Dissertation > Excellent graduate degree dissertation topics show

Breeding and Characterization of High-Yield L-Lactic Acid Producing Bacteria by Microwave Irradiation

Author: ZhangXing
Tutor: WangPeng
School: Harbin Institute of Technology
Course: Environmental Science and Engineering
Keywords: microwave irradiation mutagenic effects L-lattic acid Lactobacillus case AFM
CLC: Q93
Type: Master's thesis
Year: 2007
Downloads: 208
Quote: 2
Read: Download Dissertation

Abstract


Lactate is one of the three major organic acids, widely used in the fields of food, pharmaceutical, chemical, leather, textiles industries etc. Biodegradable polylactide products are being of concern as a result of the serious white forth pollution caused by the white thermoplastic products. It is focused on a strain of Lactobacillus rhamnosus in this paper, by which the L-lactic acid produced has optimal purity and meets the requirements of industrial production.The mutagenesis of Lactobacillus rhamnosus was carried out by the continuous low-power microwave irradiation exploded by a power-adjustable breeding equipment, which has the cooling water cycle to offset the heat of the microwave. Under the microwave power of 400W and irradiation length of 3min, the survival rate of Lactobacillus rhamnosus was 24.1% and the mutagenic effects were good. Three mutant strains W4-3-9, W4-3-28 and W2-3-7 of genetic stability and high-yield L-lactic acid were found by screening, the L-lattic acid production of which were 115.1g/L, 114.8g/L and 114.1g/L, respectively. Comparing with the parent mutant, the improvement of L-lactic acid produced were up to 56.2%、56.6% and 55.7%.It was indicated that some different microbial morphology, physiological biochemical characters and molecular biological aspects existed after microwave radiation between the parent strains and the mutant ones, of which the individual colonies became smaller, the transparent zone was larger and the thickness of colonies became thinner. Also the mutants were easy to assemble and some oil-like substance appeared on the surface of the colonies. The differences of physiological and biochemical characteristics between the parent and mutant strains caused by the microwave radiation mainly manifested in the appearance of gram-negative bacteria and some mutants which can’t utilize cellobiose and esculoside. The parent and mutant images of surface morphology and AFM of DNA were observed through the atomic force microscopy for the first time. It provided technical support and theoretical basis for further study of the effect of microwave irradiation on Lactobacillus rhamnosus and the innovation of mutation techniques. And it was firmly showed that microwave irradiation had induced mutation by comparing amplified fragment length polymorphism (AFLP) fingerprints of DNA of the parent strain and the mutant one.

Related Dissertations

  1. α- aminoalkyl phosphonates Green Synthesis of,O627.51
  2. Low Energy N ~ ion implantation mutagenesis Impatiens mutant tissue culture and mutagenesis Mechanism,S681.1
  3. ATO zeolite microwave synthesis and hydroisomerization of n-decane Performance,TQ424.25
  4. APTES and protein A -based joint immobilization technology hepatitis B virus immunization sensitive film for biosensor research,TP212.3
  5. Condensation of DNA Caused by PAMAM and Photodetachment of H~- Near the Metal Surfaces,Q523
  6. AFM Observation of Collapse and Expansion in Collagen Fibrils Network of Dentin Treated with Different Echants/primers,R781.2
  7. Synthesis and Characterization of Hexabromocyclotriphosphazene,O634.51
  8. The Activation Study of Unburned Coal Gangue by Microwave Radiation in Yunnan,TU528.041
  9. Synthesis of Nanomaterials and Its Application in Analytical Chemistry,O651
  10. Synthesis and Application of Titanium Silicate-1 Films,O614.411
  11. Effect of Collagenase and Its Inhibitors on the Durability of Dentin Bond,R781.2
  12. Research of the Surface Structure of Tumor Cell Membrane on AFM,R730.2
  13. Modeling and Experiments of Interactive Forces in AFM Nanomanipulation,TB383.1
  14. Experimental Research of Machining Large-scale Micro-Nano Polymer Structrues Based on AFM,TB383.1
  15. The Self-Assembled Structure Study of Thiophene Compounds,O626.12
  16. Structure and Morphology of the LB Films of Homo-PS and PS/PS-b-PEO Blends,O631.3
  17. Design of a Laser Force Measuring System for AFM Nanotweezer,TH744.5
  18. The Fabrication of Spherical AFM Tip and Experimental Research of Mechanical Properties of Cancer Cells,R73-36
  19. Study of Structure and Composition of Human Dentine After Er,Cr:YSGG Laser Irradiation,R781.2
  20. Study of Nano-mechanical Characterization of Chip Formation Using Atomic Force Microscopy,TG501
  21. Mechanism of Film Formation of Acrylic Core-Shell Latex,TQ630.1

CLC: > Biological Sciences > Microbiology
© 2012 www.DissertationTopic.Net  Mobile