If you really wish to measure total cellular protein then you need to lyse the bacterial cells, remove the debris (usually by centrifugation) and then measure protein by either Bradford or any one of numerous other ways to measure protein.

However this is not really the simplest way to monitor the growth curve of a culture. Most frequently this is done by measuring the optical density of the culture, the more cells there are then the more light will be reflected and not passed through. This increase density can be correlated with cell growth. Alternatively you can actually count cells for a fixed volume under a microscope (usually using a counting chamber to define a volume - like a Petroff Hausser chamber). Or you can plate serial dilutions and do colony counts although that might be tricker with with an anaerobe.

Thank you for your answer.

The reason why I did not measure the OD of the strain during its growth because the presence of xylan, an insoluble substrate in the broth culture medium.

I tried applied to measure dry weight but also obtained abnormal growth curve shape.

But i found your suggestion about dilution can fix my problem. I will try that direction.

a little turbidity from the xylan should not matter too much, but if you have a lot then of course that would be hard to make measurements.

if you have access to a FACS that would also work, but those are not so common