Advertisement

Fungal morphology in submerged cultures and its relation to glucose oxidase excretion by recombinant Aspergillus niger

  • Hesham El-Enshasy
  • Karsten Hellmuth
  • Ursula Rinas
Article

Abstract

The effect of culture conditions such as medium composition and shear stress on the fungal pellet morphology in shake-flask cultures and its relation to glucose oxidase (GOD) excretion by recombinant Aspergillus niger NRRL 3 (GOD 3–18) was investigated. It was shown that culture conditions resulting in the formation of smaller fungal pellets with an increased mycelial density result in higher yields of exocellular GOD. The pellets obtained in shake-flask cultures showed distinct layers of mycelial density with only the thin outer layer consisting of a dense mycelial network. The performance of the recombinant strain and the process of pellet formation was also analyzed during batch cultivation in a stirred-tank bioreactor. It was shown that the process of pellet formation occurred in two steps: (1) aggregation of free spores to spore clusters with subsequent germination and formation of small aggregates surrounded by a loose hyphal network, and (2) aggregation of the primary aggregates to the final full-size pellets. The fungal pellets formed during bioreactor cultivation were smaller, did not show large differences in mycelial density, and were more efficient with respect to the production of exocellular GOD. The decreasing pellet size also correlated with an increased mycelial density, indicating an improvement of the transport of nutrients to the inner parts of the pellet.

Index Entries

Aspergillus niger recombinant strain glucose oxidase protein excretion fungal morphology 

References

  1. 1.
    Kopetzki, E., Lehnert, K., and Buckel, P. (1994), Clin. Chem. 40, 688–704.Google Scholar
  2. 2.
    Ruttloff, H. (1994), in Industrielle Enzyme, 2nd ed., Ruttloff, H., ed., Behr’s Verlag, Hamburg, Germany, pp. 843–855.Google Scholar
  3. 3.
    Bucke, C. (1983), in Microbial Enzymes and Biotechnology, Fogarty, W. M., ed., Applied Science Publishers, London, pp. 93–129.Google Scholar
  4. 4.
    Foster, K. A., Frackman, S., and Jolly, J. F. (1995), in Biotechnology, 2nd ed., vol. 9, Rehm, H. J. and Reed, G., eds., VCH, Weinheim, Germany, pp. 73–120.Google Scholar
  5. 5.
    Hellmuth, K., Pluschkell, S., Jung, J.-K., Ruttkowski, E., and Rinas, U. (1995), Appl. Microbiol. Biotechnol. 43, 978–984.CrossRefGoogle Scholar
  6. 6.
    Pluschkell, S., Hellmuth, K., and Rinas, U. (1996), Biotechnol. Bioeng. 51, 215–220.CrossRefGoogle Scholar
  7. 7.
    Archer, D. B., MacKenzie, D. A., and Ridout, M. J. (1995), Appl. Microbiol. Biotechnol. 44, 157–160.Google Scholar
  8. 8.
    Wittler, R., Baumgartl, H., Lübbers, D. W., and Schügerl, K. (1986), Biotechnol. Bioeng. 28, 1024–1036.CrossRefGoogle Scholar
  9. 9.
    Hotop, S., Möller, J., Niehoff, J., and Schügerl, K. (1993), Process Biochem. 28, 99–104.CrossRefGoogle Scholar
  10. 10.
    Elmayergi, H., Scharer, J. M., and Moo-Young, M. (1973), Biotechnol. Bioeng. 15, 845–859.CrossRefGoogle Scholar
  11. 11.
    Galbraith, J. C. and Smith, J. E. (1969), Trans. Br. Mycol. Soc. 52, 237–246.CrossRefGoogle Scholar
  12. 12.
    Prosser, J. I. and Tough, A. J. (1991), Crit. Rev. Biotechnol. 10, 253–274.Google Scholar
  13. 13.
    Franke, W., Eichhorn, G., Möchel, L., and Bertram, I. (1963), Arch. Mikrobiol. 46, 96–116.CrossRefGoogle Scholar

Copyright information

© Humana Press Inc. 1999

Authors and Affiliations

  • Hesham El-Enshasy
    • 1
  • Karsten Hellmuth
    • 1
  • Ursula Rinas
    • 1
  1. 1.GBF National Research Center for BiotechnologyBiochemical Engineering DivisionBraunschweigGermany

Personalised recommendations