(A) study on factors involved in protoplast formation of rhodotorula species

Abstract

The available growth substrates are limited to Rhodotorula glutinis which is an important source organism of single cell oil (SCO). The extension of growth substrate spectrum in this organism can be aided by protoplast fusion technique. The first step of protoplast fusion is protoplast formation from intact cell, and several factors that affected the protoplast formation were examined. Protoplast formation was performed with lytic enzyme mixture of F-5 culture broth after pretreatment of thiol compounds. For increasing the protoplast yield, it is better to select maltose or lactose as a sole carbon source in nitrogen-limited conditions. The higher the degree of lysis was to be obtained, the lower cell concentration was. Exponential phase of the culture are sensitive to lysis while stationary phase yeasts are resistant. Dithiothreitol(DTT) was much more powerful than 2-mercaptoethanol. Higher the concentration of DTT was, higher the degree of lysis was observed. Snail enzyme had no affect cell lysis in Rhodotorula species. Among the carbon substrates selected to induce lytic enzyme, Autolyzed-Washed Yeast (AWY) gave more excellent production than other carbon sources. The lytic activity appeared in the medium in the early stationary phase of F-5 fungal growth, and the highest activity was observed in the culture on the 1.5 day and then the activity decreased rather rapidly.