English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

SUMMARY: A method for isolating and identifying high acid-yielding mutants of Aspergillus niger is described. This involves cultivation of the organisms on absorbent paper soaked in an indicator medium. The advantages of the technique and the criteria used for selecting biochemically interesting mutants are briefly described. The greater acid production of mutants selected by paper culture has been confirmed by comparing yields of citric acid in surface and submerged fermentations with those given by the wild type strain. The selection of acid-producing fungi described by Foster & Davis (1949) and modified by Quilico, Panizzi & Visconti (1949) has been used frequently for iso- lating fungi showing marked differences in acid production. Their methods of cultivation on indicator media are unsatisfactory for selection of colonies which produce large amounts of acid because of the extensive diffusion of the acid zones around the colonies. With such strains large quantities of media are required since each colony to be screened would have to be tested on a separate agar plate, and there is no simple means of determining whether such colonies arise from one or more spores. METHODS The irradiation techniques used, and a description of the mutant strains isolated by the technique to be described, are given in the following paper (Gardner, James & Rubbo, 1956).

Isolation of High Acid-yielding Mutants of Aspergillus niger by a Paper Culture Selection Technique