Charlie Ester de Fretes ¹, Ria Suryani ¹, Yekti Asih Purwestri ¹, Tri Rini Nuringtyas ¹, Donny Widianto ¹

Affiliations
1 Research Center for Biotechnology, Universitas Gadjah Mada, Jl. Teknika Utara, Barek, Yogyakarta, 55281, ID

Abstract

Objectives: To isolate endophytic bacteria of sweet sorghum cv. FS501 adapted to two locations in Bunder and Mulo, Indonesia and characterize their properties including fixing nitrogen, solubilizing phosphate, and producing (Indole -3-Acetic Acid)IAA. Methods/Statistical Analysis: The bacteria were isolated from ischolar_mains, stems, and shoots and followed by repetitive element PCR (rep-PCR) for endophyte determination. The 16S rRNA genes amplifications were sequenced using ABI Prism 3730. Sequence’s similarity was evaluated using BLAST then analyzed with MEGA 5.0. Bacteria properties including nitrogen-fixation ability, dissolving phosphate and IAA production was performed in a semisolid LGI medium, Pikovskaya media and colorimetric method, respectively. Findings: Forty-eight isolates of endophytic bacteria were isolated from ischolar_mains, stems, and shoots of sweet sorghum. The rep-PCR resulted the isolated bacteria belonged to 23 groups consisted of 9 isolates from Bunder and 14 isolates from Mulo. Sequences from the 23 isolates were determined and aligned with those of reference strains in GenBank. BLAST analysis indicated that the isolated endophytic bacteria belonged to 10 different genera: Beijerinckia, Ralstonia, Microbacterium, Curtobacterium, Brevibacterium, Leifsonia, Bacillus, Staphylococcus, Lysinibacillus, and Fictibacillus. Of the total 23 endophytic bacterial isolates acquired the five diazotrophic isolates were from the genera Beijerinckia, Microbacterium, Curtobacterium, Bacillus, and Staphylococcus; the four isolates capable of dissolving the phosphate from the genera Microbacteriumand Brevibacterium; and nine isolates were able to produce IAA from the genera Microbacterium, Brevibacterium, and Bacillus. Isolates BA3 (Microbacterium testaceum), BA8 (Microbacterium oleivorans), BA14 (Brevibacterium iodinum), and MA24 (Microbacterium arborescens) positive for more than one mechanism promoting plant growth. Application/Improvements: The four isolates having more than one mechanism promoting plant growth would be of commercial interest to biotechnology companies with a goal of producing an inoculant for sweet sorghum cultivars.

Keywords

Endophytic bacteria, sweet sorghum, nitrogen fixation, IAA production, phosphate solubilization

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