Rhamnolipid production by single Δ rhlA mutants. Total rhamnolipid production by the B. thailandensis E264 wild type strain and both single ΔrhlA mutant cultures grown in NB with glycerol (2%), as quantified by LC/MS. Each data point shows the mean of triplicate measurements. Error bars represent the SD. The double ΔrhlA1rhlA2 mutant does not produce any rhamnolipids.