Under anoxic conditions Pseudomonas sp. strain JLR11 can use 2,4,6-trinitrotoluene (TNT) as the sole N source, releasing nitrite from the aromatic ring and subsequently reducing it to ammonium and incorporating it into C skeletons. This study shows that TNT can also be used as a terminal electron acceptor in respiratory chains under anoxic conditions by Pseudomonas sp. strain JLR11. TNT-dependent proton translocation coupled to the reduction of TNT to aminonitrotoluenes has been observed in TNT-grown cells. This extrusion did not occur in nitrate-grown cells or in anaerobic TNT-grown cells treated with cyanide, a respiratory chain inhibitor. We have shown that in a membrane fraction prepared from Pseudomonas sp. strain JLR11 grown on TNT under anaerobic conditions, the synthesis of ATP was coupled to the oxidation of molecular hydrogen and to the reduction of TNT. This phosphorylation was uncoupled by gramicidin. Respiration by Pseudomonas sp. strain JLR11 is potentially useful for the biotreatment of TNT in polluted waters and soils, particularly in phytorhizoremediation, in which bacterial cells are transported to the deepest root zones, which are poor in oxygen.2,4,6-Trinitrotoluene (TNT) is a major contaminant in many military sites, where manufacturing and decommissioning operations generate large quantities of this explosive as a waste product. Much of this waste is deposited in the soil and in unlined lagoons, from which it often reaches groundwaters through leaching (16,21). TNT is toxic for many prokaryotes and eukaryotes, and it is mutagenic in Salmonella enterica serovar Typhimurium (23)(24)(25)27). This effect arises from the electrophilic nature of the substituent on the aromatic ring. In fact, TNT oxidizes biological reductants, causing toxicity both directly and through the formation of other reactive products, such as nitroarene radicals (14). Remediation is therefore urgently needed to clean up contaminated sites.A number of studies have found that mineralization of TNT under aerobic conditions is limited (2,5,7,8,10,20,26). In addition, many aerobic microbes reduce the nitro groups on the aromatic ring to nitroso and hydroxylamino groups, which have a high propensity to react with each other to produce azoxynitrotoluenes in the presence of oxygen (9). These azoxynitrotoluenes are recalcitrant to bioremediation. Degradation of TNT under anaerobic conditions has been explored as an alternative approach to remediation (3,4,6,11,12,13,18,22). This process has the potential advantages of rapid reduction at a low redox potential and of diminished polymerization reactions due to the absence of oxygen (9,12,18).Pseudomonas sp. strain JLR11, isolated from a wastewater treatment plant, is able to use nitrate, nitrite, and TNT as the N source under anoxic conditions (6). Mass balances with TNT have revealed that about 85% of the total N-TNT content was incorporated as cell biomass (6).Analyses of culture supernatants detected plausible pathway intermediates, such as 2,4,6-trinitrobenzaldehyde, 2-nitro-4-h...
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 demonstrates that under conditions of iso or hyperosmolarity, P. aeruginosa utilized carnitine as the carbon, nitrogen or carbon and nitrogen sources. As occurred in the case of choline, the bacteria synthesized cholinesterase (ChE), acid phosphatase (Ac.Pase) and phospholipase C (PLC) under any of these conditions and in the presence of high or low Pi concentrations. Carnitine acted as an osmoprotectant when the cells were grown in the presence of preferred carbon and nitrogen sources and high NaCl concentrations. Under these conditions the three enzyme activities were not produced. The osmotically stressed bacteria grown under any of the above conditions accumulated betaine. Its presence indicated that carnitine may be metabolized by P. aeruginosa to produce betaine which could account for the induction of the three enzyme activities or its action as an osmoprotectant. The phosphatidylcholine encountered in the host cell membranes allows the bacteria to obtain free choline by the coordinated action of PLC and Ac.Pase. Since the consequence of this action may be cell disruption, the increase of free carnitine in the natural environment of the bacteria is also possible. These two compounds, choline and carnitine, acting in conjunction or separately, may increase the production of PLC and Ac.Pase activities by P. aeruginosa and thus enhance the degradative effect upon the host cells.
Aims: To establish if tetradecyltrimethylammonium (TDTMA) might be degraded by pure culture of Pseudomonas strains, and how the presence of a Lewis’ acid in the medium influences its biodegradability. Methods and Results: From different strains of Pseudomonas screened, only Pseudomonas putida A ATCC 12633 grows with 50 mg l−1 of TDTMA as the sole carbon and nitrogen source. A monooxygenase activity catalyzed the initial step of the biodegradation. The trimethylamine (TMA) produced was used as nitrogen source or accumulated inside the cell. To decrease the intracellular TMA, the culture was divided, and 0·1 mmol l−1 AlCl3 added. In this way, the growth and TDTMA consumption increased. The internal concentration of TMA, determined using the fluorochrome Morin, decreased by the formation of Al3+ : TMA complex. Conclusions: Pseudomonas putida utilized TDTMA as its sole carbon and nitrogen source. The TMA produced in the initial step of the biodegradation by a monooxygenase activity was used as nitrogen source or accumulated inside the cell, affecting the bacterial growth. This effect was alleviated by the addition of AlCl3. Significance and Impact of the Study: The use of Lewis’ acids to sequester intracellular amines offers an alternative to achieve an efficient utilization of TDTMA by Ps. putida.
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.