Bacterial CRISPR screens for gene function

•Bacterial CRISPR approaches are used for gene editing, repression, and activation.•CRISPRi, which blocks transcription of targeted genes, is the main bacterial modality.•Chemical genomics and titratable CRISPRi enable studies of essential gene functions.•Pooled, genome-wide CRISPRi screens identify novel gene functions.•CRISPRi has been demonstrated in many non-model bacteria.