PCR double-bands - (Feb/11/2011 )

Hi.

Im running some PCRs with bacterial DNA as sample and primers that are "universal" for 16S.
The sample I have should have a fairly low number of bacteria in.

I thought I would just ask the people in here if you have any explanations to these "double-bands" that I get.
Does it indicate several species of bacteria or could it be something else?

/Anders

Different allels perhaps? Though I'm not sure if bacteria have this...Or different strains or clones that have some difference in this DNA region? Depends what samples you used.