SELECTION AND ISOLATION OF GLUCOSE-TOLERANT AMYLOLYTIC ASPERGILLUS BY CYCLIC FED BATCH CULTURE PROCESS.

Abstract

A simple cyclic fed batch culture system was developed for selection and subsequent isolation of glucose-tolerant Aspergillus niger strain. A culture medium which contained 1. 2 g dm** minus **3 of glucose was inoculated with a non-glucose-tolerant A. niger (K//i equals 20. 25 g dm** minus **3). A culture medium of higher glucose concentration (100 g dm** minus **3 and 200 g dm** minus **3) was fed at a rate equal to the rate of HN//4** plus consumption by means of a pH control system. The maximum and minimum liquid levels in the fed batch culture vessel were determined by two liquid level detectors which activated and deactivated a harvest pump. The novelty of the selection system is that the frequency and pressure of selection increase gradually but continuously, and they are determined by the intrinsic potential of the culture.