Synthesis of the alternative sweetener 5-ketofructose from sucrose by fructose dehydrogenase and invertase producing Gluconobacter strains.
J Biotechnol
; 307: 164-174, 2020 Jan 10.
Article
in En
| MEDLINE
| ID: mdl-31704125
ABSTRACT
A promising alternative to high-calorie sugars and artificial sweeteners is the microbially produced fructose derivative 5-ketofructose (5-KF). The key enzyme for biotransformation, fructose dehydrogenase (Fdh), was overproduced in Gluconobacter (G.) oxydans and G. japonicus LMG 26773. Furthermore, the fdh genes were integrated into the chromosome of G. oxydans (G. oxydans Δmgdhfdh). All mutants showed high fructose oxidation rates forming 5-KF. G. japonicus LMG 26773 fdh was selected for 5-KF production from the cost-efficient and renewable feedstock sucrose because the organism possessed both, a highly active Fdh and an enzyme able to cleave sucrose. However, 5-KF yield was low because the strain formed levan and consumed 5-KF in the second growth phase. Several Gluconobacter strains were screened for sucrose-hydrolyzing enzymes. One of these proteins (Inv1417) was characterized and it was found that the enzyme showed the highest specific activity compared to all mesophilic invertases described so far (Vmax = 2295 ± 243 U mg protein-1). The corresponding gene was expressed in G. oxydans Δmgdhfdh. The results clearly indicated that both heterologously produced enzymes Fdh and Inv1417 were active in this single-strain system for 5-KF synthesis. Overall 84 ± 2% of the available fructose units of sucrose were converted to 5-KF.
Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Oxidoreductases
/
Sweetening Agents
/
Gluconobacter
/
Beta-Fructofuranosidase
/
Fructose
Language:
En
Journal:
J Biotechnol
Journal subject:
BIOTECNOLOGIA
Year:
2020
Document type:
Article
Affiliation country:
Germany