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Production, purification and characterization of antibacterial biomolecules from an alkaliphilic Bacillus

Danesh, Abolghasem LU (2011)
Abstract (Swedish)
Popular Abstract in English

As there is a demand for new antibacterial agents due to antimicrobial resistance, the ability of one kind of microorganisms to produce antimicrobial substances has been evaluated. Then, after determining the antibacterial-producer microorganism, the production of active compound in large scale, followed by optimization the conditions investigated. Next, the bioactive agent purified and identified with some scientific methods. Finally, the improvement effect of separated-active compound in combination with one usual antibiotic called chloramphenicol determined. Fortunately, there is a promising prospective of this combination to overcome the antimicrobial resistance problem.
Abstract
Forty alkaliphiles, which were isolated from samples collected in Eastern Africa, have been screened for production of antibacterial compounds. One of these isolates, Bacillus halodurans B20, was able to produce a prominent amount of antibacterial activity against a Gram-positive bacteria on agar plates [paper I] and selected for further study.

Production of the active compound in submerged cultivation by B. halodurans B20 was not successful. However, Solid State Fermentation (SSF) turned out to be the best alternative for production of the antibacterial substance [paper I]. Optimization of the production conditions for antibacterial compound revealed that the production was stimulated by addition of Mg2SO4 and K2HPO4. The... (More)
Forty alkaliphiles, which were isolated from samples collected in Eastern Africa, have been screened for production of antibacterial compounds. One of these isolates, Bacillus halodurans B20, was able to produce a prominent amount of antibacterial activity against a Gram-positive bacteria on agar plates [paper I] and selected for further study.

Production of the active compound in submerged cultivation by B. halodurans B20 was not successful. However, Solid State Fermentation (SSF) turned out to be the best alternative for production of the antibacterial substance [paper I]. Optimization of the production conditions for antibacterial compound revealed that the production was stimulated by addition of Mg2SO4 and K2HPO4. The highest production was achieved at a wheat bran/moisture ratio of 1:1.8 and in the presence of 10% (w/w) Na2CO3 [paper II].

The active substance was purified using hydrophobic interaction chromatography. Mass spectrometer (MS) and tandem MS/MS analysis showed that the purified bioactive compound was composed of two peptides with molecular mass of about 3043 and 2330 Da. The size of the peptides and the strain suggest that the bacteriocin belongs to the two-component lantibiotics of haloduracin type [paper I]. Its antibacterial effect against clinically important pathogens has been studied alone or in combination with chloramphenicol. A synergistic effect of the haloduracin and chloramphenicol has been observed against strains of Staphylococcus aureus, Enterococcus faecium, Enterococcus faecalis and different groups of Streoptococcus [paper III].

In addition, another bacterial metabolite was purified from the solid state culture of B. halodurans 20 using ion exchange chromatography column. The purified compound has shown antibacterial activity only against Gram-positive bacteria. The compound is proposed to be a phenyl fatty acid derivative [paper IV]. However, further study is necessary to determine the exact structure of this compound. (Less)
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author
supervisor
opponent
  • Professor Nes, Ingolf, Norvegian University of Life Sciences (UMB), Norway
organization
publishing date
type
Thesis
publication status
published
subject
pages
136 pages
defense location
Lecture hall C, Kemicentrum, Getingev├Ągen 60, Lund University Faculty of Engineering
defense date
2011-12-16 10:30
ISBN
978-91-89627-78-9
language
English
LU publication?
yes
id
cde31ba7-3f93-452f-82b8-48036e8c49a8 (old id 2213035)
date added to LUP
2011-11-23 10:03:00
date last changed
2016-09-19 08:45:17
@misc{cde31ba7-3f93-452f-82b8-48036e8c49a8,
  abstract     = {Forty alkaliphiles, which were isolated from samples collected in Eastern Africa, have been screened for production of antibacterial compounds. One of these isolates, Bacillus halodurans B20, was able to produce a prominent amount of antibacterial activity against a Gram-positive bacteria on agar plates [paper I] and selected for further study. <br/><br>
Production of the active compound in submerged cultivation by B. halodurans B20 was not successful. However, Solid State Fermentation (SSF) turned out to be the best alternative for production of the antibacterial substance [paper I]. Optimization of the production conditions for antibacterial compound revealed that the production was stimulated by addition of Mg2SO4 and K2HPO4. The highest production was achieved at a wheat bran/moisture ratio of 1:1.8 and in the presence of 10% (w/w) Na2CO3 [paper II]. <br/><br>
The active substance was purified using hydrophobic interaction chromatography. Mass spectrometer (MS) and tandem MS/MS analysis showed that the purified bioactive compound was composed of two peptides with molecular mass of about 3043 and 2330 Da. The size of the peptides and the strain suggest that the bacteriocin belongs to the two-component lantibiotics of haloduracin type [paper I]. Its antibacterial effect against clinically important pathogens has been studied alone or in combination with chloramphenicol. A synergistic effect of the haloduracin and chloramphenicol has been observed against strains of Staphylococcus aureus, Enterococcus faecium, Enterococcus faecalis and different groups of Streoptococcus [paper III].<br/><br>
In addition, another bacterial metabolite was purified from the solid state culture of B. halodurans 20 using ion exchange chromatography column. The purified compound has shown antibacterial activity only against Gram-positive bacteria. The compound is proposed to be a phenyl fatty acid derivative [paper IV]. However, further study is necessary to determine the exact structure of this compound.},
  author       = {Danesh, Abolghasem},
  isbn         = {978-91-89627-78-9},
  language     = {eng},
  pages        = {136},
  title        = {Production, purification and characterization of antibacterial biomolecules from an alkaliphilic Bacillus},
  year         = {2011},
}