Abstract
In order to study the stability of a recombinant strain of T.reesei
expressing tissue plasminogen activator (t-PA), the recombinant strain 306/36
(with t-PA under the control of the native cbhl promoter) and its parent
strain (Rut-C30) were grown in chemostat cultures at a dilution rate of 0.05
h--1 in lactose limited chemostats and the secreted levels of recombinant t-PA
and native cellulases determined.
It was found, that t-PA and native cellulase production by the recombinant
strain 306/36 was not stable with morphological mutants displacing the
parental strain. This displacement was correlated with a loss in native
cellulase and t-PA secretion. Strain Rut-C30 yielded similar morphological
mutants, but their appearance was not correlated with a loss of native
cellulase production and some mutants at the end of the cultivation even
showed enhanced cellulase secretion.
Isolated mutants were grown in batch cultivation and the cellulase and t-PA
levels compared to parental strain 306/36 and wild type Rut-C30.
All mutant isolates derived from the recombinant strain 306/36 showed severe
reduction in their ability to secrete native cellulases and t-PA production
was virtually undetectable, although Southern blotting revealed no apparent
loss in gene copy numbers of the t-PA::cbh1 construct.
The reduction may be well due to the fact, that recombinant protein production
challenges the fungal secretion machinery to an extent that favours mutants
in which recombinant protein production is suppressed. As both t-PA and native
cellulase are down-regulated, we are investigating the potential role of the
transcriptional regulators of the cellulase genes, ACEI and ACE II.
Original language | English |
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Title of host publication | Poster Abstracts |
Pages | 189 |
Publication status | Published - 2004 |
Event | 7th European Conference on Fungal Genetics - Copenhagen, Denmark Duration: 17 Apr 2004 → 20 Apr 2004 |
Conference
Conference | 7th European Conference on Fungal Genetics |
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Country/Territory | Denmark |
City | Copenhagen |
Period | 17/04/04 → 20/04/04 |