For 24-roundwell microtiter plates, culture volumes between 0.5 and 1 ml are used, mostly either at 300 rpm on a shaker with a 25 mm amplitude (video on the left) or at 225 rpm on a shaker with a 50 mm amplitude (video on the right). Under both conditions (at a culture volume of 0.75 ml), oxygen-transfer rates approximate 30 mmol O 2 l -1 h -1 (corresponding to kLa values of 150 h -1 ). For the (slowed-down) high-speed videos below we used 24-well plates from Corning, which are widely used for the cultivation of bacteria and cells, also because they are worldwide available with various surface treatements (causing different binding characteristics) and gamma irradiated.
Adviced (default) condtion 1: 25 mm shaker amplitude, 300 rpm (E. coli culture on NB, 30 times slowed down) 0.5 ml 0.75 ml 1 ml
Hydrodynamics inside wells of a 24-roundwell microplate
The mixing times in 24-roundwell plates are in the order of 2 seconds, as determined by adding a drop of acid to an alkaline solution (containing a pH indicator), and following the colour change with a high-speed camera.
50 mm shaker amplitude 225 rpm
Mixing time test during orbital shaking at an amplitude of 50 mm, 225 rpm, video made with a high-speed camera, 15 times slowed down
Still from high-speed MP4 video at the right
Adviced (default) condtion 2: 50 mm shaker amplitude, 225 rpm (E. coli culture on NB, 20 times slowed down) 0.5 ml 0.75 ml 1 ml
Below: video database showing alternative shaking conditions (using E. coli cultures of 0.5, 0.75 and 1 ml, our advice: only apply any of the below conditions if you have a good reason to deviate from the shaking conditions shown above)
25 mm / 200 rpm
25 mm / 225 rpm
25 mm / 250 rpm
25 mm / 275 rpm
25 mm / 325 rpm
50 mm / 200 rpm
50 mm / 250 rpm
50 mm / 275 rpm
50 mm / 300 rpm
Mixing times in 24-roudwell plate