3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology
P05 GROwTh CuRVES OF MIxED
ThERMOPhILIC bACTERIA
LIBOR BABáK, RADKA BURDYCHOVá and
VLASTIMIL DOHnAL
Institute of Food Science and Biotechnology, Faculty of
Chemistry, Brno University of Technology, Purkyňova 118,
612 00 Brno, Czech Republic,
babak@fch.vutbr.cz
Introduction
Temperature is one of the most important enviromental
factors controlling the activities and evolution of organisms
and is one of the easiest variables to measure. not all temperatures
are equally suitable for the growth and reproduction
of living organisms. Most of animals, plants and eucaryotic
microorganisms are not able to exist at temperatures above
50 °C. It contrast to this fact, some procaryotic microorganisms
can grow at temperatures above 60 °C commonly. We
call them thermophiles. The most thermophilic microorganisms
live in the thermal zone of the Earth. Their industrial use
is various, from food industry to waste-water treatment. The
important knowladge for any application of these microorganisms
is their basic growth characteristics. The aim of this
work was testing of growth of the mixture of thermophilic
bacteria with possible potential to be used in waste-water industry.
Experimental
Experiments were carried out using the mixture of thermophilic
bacteria of the genus Bacilus and genus Thermus
(sludge from waste treatment plant Bystřice pod Hostýnem).
The substrates composition: C-source 4 g dm –3 , MgSO 4 .7H 2 O,
1. g dm –3 , (nH 4 ) 2 SO 4 0.3 g dm –3 , KH 2 PO 4 7 g dm –3 , yeast extract
2.4 g dm –3 , Peptone 8.5 g dm –3 . Glucose, lactose, sacharose
and maltose were tested as the main source of carbon in
succesive steps. Inoculum was prepared in the same conditions
as tested cultivations. Inoculation rate: 1 : 10. Cultivations
were practised 50 hours in two different systems – in
1.5 ml vials (anaerobic conditions) and in 1.5 dm 3 laboratory
fermentor (aerobic conditions).
The vials, with magnetic bar and tightly screw capped,
were placed into autosampler plate thermostated at 60 °C.
Flow injection analysis (FIA) was used for measurement of
microorganism quantity. The amount of 10 µl of the sample
was injected into water stream (0.2 ml min –1 ) and the absorbance
at 600 nm was measured. The area under the curve of
chromatogram was used for microorganism quantification.
The sample was drawn and analysed each 5 minutes for
50 hours. The HPLC system HP 1100 (Agilent Technologies,
Palo Alto, USA) consisted of vacuum degasser unit
(model G1322A), quaternary pump (G1311A), autosampler
(G1313A) and quadrupole mass spectrometer (G1946VL)
with electrospray ionization was used. The ChemStation software
(Rev. A 10.02) controlled the chromatographic system
and it was used for chromatogram evaluation. The vials with
s583
cultivation media were placed in thermostated plate KEVA
(Ing. Pavel Krásenský, Brno, Czech Republic) and stirred using
magnetic stirrer.
The cultivations in bioreactor were practised in a laboratory
batch fermentor BIOSTAT B (B. Braun Biotech.) Cultivation
conditions: multiple turbo-stirrer 250 min –1 , aeration
10 dm3 min –1 , pH adjusted on value 6.5, medium temperature
60 °C, vessel isolation Mirelon. Biomass concentration was
determined by the help of samples taking and their analyses
in turbidimeter.
Results
The experimental results are summarized in Fig. 1. & 2.
Fig. 1. Growth curves on different substrates into vial
(10,000 mAu.s ~ 1 g dm –3 (biomass concentration)
Fig. 2. Growth curves on different substrates in fermentor
•
Hence it follows (Fig. 1.):
Sacharose was not utilised by mixed thermophilic bacteria
in anaerobic system only. Enzyme decomposed sacha-