Title page for ETD etd-53261753976940

Type of Document

Dissertation

Author

Nassif, Lana Amine

Author's Email Address

lnassif@vt.edu

URN

etd-53261753976940

Title

The Production of 2-Keto-L-Gulonic Acid by Different Gluconobacter Strains

Degree

Master of Science

Department

Biology

Advisory Committee

Advisor Name	Title
G. William Claus	chair
Harold M. McNair	none
James F. Wolfe	none
Noel R. Krieg	none

Keywords

mixed culture
sorbose
2-keto-L-gulonic acid
thin layer chromatography
Gluconobacter
high performance liquid chromatography

Date of Defense

1997-02-14

Availability

unrestricted

Abstract

Vitamin C is industrially produced by the Reichstein

method, which uses gluconobacters to oxidize sorbitol

to sorbose then a chemical process to convert

sorbose to 2-keto-L-gulonic acid (2-KLG). The

establishment of a more extensive microbial process

for 2-KLG production translates into a less expensive

and more efficient production of vitamin C. I

examined pure strains and mixed cultures for their

ability to produce 2-KLG using thin layer and high

performance liquid chromatography. The DSM 4027

mixed culture produced the highest yield, 25 g/L, of

2-KLG from 100 g/L of sorbose, while the

gram-negative rods isolated from DSM 4027

produced 8.8 g/L, and B. megaterium isolated from

DSM 4027 produced 1.4 g/L. Thus, the

gram-negative rods in the mixed culture were the

primary 2-KLG producer, but B. megaterium in the

DSM 4027 mixture enhanced this synthesis. Authentic

pure cultures of Gluconobacter oxydans IFO strain

3293 and ATCC strain 621 produced 3.4 g/L and

5.7 g/L, respectively. Attempts to co-culture the

isolated B. megaterium with the isolated

gram-negative rods and authentic Gluconobacter

strains did not increase 2-KLG production, nor did

growing the cultures on B. megaterium spent media.

Bacillus megaterium produced an unidentified

keto-compound detected on the TLC

chromatograms, which suggested that B. megaterium

converted sorbose to an intermediate that may then be

converted by the gram-negative rods in DSM 4027 to

2-KLG. Limited phenotypic tests suggested that the

gram-negative rods in the DSM 4027 mixture are not

gluconobacters.

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