3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology
Table I
Cell envelope fatty acid composition. Cells were harvested by centrifugation and lyophilized fatty acids
were esterified to methyl esters, extracted to hexan and analysed by GC-FID
Fatty acid (methyl ester) t R [min] Carbon atoms Phenol [g dm –3 ]
0.3 0.7
not identified 7.6 x
14 : 0 tetradecanoate 13.3 14 4.8
i-15 : 0 13-methyltetradecanoate 14.9 15
not identified 17.8 x
16 : 1 cis-9-hexadecanoate 17.9 16 8.3 12.7
16 : 0 hexadecanoate 18.3 16 41.8 51.7
not identified 19.4 x 3.2
17 : 0 Δ cis-9,10-methylenhexadecanoate 20.6 17 8.8
17 : 0 heptadecanoate 20.9 17
18 : 1 9 cis-9-oktadecanoate 22.7 18
18 : 0 oktadecanoate 23.4 18 2.1 8.0
not identified 24.2 x 33.6 24.5
not identified 26.8 x 2.1
C e l l A d h e s i o n
The determination of material hydrophobicity and other
surface characteristics influence on cell adhesion was the aim
of our work. Five materials were tested, both hydrophilic and
hydrophobic. The hydrophilic materials were: glass without
any modifications (strictly hydrophilic) and coated glass with
slightly less hydrophilic surface. The hydrophobic materials
were: hydrophobized glass and silicone with equal hydrophobicity,
to ascertain the influence of surface moieties. The last
material was teflon, known for its extreme hydrophobicity 5
and antiadhesion properties.
Experiments were carried out using cells precultivated
in Erlenmeyer flasks. The hydrophobicity of these cells was
approximately 85 % (Fig. 1.). Initial adhesion experiments
(see Table II) were carried out in the presence of phenol
(0.3 g dm –3 ). The adhesion was monitored after one hour and
after 24 hours. The results confirmed that hydrophobic cells
do not adhere to hydrophilic surface. The results also verified
our assumption that beside hydrophobicity there are other
important factors in the process of cell adhesion. The teflon
was proven to be an unfavourable material for cell adhesion.
Table II
The adhesion of Rhodococcus erythropolis cells on different
materials after one and twenty-four hours
Experiment duration [h] 1 24
material
material
hydrophobicity
colonized area
[%]
glass 26.4 ± 6.6 0 0.2
coated glass 55.9 ± 8.2 4.9 3.2
hydrophobized glass 97.0 ± 2.0 12.1 12.9
silicone 97.0 ± 3.6 39.5 40.1
teflon 108 5 7.6 4.9
s781
The colonized area was three times higher on silicone
than on the hydrophobized glass with the same hydrophobicity.
The influence of the experiment duration was not significant.
Also the adhesion of cells with different inoculation origin
was evaluated (see Table III). The cells were precultivated
in inoculum medium (nutrient broth or mineral medium with
phenol) and then transferred to experiment medium. This was
proven to be substantial in cell attachment. The cells adhered
the most to silicone, but only in medium with phenol concentration
0.3 g dm –3 . When transferred from either nutrient broth or
minimal medium to minimal medium with phenol concentration
0.7 g dm –3 , cells adhered considerably less.
Table III
The influence of inoculum cultivation conditions on Rhodococcus
erythropolis cells adhesion on different materials
Experiment set-up
inoculum medium n.broth n.broth phenol
0.7 g dm –3
experiment medium
phenol phenol phenol
0.3 g dm –3 0.7 g dm –3 0.7 g dm –3
material
material
hydrophobicity
colonized area [%]
glass 26.4 ± 6.6 0 0.2 0.04
silicone 97.0 ± 3.6 39.5 4.5 9.2
teflon 108 7.6 5.5 6.0
Conclusions
In our study the influence of cultivation conditions on
cell hydrophobicity and cell adhesion was confirmed. It was
found that not only hydrophobicity of materials plays important
role in colonization, but also other surface characteristics
are significant.