bacterial culture not pelleting - (Feb/06/2018 )

Hi,

There is really strange thing happening in our lab. We are growing S.aureus in minimal media, and when we try to pellet down the cells, we are not able to. Cells sediments in the bottom with spin, however as soon as you pour the supernatant, they get disrupted. We tried taking out sup with pipette also, but there also it gets disrupted. We are using polypropylene bottles. And this is for 1 liter or more than that.

Anybody faced this problem?

Please suggest guys, whats wrong here?

Thanks

nobody faced this problem

I've never worked with S. aureus, other than as a sample in undergrad labs.

Have you tried plating it out? If so, has it changed its behavior? It could be that it has acquired a capsule or something like that, that is preventing pelleting firmly. 

You could also try pelleting at higher RCF and see if that helps.

Hey Bob, Thanks a lot for giving some insights

Yeah, we have planned to put the culture in plates to see the behavior of cells. One of my friend suggested that if the cells are forming biofilm, it will not pellet down, to rule out that possibility also, we will be plating the cells.

I checked on google that poly carbonate bottles are poor in chemical resistant. And with CaCl2, no information is available if its compatible. The bottles that we are using are pp, so ruled out that also.

polypropylene and polycarbonate should both be fine for pelleting cells. polycarbonate tends to be a little more slippery so cells detach easier, but only slightly. Both should be fine with calcium chloride.