Further thermotolerant fungi for the conversion of cassava starch to protein

Abstract

Fungi capable of growing with cassava starch at 50°C and 55°C at pH 3.5 were sought from 687 soil samples. The higher selection temperature favored the isolation of fungi with high (> 44%) crude protein content. From the 139 cultures isolated, the 20 highest-protein cultures were assessed for yield in a cassava-based medium, growth rates at 45°C, 50°C and 55°C, and content of α-amino nitrogen and methionine. The seven cultures judged to have greatest potential for the high-temperature, nonaseptic production of protein-rich animal feed were used in rat-feeding trials. Mycelia from two cultures, Cephalosporium eichhorniae 152 and Rhizopus chinensis 180, gave protein efficiency ratios and net protein ratios which equaled or exceeded those given by casein when all diets contained 10% “true” protein and were supplemented with methionine.