In prokaryotes, GroEL protein (together with GroES) is required for protein folding.
Question: Can a bacterium survive without GroEL protein?
In E. coli, GroEL/GroES is found to interact with about 10% of all soluble proteins (Kerner et al. Cell 2005) and is the only chaperone essential to the bacterium under all tested conditions (Horwich et al. Cell 1993).
There doesn't appear to be a knockout for it in the Keio collection (they systematically knocked out genes in E coli to assess essentiality, via recombineering).
If they couldn't knock it out, that strongly suggests it's an essential gene and the organism cannot survive without it.