The utility of a fungal bibonuclease for reducing the nucleic acid content of permeabilized yeast cells

Summary

The main drawback of yeast biomass as a source of protein for human consumption is its high nucleic acid content. The present study deals with the development of a process for reducing the nucleic acid content of strains of Saccharomyces cerevisiae, Candida utilis, C.tropicalis and C.lipolytica by treating with an RNase of Aspergillus candidus strain Ml6a. The cells were permeabilised either by heat‐treatment at 95°C for 5 min. or by treatment with chloroform for 6h followed by a heat treatment at 65°C for 3 min. The former pretreatment was sufficient for C. utilis and C.tropicalis strains whereas S.cerevisiae required the latter treatment. The optimum conditions for the enzymatic treatment were a pH of 4.5–5.0, temperature of 45–55°C, incubation period of 60–90 min and an enzyme to cell ratio of 1:6,000 (w/v). Crude enzyme preparations showed a better activity than the pure enzyme. Under optimal conditions 80–85% of the total nucleic acid could be removed from yeast cells by the enzymatic treatment without any significant concomitant loss of protein.

Notes

died on 9th June 1992