Aims: The aim of this work was to establish if the response to tetradecyltrimethylammonium (TDTMA), a representative quaternary ammonium compound (QAC), involves changes in the phospholipid (PL) composition of Pseudomonas putida A ATCC 12633. Methods and Results: Pseudomonas putida was exposed to 50 mg l−1 of TDTMA for 15 min, and PL composition was analysed. With respect to control values, phosphatidic acid and phosphatidylglycerol increased by 140% and 120%, respectively; cardiolipin decreased about 60%. In TDTMA‐adapted bacteria, the most significant change was a 380% increase in phosphatidic acid. Accompanying this change was a 130% increase in phosphatidylglycerol and a 70% decrease in cardiolipin. The changes in adapted cells were reverted after two subcultures without biocide. Conclusions: Pseudomonas putida responded to TDTMA through quantitative changes in PLs with specific variations in the content of phosphatidic acid, phosphatidylglycerol and cardiolipin. These modifications indicated that these PLs are involved in cellular responses to QACs, utilizing phosphatidic acid principally to neutralize the high positive charge density given for the ammonium quaternary moiety from TDTMA. Significance and Impact of the Study: The changes in PL composition give a new insight about the response inflicted by Ps. putida when these bacteria are exposed to QACs.
The present study assessed the role of membrane components of Pseudomonas putida A (ATCC 12633) under chemical stress conditions originated by treatment with tetradecyltrimethylammonium bromide (TTAB), a cationic surfactant. We examined changes in fatty acid composition and in the fluidity of the membranes of cells exposed to TTAB at a specific point of growth as well as of cells growing with TTAB. The addition of 10-50 mg TTAB l "1 promoted an increase in the saturated/unsaturated fatty acid ratio. By using fluorescence polarization techniques, we found that TTAB exerted a fluidizing effect on P. putida A (ATCC 12633) membranes. However, a complete reversal of induced membrane fluidification was detected after 15 min of incubation with TTAB. Consistently, the proportion of unsaturated fatty acids was lower in TTAB-treated cells as compared with non-treated cells. In the presence of TTAB, the content of phosphatidylglycerol increased (120 %), whilst that of cardiolipin decreased (60 %). Analysis of the fatty acid composition of P. putida A (ATCC 12633) showed that phosphatidylglycerol carried the major proportion of saturated fatty acids (89 %), whilst cardiolipin carried an elevated proportion of unsaturated fatty acids (18 %). The increase in phosphatidylglycerol and consequently in saturated fatty acids, together with a decrease in cardiolipin content, enabled greater membrane resistance, reversing the fluidizing effect of TTAB. Therefore, results obtained in the present study point to changes in the fatty acid profile as an adaptive response of P. putida A (ATCC 12633) cells to stress caused by a cationic surfactant.
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.
The modification in the membrane phospholipids composition allows knowing the adaptation strategy of Ps. putida when these bacteria are exposed to cationic surfactant.
Release of outer membrane vesicles inPseudomonas putida A (ATCC 12633), a degrader of cationic surfactants, releases outer membrane vesicles (OMVs) when grown with tetradecyltrimethylammonium bromide (TTAB) as the sole carbon, nitrogen and energy source. The OMVs exhibit a bilayer structure and were found to be composed of lipopolysaccharides, proteins and phospholipids (PLs) such as cardiolipin, phosphatidylcholine, phosphatidic acid and phosphatidylglycerol (PG). The OMVs showed a marked increase in the PG content, approximately 43 % higher than the amount registered in the parent cells from which the vesicles were derived. After growth of P. putida with TTAB, the amount of lipoprotein covalently cross-linked to the peptidoglycan showed a twofold decrease when compared with values found after growth without the surfactant [16¡2 and 28¡3 mg (mg cell envelope protein) 21, respectively]. This decrease in the amount of lipoprotein can be related to areas of loss of contact between the outer membrane and the peptidoglycan and, therefore, to OMV production. In addition, due to its amphiphilic nature, TTAB can contribute to OMV biogenesis, through a physical mechanism, by induction of the curvature of the membrane. Taking into account that OVMs were produced when the cells were grown under external stress, caused by the surfactant, and that TTAB was detected in the vesicles [48 nmol TTAB (nmol PL) 21], we concluded that this system of TTAB elimination is a mechanism that P. putida A (ATCC 12633) would utilize for alleviating stress caused by cationic surfactants.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.