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Characterization of a newly isolated <i>Rubrivivax benzoatilyticus</i> PS-5 with self-flocculation property and optimization pathway for 5-aminolevulinic acid production


Supalak Sattayasamitsathit
Poonsuk Prasertsan

Abstract

Six strains of phototrophic purple non-sulfur bacteria were isolated from paddy soil, lake water and pond sediment samples. They showed the ability to produce 5-aminolevulinic acid under anaerobic-light (3,000 lux) condition. A selected strain, designated as PS-5, produced the highest 5-aminolevulinic acid (ALA) concentration (45.10 μM) and productivity (0.94 μ M h-1) in glutamate-malate (GM) medium as well as possessed self-flocculating ability. Based on physiological and 16S rRNA sequence, the isolate PS-5 was identified to be Rubrivivax benzoatilyticus. The optimum concentration of C4 pathway precursors was 7.5 mM glycine and 10 mM succinate with supplementation of 10 mM levulinic acid. This resulted in 4.2 fold increase of 5-aminolevulinic acid production to 190.74 μM and 2.7-fold increase of its productivity to 2.57 μM h-1 compared to the control. In addition, the optimum concentration of C5 pathway precursor was 50 mM glutamate with the maximum 5-aminolevulinic acid production of 84.12 μM and productivity of 1.56 μM h-1. Therefore, R. benzoatilyticus PS-5 could produce 5-aminolevulinic acid using both C4 and C5 pathway precursors and preferred C4 pathway over C5 pathway as it produced more than 2.3 folds higher 5-aminolevulinic acid concentration.

Keywords: 5-Aminolevulinic acid, photosynthetic bacteria, self-flocculation, optimization, Rubrivivax benzoatilyticus

African Journal of Biotechnology Vol. 12(16), pp. 2069-2081

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