ABSTRACT
Cyclodextrins are a family of cyclic oligosaccharides typically containing six, seven, or eight 1,4-linked d-glucose units. Because the glucose units adopt the chair conformation, the cyclodextrins are shaped like a hollow truncated cone with a hydrophilic outer surface, which makes them water-soluble. All three cyclodextrins have similar structures, apart from the structural necessities of accommodating a different number of glucose units. The truncated cone-shaped cyclodextrin molecules are stiffened by hydrogen bonding between the 3-OH and 2-OH groups around the wider rim. The hydrophobic fluorescent probe NPN was used as an indicator of outer membrane integrity. NPN has a low fluorescence quantum yield in aqueous solution but fluoresces strongly in the hydrophobic environment of a biological membrane. The yield of recombinant protein production depends on both the biomass concentration as well as the specific cellular productivity. Nitrogen is the critical medium component for bacteria growth and production performance.
