Dissertation > Industrial Technology > Light industry,handicrafts > Paper Industry > Basic theory > Pulp and chemical

Screening, Bio-Characteristics and Biopulping Application of a High Pectin-Degrading Baeterial Strain by Ultraviolet-Ray Mutation

Author XieWei
Tutor XuLangLai
School Nanjing Agricultural College
Course Biochemistry and Molecular Biology
Keywords Ultraviolet ray mutation Pectobacterium carotovorum subsp. carotovorum Pectin Alkalophilic endo-polygalacturonase Biodegradation of pectin Bark of Broussonetia papyrifera (L)
Type Master's thesis
Year 2011
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In the process of papermaking, the pectin must be removed from raw materials, so that the Cellulose can to be decentralized, which is a very important step.This paper first studied domestieating and screening highly effective pectin degradation strains from rotting cabbage leaves, the variation strain has been obtained by the technique of UV—induced which has the special degeneration function under high PH to pectin. Then we examined the optimization of biodegradation conditions and explore the mechanism of the conditions include pH value, temperature, shaker rotation, illumination, concentration of dextrose, quantity of bacterial consortium, etc.A bacterial strain 1 was isolated from rotting cabbage leaves, which could grow with pectin as the sole source of carbon and energy. The molecular structure of the microorganism deoxyribo nucleieacid (DNA) form the thy mine diatomic bodies by the ultravioletray illumination, creates the duplication mistake, causes the gene mutation, Use ultraviolet——ray irradiate strain 1, from the ultraviolet-ray illumination time and the lethality effect curve confirm the best illumination time is 50s. After inducement obtain three Positive mutationstrains (M2, M3, M4), the strain 1 can degrade pectin and the biodegradation rates was 30.4%, the strain M2 degenerationrate were highest, had achieved 78.1%, which is over 47.7% higher than that. Simuitaneously the preponderant strain M2 cultivatel.5 h to enter the logarithm vegetal period, after llh the mycelium arrived the biggest growth quantity, OD600 had achieved 0.581, showed that strain M2 is the best superiority strain, the pectin degeneration greatly enhanced. The colony of 1 and M2 are bottle yellow on the solid culture medium or beef extract, because the bacterial strains 1 and M2 are able to produce water—solubility Pigment.The examination of cell growth and degradation characteristics of strain M2 was conducted in the further studies. The results showed that the strain M2 could highly degrade pectin (the initial concentration was 25mg/L,82.1% of pectin were degraded) in pH 10.0, at 30℃and 120r/min shaking speed, under the illumination and added 10% (volume Percent) bacterial inoculated, and adding 0.2g/L glucose could greatly enhanced degrading efficiency, the biodegradation rate of strain M2 was above 78.1%.

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