Figure 7. L-histidine effect on cell growth is FLO11-dependent, and related to pH and cell-surface charge.

The histogram and the line graph illustrate the cell growth and the cell surface net charge, respectively, of the 3238-32 and 3238Δflo11 strains. Cells (10⁴ cells/mL) were incubated in SC minimal medium. The media were buffered at pH 3, 4, 5 and 6 using 0.1 M citric acid monohydrate and 0.2 M sodium phosphate. Cells were grown in 96-well microplates, statically at 30°C for 48 h. Growth was monitored measuring the OD₆₀₀ in a SPECTROstar nano-microplate spectrophotometer (BMG Labtech, Germany). Cell surface net charge (Z-potential) was measured under the same conditions using the Zetasizer Ver. 6.20 (Malvern Instruments Ltd) after 48 h of treatment. Data are means ±SD of three replicates. A one-way analysis of varience (ANOVA) was performed and followed by Tukey honestly significant difference test (P<0.05). The analyses were performed independently for growth and cell surface charge data and values with the same letter/symbol are not statistically different.