Autolytic enzymes are responsible for increased melanization of carbon stressed Aspergillus nidulans cultures

Melinda Szilágyi, Fruzsina Anton, I. Pócsi, T. Emri

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Melanization of carbon stressed Aspergillus nidulans cultures were studied. Melanin production showed strong positive correlation with the activity of the secreted chitinase and ß-1,3-glucanase. Deletion of either chiB encoding an autolytic endochitinase or engA encoding an autolytic ß-1,3-endoglucanase, or both, almost completely prevented melanization of carbon stressed cultures. In contrast, addition of Trichoderma lyticase to cultures induced melanin production. Synthetic melanin could efficiently inhibit the purified ChiB chitinase activity. It could also efficiently decrease the intensity of hyphal fragmentation and pellet disorganization in Trichoderma lyticase treated cultures. Glyphosate, an inhibitor of L-3,4-dihydroxyphenylalanine-type melanin synthesis, could prevent melanization of carbon-starved cultures and enhanced pellet disorganization, while pyroquilon, a 1,8-dihydroxynaphthalene-type melanin synthesis inhibitor, enhanced melanization, and prevented pellet disorganization. We concluded that cell wall stress induced by autolytic cell wall hydrolases was responsible for melanization of carbon-starved cultures. The produced melanin can shield the living cells but may not inhibit the degradation and reutilization of cell wall materials of dead hyphae. Controlling the activity of autolytic hydrolase production can be an efficient approach to prevent unwanted melanization in the fermentation industry, while applying melanin synthesis inhibitors can decrease the resistance of pathogenic fungi against the chitinases produced by the host organism.

Original languageEnglish
Pages (from-to)440-447
Number of pages8
JournalJournal of Basic Microbiology
Volume58
Issue number5
DOIs
Publication statusPublished - May 1 2018

Fingerprint

Aspergillus nidulans
Melanins
Chitinases
Carbon
Enzymes
Cell Wall
Trichoderma
glyphosate
Hydrolases
Hyphae
Cellulase
Levodopa
Fermentation
Industry
Fungi

Keywords

  • Aspergillus nidulans
  • cell wall stress
  • ChiB chitinase
  • melanization

ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology

Cite this

Autolytic enzymes are responsible for increased melanization of carbon stressed Aspergillus nidulans cultures. / Szilágyi, Melinda; Anton, Fruzsina; Pócsi, I.; Emri, T.

In: Journal of Basic Microbiology, Vol. 58, No. 5, 01.05.2018, p. 440-447.

Research output: Contribution to journalArticle

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