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 mM) and productivity (0.94 mM 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 mM and 2.7-fold increase of its productivity to 2.57 mM h-1 compared to the control. In addition, the optimum concentration of C5pathway precursor was 50 mM glutamate with the maximum 5-aminolevulinic acid production of 84.12 mM and productivity of 1.56 mM h-1. Therefore, R. benzoatilyticusPS-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. Key words: 5-Aminolevulinic acid, photosynthetic bacteria, self-flocculation, optimization, Rubrivivax benzoatilyticus.
Highlights
Photosynthetic bacteria (PSB) are gram-negative prokaryotes that convert light energy into chemical energy by the process of anoxygenic photosynthesis.They contain photosynthetic pigments, bacteriochlorophylls and carotenoids, and can grow autotrophically with CO2 as the sole carbon sourceAbbreviations: aminolevulinic acid (ALA), 5-Aminolevulinic acid; GM, glutamatemalate.(Pfennig, 1969)
Thirty (30) samples collected from paddy soil, lake, and pond sediment mud were enriched in the Rhodospirillum medium (RM) medium and incubated under anaerobic-light (3,000 lux) condition for growth of photosynthetic bacteria
The RM medium contained high malate that could enhance the growth of photosynthetic bacteria as malate is a photosynthetic reductant that plays a critical role in the noncyclic photophosphorylation of Rhodospirillum rubrum (Stenn, 1968)
Summary
Photosynthetic bacteria (PSB) are gram-negative prokaryotes that convert light energy into chemical energy by the process of anoxygenic photosynthesis.They contain photosynthetic pigments, bacteriochlorophylls and carotenoids, and can grow autotrophically with CO2 as the sole carbon source(Pfennig, 1969). Photosynthetic bacteria (PSB) are gram-negative prokaryotes that convert light energy into chemical energy by the process of anoxygenic photosynthesis. They contain photosynthetic pigments, bacteriochlorophylls and carotenoids, and can grow autotrophically with CO2 as the sole carbon source. PSB has been used for production of 5aminolevulinic acid commercially with various applications, such as function as a natural photodynamic compound effective as a biodegradable herbicide, growth-promoting factor and a stress tolerance enhancer for plants (Tanaka et al, 1992).
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