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Figure 6 | Microbial Cell Factories

Figure 6

From: Accumulation of inorganic polyphosphate enables stress endurance and catalytic vigour in Pseudomonas putida KT2440

Figure 6

Catalytic vigour test for P . putida KT2440 and its Δ ppk and Δ ppx mutant derivatives. (A) Final biomass concentration (estimated from OD600 readings) for cultures of P. putida KT2440 (wt) and its Δppk and Δppx mutant derivatives grown in M9 minimal medium containing m-xylene as the sole C source. Bars represent the mean value of the OD600 readings ± SD of duplicate measurements from at least three independent experiments, and asterisks (**) identify significant differences at the P < 0.01 level (ANOVA). (B) Normalized growth coefficients for cultures of P. putida KT2440 (wt) and its Δppk and Δppx mutant derivatives grown in M9 minimal medium containing m-xylene as the sole C source, representing the fraction of the specific growth rate attained by mutant cells when compared to that computed for P. putida KT2440 (arbitrarily set to 100%). Bars represent the mean value of the normalized growth coefficient ± SD of triplicate measurements from at least four independent experiments, and asterisks (*) identify significant differences at the P < 0.05 level (ANOVA). (C) Growth kinetics for cultures of P. putida KT2440 (wt) and its Δppk and Δppx mutant derivatives, as well as the Δppk mutant complemented with ppk in trans (ppk+), grown in M9 minimal medium containing m-xylene as the sole C source. Expression of ppk (under control of a XylS/Pm element in plasmid pSEM-ppk) was induced by addition of 2.5 mM 3-methylbenzoate to the cultures upon inoculation. Growth trajectories in control experiments, run with the same strains carrying pSEVA238 [54], the empty expression vector used to complement ppk, were indistinguishable to those shown in this figure (not shown). Results represent the average of three independent replicates from at least two independent cultures. Error bars (<20% of the means) were omitted for the sake of clarity.

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