Purification and characterization extracellular antimicrobial substances of Pseudomonas aeruginosa
| Autor: | Chang-Yi Kuo, 郭章一 |
|---|---|
| Rok vydání: | 2008 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 96 In recent years, because the antibiotic is abused which result in antibiotic resistant strain appearances. Acinetobacter baumannii is the most serious among all antibiotic resistant strain, due to its Pandrug-Resistant A. baumannii. When the patients were infected with A. baumannii would usually induce bacteremia, pneumonia, tracheobronchitis, respiratory failure and sepsis, the pneumonia is the most deadly one. In view of this, we hope to find the resolution that is non-antibiotic to treat for the overflowing of A. baumannii. Generally speaking, the bacterium will produce inhibiting substance. The inhibiting substances are antimicrobial agents and can kill the bacterial about the homologous species. But it doesn’t affect other bacteria. The inhibiting substance, bacteriocin, is different from antibiotic. Bacteriocin is a protein that is produced by Gran-positive or Gram-negative bacteria. Antibiotic is a organic compounds that is produced by fungi. Bacteriocin has a narrow inhibitory spectrum that compares with antibiotic. But it’s a practical way to treat antibiotic resistant strain infection. From our previous study, we discover Pseudomonas aeruginosa which isolate from hospital sample has 584 strains, but only 28 strains of P. aeruginosa could lyse A. baumannii. From these 28 antagonistic strains, the P. aeruginosa 076 that have better lytic for A. baumannii was chosen for further study. In this study, We observe the form in which P. aeruginosa 076 lyse A. baumannii. The result show P. aeruginosa 076 can cause the lysis zone to A. baumannii in third days. The secretion substance of P. aeruginosa 076 is collected, and find that it will cause the lysis zone to A. baumannii. The P. aeruginosa 076 was incubated with LB broth and shaken with 200 rpm on 37℃, after 72 hrs the supernatant was collected and was concentrated precipitation by 40-60% partition of ammonia sulfate. This product is named Bacteriocin-like substance (BLS). By the spot test, BLS showed lytic ability by forming the lysis zone (23 mm) on the soft agar contained A. baumannii. Because the BLS was sensitive to proteinase K (100 ng/ml) which indicate that BLS is protein. After BLS dealing with NaCl of different concentration the best activation of BLS occurs at 150 mM NaCl. The best concentration of BLS for inhibiting A. baumannii growth in LB broth was 400 AU/ml and the bacterium was totally lyse. Because BLS has half inhibit efficacy declined when incubating in 75℃ water bath suppose BLS is a heat-labile protein. From the MTT assay for cytotoxic tests, the concentration of 500 AU/ml of crude extract was still nontoxic to cells. The effective substance of BLS belongs to the ClassⅢ bacteriocin. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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