Help with fermentation please!!

Hello Everyone

I am asking for a word of advice.

I am supposed to be doing fermentations soon. My problem is I never really had much experiences with these.

I need to run 3 fermentations like this.

1- Yeast DSM 1333 s cerevisiae

2- Yeast + Gram positive contaminant (Lactobacillus fermentum)

3- Yeast + Gram negative contaminant (E.coli)

I decided to use these conditions for 3 fermentations

Broth= Water 1L, yeast extract 10g/L, glucose 20g/L, peptone 20g/L

pH = 6

temperature 30C

160rpm

For starter cultures and yeast i used hemocytometer and the formula

initial concentration x volume i want to know = final concentration (start fermentation) x volume of fermentation (250mL).

so ill find what volume i should pour in to start fermentation

but i find very hard to count bacteria in hemocytomer. can I use OD600 to calculate the volume i need to pour of bacteria cultures>

if so how do I do it?

my bacteria (starter culture) ended growth in OD=2 can i dilute it? and sayOD = 1 = 10^7 cfu/ml?

Thank you for your time

Adriana