Bacterial liquid cultures should be shaken always (but not too vigorously), in order to ensure aeration and oxygen and nutrient availability as well as to avoid bacterial settlement on the flask bottom which would result in cell death from the lack of nutrient availability. Also, shaking prevents bacterial clumps or biofilm formation, ensuring prolific bacterial reproduction. Depending on the type of bacteria and the size of the flask, adjust rpm so that it's not too vigorous that it will damage the cells and prevent proper replication.

I hope this helps.

Vasilieios

Oxygenation is also important

Shaking is neccesary for aeration and equal distribution of nutrients.

Shaking improves the oxygen penetration in the medium that become more viscous while cells grow. Furthermore, if you perfectly seal the flask you'll decrease the bacteria proliferation efficiency.

Bacterial cultures are grown in sealed flasks. This stops the oxygen flow in the medium. Shaking the flasks increases the mixing of the oxygen present in the flask with the medium, thus helping in their growth. This is mostly true for aerobic bacteria. Also, it helps the medium to be almost equally distributed to the growing number of bacterial population, thus increasing their surviving rate. Also, the bacteria don't sediment down in the flask if the flask is shaken throughout the culture time. Hope that helped

For medium aeration and equal distribution of oxygen and nutrient

Bioflims?

Bacterial liquid cultures should be shaken always (but not too vigorously), in order to ensure aeration and oxygen and nutrient availability as well as to avoid bacterial settlement on the flask bottom which would result in cell death from the lack of nutrient availability. Also, shaking prevents bacterial clumps or biofilm formation, ensuring prolific bacterial reproduction. Depending on the type of bacteria and the size of the flask, adjust rpm so that it's not too vigorous that it will damage the cells and prevent proper replication.

I hope this helps.

Vasilieios

Agreed with Vasileois, very good complete answer.

I learned about the not shaking too hard, when I tried ligation for the first time. The instructions read "mix the culture thoroughly", and I thought "what better way to mix thoroughly than to pipette up and down!" (I was working previously with RNA extraction etc and other non-biological preparations).

No prize for guessing why my ligation was unsuccessful. :)

Interesting to hear people speaking about 'not shaking too vigorously. I grow ecoli in a smooth conical flask covered with foil (not tight sealed). I find the best growth conditions to be 400 rpm using 1/10th - 1/5th volume. i.e. 0.5 - 1L in a 5 L flask. The only time that shaking has been a problem for me is when using baffled flasks, as presumably the foam prevents efficient air transfer into the medium. I only use baffled flasks when i cant shake above 150 rpm for some reason.

Simply,

- Shaking is good for aeration and nutrient distribution in the solution.

- Shaking prevent biofilm formation.

- Shaking too vigorous have negative effects on bacterial growth.

Agrobacterium and ecoli as we know are immotile (they can't move from one place to other). So while growing exponentially there is issue of clamp or colony formation in static growth media. So shaking helps the bacteria to have excess to rest of the nutrients in the flask or whatever container you use.

Shaking your flask will hugely increase your surface area for oxygen transfer from air to liquid medium. Especially if you have high cell densities this is important as your cells will use up oxygen dissolved in the medium very quickly. In fermenters with very very high cell densities the oxygen levels in the medium can drop within seconds to almost zero if you stop stirring.

Other than foaming and spillage problems, there is no such thing as shaking too hard for bacterial cultures. Good fermentors have very high speed paddles to ensure good mixing and oxygen uptake. Oxygen uptake is frequently the limiting factor in bacterial growth at higher densities.

Note this is only true for aerobic cultures. Anaerobic strains either grow with no shaking or gentle shaking just to keep things well mixed.

It will be good for proper aeration and uniform distribution of nutrients in turn result in to a better growth of bacterial culture

Because some bacteria are like James Bond, they like it shaken but not stirred.

Bacterial cultures are shaken for facilitate aeration and efficient mass transfer...For aerobic organisms its a must, whereas for anaerobic cultures it is not mandatory.

Aerobic bacteria need Oxygen to grow and shaking the flask provides aeration for their sufficient growth. While anaerobes didn't need any oxygen so its plates are also kept inverted during incubation to avoid clumped bacterial growth.

So it depends upon the bacteria.

I think we talking mainly here about Aerobic Bacteria

Bacterial suspension culture should be regularly agitated for proper aeration and nutrient availability and to avoid bacterial settlement in the flask bottom which would result in cell death as well as clump formation.

To ensure optimal oxygen and other gas exchanges, to minimise concentration gradients (e.g. Of substrates) and to maintain equal environmental conditions throughout the culture.................

How about culturing anaerobic bacteria in reduced media?

shake flask cultures:

It is a method used for reviving bacterial cultures in order to get fresh actively growing culture which can be used for many purposes.

also to maintain well aerobic conditions which is needed for the growth of aerobic bacteria, while shaking the culture flasks the distribution of oxygen through out the broth will be maintained uniformly, this enhance the growth of bacteria & prevent its clogging.

i hope i could add new information for you   

what if it is molds?

i  found  that shaking during bacteria culture shaking results in the production of short chains of  bacteria. When this happens, particularly  with pathogenic bacteria, they  loss virulence.  Has  anyone experienced this?

Is there any relationship between shaking and soluble protein fraction (recombinant)  produced by E. coli ?

“Grounding”of equipment/container and regular feeding of bacteria is wehry important

I have a doub about the rate of shaking and aggrigation of proper folded proteins in periplasm of E. coli.

It is not possible to supply oxygen from outside in a sealed tube so shaker is used to avoid the clump in bottom and bacteria can move throughout the tube and get nutrient properly.