Breeding Of Strains Producing Lycopene And Primary Studies On Metabolism Regulation

Lycopene is a straight-chain hydrocarbon which has 11 conjugated double bonds and two non-conjugated double bonds. As a result, it is capable of quenching singlet oxygen and removing free radicals. The antioxidant capacity of it is as much as two times that ofβ-carotene and 100 times that of vitamin E. That is why people pay more attention to lycopene.This paper focused on the breeding of high-production strain Blakeslea trispora(-) as well as the speciality of the strain. The fermentation condition and the effect of activator of key enzymes on lycopene production of Blakeslea trispora strain(-) were also studied.Higher production strains was selected by mutation breeding. A strain UV-312 with high production of lycopene was selected which was treated with UV. The lycopene production was 22.54% higher than that of the original strain. NA-62 was mutant strain treated with nitrous acid whose production was 31.52% higher than that of the original strain. UN-10 was mutant strain treated by ultraviolet and nitrous acid combination mutation whose production was 59.72% higher than the original strain.The optimum fermentation medium was as follows: corn mea 3.0%, cottonseed meal 4.0%, cottonseed oil 9.0%, KH2PO4 0.3%. The optimum fermentation conditions were as follows: pH 7.5, inoculation size 15%(V/V), medium load amount 20 mL/250 mL shaking flask, temperature 27℃, best proportion of (+),(-) 1:20, culture time 5 days, rotary speeds of shaking flask 180 r/min. Under the optimum conditions, the mycelium of Blakeslea trispora dispersed well, and the yields of mycelium dry weight and lycopene were repectively 73.46 g/L, 1.36 g/L.The width of pigments band formed could predicted the heterothallic, which was closely related to lycopene production. The wider pigments band was, the higher lycopene produced. The addition of soybean lecithin stimulated the formation of pigment. When 0.3% soybean lecithin was added, lycopene yields reached 1.61 g/L which was 21.97% higher than the control. The addition concentrations of sodium acetate and sodium lactate were 0.10 g/L, 0.15 g/L respectively which were the most favorable to the lycopene yields, and the lycopene yields reached 1.56 g/L, 1.45 g/L respectively.Metabolic regulations of lycopene synthesis with metabolic enhancers and blockers were investigated. Alcohol, ampicillin and H2O2 were selected as the metabolic enhancers. When 0.10% alcohol was added at 36 h, the lycopene yields reached 1.64 g/L which was 22.38% higher than the control; When 0.075 g/L ampicillin was added at 24 h, the lycopene yields reached 1.65 g/L which was 24.06% higher than the control. When 0.10% H2O2 was added at 36 h, the lycopene yields reached 1.63 g/L which was 23.48% higher than the control. Imidazole was the best metabolic blocker to theβ-carotene synthesis. When 1.0 g/L imidazole was added at 40 h, the lycopene yields reached 1.62 g/L. When 0.075 g/L ampicillin was added at 24 h, 0.3% soy lecithin and 1.0 g/L linoleic acid were added at 36 h, and 1.0 g/L imidazole was added at 40 h, the lycopene yields reached 1.72 g/L.