putida click here KT2440 grown in filament and non-filament inducing conditions The formation of filaments by P. putida KT2440 Thiazovivin cultures was induced by overnight shaking at low speed (i.e., 50 rpm) [6], and corroborated by microscopic and flow cytometry analysis (Figure  1A and C). A bacterial culture shaken at high speed (i.e., 150 rpm) was used as a non-filamentous control

(Figure  1B and D). Figure  1 demonstrates a clear difference in population heterogeneity between 50 rpm and 150 rpm-grown P. putida KT2440, with 50 rpm-grown bacteria showing an increased size distribution (based on forward scatter). The increase in bacterial size for 50 rpm-grown P. putida is also reflected in the comparative flow cytometry histogram (Figure  1E). Nucleic acid staining of 50 rpm and 150 rpm-grown bacteria (Figure  1C and D) confirmed the size differences. In order to rule out any effects of differences in growth phase between the two test conditions, the growth of P. putida KT2440 as a function of shaking speed was determined (Figure  2). No statistically

significant (p<0.05) differences were found, only a slight significant increase in cell numbers was observed at 6 h for the 150 rpm-grown cultures. In agreement with the OD measurements, no statistically significant (p<0.05) differences were observed at 15 h in viable counts nor in biomass (45.3 ± 1.6 mg wet weight/5 mL for 50-rpm and 44.1 ± 0.9 mg weight/5 mL for 150-rpm cultures). As differences in the dissolved oxygen concentrations are expected to selleck compound occur at different shaking speeds, the dissolved oxygen was measured for 50 rpm and 150 rpm-grown bacteria as a function of culture time. As presented in Figure  2, 50 rpm cultures reached undetectable oxygen levels after approximately 1.75 h, while this was only after 4 h for 150 rpm. Further, the maximum oxygen transfer rate at 150 rpm, calculated based on [15], was approximately 2.5 times higher than Urocanase at 50 rpm. Figure 1 Morphologic analysis of P. putida KT2440 grown at 50 and 150 rpm. Flow cytometry dot plot

(forward scatter versus side scatter) of P. putida KT2440 grown at 50 rpm (A) and 150 rpm (B). Microscopic imaging of Hoechst-stained P. putida KT2440 grown at 50 rpm (C) and 150 rpm (D) (magnification = 1000x). Flow cytometry histogram of P. putida grown at 50 rpm (black line) and 150 rpm (blue line) (E), representing the average bacterial length. Figure 2 Growth curves (black line) and dissolved oxygen concentrations (striped line) of 50 (circles) and 150 (diamonds) rpm cultures of P. putida KT2440 (inset showing zoom on first hours). Stress resistance of P. putida KT2440 grown in filament and non-filament inducing conditions The stress resistance of P. putida KT2440 grown in filament-inducing and non-filament-inducing conditions (15 hours of growth) was investigated. P. putida KT2440 grown at 50 rpm demonstrated an increased resistance to heat shock (12.5-fold, p = 0.003) and saline stress (2.1-fold, p = 0.