Previous Article | Next Article 
Applied and Environmental Microbiology, February 2000, p. 659-663, Vol. 66, No. 2
Department of Biomedical Engineering,
University of Groningen, 9712 KZ Groningen, The Netherlands
Received 24 May 1999/Accepted 15 November 1999
The release of biosurfactants by adhering microorganisms as a
defense mechanism against other colonizing strains on the same substratum surface has been described previously for probiotic bacteria
in the urogenital tract, the intestines, and the oropharynx but not for
microorganisms in the oral cavity. Two Streptococcus mitis
strains (BA and BMS) released maximal amounts of biosurfactants when
they were grown in the presence of sucrose and were harvested in the
early stationary phase. The S. mitis biosurfactants reduced the surface tensions of aqueous solutions to about 30 to 40 mJ m Dental plaque is a complex,
multispecies biofilm that forms on oral surfaces in which bacteria are
embedded in bacterial and salivary polymers. Many species and strains
have been identified in dental plaque; some of these organisms
(29, 32) are now recognized as early colonizers, and others
(16, 34) are considered cariogenic organisms or
periodontopathogens (36). However, no real ecological role
has been defined for most strains and species in dental plaque, and it
is possible that these organisms should be considered part of the
normal, indigenous, healthy microflora in the oral cavity.
Similarly, normal healthy microfloras have been identified for the
gastrointestinal tract (31), the urogenital tract (17, 24), the skin (15), and the eyes (18). In a
healthy host, a normal microflora effectively competes with invading
pathogens. The mechanisms employed by the healthy microflora to
interfere with the adhesion of invading pathogens include competitive
exclusion (26) and displacement (20), production
of antibacterial compounds, such as lactic acid, hydrogen peroxide,
bacteriocins, and bacteriocin-like substances, by lactobacilli
(13, 19), coaggregation (7, 25), and release of
biosurfactants (8).
Recently, it has been demonstrated that biosurfactants released by
lactobacilli can be adsorbed to catheter materials in order to
discourage uropathogen adhesion (37). Microorganisms in
certain dairy products also release biosurfactants that inhibit
adhesion of yeasts, most notably to voice prostheses in the oropharynx (1). Several years ago, it was pointed out that
Streptococcus mitis BMS released substances, which were
later recognized as biosurfactants (33), that discourage
adhesion of Streptococcus mutans (23). This
observation has never been followed up on, but such a process is of
considerable interest as a mechanism that could be used to prevent
dental caries, since S. mutans is an important etiological
agent of coronal (16, 34) and root surface caries
(30).
The aim of this study was twofold: (i) to determine the surface
tensions of biosurfactant solutions and their chemical characteristics when they are released by two oral S. mitis strains grown on
different carbohydrate sources and (ii) to determine the effect of
biosurfactant-releasing S. mitis cells adhering to an
artificial (glass) substratum with and without a salivary conditioning
film on the subsequent adhesion of a S. mutans strain. In
addition, surface properties of S. mitis cells before and
after biosurfactants were released were measured in order to rule out
the possibility that the compounds released were cell surface compounds
whose release affected the adhesive properties of the cell surface.
Microorganisms.
S. mutans NS and S. mitis
BA and BMS were originally isolated from the human oral cavity and were
stored in Todd-Hewitt broth (THB) (Oxoid, Basingstoke, England)
supplemented with 0.5% sucrose and 7% (vol/vol) dimethyl sulfoxide at
0099-2240/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Inhibition of Streptococcus mutans NS Adhesion to
Glass with and without a Salivary Conditioning Film by
Biosurfactant- Releasing Streptococcus mitis
Strains
ABSTRACT
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
2. Biochemical and physicochemical analyses revealed
that the biosurfactants released were glycolipids. An acid-precipitated
fraction was extremely surfactive and was identified as a
rhamnolipidlike compound. In a parallel-plate flow chamber, the number
of Streptococcus mutans NS cells adhering to glass with and
without a salivary conditioning film in the presence of
biosurfactant-releasing S. mitis BA and BMS (surface
coverage, 1 to 4%) was significantly reduced compared with the number
of S. mutans NS cells adhering to glass in the absence of
S. mitis. S. mutans NS adhesion in the presence of non-biosurfactant-releasing S. mitis BA and BMS was not
reduced at all. In addition, preadsorption of isolated S. mitis biosurfactants to glass drastically reduced the adhesion of
S. mutans NS cells and the strength of their bonds to
glass, as shown by the increased percentage of S. mutans NS
cells detached by the passage of air bubbles through the flow chamber.
Preadsorption of the acid-precipitated fraction inhibited S. mutans adhesion up to 80% in a dose-responsive manner. These
observations indicate that S. mitis plays a protective role
in the oral cavity and protects against colonization of saliva-coated surfaces by cariogenic S. mutans.
INTRODUCTION
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
MATERIALS AND METHODS
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
60°C. Streptococci from the frozen stock preparations were streaked
every 2 weeks onto blood agar plates and incubated at 37°C. After 2 days the plates were stored at 5°C.
1 by using a Bürker-Türk counting chamber.
Biosurfactant release. To release biosurfactant from S. mitis BA and BMS, subcultures (10 ml) from blood agar plates were prepared by inoculating THB supplemented with 0.5% (wt/vol) glucose, 0.5% (wt/vol) glycerol, 0.5% (wt/vol) galactose, or 0.5% (wt/vol) sucrose and incubating the preparations overnight at 37°C.
An overnight subculture was used to inoculate 1,400 ml of a second culture. Cells were harvested in the mid-exponential, early-stationary, and stationary phases by centrifugation at 4,000 × g, washed twice in adhesion buffer, and resuspended in 200 ml of water. Crude biosurfactant was produced by gently stirring the suspension for 2 h at room temperature. Subsequently, the microorganisms and the biosurfactants released were separated by centrifugation at 10,000 × g. To ensure that all of the cell remnants were removed, the supernatant was centrifuged twice at 10,000 × g. After the final centrifugation, both the cellular pellet and the crude biosurfactant were freeze-dried and weighed, and the crude biosurfactant was stored at20°C until it
was used.
In a separate experiment, the freeze-dried crude biosurfactant of
S. mitis BMS was resuspended in water and subsequently acid precipitated with concentrated HCl at pH 2.0. After the supernatant was
decanted, the precipitate was washed twice with acidic water (pH 2) and
collected by centrifugation at 4,000 × g. After the acid precipitate was redissolved, it was freeze-dried. The supernatant was adjusted to pH 7 with KOH and also freeze-dried.
Surface tension measurements. Axisymmetric drop shape analysis by profile (ADSA-P) was performed as described by Noordmans and Busscher (22) in order to determine the surface tensions of biosurfactant solutions. Briefly, ADSA-P involves digitizing the circumference of a liquid droplet on a solid surface. The circumference of the droplet is fitted to the Laplace equation of capillarity (27), which yields the surface tension of the biosurfactant solution. Droplets containing biosurfactant dissolved in water (volume, approximately 100 µl) were placed on a clean piece of fluoroethylenepropylene (Teflon). Measurements for one solution droplet were obtained after 2 h in order to allow equilibration of the interface in an enclosed chamber at room temperature. One liquid profile was recorded twice with a minimal time interval (<0.5 s) between measurements, and the ADSA-P surface tensions were averaged. This procedure was performed in duplicate with separate liquid droplets.
ADSA-P surface tension measurements were obtained for crude biosurfactant solutions in water as a function of biosurfactant concentration, as well as for the freeze-dried acid-precipitated fraction and supernatant of crude S. mitis BMS biosurfactant.Biochemical assay. The protein content of the crude biosurfactant was determined by the Bio-Rad protein assay; bovine albumin was used as the standard.
XPS.
For X-ray photoelectron spectroscopy (XPS), 100-µl
droplets of crude stationary-phase biosurfactants and the
acid-precipitated fraction dissolved in water (approximately 10 mg
ml1) were placed on gold-coated glass slides (1 by 1 cm).
After air drying, the glass slides were inserted into the chamber of a
spectrometer (Surface Science Instruments, S-probe, Mountain View,
Calif.). The residual pressure in the spectrometer during operation was approximately 109 Pa. A magnesium anode was used to
produce X-rays (10 kV, 22 mA) with a spot size of 250 by 1,000 µm.
After scans of the overall spectrum in the binding energy range from 1 to 1,200 eV at low resolution (150-eV pass energy) were obtained, peaks
over a 20-eV binding energy range were recorded at high resolution
(50-eV pass energy) in the following order: C1s (four
scans), O1s (four scans), N1s (eight scans),
P2p (eight scans), and C1s again in order to account for contamination or deterioration under X rays of the samples.
Cell surface properties. The bacterial cell surface hydrophobicity of the S. mitis strains was assessed by measuring water contact angles on bacterial lawns (35) on membrane filters (pore diameter, 0.45 µm). Wet filters with deposited organisms were fixed on sample holder plates with double-sided sticky tape and air dried. Water contact angles were measured after 20 min by using image analysis techniques at 25°C and sessile droplets of water. At least three different filters containing samples from separate cultures were prepared.
The zeta potentials of the S. mitis strains were determined in adhesion buffer from the speed of suspended bacteria in a 150-V applied electric field by using the Helmholtz-Smoluchowski equation (12). The instrument used, a model 501 Lazer Zee meter (PenKem, Bedford Hills, N.Y.), was equipped with an image analysis option for tracking and zeta sizing (38).Saliva.
Human whole saliva was collected from 10 healthy
volunteers of both sexes in ice-chilled cups. Saliva production by the
volunteers was stimulated by chewing Parafilm (3M Company, Minneapolis,
Minn.). After the saliva was pooled and centrifuged at
10,000 × g for 5 min at 10°C, phenylmethylsulfonyl
fluoride (0.2 M; Merck, Darmstadt, Germany) was added to a final
concentration of 1 mM as a protease inhibitor. The solution was
centrifuged again, dialyzed overnight at 4°C against water, and
freeze-dried for storage. A 1.5-mg ml1 solution of
freeze-dried stock in adhesion buffer (see above) was designated
reconstituted human whole saliva.
Adhesion experiments. The flow chamber (length, 7.6 cm; width, 3.8 cm; height, 0.06 cm) and image analysis system used have been described in detail previously (28). Images were obtained from the bottom glass plate (5.8 by 3.8 cm) of the parallel-plate flow chamber. The top plate of the chamber was also made of glass.
Prior to each experiment, all tubes and the flow chamber were filled with adhesion buffer, and care was taken to remove air bubbles from the system. Flasks containing microbial suspensions, buffer, and saliva when appropriate were placed at the same height with respect to the chamber, so that immediately after the flow was switched, all of the fluids would circulate through the chamber under the influence of hydrostatic pressure at a shear rate of 20 s1 (0.05 ml
s1; well within the limits of laminar flow), which
represented a shear rate between the shear rates exerted by stimulated
and unstimulated salivary flow at the level of the tooth surface
(4). First, the flow was switched to saliva (when
appropriate) for 1.5 h in order to create a salivary conditioning
film, and then the flow was switched for 15 min to buffer to remove all
remnants of saliva from the tubing and the flow chamber. After this,
the flow was switched (when appropriate) to an S. mitis BMS
or BA suspension until the desired surface coverage by adhering
S. mitis BMS or BA cells (between 1 and 4%) was attained,
as measured in real time with the image analysis system. In the
experiments carried out to determine the effects of preadsorbed
biosurfactants, biosurfactants in a 20-mg ml1 solution
were adsorbed overnight to the glass plate. Between flow steps, buffer
was run through the system to remove unbound material from the tubes
and chamber. Finally, a S. mutans suspension was circulated
through the system for 4 h.
The initial increase in the number of adhering S. mutans NS
cells with time was expressed by a so-called initial deposition rate;
this rate was the number of microorganisms that adhered initially per
unit of time and area. The number of bacteria adhering after 4 h
was considered an estimate of microbial adhesion at a more advanced
stage of the adhesion process.
Finally, after 4 h, air bubbles were passed through the chamber in
order to obtain an indication of the adhesive forces (14). The passage of an air-liquid interface (i.e., an air bubble) over adhering micron-sized particles is accompanied by a detachment force of
about 107 N per adhering microorganism. After the passage
of each air bubble, the mean percentage of bacteria detached by the
high removal force was determined at five different spots on the
substratum surface with respect to the mean number of organisms
adhering at five spots prior to the introduction of the first air bubble.
All adhesion experiments were performed in triplicate with separately
cultured organisms at room temperature.
| |
RESULTS |
|---|
|
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
|
|---|
Table 1 shows the amounts of
biosurfactant released by S. mitis BA and BMS grown on
different carbohydrates in various growth phases. The amount of
biosurfactant released per gram of dry cell weight was largest for
bacteria in the mid-exponential growth phase and decreased as the
organisms entered the stationary growth phase. Adding glycerol to the
medium increased the biosurfactant yield of S. mitis BMS in
the stationary phase compared to the other carbohydrates used. S. mitis BA in the stationary growth phase released similar amounts
of biosurfactants irrespective of the carbohydrate present.
|
Figure 1 shows that the S. mitis biosurfactants could reduce the surface tension of an
aqueous solution to around 30 to 40 mJ m2 irrespective of
the growth phase or the carbohydrate present. When glucose was used as
the carbohydrate, the surface activity of the compounds released was
less than the surface activities after growth on the other
carbohydrates used.
|
), glycerol (
), galactose (
), or sucrose (
, 
,
and 
) and harvested in the mid-exponential phase (The protein contents of the biosurfactants released by both S. mitis BA and BMS were extremely low (less than 1%). Also, XPS physicochemical analyses (Table 2)
revealed that the biosurfactants contained little nitrogen (the N/C
ratios were between 0.101 and 0.172) compared with protein reference
compounds (the N/C ratio is 0.270 for the average protein). The
nitrogen contents of the biosurfactants were too high, however, for
association of the biosurfactants with lipoteichoic acid, which
was also ruled out by relatively low oxygen and phosphorus contents.
The absence of proteins and lipoteichoic acids in the
biosurfactants was confirmed by the low fractions of carbon doubly
bound to oxygen (C==O). C---(C,H) functionalities were abundant in the
biosurfactants released by the S. mitis strains, as they are
in rhamnolipids.
|
Table 3 shows the adhesion of S. mutans NS in the presence of adhering, biosurfactant-releasing
S. mitis strains grown on sucrose. As Table 3 shows, when
the surface coverage by S. mitis BMS on bare glass was up to
4%, the initial deposition rate of S. mutans NS was reduced
from 1,043 to 394 cm2 s1. Also, the number
of S. mutans cells adhering after 4 h decreased from
130 × 105 to 50 × 105 cells
cm2. The effects of biosurfactant-releasing S. mitis BA on S. mutans NS adhesion were far less obvious
than the effects of S. mitis BMS. Whereas surface coverage
by S. mitis BA of up to 2% resulted in similar or sometimes
even greater reductions in S. mutans adhesion than the
reductions observed in the presence of S. mitis BMS, the
effect of S. mitis BA on S. mutans adhesion
completely disappeared when the surface coverage was 4%. Finally,
S. mitis BA and BMS biosurfactants decreased the strength of
S. mutans NS bonds to glass, as the percentage of
adhering S. mutans cells that were detached by
air bubble passage increased as the surface coverage by the
S. mitis strains increased.
|
In order to determine whether the decreases in S. mutans NS
adhesion in the presence of adhering S. mitis strains were
due to simple geometrical effects or to the biosurfactants released by
the adhering S. mitis strains, we performed experiments with two non-biosurfactant-releasing preparations, S. mitis
BA and BMS. Nonreleasing bacteria were
prepared by allowing the S. mitis strains to release their
biosurfactants overnight; after this they were used in adhesion
experiments with S. mutans NS. Using ADSA-P surface tension
measurements, we determined that the BA and
BMS bacteria had lost the ability to reduce the surface
tension of an aqueous suspension (
= 0 and 2 mJ
m2, respectively) and thus their ability to release
biosurfactants. Furthermore, we observed no significant changes in the
cell surface hydrophobicities and zeta potentials of the organisms that
might affect S. mutans adhesion. The water contact angle on
S. mitis BMS was 99° before and after the biosurfactant
was released, while the water contact angle on S. mitis BA
was 104°. Similarly, the zeta potential of S. mitis BMS in
adhesion buffer was not altered by biosurfactant release; it remained
9 mV. For S. mitis BA, there was an insignificant change
in the bacterial zeta potential from 8 to 5 mV that occurred when
the biosurfactant was released.
Table 3 shows that there was not a significant difference between
adhesion of S. mutans NS in the presence of adhering,
nonreleasing S. mitis BA and BMS
(surface coverage, 4%) and adhesion to bare glass. Table 3 also shows
that preadsorption of crude biosurfactants released by S. mitis BA, as well as by S. mitis BMS, significantly
reduced the adhesion of S. mutans to glass. The initial
deposition rates and the numbers of S. mutans cells
adhering after 4 h to biosurfactant-coated glass were almost
10-fold lower in the presence of S. mitis BMS biosurfactant
and more than 20-fold lower in the presence of S. mitis BA
biosurfactant. Also, detachment of adhering S. mutans cells
by air bubble passage increased drastically in the presence of
preadsorbed crude biosurfactants.
The acid-precipitated fraction of S. mitis BMS biosurfactant
was extremely surface active compared with the crude biosurfactant, and
an aqueous solution of the acid precipitate containing only 1 mg
ml1 had a surface tension of 35 mJ m2
(compare with Fig. 1) while an aqueous solution of the freeze-dried supernatant (the supernatant left after acid precipitation) hardly decreased the surface tension of water in the same concentration range.
Moreover, substratum coverage by adsorption of the acid-precipitated fraction from an aqueous solution (between 0.1 and 1 mg
ml1) resulted in up to 80% inhibition of S. mutans NS adhesion in a dose-responsive manner. XPS analysis of
the acid-precipitated fraction revealed a reduced nitrogen content
compared to the crude biosurfactant (Table 2), while the O/C elemental
concentration ratio was between the ratios for rhamnolipids R1 and R2.
Table 3 also shows the adhesion of S. mutans NS to glass with a salivary conditioning film in the presence of stationary-phase biosurfactant-releasing S. mitis BA and BMS grown on sucrose. This table shows that biosurfactant-releasing S. mitis strains interfered not only with S. mutans adhesion to glass but also with S. mutans adhesion to salivary conditioning films.
| |
DISCUSSION |
|---|
|
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
|
|---|
In this study we found that release of biosurfactants by adhering S. mitis strains interferes with adhesion of a cariogenic S. mutans strain. A chemical characterization study suggested that glycolipids were present in the crude biosurfactant, while further purification revealed that the active component was rhamnolipidlike. It was found previously that S. mitis ATCC 9811 released extracellular substances that were surface active (10, 33). However, these extracellular substances were identified as an exohemagglutinin, a lectinlike substance that is responsible for interaction with saliva (10).
The most commonly isolated biosurfactants are glycolipids (e.g.,
rhamnolipids produced by Pseudomonas aeruginosa
[9]) and lipopeptides (e.g., surfactin released by
Bacillus subtilis [3]). The yields of both
of these types of biosurfactants are relatively high (approximately
2.5 g liter of medium1), and these biosurfactants
reduce the surface tension of spent culture supernatant to less than 30 mJ m2. Streptococcus thermophilus B
(2) and Lactobacillus species (37) are
also biosurfactant-releasing strains. The biosurfactants of these
organisms decrease the surface tension of water to around 37 mJ
m2, but the amounts released per liter of culture medium
were orders of magnitude smaller than the amounts of the rhamnolipids
and lipopeptides released (approximately 100 mg liter1
for Lactobacillus species and 20 mg liter1 for
S. thermophilus B). A simple calculation revealed that small amounts of biosurfactants may have substantial effects on adhesion to
substratum surfaces. If it is assumed that the biosurfactant is a small
molecule with a molecular weight of about 1,000, it can be estimated
based on a biosurfactant yield of around 108 mg per cell
that a substratum surface coverage value of around 8% for
biosurfactant-releasing S. mitis BA or BMS cells results in
100% coverage of the surface by biosurfactants (2). Indeed, the adhesion experiments performed with S. mitis BA and BMS
grown on medium supplemented with sucrose showed that the presence of biosurfactant-releasing S. mitis BA and BMS cells on glass
and on glass with a salivary conditioning film effectively reduced the
adhesion of S. mutans NS even with the influence of
geometrical effects (i.e., physical collisions between suspended and
adhering organisms which resulted in increased deposition) (Table 3). Moreover, preadsorption of the biosurfactants to glass also drastically reduced S. mutans NS adhesion.
With regard to the oral cavity, the increased detachment of adhering S. mutans cells in the presence of biosurfactants after air bubble passage is very important, as air-liquid interfaces frequently pass over the enamel surface and the adhering microorganisms during eating and swallowing (i.e., adhering microorganisms are exposed to high detachment forces). Our results indicate that even if S. mutans NS adheres to bare surfaces or to a salivary conditioning film, biosurfactants effectively stimulate detachment of this organism by the dynamic shear forces that occur in the oral cavity.
In conclusion, adhering S. mitis BA and BMS cells decrease the adhesion of S. mutans NS to glass and to glass with a salivary conditioning film through the release of rhamnolipidlike biosurfactants. Thus, we propose that S. mitis plays an ecological role in the oral cavity.
| |
FOOTNOTES |
|---|
* Corresponding author. Mailing address: Department of Biomedical Engineering, University of Groningen, Bloemsingel 10, 9712 KZ Groningen, The Netherlands. Phone: 31-50-3633140. Fax: 31-50-3633159. E-mail: H.J.Busscher{at}med.rug.nl.
| |
REFERENCES |
|---|
|
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
|
|---|
| 1. | Busscher, H. J., G. Bruinsma, R. van Weissenbruch, C. Leunisse, H. C. van der Mei, F. Dijk, and F. W. J. Albers. 1998. The effect of buttermilk consumption on biofilm formation on silicone rubber prostheses in an artificial throat. Eur. Arch. Otorhinolaryngol. 255:410-413[CrossRef][Medline]. |
| 2. | Busscher, H. J., C. G. van Hoogmoed, G. I. Geertsema-Doornbusch, M. van der Kuijl-Booij, and H. C. van der Mei. 1997. Streptococcus thermophilus and its biosurfactants inhibit adhesion by Candida spp. on silicone rubber. Appl. Environ. Microbiol. 63:3810-3817[Abstract]. |
| 3. |
Cooper, D. G.,
C. R. MacDonald,
J. J. B. Duff, and W. Kosaric.
1981.
Enhanced production of surfactin from Bacillus subtilis by continuous product removal and metal cation addition.
Appl. Environ. Microbiol.
42:408-412 |
| 4. |
Dawes, C.,
S. Watanabe,
P. Biglow-Lecomte, and G. H. Dibdin.
1989.
Estimation of the velocity of the salivary film at some different locations in the mouth.
J. Dent. Res.
68:1479-1482 |
| 5. | Desai, J. D., and A. J. Desai. 1993. Production of biosurfactants, p. 65-97. In N. Kosaric (ed.), Biosurfactants. Production, properties, applications. Marcel Dekker, Inc., New York, N.Y. |
| 6. | Edwards, J., and J. A. Hayashy. 1965. Structure of a rhamnolipid from Pseudomonas aeruginosa. Arch. Biochem. Biophys. 111:415-421[CrossRef][Medline]. |
| 7. | Ganeshkumar, N., C. V. Hughes, and E. I. Weiss. 1998. Coaggregation in dental plaque formation, p. 125-144. In H. J. Busscher, and L. V. Evans (ed.), Oral biofilms and plaque control. Harwood Academic Publishers, India. |
| 8. | Gerson, D. F. 1993. The biophysics of microbial surfactants: growth on insoluble substrates, p. 269-286. In N. Kosaric (ed.), Biosurfactants. Production, properties, applications. Marcel Dekker, Inc., New York, N.Y. |
| 9. | Hisatsuka, K., F. Nakahara, N. Sano, and K. Yamada. 1971. Formation of rhamnolipid by Pseudomonas aeruginosa and its function in hydrocarbon fermentation. Agric. Biol. Chem. 33:686-692. |
| 10. | Hsieh, C. C., K. Iwakura, M. Takagaki, and S. Shibata. 1984. Exohemagglutinin derived from Streptococcus mitis ATCC9811. J. Osaka Univ. Dent. Sch. 24:67-76[Medline]. |
| 11. | Itoh, S., and T. Suzuki. 1972. Effect of rhamnolipids on growth of Pseudomonas aeruginosa mutant deficient in n-paraffin utilizing ability. Agric. Biol. Chem. 36:2233-2235. |
| 12. | James, A. M. 1979. Electrophoresis of particles in suspension. Surf. Colloid Sci. 11:121-185. |
| 13. | Klaenhammer, T. R. 1988. Bacteriocins of lactic acid bacteria. Biochimie 70:337-349[Medline]. |
| 14. | Leenaars, A. F. M. 1989. A new approach to the removal of sub-micron particles from solid (silicon) substrates, p. 361-372. In K. L. Mittal (ed.), Particles on surfaces: detection, adhesion and removal. Plenum Press, New York, N.Y. |
| 15. | Leyden, J. J., K. J. McGinley, K. M. Nordstrom, and G. F. Webster. 1987. Skin microflora. J. Invest. Dermatol. 88:65s-72s[CrossRef][Medline]. |
| 16. |
Loesche, W. J.
1986.
Role of Streptococcus mutans in human dental decay.
Microbiol. Rev.
50:353-380 |
| 17. |
Marrie, T. J.,
C. A. Swantee, and M. Hartlen.
1980.
Aerobic and anaerobic urethral flora of healthy females in various physiological age groups and of females with urinary tract infections.
J. Clin. Microbiol.
11:654-659 |
| 18. |
McBride, M. E.
1979.
Evaluation of microbial flora of the eye during wear of soft contact lenses.
Appl. Environ. Microbiol.
37:233-236 |
| 19. | McGroarty, J. A., and G. Reid. 1988. Detection of a Lactobacillus substance that inhibits Escherichia coli. Can. J. Microbiol. 34:974-978[Medline]. |
| 20. |
Millsap, K. W.,
G. Reid,
H. C. van der Mei, and H. J. Busscher.
1994.
Displacement of Enterococcus faecalis from hydrophobic and hydrophilic substrata by Lactobacillus and Streptococcus spp. as studied in a parallel plate flow chamber.
Appl. Environ. Microbiol.
60:1867-1874 |
| 21. | Mozes, N., and S. Lortal. 1995. X-ray photoelectron spectroscopy and biochemical analysis of the surface of Lactobacillus helveticus ATCC 12046. Microbiology 141:11-19. |
| 22. | Noordmans, J., and H. J. Busscher. 1991. The influence of the droplet volume and contact angle on liquid surface tension measurements by axisymmetric drop shape analysis-profile. (ADSA-P). Colloids Surf. 58:239-249[CrossRef]. |
| 23. | Pratt-Terpstra, I. H., A. H. Weerkamp, and H. J. Busscher. 1989. Microbial factors in a thermodynamic approach of oral streptococcal adhesion to solid substrata. J. Colloid Interface Sci. 129:568-574[CrossRef]. |
| 24. | Redondo-Lopez, V., R. L. Cook, and J. D. Sobel. 1990. Emerging role of lactobacilli in the control and maintenance of the vaginal bacterial microflora. Rev. Infect. Dis. 12:856-872[Medline]. |
| 25. | Reid, G., J. A. McGroarty, R. Angotti, and R. L. Cook. 1988. Lactobacillus inhibitor production against Escherichia coli and coaggregation ability with uropathogens. Can. J. Microbiol. 34:344-351[Medline]. |
| 26. | Reid, G., and C. Tieszer. 1993. Preferential adhesion of urethral bacteria from a mixed population to a urinary catheter. Cells Mater. 3:171-176. |
| 27. | Rotenberg, Y., L. Boruvka, and A. W. Neumann. 1983. Determination of surface tension and contact angle from the shape of axisymmetric fluid interfaces. J. Colloid Interface Sci. 93:169-183[CrossRef]. |
| 28. | Sjollema, J., H. J. Busscher, and A. H. Weerkamp. 1989. Real-time enumeration of adhering microorganisms in a parallel plate flow cell using automated image analysis. J. Microbiol. Methods 9:73-78[CrossRef]. |
| 29. | Socransky, S. S., A. D. Manganielo, D. Propas, V. Oram, and J. van Houte. 1977. Bacteriological studies of developing supragingival dental plaque. J. Periodontal Res. 12:90-106[CrossRef][Medline]. |
| 30. |
Syed, S. A.,
W. J. Loesche,
H. L. Pape, Jr., and E. Grenier.
1975.
Predominant cultivable flora isolated from human root surface caries plaque.
Infect. Immun.
11:727-731 |
| 31. | Tannock, G. W. 1990. The microecology of lactobacilli inhabiting the gastrointestinal tract. Adv. Microb. Ecol. 11:147-171. |
| 32. | Theilade, E., J. Theilade, and L. Mikkelsen. 1982. Microbiological studies on early dento-gingival plaque on teeth and mylar strips in humans. J. Periodontal Res. 17:12-25[CrossRef][Medline]. |
| 33. | Van der Vegt, W., H. C. van der Mei, J. Noordmans, and H. J. Busscher. 1991. Assessment of bacterial biosurfactant production through axisymmetric drop shape analysis by profile. Appl. Microbiol. Biotechnol. 35:766-770. |
| 34. | Van Houte, J. 1980. Bacterial specificity in the etiology of dental caries. Int. Dent. J. 30:305-326[Medline]. |
| 35. | Van Oss, C. J., and C. F. Gillman. 1972. Phagocytosis as a surface phenomenon. I. Contact angles and phagocytosis of non-opsonized bacteria. J. Reticuloendothel. Soc. 12:283-292[Medline]. |
| 36. | Van Palenstein-Helderman, W. H. 1981. Microbial aetiology of periodontal disease. J. Clin. Periodontol. 8:261-280[CrossRef][Medline]. |
| 37. | Velraeds, M. M. C., H. C. van der Mei, G. Reid, and H. J. Busscher. 1996. Inhibition of initial adhesion of uropathogenic Enterococcus faecalis by biosurfactants from Lactobacillus isolates. Appl. Environ. Microbiol. 62:1958-1963[Abstract]. |
| 38. | Wit, P. J., J. Noordmans, and H. J. Busscher. 1997. Tracking of colloidal particles using microscopic image sequence analysis. Application to particulate microelectrophoresis and particle deposition. Colloids Surf. A Physicochem. Eng. Aspects 125:85-92[CrossRef]. |
Applied and Environmental Microbiology, February 2000, p. 659-663, Vol. 66, No. 2
0099-2240/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
This article has been cited by other articles:
-
de Kerchove, A. J., Elimelech, M.
(2007). Impact of Alginate Conditioning Film on Deposition Kinetics of Motile and Nonmotile Pseudomonas aeruginosa Strains. Appl. Environ. Microbiol.
73: 5227-5234
[Abstract] [Full Text] -
Roosjen, A., Busscher, H. J., Norde, W., van der Mei, H. C.
(2006). Bacterial factors influencing adhesion of Pseudomonas aeruginosa strains to a poly(ethylene oxide) brush.. Microbiology
152: 2673-2682
[Abstract] [Full Text] -
Rodrigues, L., Banat, I. M., Teixeira, J., Oliveira, R.
(2006). Biosurfactants: potential applications in medicine. J Antimicrob Chemother
57: 609-618
[Abstract] [Full Text] -
van Hoogmoed, C.G., Dijkstra, R.J.B., van der Mei, H.C., Busscher, H.J.
(2006). Influence of Biosurfactant on Interactive Forces between Mutans Streptococci and Enamel Measured by Atomic Force Microscopy. JDR
85: 54-58
[Abstract] [Full Text] -
Gomez-Suarez, C., Pasma, J., van der Borden, A. J., Wingender, J., Flemming, H.-C., Busscher, H. J., van der Mei, H. C.
(2002). Influence of extracellular polymeric substances on deposition and redeposition of Pseudomonas aeruginosa to surfaces. Microbiology
148: 1161-1169
[Abstract] [Full Text] -
Petersen, F. C., Assev, S., van der Mei, H. C., Busscher, H. J., Scheie, A. A.
(2002). Functional Variation of the Antigen I/II Surface Protein in Streptococcus mutans and Streptococcus intermedius. Infect. Immun.
70: 249-256
[Abstract] [Full Text]
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»