Growth behaviour and glucoamylase production by Aspergillus niger N402 and a glucoamylase overproducing transformant in recycling culture without a nitrogen source.
When wild-type Aspergillus niger N402 and a glucoamylase-overproducing transformant were grown in recycling culture without a nitrogen source, hyphal tip extension and glucoamylase production still occurred, but overproduction of glucoamylase by the transformant strain stopped. The mycelium retained a low metabolic activity. Light micrographs of mycelial samples showed that some hyphae were broken at their tip and partially empty, while after continuing recycling fermentation for more than 500 h many small and empty pieces of broken mycelium could be found. A model has been developed to calculate the mycelial growth and death rates. The mycelial death rate just exceeded the mycelial growth rate and as a consequence the amount of biomass in the fermentor vessel slightly decreased. It is concluded that the cytoplasmic contents of broken mycelial threads were released into the medium and acted as a nitrogen source for the growing parts of the mycelium.
Schrickx
J M
JM
Department of Microbiology, Vrije Universiteit, Amsterdam, The Netherlands.
Stouthamer
A H
AH
van Verseveld
H W
HW
D001234:Aspergillus niger / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D005087:Glucan 1,4-alpha-Glucosidase / Q000096:biosynthesis*; D009584:Nitrogen / Q000378:metabolism; D014170:Transformation, Genetic
D005087:Glucan 1,4-alpha-Glucosidase; D009584:Nitrogen