I am giving an attachment below. It is pretty old but the medium gives excellent results. Try and see.

Thank you

B. abortus is nutritionally fastidious and it is an obligate aerobe. You did not mention what medium you were using or if you were supplementing it with a vitamin mix. You also need to aerate the culture. I would grow it as 50ml cultures in 250ml flasks shaking at 300 rpm. They really like sugar in the medium and their growth will be stimulated by having both glucose and erythritol in the medium.

I agree with Sperry for most of the things he said except for the fact of shaking 250ml flasks with 50 ml medium at 300 rpm. I am afraid that due to the shear action of the liquid with air bubbles (even the minuest of all) would increase the mortality rate of the biomass.

As far as I know, we never saw any loss of cell growth from high speed shaking. We would get dilution sample readings that represented a final OD at 600 nm readings that were 20 or higher per ml of culture. I think we had an OD reading of around 40 when we cultured the cells on 2% w/v glucose. These are memories from 1970-74, so I am not sure what the exact numbers were.

Thanks both of you