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Rheological characteristics of suspensions of Aspergilus niger: correlation of rheological parameters with microbial concentration and shape of the mycelial aggregate

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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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Keywords

  • Rheological Property
  • Rheological Behaviour
  • Similar Form
  • Rheological Parameter
  • Rheological Characteristic