Applied Microbiology and Biotechnology

, Volume 30, Issue 2, pp 135-140

First online:

A one-step process for the production of single-cell protein and amyloglucosidase

  • Endang SukaraAffiliated withDepartment of Microbiology, MIRCEN-Biotechnology, University of Queensland
  • , Horst W. DoelleAffiliated withDepartment of Microbiology, MIRCEN-Biotechnology, University of Queensland

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A new Rhizopus species was isolated from traditional Indonesian food, tempeh. The newly isolated species was similar in its morphological characteristics to Rhizopus oligosporus UQM 145F, but grew faster on potato-dextrose agar as well as in submerged culture. The new isolate was found to convert ground cassava tuber directly into single cell protein without pretreatment due to its high amyloglucosidase formation.

From 100 g ground tuber, a dry biomass of 33.75 g containing 26.48% true protein together with 60 ml of highly active amyloglucosidase (282 units) was obtained in 12 h. The amyloglucosidase was recovered by ultrafiltration, releasing 26.226 millimol glucose/l/min from soluble starch. The crude enzyme exhibited a pH optimum between 4.6 and 5.0, a temperature optimum between 55 and 60° C and an apparent Km of 3.125 g/l. High substrate concentrations and ammonium sulphate are inhibitory to the enzyme.