Screening of IAA Production on the Interaction of Microalgae and Bacteria in the Glagah Consortium

Betty Rahmawati^1, Miftahul ‘Ilmi¹, Arief Budiman^2,3and Eko Agus Suyono^1,3*

¹Department of Tropical Biology, Faculty of Biology, Universitas Gadjah Mada, Yogyakarta, 55281, Indonesia.

²Chemical Engineering Department, Gadjah Mada University, Jalan Grafika No. 2 Yogyakarta 55281, Indonesia

³Centre for Energi Studies, Universitas Gadjah Mada, Yogyakarta, 55281, Indonesia.

Corresponding Author E-mail: eko_suyono@ugm.ac.id

DOI : http://dx.doi.org/10.13005/bbra/2808

ABSTRACT: The Glagah Consortium is a mixed culture of microalgae and bacteria isolated from Glagah Beach, Yogyakarta. Microalgae and bacteria in the consortium interact with each other. There is an assumed Bacillus bacterium that can produce IAA in the Glagah Consortium. Tryptophan is one of the precursors in IAA biosynthesis. L-tryptophan and antibiotics were given to the Glagah consortium culture medium to determine the role of bacteria in producing IAA. This research used BBM medium by giving three variations of L-tryptophan concentration, namely 0; 0,02; and 0.2 g L^-1. Each concentration is given antibiotics Vancomycin and Gentamycin for 100 ppm and 25 ppm. Quantification of IAA by using Salkowski reagents and calculated IAA concentrations with a spectrophotometer. Each treatment consisted of three replications. The other parameters tested were the number of microalgae cells, dry weight, cell productivity, biomass productivity and lipid productivity. The results in this research shows that IAA in all samples with the highest concentration on the second day of observation, they are 0.420 ± µg mL^-1; 0.681 µg mL^-1; 1,725 ​​µg mL^-1; 0.261 µg mL^-1; 0.565 µg mL^-1; and 0.667 µg mL^-1. The giving of L-tryptophan in the Glagah consortium culture can increase IAA concentrations, specific growth rates, biomass and lipids. Besides that, the  giving of antibiotics led to lower productivity of cells, biomass and lipids of the Glagah consortium.

KEYWORDS: Antibiotic; Glagah Consortium; Interaction; IAA;  L-Tryptophan

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