a–c RCCS-biofilm (circle) or non-rotating control (square) bacilli were homogenised to single cell suspensions and exposed to isoniazid, streptomycin or rifampicin. Biofilm-derived bacilli showed enhanced survival to isoniazid and streptomycin, but not rifampicin. d–f This drug tolerant phenotype was lost after passage in drug-free media. Area under the curve (AUC) plots illustrating the difference in drug efficacy over multiple drug concentrations are detailed alongside each plot. Percentage survival calculated relative to untreated bacilli. Error bars are ±standard error of the mean from two biological replicates each with duplicate technical replicates. *p value ≤ 0.05; **p value ≤ 0.01.