Study On Production Of 5-Aminolevulinic Acid From Industrial Organic Waster Water With Photosynthetic Bacteria

5-Aminolevulinic acid (ALA) can be used as a non-pollution herbicide, insecticide, photodynamic agent, antimicrobial drug, and accelerant of plant growth. Microbial production of ALA may be expected to become commercially viable because of simple process and high production, so it is attended by researchers and enterprises. In this work, ALA production from organic wastewater by photosynthetic bacteria was studied. Seven high ALA production photosynthetic bacteria stains were screened out from 36 photosynthetic bacteria strains isolated from various environments. The ALA production of strain 99-28, which was up to 3.145mg/L in GM culture, was the highest. By morphologic, physiologic and biochemistry test, this strain was idenfified as purple nonsulphur Rhodopseudomonas sp. The optimal growth condition of strain 99-28 was pH 7.5, 3000 Lux of illumination intensity and 0.2% yeast extraction. Rhodopseudomonas sp 99-28 strain was mutated by ultraviolet radiation and a mutant strain L-1, which ALA production was higher than wild strain 99-28 about one time was obtained. The optimal ALA production condition of strain L-l was pH 7.5, 3000 Lux of illumination intensity and 10% (vlv) of inoculate quantity. ALA production of L-l was up to 7.266 mg/L in this condition. Glycine and succinate was ALA precursor in tetrapyrrole biosynthesis pathway, levulinic acid (LA) was a competitive inhibitor of ALA dehydratase (ALAD). Experimental results indicated: glycin was necessary precursor of ALA synthesis, while succinate was not; supply of LA could significantly increase ALA production, the optimal supply time was 48 h after cultured under light, supplying 3 times could almost get the best effect. In GM medium, pH 7.5, 3000 lv Lux, 0.2% yeast extract, supply of 30 mmol/L LA, 30 mmol/L glycine and 30 mmol/L succinate in 48 h after cultured under light, ALA production of strain 99-28 was 9.154 mg/L, that of strain L-1 was up to 22.15 mg/L. Incubated 120 h, strain 99-28 CODer removal efficiency of monosodium glutamate wastewater was 93.5%, ALA production was 2.578 mg/L; CODcr removal efficiency of succotash wastewater was 94.8%, ALA production was 1 .428mg/L; CODcr removal efficiency of brewage wastewater was 92.4%, ALA production wasl .651 mg/L; CODcr removal efficiency of citric acid wastewater was 73.5%, ALA production was 2.029 mg/L. When LA, glycin and succinate were supplied, ALA production of strain 99-28 after 96 h were: monosodium glutamate wastewater, 3.488 mg/L; succotash wastewater, 2.45 8 mg/L; brewage wastewater, 2.097 mg/L; citric acid wastewater, 2.801 mg/L, which was significantly higher than no supply of LA, glycin and succinate. However, after LA, glycin and succinate were supplied, CODcr could hardly be removed. In monosodium glutamate wastewater, the optimal ALA production condition of strain L-1 was: pH 7.5. innculate quanlity 10%(v/v), light 3000Lux. Incubated 120 h, strain L-1 CODcr removal efficiency of monosodium glutamate wastewater was 91.6%, ALA production was 2.8 19 mg/L; CODcr removal efficiency of succotash wastewater was 91.8%, ALA production was 1.531 mg/L; CODcr removal efficiency of brewage wastewater was 91.5%, ALA production was2. 166 mg/L; CODer removal efficiency of citric acid wastewater was 73.4%, ALA production was 2.424 mg/L. When LA, glycin and succinate were supplied, ALA production of strain L-1 after...