<it>Aspergillus flavus</it> grown in peptone as the carbon source exhibits spore density- and peptone concentration-dependent aflatoxin biosynthesis
<p>Abstract</p> <p>Background</p> <p>Aflatoxins (AFs) are highly carcinogenic compounds produced by <it>Aspergillus</it> species in seeds with high lipid and protein contents. It has been known for over 30 years that peptone is not conducive for AF productio...
Main Authors: | , , , |
---|---|
Format: | Article |
Language: | English |
Published: |
BMC
2012-06-01
|
Series: | BMC Microbiology |
Subjects: | |
Online Access: | http://www.biomedcentral.com/1471-2180/12/106 |
id |
doaj-f689f99fd15147e5803ba2e3d725674a |
---|---|
record_format |
Article |
spelling |
doaj-f689f99fd15147e5803ba2e3d725674a2020-11-24T21:08:44ZengBMCBMC Microbiology1471-21802012-06-0112110610.1186/1471-2180-12-106<it>Aspergillus flavus</it> grown in peptone as the carbon source exhibits spore density- and peptone concentration-dependent aflatoxin biosynthesisYan ShijuanLiang YatingZhang JindanLiu Chun-Ming<p>Abstract</p> <p>Background</p> <p>Aflatoxins (AFs) are highly carcinogenic compounds produced by <it>Aspergillus</it> species in seeds with high lipid and protein contents. It has been known for over 30 years that peptone is not conducive for AF productions, although reasons for this remain unknown.</p> <p>Results</p> <p>In this study, we showed that when <it>Aspergillus flavus</it> was grown in peptone-containing media, higher initial spore densities inhibited AF biosynthesis, but promoted mycelial growth; while in glucose-containing media, more AFs were produced when initial spore densities were increased. This phenomenon was also observed in other AF-producing strains including <it>A. parasiticus</it> and <it>A. nomius</it>. Higher peptone concentrations led to inhibited AF production, even in culture with a low spore density. High peptone concentrations did however promote mycelial growth. Spent medium experiments showed that the inhibited AF production in peptone media was regulated in a cell-autonomous manner. mRNA expression analyses showed that both regulatory and AF biosynthesis genes were repressed in mycelia cultured with high initial spore densities. Metabolomic studies revealed that, in addition to inhibited AF biosynthesis, mycelia grown in peptone media with a high initial spore density showed suppressed fatty acid biosynthesis, reduced tricarboxylic acid (TCA) cycle intermediates, and increased pentose phosphate pathway products. Additions of TCA cycle intermediates had no effect on AF biosynthesis, suggesting the inhibited AF biosynthesis was not caused by depleted TCA cycle intermediates.</p> <p>Conclusions</p> <p>We here demonstrate that <it>Aspergillus</it> species grown in media with peptone as the sole carbon source are able to sense their own population densities and peptone concentrations to switch between rapid growth and AF production. This switching ability may offer <it>Aspergillus</it> species a competition advantage in natural ecosystems, producing AFs only when self-population is low and food is scarce.</p> http://www.biomedcentral.com/1471-2180/12/106<it>A. flavus</it><it>A. parasiticus</it><it>A. nomius</it>PeptoneAflatoxin biosynthesisDensity effect |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Yan Shijuan Liang Yating Zhang Jindan Liu Chun-Ming |
spellingShingle |
Yan Shijuan Liang Yating Zhang Jindan Liu Chun-Ming <it>Aspergillus flavus</it> grown in peptone as the carbon source exhibits spore density- and peptone concentration-dependent aflatoxin biosynthesis BMC Microbiology <it>A. flavus</it> <it>A. parasiticus</it> <it>A. nomius</it> Peptone Aflatoxin biosynthesis Density effect |
author_facet |
Yan Shijuan Liang Yating Zhang Jindan Liu Chun-Ming |
author_sort |
Yan Shijuan |
title |
<it>Aspergillus flavus</it> grown in peptone as the carbon source exhibits spore density- and peptone concentration-dependent aflatoxin biosynthesis |
title_short |
<it>Aspergillus flavus</it> grown in peptone as the carbon source exhibits spore density- and peptone concentration-dependent aflatoxin biosynthesis |
title_full |
<it>Aspergillus flavus</it> grown in peptone as the carbon source exhibits spore density- and peptone concentration-dependent aflatoxin biosynthesis |
title_fullStr |
<it>Aspergillus flavus</it> grown in peptone as the carbon source exhibits spore density- and peptone concentration-dependent aflatoxin biosynthesis |
title_full_unstemmed |
<it>Aspergillus flavus</it> grown in peptone as the carbon source exhibits spore density- and peptone concentration-dependent aflatoxin biosynthesis |
title_sort |
<it>aspergillus flavus</it> grown in peptone as the carbon source exhibits spore density- and peptone concentration-dependent aflatoxin biosynthesis |
publisher |
BMC |
series |
BMC Microbiology |
issn |
1471-2180 |
publishDate |
2012-06-01 |
description |
<p>Abstract</p> <p>Background</p> <p>Aflatoxins (AFs) are highly carcinogenic compounds produced by <it>Aspergillus</it> species in seeds with high lipid and protein contents. It has been known for over 30 years that peptone is not conducive for AF productions, although reasons for this remain unknown.</p> <p>Results</p> <p>In this study, we showed that when <it>Aspergillus flavus</it> was grown in peptone-containing media, higher initial spore densities inhibited AF biosynthesis, but promoted mycelial growth; while in glucose-containing media, more AFs were produced when initial spore densities were increased. This phenomenon was also observed in other AF-producing strains including <it>A. parasiticus</it> and <it>A. nomius</it>. Higher peptone concentrations led to inhibited AF production, even in culture with a low spore density. High peptone concentrations did however promote mycelial growth. Spent medium experiments showed that the inhibited AF production in peptone media was regulated in a cell-autonomous manner. mRNA expression analyses showed that both regulatory and AF biosynthesis genes were repressed in mycelia cultured with high initial spore densities. Metabolomic studies revealed that, in addition to inhibited AF biosynthesis, mycelia grown in peptone media with a high initial spore density showed suppressed fatty acid biosynthesis, reduced tricarboxylic acid (TCA) cycle intermediates, and increased pentose phosphate pathway products. Additions of TCA cycle intermediates had no effect on AF biosynthesis, suggesting the inhibited AF biosynthesis was not caused by depleted TCA cycle intermediates.</p> <p>Conclusions</p> <p>We here demonstrate that <it>Aspergillus</it> species grown in media with peptone as the sole carbon source are able to sense their own population densities and peptone concentrations to switch between rapid growth and AF production. This switching ability may offer <it>Aspergillus</it> species a competition advantage in natural ecosystems, producing AFs only when self-population is low and food is scarce.</p> |
topic |
<it>A. flavus</it> <it>A. parasiticus</it> <it>A. nomius</it> Peptone Aflatoxin biosynthesis Density effect |
url |
http://www.biomedcentral.com/1471-2180/12/106 |
work_keys_str_mv |
AT yanshijuan itaspergillusflavusitgrowninpeptoneasthecarbonsourceexhibitssporedensityandpeptoneconcentrationdependentaflatoxinbiosynthesis AT liangyating itaspergillusflavusitgrowninpeptoneasthecarbonsourceexhibitssporedensityandpeptoneconcentrationdependentaflatoxinbiosynthesis AT zhangjindan itaspergillusflavusitgrowninpeptoneasthecarbonsourceexhibitssporedensityandpeptoneconcentrationdependentaflatoxinbiosynthesis AT liuchunming itaspergillusflavusitgrowninpeptoneasthecarbonsourceexhibitssporedensityandpeptoneconcentrationdependentaflatoxinbiosynthesis |
_version_ |
1716759650516336640 |