Formation of sclerotia and production of indoloterpenes by Aspergillus niger and other species in section Nigri.

Jens C. Frisvad,E. Kirstine Lyhne,Thomas O. Larsen,Lene M. Petersen,Kevin McCluskey

doi:10.1371/journal.pone.0094857

Jens C. Frisvad, E. Kirstine Lyhne + Show 3 more

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https://doi.org/10.1371/journal.pone.0094857

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Journal: PloS one	Publication Date: Apr 15, 2014
Citations: 56	License type: CC BY 4.0

Affiliation: Technical University of Denmark

Abstract

Several species in Aspergillus section Nigri have been reported to produce sclerotia on well-known growth media, such as Czapek yeast autolysate (CYA) agar, with sclerotia considered to be an important prerequisite for sexual development. However Aspergillus niger sensu stricto has not been reported to produce sclerotia, and is thought to be a purely asexual organism. Here we report, for the first time, the production of sclerotia by certain strains of Aspergillus niger when grown on CYA agar with raisins, or on other fruits or on rice. Up to 11 apolar indoloterpenes of the aflavinine type were detected by liquid chromatography and diode array and mass spectrometric detection where sclerotia were formed, including 10,23-dihydro-24,25-dehydroaflavinine. Sclerotium induction can thus be a way of inducing the production of new secondary metabolites from previously silent gene clusters. Cultivation of other species of the black aspergilli showed that raisins induced sclerotium formation by A. brasiliensis, A. floridensis A. ibericus, A. luchuensis, A. neoniger, A. trinidadensis and A. saccharolyticus for the first time.

Highlights

Certain strains in several species of Aspergillus section Nigri have been reported to produce sclerotia, notably Aspergillus sclerotioniger, A. carbonarius, A. tubingensis, A. sclerotiicarbonarius, A. costaricaensis, A. ellipticus, A. japonicus, A. piperis, A. aculeatus, A. aculeatinus, A. brunneoviolaceus and A. violaceofuscus [1,2,3,4,5,6,7,8,9]
During identification the strains were inoculated on malt extract agar according to Blakeslee (MEA), yeast extract sucrose (YES) agar, creatine-sucrose (CREA) agar, oat-meal agar (OA), and some isolates were inoculated on Wickerhams antibiotic test medium (WATM), and potato dextrose agar (PDA)
A. niger IBT 29019 and IBT 24631 produced sclerotia on a medium made with dark Californian raisins added to the medium

Summary

Introduction

Certain strains in several species of Aspergillus section Nigri have been reported to produce sclerotia, notably Aspergillus sclerotioniger, A. carbonarius, A. tubingensis, A. sclerotiicarbonarius, A. costaricaensis, A. ellipticus, A. japonicus, A. piperis, A. aculeatus, A. aculeatinus, A. brunneoviolaceus and A. violaceofuscus [1,2,3,4,5,6,7,8,9]. Concerning Aspergillus niger, only a few strains have been reported to produce sclerotia, WB 346 [1,11,12], WB 5121 = CBS 553.65 [1], CBS 425.65 [3] and WB 4700 [13] These strains represent other species than Aspergillus niger sensu stricto, for example CBS 553.65 was allocated to Aspergillus costaricanesis by Samson et al [6] and WB 346 is representative of Sterigmatocystis fusca Bain., regarded as Aspergillus carbonarius [3], CBS 425.65 is an A. tubingensis [14] and WB 4700 is an A. tubingensis [13]. Sclerotium-producing strains from Tubingen and other German cities, identified as A. niger [15], are probably A. tubingensis

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