World Journal of Microbiology and Biotechnology

, Volume 16, Issue 8, pp 853–858

Effects of temperature, water activity and gas atmosphere on mycelial growth of tempe fungi Rhizopus microsporus var. microsporus and R. microsporus var. oligosporus

Authors

  • Bei-Zhong Han
    • Laboratory of Food Microbiology, Department of Agrotechnology and Food SciencesWageningen University
    • College of Food Science and EngineeringChina Agricultural University
  • Robert M.J. Nout
    • Laboratory of Food Microbiology, Department of Agrotechnology and Food SciencesWageningen University
Article

DOI: 10.1023/A:1008974621698

Cite this article as:
Han, B. & Nout, R.M. World Journal of Microbiology and Biotechnology (2000) 16: 853. doi:10.1023/A:1008974621698

Abstract

Rhizopus microsporus var. microsporus and var. oligosporus are used in the manufacture of various Asian fermented foods (tempe, black oncom, sufu). In view of solid-substrate fermentation (SSF) control, mycelial growth of strains of both varieties was tested for sensitivity to fluctuations of temperature, water activity and interstitial gas composition. This was achieved by measuring radial growth as well as biomass dry weight of pre-germinated microcolonies on defined media. The optimum conditions were temperature 40 °C, aw 0.995 and a gas composition of air for the growth of both strains on a model medium. Whereas radial growth rates of var. microsporus and var. oligosporus were similar, biomass growth rates of var. oligosporus were higher than those of var. microsporus under optimum conditions. The temperature-dependent growth of Rhizopus spp. at aw > 0.98 could be described by the Ratkowsky Equation. Carbon dioxide (5–10% v/v) inhibited the growth of Rhizopus spp. at non-limiting levels of oxygen. The two strains were able to grow at low (0.5% v/v) oxygen levels, but the mycelial density was rather low. No interrelation of water activity and gas composition was observed, but at high water activity the fungi were more sensitive to changes of temperature. The implications for process control are discussed.

CarbondioxidefungioxygenRhizopussolid-substrate fermentation SSFtempe modellingtemperaturewater activity

Copyright information

© Kluwer Academic Publishers 2000