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- doi: 10.3390/microorganisms10020221
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Natural variation and the role of Zn2Cys6 transcription factors SdrA, WarA and WarB in sorbic acid resistance of aspergillus niger
overcome this weak-acid stress by inducing cellular responses mediated by transcription factors. In our
research, a large-scale sorbic acid resistance screening was performed on 100 A. niger sensu stricto strains isolated fromvarious sources to study strain variability in sorbic acid resistance. Theminimal inhibitory concentration of undissociated (MICu) sorbic acid at pH = 4 in the MEB of the A. niger strains varies between 4.0 mMand 7.0 mM, with the average out of 100 strains being 4.8 0.8 mM, when scored after 28 days. MICu valueswere roughly 1mMlowerwhen tested in commercial ice tea. Genome sequencing
of the most sorbic-acid-sensitive strain among the isolates revealed a premature stop codon inside the
sorbic acid response regulator encoding gene sdrA. Repairing this missense mutation increased the
sorbic acid resistance, showing that the sorbic-acid-sensitive...Show moreWeak acids, such as sorbic acid, are used as chemical food preservatives by the industry. Fungi
overcome this weak-acid stress by inducing cellular responses mediated by transcription factors. In our
research, a large-scale sorbic acid resistance screening was performed on 100 A. niger sensu stricto strains isolated fromvarious sources to study strain variability in sorbic acid resistance. Theminimal inhibitory concentration of undissociated (MICu) sorbic acid at pH = 4 in the MEB of the A. niger strains varies between 4.0 mMand 7.0 mM, with the average out of 100 strains being 4.8 0.8 mM, when scored after 28 days. MICu valueswere roughly 1mMlowerwhen tested in commercial ice tea. Genome sequencing
of the most sorbic-acid-sensitive strain among the isolates revealed a premature stop codon inside the
sorbic acid response regulator encoding gene sdrA. Repairing this missense mutation increased the
sorbic acid resistance, showing that the sorbic-acid-sensitive phenotype of this strain is caused by the
loss of SdrA function. To identify additional transcription factors involved in weak-acid resistance,
a transcription factor knock-out library consisting of 240 A. niger deletion strains was screened. The
screen identified a novel transcription factor,WarB, which contributes to the resistance against a broad
range of weak acids, including sorbic acid. The roles of SdrA,WarA andWarB in weak-acid resistance,
including sorbic acid, were compared by creating single, double and the triple knock-out strains. All
three transcription factors were found to have an additive effect on the sorbic acid stress response.Show less
- All authors
- Seekles, S.J.; Dam, J. van; Arentshorst, M.; Ram, A.F.J.
- Date
- 2022-01-20
- Journal
- Microorganisms
- Volume
- 10
- Issue
- 2
- Pages
- 221