Pushpakiran Gullapalli

Direct Production of l-Tagatose from l-Psicose by Enterobacter aerogenes 230S

L-tagatose was produced directly from L-psicose by subjecting the same biomass suspension to microbial reduction followed by oxidation using a newly isolated bacteria Enterobacter aerogenes 230S. After various optimizations, it was observed that cells grown on xylitol have the best conversion potential. Moreover, E. aerogenes 230S converted L-psicose to L-tagatose at a faster rate in the presence of polyols such as glycerol, D-sorbitol, ribitol, L-arabitol, D-mannitol and xylitol. At 5% substrate concentration, the conversion ratio of L-psicose to L-tagatose was above 60% in the presence of glycerol. Identity of crystalline L-tagatose was confirmed by HPLC analysis, (13)C-NMR spectra, and optical rotation.

Bioproduction of D-Psicose from Allitol with Enterobacter aerogenes IK7: A New Frontier in Rare Ketose Production

D-Psicose, a new alternative sweetener, was produced from allitol by microbial oxidation of the newly isolated strain Enterobacter aerogenes IK7. Cells grown in tryptic soy broth medium (TSB) supplemented with D-mannitol at 37 °C were found to have the best oxidation potential. The cells, owing to broad substrate specificity, oxidized various polyols (tetritol, pentitol, and hexitol) to corresponding rare ketoses. By a resting cell reaction, 10% of allitol was completely transformed to the product D-psicose, which thus becomes economically feasible for the mass production of D-psicose. Finally, the product was crystallized and confirmed to be D-psicose by analytical methods.

6-De­oxy-α-l-talopyran­ose

X-ray crystallography showed that the title compound, C6H12O5, crystallizes in the α-pyranose form with the six-membered ring in a chair conformation. The crystal structure exists as a three-dimensional hydrogen-bonded network of molecules with each molecule acting as a donor and aceptor for four hydrogen bonds. The absolute configuration was determined by the use of l-fucose as starting material.

1-De­oxy-l-mannitol (6-de­oxy-l-mannitol or l-rhamnitol)

The crystalline form of 1-deoxy-l-mannitol, C6H14O5, exists as an extensively hydrogen-bonded structure with each molecule acting as a donor and acceptor for five hydrogen bonds. There are no unusual crystal-packing features; the absolute configuration was determined from the use of 6-deoxy-l-mannose (l-rhamnose) as the starting material.