Open AccessGrowth and indole‐3‐acetic acid biosynthesis of Azospirillum brasilense Sp245 is environmentally controlled
Author(s) -
Ona Ositadinma,
Impe Jan,
Prinsen Els,
Vanderleyden Jos
Publication year - 2005
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1016/j.femsle.2005.03.048
Subject(s) - azospirillum brasilense , fed batch culture , biosynthesis , tryptophan , biochemistry , pyruvate decarboxylase , indole 3 acetic acid , bioreactor , chemistry , biology , fermentation , enzyme , bacteria , food science , microbial inoculant , botany , gene , auxin , amino acid , alcohol dehydrogenase , genetics
Abstract Batch and fed batch cultures of Azospirillum brasilense Sp245 were conducted in a bioreactor. Growth response, IAA biosynthesis and the expression of the ipdC gene were monitored in relation to the environmental conditions (temperature, availability of a carbon source and aeration). A. brasilense can grow and produce IAA in batch cultures between 20 and 38 °C in a standard minimal medium (MMAB) containing 2.5 g l −1 l ‐malate and 50 μg ml −1 tryptophan. IAA synthesis requires depletion of the carbon source from the growth medium in batch culture, causing growth arrest. No significant amount of IAA can be detected in a fed batch culture. Varying the concentration of tryptophan in batch experiments has an effect on both growth and IAA synthesis. Finally we confirmed that aerobic growth inhibits IAA synthesis. The obtained profile for IAA synthesis coincides with the expression of the indole‐3‐pyruvate decarboxylase gene ( ipdC ), encoding a key enzyme in the IAA biosynthesis of A. brasilense .