Hello Zaynab Saad

Use freshly prepared suspension of bacterial cells. As far as possible avoid subjecting cells to stress (freeze-thaw) before performing any cell-based assay. Assay data will only be of relevance if the cells used are healthy.

Best.

Thank you Malcolm Nobre for your reply

I will do as soon as possible PLUS I will put the suspension in the refrigerator for next morning of the assay

regards xx