Abstract
The use of tidal land for agricultural still faces constraints, mainly due to high iron content. Actinobacteria produce bioactive compound with many functions. The aim of this work was to assess the growth of actinobacteria at various iron concentrations and its capability as plant growth promoter. Four actinobacteria isolates (Cal31t, Dbi28t, Crc32t and Cal24h) were grown at various iron concentrations. The isolates were examined for their capability to produce IAA and fix N2 under in vitro assay. The growth of actinobacteria under stress conditions was examined by cultivating them in ISP2 medium at pH 4, 3% NaCl, 750 mg.L−1 AlCl3 and 8 concentrations of FeCl3, i.e. 0, 500, 1000, 2000, 4000, 8000, 16000, 32000 mg.L−1. Actinobacteria isolates were able to grow under iron stress condition up to 32.000 mg.L−1. Both Cal3t and Dbi28t produced higher cell biomass compared with the other two tested isolates. All isolates produced IAA when grown under iron stress condition up to 4000 mg.L−1 of FeCl3, were able to grow under N-free medium and capable to produce ammonia at various concentrations. Crc32t produced the highest number of ammonia (0,354 mg.L−1). Cal31t and Crc32t isolates have the potency as plant growth promoter in tidal land farming.