1.Pullulan and pullulan derivatives as promising biomolecules for drug and gene targeting.
Singh RS1, Kaur N2, Kennedy JF3. Carbohydr Polym. 2015 Jun 5;123:190-207. doi: 10.1016/j.carbpol.2015.01.032. Epub 2015 Feb 4.
Pullulan is a water soluble exo-polysaccharide produced by yeast like fungus Aureobasidium pullulans. Pullulan structure have a unique characteristic i.e. co-existence of α-(1→4) and α-(1→6) linkages. Pullulan nanoparticle consists of both hydrophobic and hydrophilic characteristics which are due to its unique structure. It can be derivatized via various chemical reactions to increase its utility in the field of pharmaceuticals. Although, various drugs have the potential to become powerful therapeutic medicines, but their safe and targeted delivery to a specific site is a major challenge and rapidly growing area of research. Pullulan-drug conjugates can target infected cells/tissues and exhibit high bioactivity with the release of cytotoxic molecules. The pullulan conjugates can be used for targeted drug delivery as well as targeted gene delivery for the treatment of various diseases in liver, lungs, brain, spleen, etc. In this review, the applications of pullulan and its derivatives in drug and gene targeting are described.
2.Characterization of UGPase from Aureobasidium pullulans NRRL Y-12974 and Application in Enhanced Pullulan Production.
Li H1, Zhang Y2, Gao Y3, Lan Y3, Yin X4, Huang L3. Appl Biochem Biotechnol. 2016 Mar;178(6):1141-53. doi: 10.1007/s12010-015-1934-2. Epub 2015 Nov 27.
UDPG pyrophosphatase (UGPase) plays an important role in carbohydrate metabolism, catalyzing a reversible production of uridine diphosphate glucose (UDPG) and pyrophosphate (PPi) from Glc-1-P and UTP. UGPase gene from Aureobasidium pullulans NRRL Y-12974 was cloned, overexpressed in Escherichia coli. The recombinant UGPase possess molecular mass of 55 KDa and specific activity of 7.33 U/mg protein. The K m values of rUGPase were 5.045 μM against UTP and 3.333 μM against Glc-1-P. The V max values of rUGPase were 3.467 μM min(-1)against UTP and 2.817 μM min(-1) against Glc-1-P. And, it does not catalyze Glc-1-P and ATP, nor galactose-1-P and UTP. Homolgous expression of UGPase in native organism can improve the intracellular UDPG concentration by 4.7-fold time. The yield of pullulan in engineering strain A4 was improved to 18.2 g g(-1) cell dry weight which is 1.3-fold time of parent strain. No obvious change of growth was found between engineering strain and parent strain.
3.Understanding the influence of Tween 80 on pullulan fermentation by Aureobasidium pullulans CGMCC1234.
Sheng L1, Tang G1, Su P1, Zhang J1, Xiao Q2, Tong Q3, Ma M4. Carbohydr Polym. 2016 Jan 20;136:1332-7. doi: 10.1016/j.carbpol.2015.10.058. Epub 2015 Oct 23.
In this paper, several new perspectives concerned with the effect of Tween 80 promoting pullulan production were presented. With the presence of Tween 80, the maximum pullulan yield increased by 41% (53.04 g/L). Meanwhile, the carbon source was consumed faster and the broth viscosity was higher. The lower final pH suggested that Tween 80 could protect the integrity of the mycelia. The dispersed filaments were not easily entangled with each other and less pellets were formed in the Tween 80 culture broth. FT-IR spectrum analysis indicated that the evaluated sample structure was coincided with commercial pullulan. The molecular weight of sample significantly dropped comparing with the control. The above findings indicated that Tween 80 facilitated the uptake of nutrient from surroundings to the microorganism and the release of pullulan into the extracellular fluid. These results were useful in better understanding the regulation and optimization of efficient pullulan fermentation.