3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology
P04 ThERMOPhILIC bACTERIA APPLICATION
TO whEy bIODEGRADATION
LIBOR BABáK and RADKA BURDYCHOVá
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
In former times the whey was thought as valueless waste
of dairy industry rising in cheese, cottage and casein production.
Its application was in feed only. In these days, the whey
meaning inceases simultaneously with new knowledges of
nutrition, with sepative methods development, envirtonment
protection endeavour and rapid progress of food and pharmaceutical
industry. Environmental aspect is purity rivers maintenance
and it means the prohibition of waste-water disposal
(the whey too). It is possible to make the whey „liquidation“
by the help of microbial systems. Several microbial systems
were used for these purposes but they are still pure described.
Testing of new microbial systems for the degradation ot the
whey is in progress. In this work, the testing of degradation of
the whey medium using the mixture of thermophilic bacteria
is described.
Experimental
Experiments were practised with thermophilic aerobic
culture, the mixture of bacteria of the genus Bacilus and the
genus Thermus (sludge from waste treatment plant Bystřice
pod Hostýnem). The whey from cheese production (type
ermine) was used as the medium. Casein (0.1 mol dm –3
H 2 SO 4 ) and α,β-�lactoglobulins (20 min at 85 °C) were taken
out before cultivations. The whey was centrifuged and pH
value was adjusted. All cultivations were practised in the
laboratory fermentor BIOSTAT B (B. Braun Biotech.) with
working volume 2 dm 3 .
Fig. 1. batch cultivation progress in longer time (312 hours)
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Cultivation conditions: multiple turbo-stirrer 250 min –1 ,
aeration 10 dm 3 min –1 , pH adjusted on value 6.5, medium
temperature 60 °C, vessel isolation Mirelon. The batch was
selected as the cultivation method. The cultivation time was
66 h (1 st experiments) and 312 h (2 nd experiments). The process
characteristics were determined direct by fermentor system
(dissolved oxygen concentration) or by the help of samples
taking and their analyses (biomass – turbidimeter, COD
– spectrofotometer at 600 nm, lactose – HPLC after microfiltration,
100 % lactose ≈ 46 g.dm –3 . The statistical analyse
was realized in the relevancy level 0.05.
Results
The experimental results are summarized in Fig. 1. & 2.
Fig. 2. batch cultivation progress in shorter time (66 hours)
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Hence it follows:
Lactose was not used as primary substrate source
(Fig. 2.), consequently the exponential growth
phase in time 3–43 hours (specific growth rate
µ = 0.05 ± 0.01 h –1 ) is a result of simpler whey compound
utilization probably, for example lactate.
Lactose metabolisation was combined with the 2 nd
growth phase in time 120–260 hours (specific growth
rate µ = 0.010 ± 0.006 h –1 ) (Fig. 1.).
The biomass accrument was very slow. It was probably
an inhibition effect of concentrated substrate, especially
in the 1 st cultivation period (Fig. 1., Fig 2.). Total biomass
concentration after 312 hours: (3.3 ± 0.3) g dm –3 at
productivity 0.01 g.dm –3 h –1 .
The oxygen limitation can contibute to slow biomass
growth (primarily in the 1 st growth phase).
Maximum COD elimination was in the 1 st half of every
exponetial growth phase: 15 ± 3 % after the 1 st growth
phase and ± 4 % after the 2 nd growth phase.
The oxygen transfer coefficient was determined too,
k L a = (270 ± 21) h –1 .