Breeding Of High-yield Polyhydroxybutyrate Mutant Strain

As an endogenetic macromolecular polymer accumulated in microorganism under nutritionalimbalance condition, biocompatible and biodengradable ploy-3--yhydroxybutyrate (PHB) possessessimilar properties to chemical sunthetic plastics, thus could be used as a raw material of biodegradableplastics. The appearance of PHB is white powder, odourless, soluble in chlorinated hydrocarbon,isopropanol and other solvents, insoluble in water, acetone, alcohol, carbinol.In this work, screening high-yielding PHB strains by atmospheric pressure at room temperatureplasma (ARTP) mutagenesis and ultraviolet mutation from field soil, sludges of factory and oil field.Stability analysis of YM-1that high-yielding mutant strain. Compared the yield and morphology in ym-1and YM-1.The results showed that the best time of ARTP mutagenesis was180s and the ultravioletmutation was90s. The mutant strain was longer and bigger than ym-1. Biomass of the mutant increased byabout44.69%, the yield of PHB of the mutant increased by about55.37%compared with the wild.Researched of the content of PHB fluorescence detect system, the conditions of fluorescencedetect and the effect of different EDTA concentration on the test result, then ploted standard curve ofPHB fluorescence detection, discussed the experiment of standard addition and precision experiment, as aresult, established a improve method of PHB fluorospectrophotometry under the conditions of excitationwavelength365nm, maximum emission wavelength647nm, gain8, scanning speed1000nm/min, theconcentration of EDTA was0.02g/L. The mass concentration (C) as abscissa, the fluorescence intensity (F)for the vertical linear regression equation was F=521.27C+40.7795(R2=0.99094), the concentration ofPHB in0.0125~0.1625mg/mL. The average standard addition recoveries was98.29%RSD=0.986%(n=9),the RSD of precision experiment was0.406%(n=5).Factors affecting the PHB production from YM-1were studied. The result showedthat the best carbon source was glucose and the best nitrogen source was (NH4)2SO4.Theoptimal conditions were1%glucose,0.05%(NH4)2SO4,pH7.5for72h. The feedingconditions of PHB fermentation were studied. The result showed that the final yield of PHB production from YM-1was33.56mg/mL, the biomass was49.78mg/mL, the content of PHBwas67.42%.