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Aspergillus flavus grown in peptone as the carbon source exhibits... » Isaúde
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BMC microbiology [electronic resource]
2012-06-14 03:38:41

Aspergillus flavus grown in peptone as the carbon source exhibits spore density- and peptone concentration-dependent aflatoxin biosynthesis

Descrição: Background:Aflatoxins are highly carcinogenic compounds produced by Aspergillus 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, with reasons unknown.Results:In this study, we showed that when Aspergillus flavus was grown in glucose-containing media, higher initial spore density or higher concentration of peptone promoted both mycelium growth and AF productions, while in peptone-containing media, higher initial spore densities or higher peptone concentrations inhibited AF biosynthesis. Spent medium experiments showed that the inhibited AF productions were regulated in a cell-autonomous manner. Further experiments showed that increased concentrations of peptone inhibited the low density-dependent AF productions but promoted mycelium growth. Expression analyses showed that both regulatory and AF biosynthesis genes were repressed in mycelia cultured with the high initial spore density. Metabolomic studies revealed that, in addition to inhibited AF biosynthesis, mycelia cultured in peptone media with the higher initial spore density showed suppressed fatty acid biosynthesis, while tricarboxylic acid cycle and pentose phosphate pathways were enhanced.Conclusions:We demonstrated that Aspergillus flavus grown in media with peptone as the sole carbon source was able to sense the population density and the peptone concentration to switch between rapid growths and AF productions. Such a highly regulated metabolic switch between rapid growth and AF production may offer Aspergillus flavus a competition advantage in natural ecosystems.

Identificador: doi:10.1186/1471-2180-12-106
Volume: 0
Página: 1 a


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