Growth and protease secretion of Scedosporium aurantiacum under conditions of hypoxia

Zhiping Han, Liisa Kautto, Wieland Meyer, Sharon C.-A. Chen, Helena Nevalainen

Research output: Contribution to journalArticleResearchpeer-review

Abstract

One of the micro-environmental stresses that fungal pathogens, such as Scedosporium aurantiacum, colonising human lungs encounter in vivo is hypoxia, or deficiency of oxygen. In this work, we studied the impacts of a hypoxic micro-environment (oxygen levels ≤1%) on the growth of a clinical S. aurantiacum isolate (WM 06.482; CBS 136046) and an environmental strain (S. aurantiacum WM 10.136; CBS 136049) on mucin-containing synthetic cystic fibrosis sputum medium. Additionally, profiles of secreted proteases were compared between the two isolates and protease activity was assessed using class-specific substrates and inhibitors. Overall, both isolates grew slower and produced less biomass under hypoxia compared to normoxic conditions. The pH of the medium decreased to 4.0 over the cultivation time, indicating that S. aurantiacum released acidic compounds into the medium. Accordingly, secreted proteases of the two isolates were dominated by acidic proteases, including aspartic and cysteine proteases, with optimal protease activity at pH 4.0 and 6.0 respectively. The clinical isolate produced higher aspartic and cysteine protease activities. Conversely, all serine proteases, including elastase-like, trypsin-like, chymotrypsin-like and subtilisin-like proteases had higher activities in the environmental isolate. Sequence similarities to 13 secreted proteases were identified by mass spectrometry (MS) by searching against other fungal proteases in the NCBI database. Results from MS analysis were consistent with those from activity assays. The clinical highly-virulent, and environmental low-virulence S. aurantiacum isolates responded differently to hypoxia in terms of the type of proteases secreted, which may reflect their different virulence properties.

LanguageEnglish
Pages23-29
Number of pages7
JournalMicrobiological Research
Volume216
DOIs
Publication statusPublished - Nov 2018

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Scedosporium
Peptide Hydrolases
Growth
Cysteine Proteases
Virulence
Mass Spectrometry
Hypoxia
Subtilisin
Pancreatic Elastase
Serine Proteases
Mucins
Sputum
Cystic Fibrosis
Biomass
Databases
Oxygen

Cite this

Han, Zhiping ; Kautto, Liisa ; Meyer, Wieland ; Chen, Sharon C.-A. ; Nevalainen, Helena. / Growth and protease secretion of Scedosporium aurantiacum under conditions of hypoxia. In: Microbiological Research. 2018 ; Vol. 216. pp. 23-29.
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abstract = "One of the micro-environmental stresses that fungal pathogens, such as Scedosporium aurantiacum, colonising human lungs encounter in vivo is hypoxia, or deficiency of oxygen. In this work, we studied the impacts of a hypoxic micro-environment (oxygen levels ≤1{\%}) on the growth of a clinical S. aurantiacum isolate (WM 06.482; CBS 136046) and an environmental strain (S. aurantiacum WM 10.136; CBS 136049) on mucin-containing synthetic cystic fibrosis sputum medium. Additionally, profiles of secreted proteases were compared between the two isolates and protease activity was assessed using class-specific substrates and inhibitors. Overall, both isolates grew slower and produced less biomass under hypoxia compared to normoxic conditions. The pH of the medium decreased to 4.0 over the cultivation time, indicating that S. aurantiacum released acidic compounds into the medium. Accordingly, secreted proteases of the two isolates were dominated by acidic proteases, including aspartic and cysteine proteases, with optimal protease activity at pH 4.0 and 6.0 respectively. The clinical isolate produced higher aspartic and cysteine protease activities. Conversely, all serine proteases, including elastase-like, trypsin-like, chymotrypsin-like and subtilisin-like proteases had higher activities in the environmental isolate. Sequence similarities to 13 secreted proteases were identified by mass spectrometry (MS) by searching against other fungal proteases in the NCBI database. Results from MS analysis were consistent with those from activity assays. The clinical highly-virulent, and environmental low-virulence S. aurantiacum isolates responded differently to hypoxia in terms of the type of proteases secreted, which may reflect their different virulence properties.",
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Growth and protease secretion of Scedosporium aurantiacum under conditions of hypoxia. / Han, Zhiping; Kautto, Liisa; Meyer, Wieland; Chen, Sharon C.-A.; Nevalainen, Helena.

In: Microbiological Research, Vol. 216, 11.2018, p. 23-29.

Research output: Contribution to journalArticleResearchpeer-review

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