Check https://courses.lumenlearning.com/boundless-microbiology/chapter/counting-bacteria/

Also check https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0033695

You must establish a connection between CFU/ml and absorbance (optical density OD). Take bacterial culture samples at regular intervals during the growth process. Make serial dilutions after measuring the optical density of the samples. Plate diluted samples in triplicate on agar plates (typically 10ˆ5 to 10 ˆ 7 dilutions) and count colonies after incubation. Calculate the CFU/ml value. Make a graph that shows the relationship between CFU/ml and OD. The OD of your sample can then be calculated.

Kindly check

https://asm.org/Articles/2020/February/Identifying-Bacteria-Through-Look,-Growth,-Stain

Use screen printing method as used in this paper.

https://www.sciencedirect.com/topics/food-science/lactic-acid-bacteria

Optical density and the number of living viable cells are positively correlated until the bacterial culture enters the stationary phase, so I would recommend that you first do a lactobacilli growth curve. After that, to incubate the bacteria for a shorter time (to stop the growth in the logarithmic phase (usually before 16h, depends on several factors), with sampling every hour to determine the CHU (through making a series of decimal dilutions, seeding on P. plates, incubation, colony counting and calculations) and OD610nm measurement from the same samples (at all time intervals starting from the start (0h)

Note:

In the stationary phase of growth and the phase of extinction, dead as well as decayed lactobacilli cells contribute to the optical density ...

grow the bacterial strain in MRS broth and incubate it at apropriate tem. then centrifuge the culture and resuspend the pellet into buffer and carry out decimal dilution and determine the OD and plate the dilution on mrs agar to count the colonies to get 10 6 cfu