Maja Borić Tjaša Danevčič David Stopar University of Ljubljana Biotechnical Faculty Importance of rheology in biotechnological processes Rheology studies the flow of liquids or soft matter ID: 634826
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Slide1
Rheology of liquid media influences bacterial physiology
Maja
Borić
,
Tjaša
Danevčič
, David
Stopar
University of Ljubljana, Biotechnical FacultySlide2
Importance of rheology in biotechnological processes
Rheology
studies the flow of liquids or soft matter
Water treatment plants, bioreactors
Influences pumping, hydrodynamics, mass transfer rates and sludge-water separation
Changes molecular diffusion as well as movement of microorganisms
Can a change in liquid medium rheology cause a change in bacterial physiology?Slide3
Changing medium rheology in the lab
Ideal polymer:
increases viscosity
changes Newtonian liquid to non-Newtonian
can not be degraded by bacteria and used as a nutrient
does not affect other
physico
-chemical factors (pH, water activity, DOC)
Hydroxyethyl
cellulose (HEC)
Viscosity range: 0.8
mPas
– 26.5
mPas
Model organisms:
Bacillus
subtilis
Escherichia coli
Vibrio
harveyiSlide4
Physiology of
Bacillus
subtilis
Growth rate increases but then returns to the previous level
PFK (phosphofructokinase) –
glycolysis
GPD (glucose-6-P-dehydrogenase)
–
pentose phosphate pathwayPK (piruvate kinase) – flow to the citric acid cycle
Respiration activity is the same at all viscositiesSlide5
Physiology of
E
s
cherichia
coli
At the highest tested viscosity the growth rate and respiration activity decreased significantly
PFK (phosphofructokinase) –
glycolysis
GPD (glucose-6-P-dehydrogenase)
–
pentose phosphate pathway
PK (
piruvate
kinase)
–
flow to the citric acid
cycleSlide6
Physiology of
Vibrio
harveyi
V.
harveyi
increased its respiration activity in order to maintain an unchanged growth rate. Despite this, the growth rate decreased at the highest tested viscosity.
PFK (phosphofructokinase) –
glycolysis
GPD (glucose-6-P-dehydrogenase)
–
pentose phosphate pathway
PK (
piruvate
kinase)
–
flow to the citric acid cycleSlide7
Growth efficiency
V
.
harveyi
(A
)
E
. coli
(B) B. subtilis (C) Slide8
Main conclusions and outlooks
Noteworthy differences in bacterial physiology at increased viscosity
/
changed rheology:
variability in bacterial response
Changes in viscosity / rheology can affect
:
growth rates
total metabolic activityefficiencycarbon flow through central metabolic pathwaysOther bacteria might also be subject to changes in environmental viscosity/rheology – can this be the case in water treatment plants and other biotechnological settings?Slide9
Acknowledgements
co-workers
at the Chair of Microbiology, Biotechnical Faculty, Ljubljana
prof. dr. David
Stopar
dr.
Tjaša
DanevčičJUB, d.d.Slovenian Research Agency