Summary
The influences of microbial concentration and the shape of the mycelial aggregate upon the rheological properties of suspensions of a microorganism (Aspergilus niger) were investigated using a pipe-flow viscometer in an air-lift fermenter.
Both factors affect the rheological behaviour of the suspensions which was found to be non-Newtonian, being pseudoplastic and obeying the power-law equation. Each power-law constant was correlated with an equation which included the effect of microbial concentration and the shape of the mycelial aggregate.
There is an indication that the power-law constant and these factors could be correlated by a similar form of relationship in other mycelial broths, but with different numerical coefficients.
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Abbreviations
- a :
-
constant defined by Eq. 5
- b :
-
constant defined by Eq. 5
- c :
-
flexibility parameter (-)
- D :
-
inside diameter of fermenter (m)
- d m :
-
diameter of mycelial thread (m)
- d p :
-
diameter of mycelial aggregate (m)
- k′ :
-
consistency index, defined by Eq. (2) (Nsn′·m-2)
- k :
-
consistency index of power-law fluid (N·sn·m-2)
- L :
-
distance between pressure tappings on the fermenter (m)
- l m :
-
length of mycelial thread (m)
- m :
-
constant defined by Eq. (5)
- n :
-
flow behaviour index of power-law fluid
- n′ :
-
flow behaviour index, defined by Eq. (2)
- ΔP :
-
pressure difference (N·m-2)
- V :
-
mean suspension velocity m·s-1
- X :
-
mycelial concentration (kg·m-3)
- \(\bar \iota\) :
-
shear stress (N·m-2)
- γ:
-
shear rate (s-1)
- w :
-
wall value
References
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Fatile, I.A. Rheological characteristics of suspensions of Aspergilus niger: correlation of rheological parameters with microbial concentration and shape of the mycelial aggregate. Appl Microbiol Biotechnol 21, 60–64 (1985). https://doi.org/10.1007/BF00252363
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DOI: https://doi.org/10.1007/BF00252363