3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures
3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures
3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures
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Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology<br />
P59 ThE EFFECT OF CELL ADhESION ON<br />
POLLuTANT bIODEGRADATION<br />
TEREZA KRULIKOVSKá, OLGA SCHREIBEROVá,<br />
JITKA HRDInOVá, JAn MASáK, ALEnA ČEJKOVá<br />
and VLADIMíR JIRKů<br />
Institute of Chemical Technology Prague, Department of<br />
Fermentation Chemistry and Bioengineering<br />
Technicka 5, 166 28 Prague, Czech Republic,<br />
tereza.krulikovska@vscht.cz<br />
Introduction<br />
The unicellular microorganisms naturally form multicellular<br />
communities called biofilm. Bacterial biofilms are generally<br />
described as surface associated community consisting of<br />
microcolonies surrounded by a matrix of exopolymers (EPS)<br />
with varied composition. The characteristics of biofilm which<br />
are in focus of present research are the ability to withstand<br />
and degrade high concentration of various toxic substances.<br />
Phenol and catechol are toxic and persistent pollutants<br />
of the environment. They enter the environment from a number<br />
of industrial sources, namely from the production of pesticides,<br />
herbicides and many others. The method of removal<br />
by bacterial population is one of the possible solutions 1 .<br />
For our experiments gram-positive Rhodococcus erythropolis<br />
was chosen as a bacterium with a broad degradation<br />
potential, owning to its highly versatile metabolism.<br />
Experimental<br />
Rhodococcus erythropolis CCM 2595 was cultivated in<br />
BSM 2 medium at 28 °C. Carbon source was added (phenol or<br />
catechol 0.7 g dm –3 ) after sterilisation.<br />
Phenol and catechol concentration in media were determined<br />
by HPLC: Watrex column 250 × 4 mm, nucleosil<br />
100 C18, acetonitrile/deionized water (40/60), 1.0 ml min –1 ,<br />
UV detection 254 nm.<br />
Changes in biomass concentration were measured by<br />
spectrophotometric method at 595 nm as a total protein concentration<br />
3 .<br />
The cell surface hydrophobicity was assayed using a<br />
procedure according to Rosenberg 4 – BATH test. Polymer<br />
material surface hydrophobicity was measured by a contact<br />
angle measurement method 5 .<br />
For EPS composition analysis the biomass was removed<br />
from carrier by ultrasound and 2% EDTA addition. Saccharides<br />
were assayed according to Dubois 6 , proteins according<br />
to Bradford 3 .<br />
Rate of adhesion during initial period of cultivation was<br />
determined by fluorescent microscopy (Microscope nikon<br />
Eclipse E400). After staining of biofilm by SYTO 13 the part<br />
of colonized area was measured by the method of image analysis<br />
(LUCIA, Laboratory Imaging Ltd., CZ).<br />
s703<br />
Results<br />
S u s p e n d e d C e l l s<br />
Experiments were carried out in shaken flasks (120 rpm)<br />
in medium with phenol or catechol as a sole carbon source.<br />
The concentration of 0.7 dm l –3 of the pollutant was chosen<br />
as a stressed concentration according to previous experiments<br />
(data not shown). The changes of biomass concentration<br />
during cultivation were expressed as a total protein<br />
concentration. The results are presented in the Fig. 1. The<br />
biomass concentrations at the end of both cultivations were<br />
13 mg dm –3 . The phenol (0.7 g dm –3 ) was totally degraded after<br />
49.5 h, catechol (0.7 g dm –3 ) after 119.4 h.<br />
Experiments have shown that catechol biodegradation<br />
is affected by day light. During cultivation catechol was<br />
decomposed to compounds which interacted with glass. The<br />
repeated use of glass vessels was impossible.<br />
Fig. 1. rhodococcus erythopolis suspended cells growth and<br />
pollutant biodegradation. The cells were cultivated in shaken<br />
flasks in BSM medium at 28 °C. The phenol or catechol was used<br />
as sole carbon source (concentration 0.7 g dm –3 ). The phenol/catechol<br />
and biomass (expressed as a total protein) concentration<br />
were monitored.<br />
B i o f i l m<br />
The cell adhesion on solid materials is significantly<br />
affected by cell envelope composition and by hydrophobic/<br />
hydrophilic interactions between cells and carrier materials.<br />
The hydrophobicity and variance in EPS composition were<br />
studied.<br />
Table I<br />
Carrier materials hydrophobocity<br />
Material hydrophobicity Contact angle<br />
[°]<br />
Glass (microscopic slide) 26.4 ± 6.6<br />
Silicone 97.0 ± <strong>3.</strong>6