacterial cooperation leads to heteroresistance.

Populations and Evolution