Fig. 4
The ZbHAA1 is a determinant of tolerance to acetic acid in Z. bailii. a Growth of Z. bailii IST302 and derived mutant Zbhaa1∆ was compared by spot assays in MM medium (pH 4.5) supplemented, or not, with equivalent concentrations of acetic, benzoic and sorbic acids (i.e. concentrations that induced similar growth inhibition in strain IST302). b Growth of Z. bailii IST302 harbouring the cloning vector pZ3 bT (+v) and Z. bailii IST302 expressing an extra copy of ZbHAA1 (+ZbHAA1) was compared by spot assays in MM medium (pH 4.5) supplemented, or not, with concentrations of the different weak acids that impaired growth of Z. bailii IST302 (+v). The images depicted in a) and b) were taken, respectively, after 4 or 5 days of incubation at 30 °C and are representative of at least three independent experiments. For both a) and b), cell suspensions with an absorbance at 600 nm of 0.05 ± 0.005 (lane a) and subsequent dilutions of 1:5, 1:10 and 1:20 (lanes b, c and d, respectively) were spotted onto the surface of agarized medium; c Growth curves of Z. bailii IST302 expressing an extra copy of ZbHAA1 (●) or harbouring the cloning vector pZ3 bT (○). Growth was performed in MM medium (pH 4.0) supplemented with 0, 180 or 220 mM acetic acid. Growth curves are representative of at least three independent growth assays that produced similar results