Fig. 16

Role of TezRs in chemosensing and bacterial memory. Growth of control B. pumilus or E. coli and their counterparts lacking primary TezRs on M9 medium with and without dexamethasone (DEX) or lactose (LAC) was monitored over time. A Control B. pumilus and B. pumilus TezR–R1^d grown in M9 medium with or without dexamethasone. B Control E. coli and E. coli TezR–R1^d grown in M9 medium with or without dexamethasone. C Pretreatment of control E. coli with dexamethasone for 20 min followed by TezR–R1 removal and subsequent growth on M9 medium supplemented with dexamethasone. D Biochemical profile of control B. pumilus and B. pumilus TezR–R1^d grown on minimal M9 medium without (M9) or with dexamethasone (M9 + DEX). Green denotes positive test reaction results, red denotes negative results. Values show representative results of three independent experiments. E Control E. coli and E. coli TezR–R1^d grown in M9 medium with or without lactose. F Pretreatment of control E. coli with lactose for 20 min followed by TezR–R1 removal and subsequent growth on M9 medium supplemented with dexamethasone. G Time required for dexamethasone-naïve and dexamethasone-sentient control E. coli to commence growth on M9 medium supplemented with dexamethasone. H Time required for dexamethasone-naïve and dexamethasone-sentient control B. pumilus to commence growth on M9 medium supplemented with dexamethasone. I Minimal time required for E. coli to start utilization of dexamethasone. The X-axis represents the time lag of control E. coli upon initial and second exposure to DEX. J Time to the start of DEX utilization (t_lag) by dexamethasone-naïve and dexamethasone-sentient B. pumilus. The experimental protocol is shown to the left. The t_lag after each passage in nutrient broth with or without dexamethasone is shown to the right as a heat map, whose color scale ranges from white (0 h) to red [5 h]. K Minimal time required for B. pumilus to start dexamethasone utilization after one-two or three times destruction of TezR–R1