Process development and simulation of glucose isomerase production from birchwood xylan by a Streptomycetes fusant

Abstract

A process for glucose isomerase production from an unutilized substrate, xylan, was investigated, employing strain development, investigation of the culture conditions, and an expedient simulation method. Streptomyces sp. strain D3 obtained through protoplast fusion between Streptomyces cyaneus 190-1 and Streptomyces greiseoruber 42-9 was able to produce a substantial amount of intracellular glucose isomerase from xylan. The induction of glucose isomerase synthesis by xylose was confirmed in shaken flask cultivation. In fermentor cultivation, an initial concentration of 8 g l −1 xylan yielded glucose isomerase, 1100 U l −1. Taking into account the experimental data, a simplified model for the simulation of glucose isomerase production from xylan substrate was constructed based on a statistical regression method. The data selection for the estimation of the specific rates in the regression model was carried out based on the culture time and statistical distance measurement, such as Euclidean, Mahalanobis and modified distances. The results of the simulation of the growth and enzyme production using the model were close to the experimental results, which indicates that the statistical method can be extended to estimate the time courses of process of glucose isomerase production from xylan reasonably well.