Studies on Aspergillus oryzae Mutants for the Production of Single Cell Proteins from Deoiled Rice Bran
Rudravaram Ravinder1, Linga Venkateshwar Rao1 and Pogaku Ravindra2*
1Department of Microbiology, Osmania University, Hyderabad 500 007, India
2University College of Technology, Osmania University, Hyderabad 500 007, India
Article history:
Received: November 4, 2002
Accepted: June 9, 2003
Key words:
solid state fermentation, mutants screening, deoiled rice bran, single cell protein, Aspergillus oryzae (MTCC 1846), Shan1, Shan2 and Shan3 mutants
Summary:
Ethyl methyl sulphonate was used to induce point mutation in Aspergillus oryzae (MTCC 1846). Incubation with ethyl methyl sulphonate for 1 h resulted in 98 % killing of spores. By screening the survived colonies three hypermorphs were found (Shan1, Shan2 and Shan3). These three mutants along with the A. oryzae (MTCC 1846) were used for the production of single cell proteins. They grew profusely on deoiled rice bran and produced higher percentage of protein. Among the three mutants Shan2 had higher protein content in the pH range of 3–7 and temperatures 36–45 °C, maintaining low quantities of nucleic acids. The specific growth rate of Shan2 was higher on the media containing substrates like glucose, maltose and cellulose. Shan2 had higher content of amino acids when compared with FAO standard and A. oryzae (MTCC 1846), but the amino acid content of Shan2 was approximately equal to that of soyabean meal. The comparative protein content of Shan2 and A. oryzae (MTCC 1846) was 57 and 43 %, respectively, while their nucleic acid content was 3 and 7.2 %, respectively. Protein enrichment of 18.9 % in Shan2 resulted from the cultivation on deoiled rice bran as compared to protein content of the A. oryzae (MTCC1846) indicating that Shan2 possessed good amenability for SCP production.
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