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Optical Tracking of Surfactant-Tuned Bacterial Adhesion: a Single-Cell Imaging Study. Appl Environ Microbiol 2022; 88:e0162622. [PMID: 36374031 PMCID: PMC9746325 DOI: 10.1128/aem.01626-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Probing the interfacial dynamics of single bacterial cells in complex environments is crucial for understanding the microbial biofilm formation process and developing antifouling materials, but it remains a challenge. Here, we studied single bacterial interfacial behaviors modulated by surfactants via a plasmonic imaging technique. We quantified the adhesion strength of single bacterial cells by plasmonic measurement of potential energy profiles and dissected the mechanism of surfactant-tuned single bacterial adhesion. The presence of surfactant tuned single bacterial adhesion by increasing the thickness of extracellular polymeric substances (EPS) and reducing the degree of EPS cross-linking. The adhesion kinetics and equilibrium state of bacteria attached to the surface confirmed the decrease in adhesion strength tuned by surfactants. The information obtained is valuable for understanding the interaction mechanism between a single bacterial cell and surface, developing new biofilm control strategies, and designing anticontamination materials. IMPORTANCE Studying the interfacial dynamic of single bacteria in complex environments is crucial for understanding the microbial biofilm formation process and developing antifouling materials. However, quantifying the interactions between microorganisms and surfaces in the presence of pollution at the single-cell level remains a great challenge. This paper presents the analysis of single bacterial interfacial behaviors modulated by surfactants and quantification of the adhesion strength via a plasmonic imaging technique. Our study provided insights into the mechanism of initial bacterial adhesion, facilitating our understanding of the adhesion process at the microscopic scale, and is of great value for controlling membrane fouling biofilm formation.
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Yanagawa A, Couto A, Sandoz JC, Hata T, Mitra A, Ali Agha M, Marion-Poll F. LPS perception through taste-induced reflex in Drosophila melanogaster. JOURNAL OF INSECT PHYSIOLOGY 2019; 112:39-47. [PMID: 30528842 DOI: 10.1016/j.jinsphys.2018.12.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 11/07/2018] [Accepted: 12/02/2018] [Indexed: 06/09/2023]
Abstract
In flies, grooming serves several purposes, including protection against pathogens and parasites. Previously, we found Escherichia coli or lipopolysaccharides (LPS) can induce grooming behavior via activation of contact chemoreceptors on Drosophila wing. This suggested that specific taste receptors may contribute to this detection. In this study, we examined the perception of commercially available LPS on Drosophila wing chemoreceptors in grooming reflex. Behavioral tests conducted with bitter, sweet and salty gustation such as caffeine, sucrose and salt, using flies carrying a defect in one of their taste receptors related to the detection of bitter molecules (Gr66a, Gr33a), sugars (Gr5a, Gr64f), or salt (IR76b). LPS and tastants of each category were applied to wing sensilla of these taste defectflies and to wild-type Canton Special (CS) flies. Our results indicate that the grooming reflex induced by LPS requires a wide range of gustatory genes, and the inactivation of any of tested genes expressing cells causes a significant reduction of the behavior. This suggests that, while the grooming reflex is strongly regulated by cues perceived as aversive, other sapid cues traditionally related to sweet and salty tastes are also contributing to this behavior.
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Affiliation(s)
- Aya Yanagawa
- Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Japan.
| | - Antoine Couto
- UMR Evolution, Génomes, Comportement, Ecologie, CNRS, IRD, Univ Paris-Sud, Université Paris-Saclay, F-91198 Gif-sur-Yvette, France
| | - Jean-Christophe Sandoz
- UMR Evolution, Génomes, Comportement, Ecologie, CNRS, IRD, Univ Paris-Sud, Université Paris-Saclay, F-91198 Gif-sur-Yvette, France
| | - Toshimitsu Hata
- Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Japan
| | - Aniruddha Mitra
- UMR Evolution, Génomes, Comportement, Ecologie, CNRS, IRD, Univ Paris-Sud, Université Paris-Saclay, F-91198 Gif-sur-Yvette, France; School of Biological & Environmental Sciences, Shoolini University, Solan, India
| | - Moutaz Ali Agha
- AgroParisTech, Université Paris-Saclay, Paris, France; Ÿnsect-Pôle Innovia, Damparis, France
| | - Frédéric Marion-Poll
- UMR Evolution, Génomes, Comportement, Ecologie, CNRS, IRD, Univ Paris-Sud, Université Paris-Saclay, F-91198 Gif-sur-Yvette, France; AgroParisTech, Université Paris-Saclay, Paris, France.
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3
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Martins N, Pereira JL, Antunes FE, Melro E, Duarte CMG, Dias L, Soares AMVM, Lopes I. Role of surfactant headgroups on the toxicity of SLE nS-LAS mixed micelles: A case study using microtox test. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 643:1366-1372. [PMID: 30189553 DOI: 10.1016/j.scitotenv.2018.06.293] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 06/22/2018] [Accepted: 06/24/2018] [Indexed: 06/08/2023]
Abstract
Mixtures containing ether sulfate based surfactants (SLEnS) and linear alkylbenzene sulfonic acid (LAS) are relatively common in personal care and household products. When in mixture, they form mixed micelles, which act as reservoirs for the cleaning process. The increase of ethylene oxide (EO) units in the head of SLEnS lowers the critical micelle concentration, meaning that less quantity of each surfactant is needed to form the micelles. Within an eco-friendly perspective this is advantageous since less chemicals are expected to be released into the environment. But, this advantage will only be effective if variations with the higher number of EO units exhibit a lower toxicity as well. Despite its wide use in commercial products, the ecotoxicity of these micelles and the influence of the EO units on their toxicity still did not receive the necessary attention. In this context, the present study aimed at assessing the influence of the number of ethylene oxide (EO) units in the head groups of SLEnS on the toxicity of the SLEnS-LAS mixed micelles to the bacterium Vibrio fischeri (Microtox® assay, here used as a fast and preliminary ecotoxicological indicator). The SLEnS variants with fewer EO units showed higher toxicity relatively to those with more EO units - EC50 range (0-50 EO units): 0.56-8.59 mg L-1, thus they can be suggested as environmentally safer variants to be used in personal care and household products. Provided the consistency of Microtox® results as obtained here, this quick and cost-effective procedure can be an important tool towards the development of eco-friendlier surfactant-based formulations.
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Affiliation(s)
- Nuno Martins
- Department of Biology & CESAM, University of Aveiro, Aveiro, Portugal
| | - Joana L Pereira
- Department of Biology & CESAM, University of Aveiro, Aveiro, Portugal
| | - Filipe E Antunes
- Department of Chemistry, University of Coimbra, Coimbra, Portugal
| | - Elodie Melro
- Department of Chemistry, University of Coimbra, Coimbra, Portugal
| | | | - Lídia Dias
- Department of Biology & CESAM, University of Aveiro, Aveiro, Portugal
| | | | - Isabel Lopes
- Department of Biology & CESAM, University of Aveiro, Aveiro, Portugal.
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Figueiredo DB, Carvalho E, Santos MP, Kraschowetz S, Zanardo RT, Campani G, Silva GG, Sargo CR, Horta ACL, de C Giordano R, Miyaji EN, Zangirolami TC, Cabrera-Crespo J, Gonçalves VM. Production and purification of an untagged recombinant pneumococcal surface protein A (PspA4Pro) with high-purity and low endotoxin content. Appl Microbiol Biotechnol 2016; 101:2305-2317. [PMID: 27889801 DOI: 10.1007/s00253-016-7983-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 10/26/2016] [Indexed: 12/20/2022]
Abstract
Streptococcus pneumoniae is the main cause of pneumonia, meningitis, and other conditions that kill thousands of children every year worldwide. The replacement of pneumococcal serotypes among the vaccinated population has evidenced the need for new vaccines with broader coverage and driven the research for protein-based vaccines. Pneumococcal surface protein A (PspA) protects S. pneumoniae from the bactericidal effect of human apolactoferrin and prevents complement deposition. Several studies indicate that PspA is a very promising target for novel vaccine formulations. Here we describe a production and purification process for an untagged recombinant fragment of PspA from clade 4 (PspA4Pro), which has been shown to be cross-reactive with several PspA variants. PspA4Pro was obtained using lactose as inducer in Phytone auto-induction batch or glycerol limited fed-batch in 5-L bioreactor. The purification process includes two novel steps: (i) clarification using a cationic detergent to precipitate contaminant proteins, nucleic acids, and other negatively charged molecules as the lipopolysaccharide, which is the major endotoxin; and (ii) cryoprecipitation that eliminates aggregates and contaminants, which precipitate at -20 °C and pH 4.0, leaving PspA4Pro in the supernatant. The final process consisted of cell rupture in a continuous high-pressure homogenizer, clarification, anion exchange chromatography, cryoprecipitation, and cation exchange chromatography. This process avoided costly tag removal steps and recovered 35.3 ± 2.5% of PspA4Pro with 97.8 ± 0.36% purity and reduced endotoxin concentration by >99.9%. Circular dichroism and lactoferrin binding assay showed that PspA4Pro secondary structure and biological activity were preserved after purification and remained stable in a wide range of temperatures and pH values.
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Affiliation(s)
- Douglas B Figueiredo
- Centro de Biotecnologia, Instituto Butantan, Av Vital Brasil 1500, São Paulo, SP, 05503-900, Brazil.,Programa de Pós-Graduação Interunidades em Biotecnologia, Universidade de São Paulo, Avenida Prof. Lineu Prestes 2415, Edifício ICB-III, São Paulo, SP, 05508-900, Brazil
| | - Eneas Carvalho
- Centro de Biotecnologia, Instituto Butantan, Av Vital Brasil 1500, São Paulo, SP, 05503-900, Brazil
| | - Mauricio P Santos
- Departamento de Engenharia Química, Universidade Federal de São Carlos, Rodovia Washington Luís km 235, São Carlos, SP, 13565-905, Brazil
| | - Stefanie Kraschowetz
- Centro de Biotecnologia, Instituto Butantan, Av Vital Brasil 1500, São Paulo, SP, 05503-900, Brazil.,Programa de Pós-Graduação Interunidades em Biotecnologia, Universidade de São Paulo, Avenida Prof. Lineu Prestes 2415, Edifício ICB-III, São Paulo, SP, 05508-900, Brazil
| | - Rafaela T Zanardo
- Centro de Biotecnologia, Instituto Butantan, Av Vital Brasil 1500, São Paulo, SP, 05503-900, Brazil.,Programa de Pós-Graduação Interunidades em Biotecnologia, Universidade de São Paulo, Avenida Prof. Lineu Prestes 2415, Edifício ICB-III, São Paulo, SP, 05508-900, Brazil
| | - Gilson Campani
- Departamento de Engenharia Química, Universidade Federal de São Carlos, Rodovia Washington Luís km 235, São Carlos, SP, 13565-905, Brazil
| | - Gabriel G Silva
- Departamento de Engenharia Química, Universidade Federal de São Carlos, Rodovia Washington Luís km 235, São Carlos, SP, 13565-905, Brazil
| | - Cíntia R Sargo
- Departamento de Engenharia Química, Universidade Federal de São Carlos, Rodovia Washington Luís km 235, São Carlos, SP, 13565-905, Brazil
| | - Antonio Carlos L Horta
- Departamento de Engenharia Química, Universidade Federal de São Carlos, Rodovia Washington Luís km 235, São Carlos, SP, 13565-905, Brazil
| | - Roberto de C Giordano
- Departamento de Engenharia Química, Universidade Federal de São Carlos, Rodovia Washington Luís km 235, São Carlos, SP, 13565-905, Brazil
| | - Eliane N Miyaji
- Centro de Biotecnologia, Instituto Butantan, Av Vital Brasil 1500, São Paulo, SP, 05503-900, Brazil
| | - Teresa C Zangirolami
- Departamento de Engenharia Química, Universidade Federal de São Carlos, Rodovia Washington Luís km 235, São Carlos, SP, 13565-905, Brazil
| | - Joaquin Cabrera-Crespo
- Centro de Biotecnologia, Instituto Butantan, Av Vital Brasil 1500, São Paulo, SP, 05503-900, Brazil
| | - Viviane Maimoni Gonçalves
- Centro de Biotecnologia, Instituto Butantan, Av Vital Brasil 1500, São Paulo, SP, 05503-900, Brazil.
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Roy B, Panda AK, Parimi S, Ametov I, Barnes T, Prestidge CA. Physico-chemical Studies on the Interaction of Dendrimers with Lipid Bilayers. 1. Effect of Dendrimer Generation and Liposome Surface Charge. J Oleo Sci 2014; 63:1185-93. [DOI: 10.5650/jos.ess14081] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Dasgupta S, Nath RK, Manna K, Mitra A, Panda AK. Physico-Chemical Studies on the Interaction of Bacterial Polysaccharide- Surfactant Aggregates with Special Reference to their Hydrodynamic Behavior. J Oleo Sci 2014; 63:1063-75. [DOI: 10.5650/jos.ess14080] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Luciferase and fluorescent protein as dual reporters analyzing the effect of n-dodecyltrimethylammonium bromide on the physiology of Pseudomonas putida. Appl Microbiol Biotechnol 2011; 93:393-400. [DOI: 10.1007/s00253-011-3663-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 08/24/2011] [Accepted: 10/23/2011] [Indexed: 10/15/2022]
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Nandini R, Vishalakshi B. A comparative study of polyelectrolyte induced metachromasy. JOURNAL OF POLYMER ENGINEERING 2011. [DOI: 10.1515/polyeng.2011.041] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
AbstractThe interaction of two cationic dyes, namely crystal violet (CV), with anionic polyelectrolytes, namely sodium carrageenate (NaCar) and sodium heparinate (NaHep), has been investigated by spectrophotometric method. The polymers induced metachromasy in the dye resulting in the shift of the absorption maxima of the dyes towards shorter wavelengths. The stability of the complexes formed between crystal violet and sodium carrageenate was found to be greater than that formed between crystal violet and sodium heparinate. This fact was further confirmed by reversal studies using alcohols, urea surfactants and electrolytes. The interaction parameters revealed that binding between crystal violet and sodium carrageenate was mainly due to electrostatic interaction while that between crystal violet and sodium heparinate is found to involve both electrostatic and hydrophobic forces.
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Battaglini F, Pallarola D. Two efficient methods for the conjugation of smooth-form lipopolysaccharides with probes bearing hydrazine or amino groups. II. LPS activation with a cyanopyridinium agent. Methods Mol Biol 2011; 739:161-167. [PMID: 21567326 DOI: 10.1007/978-1-61779-102-4_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
This chapter presents a conjugation method for coupling probes bearing hydrazine or primary amino groups to a lipopolysaccharide (LPS). LPS is modified by the activation of the hydroxyl groups present in its O-antigen moiety with 1-cyano-4-dimethylaminopyridinium tetrafluoroborate (CDAP). The method yields conjugates with good labeling ratios, preserving the endotoxic activity of the lipid A moiety. Conjugation of smooth-form LPS from Salmonella enterica sv. Minnesota with dansyl hydrazine and horseradish peroxidase yields labeling ratios above 110 nmol dansyl/mg LPS, with nearly no loss of the original endotoxic activity. In the case of horseradish peroxidase, introducing a spacer, a ratio of 29 nmol HRP/mg LPS was obtained, preserving 65% of the original endotoxic activity and an enzymatic activity of 120 U/mg.
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Affiliation(s)
- Fernando Battaglini
- INQUIMAE - DQIAQF, Universidad de Buenos Aires, C1428EHA, Buenos Aires, Argentina.
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10
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Nath RK, Dasgupta S, Ghosh S, Mitra A, Panda AK. Spectral Studies on the Binding Behavior of Cationic Dyes and Surfactants with Bacterial Polysaccharide ofKlebsiellaK43. J DISPER SCI TECHNOL 2010. [DOI: 10.1080/01932690903269586] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Nandini R, Vishalakshi B. A study of interaction of cationic dyes with anionic polyelectrolytes. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2010; 75:14-20. [PMID: 19945337 DOI: 10.1016/j.saa.2009.08.032] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2009] [Revised: 08/10/2009] [Accepted: 08/11/2009] [Indexed: 05/28/2023]
Abstract
The interactions of Acridine Orange with Sodium Alginate and Pinacyanol Chloride with Heparin have been investigated by spectrophotometric method. The polymers induce metachromasy in the dye as evidenced from the considerable blue shift in the absorption maxima of the corresponding dyes. The interaction constant and thermodynamic parameters of polymer-dye interactions have been determined. The effect of additives such as alcohols, and urea on the reversal of metachromasy has been studied. The data has been used to determine the stability of the metachromatic complex and the nature of binding. The thermodynamic parameters of interaction revealed that binding between Acridine Orange and Sodium Alginate involved only electrostatic forces while that between Pinacyanol Chloride involved both electrostatic and hydrophobic forces. The reversal studies using surfactants indicated the involvement of both electrostatic and hydrophobic forces in binding. Based on the results it can be concluded that Pinacyanol Chloride is more effective inducing metachromasy than Acridine Orange.
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Affiliation(s)
- R Nandini
- Department of Chemistry, MITE, Moodabidri, India.
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Nandini R, Vishalakshi B. A comparative study of polyelectrolyte-dye interactions. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2009; 74:1025-1030. [PMID: 19833550 DOI: 10.1016/j.saa.2009.08.043] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Revised: 08/07/2009] [Accepted: 08/19/2009] [Indexed: 05/28/2023]
Abstract
The interaction of Azure B with sodium alginate and heparin in aqueous solution has been studied by spectrophotometric method. Absorbance of Azure B at 645 nm decreases and a new band appeared at 545 nm and at 556 nm respectively which indicated that a new metachromatic complex formed. A linear decrease in absorbance is noted. It was found that sodium alginate is more effective than heparin in decreasing the absorbance of Azure B at 645 nm. The stoichiometry of sodium alginate or heparin with Azure B was determined by spectrophotometry. The results suggested that the interaction between Azure B with sodium alginate or heparin was a result of electrostatic forces and the difference between heparin and sodium alginate were attributed to the different negative charge number on repetitive disaccharides unit. Studies on the effect of alcohol or urea indicated that sodium alginate and heparin interacted with the aggregates of Azure B. Thermodynamic parameters of interaction has been evaluated to determine the stability of the metachromatic complex. The effect of surfactants on reversal of metachromasy has also been studied.
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Affiliation(s)
- R Nandini
- Department of Chemistry, MITE, Moodabidri 572226 (DK), Karnataka, India.
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13
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Pallarola D, Battaglini F. Surfactant-Assisted Lipopolysaccharide Conjugation Employing a Cyanopyridinium Agent and Its Application to a Competitive Assay. Anal Chem 2009; 81:3824-9. [DOI: 10.1021/ac9001639] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Diego Pallarola
- INQUIMAE, Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA Buenos Aires, Argentina
| | - Fernando Battaglini
- INQUIMAE, Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón 2, C1428EHA Buenos Aires, Argentina
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14
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Spectral studies on the interaction of cationic dye/surfactants with Klebsiella K28 capsular polysaccharide. Colloids Surf A Physicochem Eng Asp 2007. [DOI: 10.1016/j.colsurfa.2007.01.035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Mitra A, Nath R, Biswas S, Chakraborty A, Panda A. A comparative study on the physico-chemical properties of bacterial capsular polysaccharides from different serotypes of Klebsiella. J Photochem Photobiol A Chem 2006. [DOI: 10.1016/j.jphotochem.2005.07.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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16
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Jana-Sur P, Chakraborty AK. Studies on the interaction of bacterial capsular polysaccharide- Klebsiella K16 with cationic and mixed surfactants. Colloid Polym Sci 2006. [DOI: 10.1007/s00396-005-1358-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Usacheva MN, Teichert MC, Biel MA. The interaction of lipopolysaccharides with phenothiazine dyes. Lasers Surg Med 2004; 33:311-9. [PMID: 14677158 DOI: 10.1002/lsm.10226] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND AND OBJECTIVES The difference in the photobactericidal efficacy of methylene blue and toluidine blue against gram-negative bacteria may result from their primary reaction with lipopolysaccharides (LPS) of the outer bacterial membrane. The aim of the present study was to compare the reactivity of these dyes with LPS extracted from different gram-negative bacteria. STUDY DESIGN/MATERIALS AND METHODS The interactions of methylene blue and toluidine blue with LPS from Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), Klebsiella pneumoniae (K. pneumoniae), and Serratia marcescens (S. marcescens) were studied spectrophotometrically in 0.45% saline. The dyes were used at the concentration of 10 microM. The concentrations of LPS ranged from 5-100 microg/ml. RESULTS Methylene blue and toluidine blue enter into a metachromatic reaction with the LPS resulting the in generation of dimers of methylene blue and higher aggregates of toluidine blue. The more significant hypochromic and hypsochromic effects in the reaction of the latter with LPS indicate a greater metachromatic efficacy of toluidine blue than methylene blue. The equilibrium constants of the metachromatic complex between toluidine blue and different LPS were calculated. The spectrophotometric titration of LPS with the dyes was used to estimate the equivalent weight of LPS. CONCLUSIONS Toluidine blue interacts with LPS more significantly than methylene blue in vitro. This may be one of the main factors determining its greater photobactericidal efficacy against gram-negative bacteria.
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Affiliation(s)
- Marina N Usacheva
- Advanced Photodynamic Technologies, Inc., Minneapolis, Minnesota 55414, USA
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