Physico-chemistry of initial microbial adhesive interactions--its mechanisms and methods for study

In this review, initial microbial adhesive interactions are divided into adhesion to substratum surfaces, coaggregation between microbial pairs and co-adhesion between sessile and planktonic microorganisms of different strains or species. The physico-chemical mechanisms underlying the adhesive interactions are described and a critical review is given of currently employed methods to study microbial adhesive interactions, with an emphasis on the use of the parallel plate flow chamber. Subsequently, for each of the three microbial adhesive interactions distinguished, the role of Lifshitz-van der Waals, acid-base and electrostatic interactions is described based on existing literature.     

土壤矿物与微生物相互作用的机理及其环境效应

土壤矿物与微生物相互作用是地球表层系统中重要的生态过程.微生物或生物分子与矿物间的吸附(粘附)是两者相互作用的基础.吸附(粘附)是一个由分子间力、静电力、疏水作用力、氢键和空间位阻效应等多种作用力或作用因素共同决定、影响的物理化学过程.因此,微生物和矿物的表面性质如表面电荷、疏水性和它们所处的环境条件如pH、电解质浓度、温度等,都影响着矿物-微生物吸附(粘附)过程.微生物细胞或酶可吸附于矿物表面,其结果是细胞代谢或酶活性会发生明显变化,并进一步影响土壤中诸多相关的生态、环境过程.结合4种典型的初始吸附理论:表面自由能热力学理论、DLVO理论、吸附等温线理论和表面复合物理论及本课题组近年来的研究成果,对土壤矿物与微生物相互作用的类型、机理、作用力和现代研究技术等方面的最新研究进展进行了较为全面的论述,对土壤矿物-微生物相互作用的环境效应进行了讨论,并就该领域今后研究工作的特点及应关注的问题进行了展望.     

On the relative importance of specific and non-specific approaches to oral microbial adhesion.

In this paper, it is suggested that specificity and non-specificity in (oral) microbial adhesion are different expressions for the same phenomena. It is argued that the same basic, physicochemical forces are responsible for so-called 'non-specific' and 'specific' binding and that from a physico-chemical point of view the distinction between the two is an artificial one. Non-specific interactions arise from Van der Waals and electrostatic forces and hydrogen bonding, and originate from the entire cell. A specific bond consists of a combination of the same type of Van der Waals and electrostatic forces and hydrogen bonding, now originating from highly localized chemical groups, which together form a stereochemical combination. The absence or presence of specific receptor sites on microbial cell surfaces must therefore be reflected in the overall, non-specific surface properties of cells as well. This point is illustrated by showing that glucan-binding lectins on mutans streptococcal strains may determine the pH dependence of the zeta potentials of these cells. When studying microbial adhesion, a non-specific approach may be better suited to explain adhesion to inert substrata, whereas a specific approach may be preferred in case of adhesion to adsorbed protein films. Adhesion is, however, not as important in plaque formation in the human oral cavity as is retention, because low shear force periods, during which adhesion presumably occurs, are followed by high shear force periods, during which adhering cells must withstand these detachment forces. Evidence is provided that such detachment will be through cohesive failure in the pellicle mass, the properties of which are conditioned by the overall, non-specific substratum properties. Therefore, in vivo plaque formation may be more readily explained by a non-specific approach.     

On the relative importance of specific and non-specific approaches to oral microbial adhesion

Abstract In this paper, it is suggested that specificity and non-specificity in (oral) microbial adhesion are different expressions for the same phenomena. It is argued that the same basic, physico-chemical forces are responsible for so-called 'non-specific' and 'specific' binding and that from a physico-chemical point of view the distinction between the two is an artificial one. Non-specific interactions arise from Van der Waals and electrostatic forces and hydrogen bonding, and originate from the entire cell. A specific bond consists of a combination of the same type of Van der Waals and electrostatic forces and hydrogen bonding, now originating from highly localized chemical groups, which together form a stereo-chemical combination. The absence or presence of specific receptor sites on microbial cell surfaces must therefore be reflected in the overall, non-specific surface properties of cells as well. This point is illustrated by showing that glucanbinding lectins on mutans streptococcal strains may determine the pH dependence of the zeta potentials of these cells. When studying microbial adhesion, a non-specific approach may be better suited to explain adhesion to inert substrata, whereas a specific approach may be preferred in case of adhesion to adsorbed protein films. Adhesion is, however, not as important in plaque formation in the human oral cavity as is retention, because low shear force periods. during which adhesion presumably occurs, are followed by high shear force periods, during which adhering cells must withstand these detachment forces. Evidence is provided that such detachment will be through cohesive failure in the pellicle mass, the properties of which are conditioned by the overall, non-specific substratum properties. Therefore, in vivo plaque formation may be more readily explained by a non-specific approach.     

Reversible and Irreversible Adhesion of Motile Escherichia coli Cells Analyzed by Total Internal Reflection Aqueous Fluorescence Microscopy

The initial events in bacterial adhesion are often explained as resulting from electrostatic and van der Waals forces between the cell and the surface, as described by DLVO theory (developed by Derjaguin, Landau, Verwey, and Overbeek). Such a theory predicts that negatively charged bacteria will experience greater attraction toward a negatively charged surface as the ionic strength of the medium is increased. In the present study we observed both smooth-swimming and nonmotile Escherichia coli bacteria close to plain, positively, and hydrophobically coated quartz surfaces in high- and low-ionic-strength media by using total internal reflection aqueous fluorescence microscopy. We found that reversibly adhering cells (cells which continue to swim along the surface for extended periods) are too distant from the surface for this behavior to be explained by DLVO-type forces. However, cells which had become immobilized on the surface did seem to be affected by electrostatic interactions. We propose that the “force” holding swimming cells near the surface is actually the result of a hydrodynamic effect, causing the cells to swim at an angle along the glass, and that DLVO-type forces are responsible only for the observed immobilization of irreversibly adhering cells. We explain our observations within the context of a conceptual model in which bacteria that are interacting with the surface may be thought of as occupying one of three compartments: bulk fluid, near-surface bulk, and near-surface constrained. A cell in these compartments feels either no effect of the surface, only the hydrodynamic effect of the surface, or both the hydrodynamic and the physicochemical effects of the surface, respectively.     

Reversible and irreversible adhesion of motile Escherichia coli cells analyzed by total internal reflection aqueous fluorescence microscopy

The initial events in bacterial adhesion are often explained as resulting from electrostatic and van der Waals forces between the cell and the surface, as described by DLVO theory (developed by Derjaguin, Landau, Verwey, and Overbeek). Such a theory predicts that negatively charged bacteria will experience greater attraction toward a negatively charged surface as the ionic strength of the medium is increased. In the present study we observed both smooth-swimming and nonmotile Escherichia coli bacteria close to plain, positively, and hydrophobically coated quartz surfaces in high- and low-ionic-strength media by using total internal reflection aqueous fluorescence microscopy. We found that reversibly adhering cells (cells which continue to swim along the surface for extended periods) are too distant from the surface for this behavior to be explained by DLVO-type forces. However, cells which had become immobilized on the surface did seem to be affected by electrostatic interactions. We propose that the "force" holding swimming cells near the surface is actually the result of a hydrodynamic effect, causing the cells to swim at an angle along the glass, and that DLVO-type forces are responsible only for the observed immobilization of irreversibly adhering cells. We explain our observations within the context of a conceptual model in which bacteria that are interacting with the surface may be thought of as occupying one of three compartments: bulk fluid, near-surface bulk, and near-surface constrained. A cell in these compartments feels either no effect of the surface, only the hydrodynamic effect of the surface, or both the hydrodynamic and the physicochemical effects of the surface, respectively.     

Adhesion and surface-aggregation of Candida albicans from saliva on acrylic surfaces with adhering bacteria as studied in a parallel plate flow chamber

Adhesive interactions between Candida albicans and oral bacteria are generally thought to play a crucial role in the microbial colonization of denture acrylic, which may lead to denture stomatitis. This study investigated the influence of saliva on the adhesive interactions between C. albicans and Streptococcus sanguis or Actinomyces naeslundii on denture acrylic. First, bacteria were allowed to adhere to the acrylic surface from a flowing suspension, and subsequently yeasts were flowed over the acrylic surface. The organisms were assayed in the presence or absence of human whole saliva. All experiments were carried out in a parallel plate flow chamber and enumeration was done in situ with an image analysis system. In the absence of adhering bacteria, adhesion of C. albicans from buffer was more extensive than from saliva. However, in the presence of adhering bacteria, yeast adhesion from saliva was increased with respect to adhesion of yeasts from buffer, indicating that specific salivary components constitute a bridge between bacteria and yeasts. In all cases, yeast aggregates consisting of 3 to 5 yeast cells were observed adhering to the surface. A surface physico-chemical analysis of the microbial cell surfaces prior to and after bathing the microorganisms in saliva, suggests that this bridging is mediated by acid-base interactions since all strains show a major increase in electron-donating surface free energy parameters upon bathing in saliva, with no change in their zeta potentials. The surface physico-chemical analysis furthermore suggests that S. sanguis and A. naeslundii may use a different mechanism for adhesive interactions with C. albicans in saliva.     

Influence of calcium and other cations on surface adhesion of bacteria and diatoms: A review

Association with a surface is an important aspect of survival for microorganisms in natural and manmade environments/Both bacteria and diatoms are involved in such associations. In many cases, this leads to surface fouling, which often results in surface deterioration and mechanical failure in industrial systems. We now know that microorganisms exploit many strategies to establish associations with surfaces. As in the case of other cellular processes, calcium ions seem to play an important role in adhesion of cells to surfaces. Calcium is involved in non-specific interactions such as neutralization of the electrical double layer between cell and substratum surface as well as specific adhesive interactions that cannot be replaced by other cations. The unique properties of calcium ions promote both specific and non-specific interactions with protein and polysaccha-ride adhesin molecules at the cell surface. As important, but less well understood, calcium ions also influence the way microbial cells interact with different substrata.     

Electric field induced desorption of bacteria from a conditioning film covered substratum.

Desorption of three oral bacterial strains from a salivary conditioning film on an indium tin oxide electrode during application of a positive (bacterial adhesion to the anode) or a negative electric current was studied in a parallel plate flow chamber. Bacterial adhesion was from a flowing suspension of high ionic strength, after which the bacterial suspension was replaced by a low ionic strength solution without bacteria and currents ranging from -800 to +800 microA were applied. Streptococcus oralis J22 desorbed during application of a positive and negative electric current with a desorption probability that increased with increasing electric current. Two actinomyces strains, however, could not be stimulated to desorb by the electric currents applied. The desorption forces acting on adhering bacteria are electroosmotic in origin and working parallel to the electrode surface in case of a positive current, whereas they are electrophoretic and electrostatic in origin and working perpendicular to the surface in case of a negative current. By comparison of the effect of positive and negative electric currents, it can be concluded that parallel forces are more effective in stimulating bacterial desorption than perpendicular forces. The results of this study point to a new pathway of cleaning industrial and biomedical surfaces without the use of detergents or biocides.     

Adsorption of biosurfactant on solid surfaces and consequences regarding the bioadhesion of Listeria monocytogenes LO28

AIMS: The influence of biosurfactant compounds produced by a strain of Pseudomonas fluorescens on the adhesion of Listeria monocytogenes LO28 to polytetrafluoroethylene (PTFE) and AISI 304 stainless steel surfaces was investigated. METHODS AND RESULTS: The biosurfactant was produced according to a simple, novel technique based on cultivation on nutrient agar. Adhesion studies were performed using L. monocytogenes cells cultured at 20 or 37 degrees C. CONCLUSIONS: A substrate-dependent behaviour of the LO28 strain (larger number of cells adhering to stainless steel than to PTFE), and a significant reduction (< 90%) in microbial adhesion levels through the prior adsorption of biosurfactants on stainless steel surfaces, which can be related to a change in the electron-donor characteristics of this substratum, was demonstrated. SIGNIFICANCE AND IMPACT OF THE STUDY: The prior adsorption of biosurfactants on solid surfaces may constitute a new and effective means of combating the implantation of pathogenic micro-organisms in food processing plants.     

Analysis of bacterial detachment from substratum surfaces by the passage of air-liquid interfaces

A theoretical analysis of the detachment of bacteria adhering to substratum surfaces upon the passage of an air-liquid interface is given, together with experimental results for bacterial detachment in the absence and presence of a conditioning film on different substratum surfaces. Bacteria (Streptococcus sobrinus HG1025, Streptococcus oralis J22, Actinomyces naeslundii T14V-J1, Bacteroides fragilis 793E, and Pseudomonas aeruginosa 974K) were first allowed to adhere to hydrophilic glass and hydrophobic dimethyldichlorosilane (DDS)-coated glass in a parallel-plate flow chamber until a density of 4 x 10(6) cells cm(-2) was reached. For S. sobrinus HG1025, S. oralis J22, and A. naeslundii T14V-J1, the conditioning film consisted of adsorbed salivary components, while for B. fragilis 793E and P. aeruginosa 974K, the film consisted of adsorbed human plasma components. Subsequently, air bubbles were passed through the flow chamber and the bacterial detachment percentages were measured. For some experimental conditions, like with P. aeruginosa 974K adhering to DDS-coated glass and an air bubble moving at high velocity (i.e., 13.6 mm s(-1)), no bacteria detached upon passage of an air-liquid interface, while for others, detachment percentages between 80 and 90% were observed. The detachment percentage increased when the velocity of the passing air bubble decreased, regardless of the bacterial strain and substratum surface hydrophobicity involved. However, the variation in percentages of detachment by a passing air bubble depended greatly upon the strain and substratum surface involved. At low air bubble velocities the hydrophobicity of the substratum had no influence on the detachment, but at high air bubble velocities all bacterial strains were more efficiently detached from hydrophilic glass substrata. Furthermore, the presence of a conditioning film could either inhibit or stimulate detachment. The shape of the bacterial cell played a major role in detachment at high air bubble velocities, and spherical strains (i.e., streptococci) detached more efficiently than rod-shaped organisms. The present results demonstrate that methodologies to study bacterial adhesion which include contact with a moving air-liquid interface (i.e., rinsing and dipping) yield detachment of an unpredictable number of adhering microorganisms. Hence, results of studies based on such methodologies should be referred as "bacterial retention" rather than "bacterial adhesion".     

Locomotion and adhesion of polymorphonuclear leukocytes effects of the supporting substratum

Contact angle measurements have been used to correlate surface hydrophobicity of a supporting substratum with adhesion and locomotion of polymorphonuclear leukocytes. The binding of human serum albumin, a well-known chemokinetic substance, to hydrophilic glass slides gave rise to hydrophobic surfaces with adhesive properties conducive, to cell polarization thus allowing cell locomotion. Parallel contact angle and cell adhesion measurements suggested that albumin modified the cellsubstratum interaction by increasing the van der Waals forces of attraction and reducing the electrostatic forces. By allowing cells to adhere to a hydrophobic surface (siliconized glass), it was found that protein could be omitted from in vitro test systems for leukocyte locomotion. It is suggested that quantitatively equal cell adhesion values may, depending on the type of attraction forces working in adhesion to the substratum, result in different locomotion patterns.     

Depletion interactions in polymer solutions promote red blood cell adhesion to albumin-coated surfaces

The effects of concentration and molecular weight of neutral dextrans on the adhesion of human red blood cells (RBC) to albumin-coated glass have been investigated using a parallel-plate flow chamber. Results indicate that the adhesion is markedly increased in the presence of 70 kDa and 500 kDa dextran, with this increase reflected by both the number of cells adhering and the strength of the adhesion. This increased adhesiveness is attributed to reduced surface concentrations of the large polymers and hence attractive forces due to depletion interaction. Depletion interaction brings the adjacent surfaces closer, leading to an increased number of binding sites available to the cell and thus more efficient and stronger adhesion of single cells. Our results suggest that depletion might play a role in other specific cell-cell or cell-surface interactions via initiating close contacts to allow specific binding.     

Locomotion and adhesion of polymorphonuclear leukocytes. Effects of the supporting substratum

Contact angle measurements have been used to correlate surface hydrophobicity of a supporting substratum with adhesion and locomotion of polymorphonuclear leukocytes. The binding of human serum albumin, a well-known chemokinetic substance, to hydrophilic glass slides gave rise to hydrophobic surfaces with adhesive properties conductive to cell polarization, thus allowing cell locomotion. Parallel contact angle and cell adhesion measurements suggested that albumin modified the cell-substratum interaction by increasing the van der Waals forces of attraction and reducing the electrostatic forces. By allowing cells to adhere to a hydrophobic surface (siliconized glass), it was found that protein could be omitted from in vitro test systems for leukocyte locomotion. It is suggested that quantitatively equal cell adhesion values may, depending on the type of attraction forces working in adhesion to the substratum, result in different locomotion patterns.     

Processes of bioadhesion on stainless steel surfaces and cleanability: A review with special reference to the food industry

Biofouling of equipment surfaces in the food industry is due initially to physico-chemical adhesion processes, and subsequently to the proliferation of microbes within an extracellular polymer matrix. Two physico-chemical theories can be applied to predict simple cases of bacterial adhesion. However, these models are limited in their applicability owing to the complexity of bacterial surfaces and the surrounding medium. Various factors that can affect the bacterial adhesion process have been listed, all directly linked to the solid substratum, the suspension liquid or the microorganism. For stainless steel surfaces, it is important to take into account the grade of steel, the type of finish, surface roughness, the cleaning procedures used and the age of the steel. Regarding the suspension fluid within which adhesion takes place, pH, ionic composition and the presence of macromolecules are important variables. In addition, the adhering microorganisms have extremely complex surfaces and many factors must be taken into account when conducting adhesion tests, such as the presence of cell appendages, the method of culture, the contact time between the microorganism and the surface, and exopolymer synthesis. Research on biofilms growing on stainless steel has confirmed results obtained with other materials, regarding resistance to disinfectants, the role of the extracellular matrix and the process by which the biofilm forms. However, it appears that the bactericidal activity of disinfectants on biofilms differs according to the type of surface on which they are growing. The main cleaners and disinfectants used in the food industry are alkaline and acid detergents, peracetic acid, quaternary ammonium chlorides and iodophors. The cleanability and disinfectability of stainless steel surfaces have been compared with those of other materials. According to the published research findings, stainless steel is comparable in its biological cleanability to glass, and significantly better than polymers, aluminium or copper. Moreover, microorganisms in a biofilm developing on a stainless steel surface can be killed with lower concentrations of disinfectant than those on polymer surfaces.     

Measuring cell forces by a photoelastic method

A new method for measuring the mechanical forces exerted by cells on the substratum and through the substratum to act on other cells is described. This method depends upon the growth of cells on a photoelastic substratum, polydimethylsiloxane coated with a near monolayer of fibronectin. Changes in the forces applied by the cells to the substratum lead to changes in birefringence, which can be measured and recorded by the Polscope computer-controlled polarizing microscope. The changes in azimuth and retardance can be measured. A method for calibrating the stress is described. The method is sensitive down to forces of 1 pN per square microns. Fairly rapid changes with time can be recorded with a time resolution of approximately 1 s. The observations show that both isolated adhering, spread cells and also cells close to contact exert stresses on the substratum and that the stresses are those that would be produced by forces of 10-1000 pN per cell. The forces are almost certainly exerted on nearby cells since movement of one cell causes strains to appear around other nearby cells. The method has the defect that strains under the cells, though detectable in principle, are unclear due to birefringence of the components of the cytoplasm and nucleus. It is of special interest that the strains on the substratum can change in the time course of a few seconds and appear to be concentrated near the base of the lamellopodium of the cell as though they originated there. As well as exerting forces on the substratum in the direction of the long axis of the cell, appreciable forces are exerted from the lateral sides of the cell. The observations and measurements tend to argue that microtopography and embedded beads can concentrate the forces.     

Study of microbial adhesion on some wood species: Theoretical prediction

The initial interaction between microorganisms and substrata is mediated by physicochemical forces, which in turn originate from the physicochemical surface properties of both interacting phases. In this context, we have determined the physicochemical proprieties of all microorganisms isolated from cedar wood decay in an old monument at the Medina of Fez-Morocco. The cedar wood was also assayed in terms of hydrophobicity and electron donor-electron acceptor (acid-base) properties. Investigations of these two aspects were performed by contact angles measurements via sessile drop technique. Except Bacillus subtilis strain (Giwi < 0), all strains studied showed positive values of the degree of hydrophobicity (Giwi > 0) and can therefore be considered as hydrophilic while cedar wood revealed a hydrophobic character (Giwi = 58.81 mJ m⁻²). All microbial strains were predominantly electron donor. The results show also that all strains were weak electron acceptors. Cedar wood exhibits a weak electron donor/acceptor character. Based on the thermodynamic approach, the Lifshitz-van der Waals interaction free energy, the acid-basic interactions free energy, the total interaction free energy between the microbial cells and six different wood species (cedar, oak, beech, ash, pine and teak) in aqueous media was calculated and used to predict which microbial strains have a higher ability to adhere to wooden surfaces. Except of weak wood, for all the situations studied, generalizations concerning the adhesion of the microbiata on wood species cannot be made and the microbial adhesion on wooden substrata was dependent on wood species and microorganisms tested.     

Retention of bacteria on a substratum surface with micro-patterned hydrophobicity

Bacteria adhere to almost any surface, despite continuing arguments about the importance of physico-chemical properties of substratum surfaces, such as hydrophobicity and charge in biofilm formation. Nevertheless, in vivo biofilm formation on teeth and also on voice prostheses in laryngectomized patients is less on hydrophobic than on hydrophilic surfaces. With the aid of micro-patterned surfaces consisting of 10-microm wide hydrophobic lines separated by 20-microm wide hydrophilic spacings, we demonstrate here, for the first time in one and the same experiment, that bacteria do not have a strong preference for adhesion to hydrophobic or hydrophilic surfaces. Upon challenging the adhering bacteria, after deposition in a parallel plate flow chamber, with a high detachment force, however, bacteria were easily wiped-off hydrophobic lines, most notably when these lines were oriented parallel to the direction of flow. Adhering bacteria detached slightly less from the hydrophilic spacings in between, but preferentially accumulated adhering on the hydrophilic regions close to the interface between the hydrophilic spacings and hydrophobic lines. It is concluded that substratum hydrophobicity is a major determinant of bacterial retention while it hardly influences bacterial adhesion.     

Fibronectin receptor exhibits high lateral mobility in embryonic locomoting cells but is immobile in focal contacts and fibrillar streaks in stationary cells

The dynamic process of embryonic cell motility was investigated by analyzing the lateral mobility of the fibronectin receptor in various locomotory or stationary avian embryonic cells, using the technique of fluorescence recovery after photobleaching. The lateral mobility of fibronectin receptors, labeled by a monoclonal antibody, was defined by the diffusion coefficient and mobile fraction of these receptors. Even though the lateral diffusion coefficient did not vary appreciably (2 X 10(-10) cm2/S less than or equal to D less than or equal to 4 X 10(-10) cm2/S) with the locomotory state and the cell type, the mobile fraction was highly dependent on the degree of cell motility. In locomoting cells, the population of fibronectin receptors, which was uniformly distributed on the cell surface, displayed a high mobile fraction of 66 +/- 19% at 25 degrees C (82 +/- 14% at 37 degrees C). In contrast, in nonmotile cells, the population of receptors was concentrated in focal contacts and fibrillar streaks associated with microfilament bundles and, in these sites, the mobile fraction was small (16 +/- 8%). When cells were in a stage intermediate between highly motile and stationary, the population of fibronectin receptors was distributed both in focal contacts with a small mobile fraction and in a diffuse pattern with a reduced mobile fraction (33 +/- 9%) relative to the diffuse population in highly locomotory cells. The mobile fraction of the fibronectin receptor was found to be temperature dependent in locomoting but not in stationary cells. The mobile fraction could be modulated by affecting the interaction between the receptor and the substratum. The strength of this interaction could be increased by growing cells on a substratum coated with polyclonal antibodies to the receptor. This caused the mobile fraction to decrease. The interaction could be decreased by using a probe, monoclonal antibodies to the receptor known to perturb the adhesion of certain cell types which caused the mobile fraction to increase. From these results, we conclude that in locomoting embryonic cells, most fibronectin receptors can readily diffuse in the plane of the membrane. This degree of lateral mobility may be correlated to the labile adhesions to the substratum presumably required for high motility. In contrast, fibronectin receptors in stationary cells are immobilized in focal contacts and fibrillar streaks which are in close association with both extracellular and cytoskeletal structures; these stable complexes appear to provide firm anchorage to the substratum.     

Adhesion of L1210 cells to sulfonated styrene copolymer surfaces: imaging of F-actin AND alpha-actinin

The static adhesion of living L1210 cells to sulfonated copolymer surfaces of different sulfonic group content and the actin cytoskeleton organization in the adhering cells were studied. The strength of the cell-substratum interaction was estimated by determining the relative number of cells remaining adherent despite experiencing a shearing force equal to 1.25 x 10(-11) N caused by the laminar flow of the medium. The cell-substratum interaction took place in a medium with or without serum. The distribution of F-actin and alpha-actinin in the adhering cells was determined in sequences of fluorescent images of cell optical slices with the use of a computer method of cell image analysis. It was shown that the surface sulfonic groups affect not only the rate and strength of cell-substratum adhesion but also the F-actin and alpha-actinin distribution (in the cell regions near the substratum surface) in cells adhering in the medium containing serum. These proteins, concentrated in the tips of microvilli, were observed as dots. The distinctness (discernibleness) and sizes of these dots depend on the surface content of sulfonic groups. F-actin is located at the periphery of the cells in cells adhering in the medium without serum and alpha-actinin is concentrated in small dots at the periphery and in the central part of the cells.