Bacterial adhesion (attachment) to solid surfaces - (Aug/10/2012 )

Hi all,

I am trying to conduct an exeperiment of bacterial (E.Coli) attachment to metallic samples. But I have one question...

Q. What should be the volume of culture medium used for the studies? Is there any ratio of bacterial culture medium volume to surface area of metal sample used?

Any help would be very much appericiated.. Thanks

Hi,

I'm not sure what kind of samples yours are but in my opinion, the volume in which to submerge/cover/dip your sample would not matter that much, if at all. A search in the literature came up with varying volumes of cell suspension.

On the other hand, you should know how much bacteria (cell concentration) you start with and the amount standardized for all your experiments.

According to this paper, 4 ml of bacterial suspension (2x10^8 cells/ml; E. coli) was used with 8 g of glass beads (0.5-2.5 mm diameter) in round bottomed vials; others used 1 ml for 1 cm² surfaces. No mention of volume:surface area ratios.

Hi,


Thanks for your comments. I have steel samples with an x-sectional area of 25 mm x 25 mm. What I summarised from your comment is that

1. It is the OD (cell concentration) which matter rather than the volume of the culture medium.

2. The culture medium volume I am going to use with OD=1 (which indicate10⁹ cells/ml), I have to make it standardized for all my experiments.

So overall its mean that it doesn't matter at all that if I conduct my experiment with 1ml of culture medium (having OD=1) or 4 ml of culture medium (with same OD=1).

But there is a big difference in the 1ml and 4ml with the same OD, which is :

1 ml of culture medium (OD =1) have approx. 10⁹ cells, whereas
4 ml of culture medium (OD =1) have approx. 4 x 10⁹ cells.

So, in my view as the number of cells increases (like in 4 ml they increases 4 times) there are more chances of bacterial adhesion as compared to the one having lower number of cells (i.e. in 1ml).

Hi again,

If we have 4 x 10⁹ cells for every 4 ml, we'll still end up with 1 x 10⁹ cells for every 1 ml. In other words, regardless of your volume, the amount of cells is expressed as "n per ml". So when you report your work, you always say "n cells per ml" instead of "4n cells per 4 ml" although both meant the same thing.

On the other hand, if you want to ensure that the 25 mm² sample gets covered then yes I'd agree that 4 ml will be enough to cover that surface.

It all depends on the nature of your experiment. You might be more interested in the total number of cells (hence, 1 vs 4 ml) attaching to the sample than how much bacteria you start with.