Young-Wook Chin

Metabolic engineering of Escherichia coli to produce 2′-fucosyllactose via salvage pathway of guanosine 5′-diphosphate (GDP)-l-fucose

2′‐Fucosyllactose (2‐FL) is one of the key oligosaccharides in human milk. In the present study, the salvage guanosine 5′‐diphosphate (GDP)‐l‐fucose biosynthetic pathway from fucose was employed in engineered Escherichia coli BL21star(DE3) for efficient production of 2‐FL. Introduction of the fkp gene coding for fucokinase/GDP‐l‐fucose pyrophosphorylase (Fkp) from Bacteroides fragilis and the fucT2 gene encoding α‐1,2‐fucosyltransferase from Helicobacter pylori allows the engineered E. coli to produce 2‐FL from fucose, lactose and glycerol. To enhance the lactose flux to 2‐FL production, the attenuated, and deleted mutants of β‐galactosidase were employed. Moreover, the 2‐FL yield and productivity were further improved by deletion of the fucI‐fucK gene cluster coding for fucose isomerase (FucI) and fuculose kinase (FucK). Finally, fed‐batch fermentation of engineered E. coli BL21star(DE3) deleting lacZ and fucI‐fucK, and expressing fkp and fucT2 resulted in 23.1 g/L of extracellular concentration of 2‐FL and 0.39 g/L/h productivity. Biotechnol. Bioeng. 2016;113: 2443–2452.

Complete genome sequence of Leuconostoc garlicum KCCM 43211 producing exopolysaccharide

Leuconostoc garlicum KCCM 43211 isolated from traditional Korean fermented food is an intensive producer of exopolysaccharide (EPS). Here we report the first complete genome sequence of L. garlicum KCCM 43211. The genome sequence displayed that this strain contains genes involved in production of EPS possibly composed of glucose monomers. An uncharacterized EPS from the L. garlicum KCCM 43211 strains was also produced during fermentation in the sucrose medium. The MALDI-TOF results displayed the typical mass spectrometry pattern of dextran. This uncharacterized EPS may have use in commercial prebiotics, food additives, and medical purposes. The complete genome sequence of L. garlicum KCCM 43211 will provide valuable information for strain engineering based on the genetic information.