초록
<P>Biodiesel, a renewable fuel produced by transesterification of animal fats and vegetable oils, generates about 10% (v/v) of crude glycerol as a core byproduct. The high volume of this non bio-degradable glycerol is becoming of a great environmental and economical concern due to its worldwide ever-growing surplus. Herein we report a high production of 2,3-butanediol (2,3-BD) from pure and biodiesel derived crude glycerol using a mutant <I>K. pneumoniae</I> SRM2 obtained from a newly isolated strain <I>Klebsiella pneumoniae</I> SRP2. The mutant strain SRM2 with standing high glycerol concentration (220 g L<SUP>-1</SUP> of medium) could rapidly convert glycerol aerobically to 2,3-BD, a versatile product extensively used in chemical, pharmaceutical and fuel industries Our study revealed that an increased GDH activity led to a substantially enhanced production of 2,3-BD. The mutant strain exhibited 1.3-fold higher activity of GDH than that of parent strain (500.08 vs. 638.6 µmol min <SUP>-1</SUP> mg <SUP>-1</SUP> protein), yielding of 32.3 g L<SUP>-1</SUP> and 77.5 g L<SUP>-1</SUP> 2,3-BD with glycerol in batch and fed-batch process respectively. However, in batch culture with crude glycerol, cell growth and glycerol consumption were expressively boosted, and 2,3-BD production was 27.7 g L<SUP>-1</SUP> from 75.0 g/L crude glycerol. In this report, the optimal conditions for high production of 2,3-BD were defined in a completely aerobic process, and 0.59 g g<SUP>-1</SUP> product yield of 2,3-BD was attained by the mutated strain <I>K. pneumoniae </I>SRM2, which is the highest amount obtained from batch biotransformation process of glycerol metabolism till today. These results indicated that our newly developed mutant can tolerate high concentration of glycerol, have a high glycerol utilization rate, and high product yield of 2,3-BD. It is demonstrated that the mutant strain <I>K. pneumoniae</I> SRM2 has an ability to produce fewer co-products at trace concentrations at higher glycerol concentrations, and could be a potential candidate for 2,3-DB production in an industrial bioconversion process.</P>