Characterisation and purification of bacterial lysates containing poly-γ-glutamic acid

Pearson, Benjamin (2015). Characterisation and purification of bacterial lysates containing poly-γ-glutamic acid. University of Birmingham. M.Res.


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\(Bacillus\) \(spp\). and other bacteria produce poly-γ-glutamic acid (PγGA), a polymer with many applications; these are briefly reviewed. As PγGA is produced biosynthetically, its price depends on the efficiency of synthesis and extraction.
This study altered the broth in cultures of \(Bacillus\) \(subtillis\) natto subspecies to determine whether manganese or NaCl concentration affected the chemical properties or yield of products precipitated and purified from culture. It also compared 2 methods of PγGA purification (using ethanol and copper solutions) published for extraction of PγGA from \(Bacillus\) \(licheniformis\).
NMR spectroscopy showed that samples contained PγGA and impurities which couldn’t be removed following purification. Analysis of this impurity showed that it was carbohydrate composed of 1,2-linked hexose monosaccharides and was likely to be larger than PγGA. Addition of Mn2+ increased the ratio of PγGA to impurity after purification and NaCl likely decreased the size of PγGA.
These findings also suggest that current techniques for purifying PγGA are sometimes inadequate and 1H NMR experiments may be a more effective method to prove the absence of carbohydrate than other methods quoted in the literature to assess PγGA purity. The identification of carbohydrate subunits may identify novel methods of PγGA purification.

Type of Work: Thesis (Masters by Research > M.Res.)
Award Type: Masters by Research > M.Res.
College/Faculty: Colleges (2008 onwards) > College of Engineering & Physical Sciences
School or Department: School of Metallurgy and Materials
Funders: None/not applicable
Subjects: T Technology > TN Mining engineering. Metallurgy


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