Production of the Phytohormone Indole-3-Acetic Acid by Estuarine Species of the Genus Vibrio

Abstract

Strains of Vibrio spp. isolated from roots of the estuarine grasses Spartina alterniflora and Juncus roemerianus produce the phytohormone indole-3-acetic acid (IAA). The colorimetric Salkowski assay was used for initial screening of IAA production. Gas chromatography-mass spectroscopy (GC-MS) was then employed to confirm and quantify IAA production. The accuracy of IAA quantification by the Salkowski assay was examined by comparison to GC-MS assay values. Indole-3-acetamide, an intermediate in IAA biosynthesis by the indole-3-acetamide pathway, was also identified by GC-MS. Multilocus sequence typing of concatenated 16S rRNA, recA, and rpoA genes was used for phylogenetic analysis of environmental isolates within the genus Vibrio. Eight Vibrio type strains and five additional species-level clades containing a total of 16 environmental isolates and representing five presumptive new species were identified as IAA-producing Vibrio species. Six additional environmental isolates similar to four of the Vibrio type strains were also IAA producers. To our knowledge, this is the first report of IAA production by species of the genus Vibrio or by bacteria isolated from an estuarine environment.

Salt and alkali stresses reduction in wheat by plant growth promoting haloalkaliphilic bacteria

“…glycerol was added to 20 ml of fresh liquid medium of each isolates and after thorough mixing, one milliliter part of it was transferred to 1.5 ml Eppendorf Plant growth promoting characteristics including, the concentration of ammonia by the modified Nesslerization method (Heonsang et al, 2013), 3-indole acetic acid concentration in the isolates and their replicates by the modified Salkowski method (Glickmann and Dessaux, 1995;Gutierrez et al, 2009) …”

In Vitro Production of Growth Regulator (IAA) and Phosphatase by Phosphate Solubilizing Bacteria

“…IAA production was determined following the method described by Gutierrez et al (2009). Bacterial strains grown in sterilized 100 ml liquid NBRIP medium containing 1 ml of 0.2% tryptophan were incubated for 48 hours with continuous shaking at 30°C.…”

Molecular Characterization of Stress Tolerant Plant Growth Promoting Rhizobacteria (PGPR) for Growth Enhancement of Rice

“…Indole-3-Acetic Acid (IAA) Production IAA produced by PGPR isolates was determined in the presence or absence of L-tryptophan by using Nutrient Both (NB, Difco TM )) and Salkowski colorimetric assay (Gutierrez et al, 2009). All PGPR isolates were grown NB on an incubator shaker (150 rpm) at room temperature (28ºC ± 2) for 24 h. After 24 h, 1 mL of bacterial culture were inoculated into 100 mL of sterile NB amended with 5 mL Ltryptophan and without L-tryptophan solution for 48 h. To determine the amount of IAA produced from the isolates, 1.5 mL of aliquot was sampled and centrifuged at 12,000 rpm for 5 min.…”