Indole-3-acetic acid from filamentous cyanobacteria: screening, strain identification and production

Abstract

This study presents Filamentous cyanobacterial isolates for their ability to produce phytohormone indole-3-acetic acid (IAA) by Salkowski’s colorimetric assay method. Among 15 isolates screened, two of them produced auxin-like secretions significantly in BG11/ ASN III media containing 4 mg/ml of tryptophan. Based on 16S rDNA sequence analysis, strains that produce maximum IAA were most closely related to <i>Geitlerinema </i>sp. (99.0% similarity) and <i>Leptolyngbya </i>sp. (95.0% similarity). IAA production was maximum (51.06 μg/ml) when strain <i>Leptolyngbya </i>sp. was cultivated in BG11 media at pH 9.0, whereas <i>Geitlerinema </i>sp. produced a maximum of 67.87 μg/ml in ASN III media at pH 9.0 in 14 days of incubation. This is the first report of IAA production by <i>Geitlerinema </i>sp. and <i>Leptolyngbya </i>sp.