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Ps. Putida (ps. + putida)
Selected AbstractsCalorimetric investigations into the starvation response of Pseudomonas putida growing on phenol and glucoseJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2009Andreas Lißner Abstract Aims:, To investigate the stress response during nutrient deprivation, particularly with regard to the application of phenol as growth substrate of Pseudomonas putida with calorimetric measurements as a new method. Methods and Results:, The online and noninvasive measurement of the thermal power P0 permits the detection of microbial activity during the starvation period. While the results of the investigations with phenol reveal a significant loss of activity as a function of the temporal nutrient dosage, only a small loss of activity was detected by using glucose. Microbiological methods (colony forming units (CFU) and activity of catechol-2,3-dioxygenase) showed a loss of the enzyme activity at a constant CFU. The introduction of a simple decay parameter kD in the kinetic description of the growth process on phenol was sufficient for the successful kinetic modelling. Conclusions:, The combination of calorimetric measurements and the determination of the enzymatic activity proved the loss of activity of Ps. putida during the deprivation of the substrate phenol. Significance and Impact of the study:, The initial heat power (P0) proves to be a suitable parameter for the characterization of the physiological state of the culture and can be used for the regulation of nutrient supply in biotechnological process development. [source] Functional, genetic and chemical characterization of biosurfactants produced by plant growth-promoting Pseudomonas putida 267JOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2009Marco Kruijt Abstract Aims:, Plant growth-promoting Pseudomonas putida strain 267, originally isolated from the rhizosphere of black pepper, produces biosurfactants that cause lysis of zoospores of the oomycete pathogen Phytophthora capsici. The biosurfactants were characterized, the biosynthesis gene(s) partially identified, and their role in control of Phytophthora damping-off of cucumber evaluated. Methods and Results:, The biosurfactants were shown to lyse zoospores of Phy. capsici and inhibit growth of the fungal pathogens Botrytis cinerea and Rhizoctonia solani. In vitro assays further showed that the biosurfactants of strain 267 are essential in swarming motility and biofilm formation. In spite of the zoosporicidal activity, the biosurfactants did not play a significant role in control of Phytophthora damping-off of cucumber, since both wild type strain 267 and its biosurfactant-deficient mutant were equally effective, and addition of the biosurfactants did not provide control. Genetic characterization revealed that surfactant biosynthesis in strain 267 is governed by homologues of PsoA and PsoB, two nonribosomal peptide synthetases involved in production of the cyclic lipopeptides (CLPs) putisolvin I and II. The structural relatedness of the biosurfactants of strain 267 to putisolvins I and II was supported by LC-MS and MS-MS analyses. Conclusions:, The biosurfactants produced by Ps. putida 267 were identified as putisolvin-like CLPs; they are essential in swarming motility and biofilm formation, and have zoosporicidal and antifungal activities. Strain 267 provides excellent biocontrol activity against Phytophthora damping-off of cucumber, but the lipopeptide surfactants are not involved in disease suppression. Significance and Impact of the Study:,Pseudomonas putida 267 suppresses Phy. capsici damping-off of cucumber and provides a potential supplementary strategy to control this economically important oomycete pathogen. The putisolvin-like biosurfactants exhibit zoosporicidal and antifungal activities, yet they do not contribute to biocontrol of Phy. capsici and colonization of cucumber roots by Ps. putida 267. These results suggest that Ps. putida 267 employs other, yet uncharacterized, mechanisms to suppress Phy. capsici. [source] Physiological role of phosphatidylcholine in the Pseudomonas putida A ATCC 12633 response to tetradecyltrimethylammonium bromide and aluminiumLETTERS IN APPLIED MICROBIOLOGY, Issue 4 2009P.S. Boeris Abstract Aims:, To evaluate the effect of tetradecyltrimethylammonium bromide (TTAB) and aluminium stresses on the phospholipid (PL) composition of Pseudomonas putida A ATCC 12633. Methods and Results:,Pseudomonas putida were grown with TTAB in the presence or absence of AlCl3, and the PL composition was analysed. The presence of TTAB resulted in an increase in phosphatidylglycerol and phosphatidic acid levels (6- and 20-fold, respectively) with respect to the levels in cells grown without the surfactant. With AlCl3, phosphatidylcholine (PC) increased (threefold) and cell-free extracts contained approximately threefold more phosphatidylcholine synthase activities than extracts without AlCl3, indicating that the PC level is dependent upon activation of this enzyme. Conclusions:, The negative charges of the headgroups of PL are the primary membrane-associated factors for the response to TTAB. PC are involved in cellular responses to binding Al3+ and should be viewed as a temporary reservoir of available Al3+ to allow a more efficient utilization of TTAB by Ps. putida. Significance and Impact of the Study:, The changes in the PL of Ps. putida in the presence of TTAB and AlCl3 indicate that different responses are utilized by bacteria to maintain optimal PL composition in the presence of such environmental pollutants. [source] Indigo production by naphthalene-degrading bacteriaLETTERS IN APPLIED MICROBIOLOGY, Issue 1 2000B. Bhushan A wild-type naphthalene-degrading strain Pseudomonas putida RKJ1 and two recombinant strains each of Ps. putida and Escherichia coli carrying the genes for naphthalene degradation on a recombinant plasmid pRKJ3, produced indigo and indirubin pigments from indole. Naphthalene, salicylate and IPTG induced cells of naphthalene-degrading recombinant bacteria produced up to two times higher indigo compared with the uninduced cells. The maximum rates of indigo formation by Ps. putida RKJ1, Ps. putida RKJ5/pRKJ3, Ps. putida KT2442/pRKJ3, E. coli TB1/pRKJ3 and E. coli AB1157/pRKJ3 were 0·60, 0·80, 0·60, 1·20 and 1·50 nmol min,1 mg dry biomass,1, respectively, using indole as the substrate. The apparent Km values of indigo formation by these same bacteria were 0·22, 0·15, 0·10, 0·21 and 0·20 mmol l,1, respectively, again using indole as the substrate. The present study revealed that E. coli AB1157 was the most efficient of the hosts tested for the expression of the plasmid encoded genes (pRKJ3) from the wild-type strain Ps. putida RKJ1. In addition, both recombinant E. coli strains were capable of producing indigo directly from nutrient medium. [source] | ||||||||||