Production of oligosaccharides

1. A process for producing a 2′-fucosyllactose in a host microorganism, wherein said 2′-fucosyllactose is not naturally occurring in said host microorganism, the process comprising the steps of:

a) cultivating the host microorganism that produces the 2′-fucosyllactose under conditions and in a fermentation medium suitable for the production of 2′ fucosyllactose, thereby producing 2′ fucosyllactose and undesired biosynthetic saccharide intermediates;

b) directly adding an exogenous beta-galactosidase enzyme to the fermentation medium at the end of the cultivation of a) to degrade unused saccharide substrates and/or undesired biosynthetic saccharide intermediates and/or saccharide side products generated during production of the 2′ fucosyllactose in step a), and

c) recovering the 2′-fucosyllactose.

2. The process of claim 1 , further comprising centrifuging the cultivated host microorganism to obtain a supernatant and a host microorganism pellet, and recovering the 2′-fucosyllactose from the supernatant.

3. The process of claim 1 , wherein the host microorganism is a bacterium or a yeast.

4. The process of claim 3 , wherein the host microorganism is an Escherichia coli strain, Lactobacillus species, a Corynebacterium glutamicum strain or a Saccharomyces sp. strain.

5. The process of claim 1 , wherein the host microorganism overexpresses a salvage pathway for a monosaccharide generated during production of the 2′-fucosyllactose, to convert the monosaccharide into its nucleotide-activated form.

6. The process of claim 1 , wherein the host microorganism is a wild-type microorganism modified to overexpress proteins for a galactose catabolic pathway under the control of an inducible promoter.

7. A method for purifying 2′-fucosyllactose from a mixture containing the 2′-fucosyllactose and

(a) non-desired oligosaccharides or metabolic saccharide products generated during production of said 2′-fucosyllactose, and/or

(b) unused saccharide substrates used in the production of said 2′-fucosyllactose,

the method comprising] adding beta-galactosidase to the mixture to degrade the non-desired oligosaccharides or metabolic saccharide products or unused substrates; and recovering the 2′-fucosyllactose from the mixture.

8. The method of claim 7 , wherein the 2′-fucosyllactose is produced by in vitro oligosaccharide synthesis or by chemical synthesis or by combinations thereof.

9. The method of claim 7 , wherein the 2′-fucosyllactose is a non-naturally occurring oligosaccharide in a host microorganism expressing a beta-galactosidase, and wherein the 2′-fucosyllactose is produced by a microbial fermentation process in the host microorganism.

10. A process for producing 2′-fucosyllactose in a host microorganism, wherein said 2′-fucosyllactose is not naturally occurring in said host microorganism, the process comprising the steps of:

a) cultivating a host microorganism that can produce 2′-fucosyllactose under conditions and in a medium suitable for the production of 2′-fucosyllactose, thereby producing 2′-fucosyllactose and-undesired biosynthetic saccharide intermediates;

b) externally adding a beta-galactosidase to the medium following production of the 2′-fucosyllactose in step a) to degrade unused saccharide substrates and/or undesired biosynthetic saccharide intermediates and/or saccharide side products generated during production of the 2′-fucosyllactose in step a), and

c) recovering the 2′-fucosyllactose;

wherein the unused saccharide substrate is lactose.

11. The method of claim 1 , wherein the host microorganism does not endogenously produce the beta-galactosidase.

12. The method of claim 10 , wherein the host microorganism does not endogenously produce the beta-galactosidase.