Safety of the extension of use of 2'-fucosyllactose/difucosyllactose (2'-FL/DFL) mixture and lacto-N-tetraose (LNT) as novel foods in food supplements for infants pursuant to Regulation (EU) 2015/2283

Efficient production of 2'-fucosyllactose from fructose through metabolically engineered recombinant Escherichia coli

BACKGROUND

The biosynthesis of human milk oligosaccharides (HMOs) using several microbial systems has garnered considerable interest for their value in pharmaceutics and food industries. 2'-Fucosyllactose (2'-FL), the most abundant oligosaccharide in HMOs, is usually produced using chemical synthesis with a complex and toxic process. Recombinant E. coli strains have been constructed by metabolic engineering strategies to produce 2'-FL, but the low stoichiometric yields (2'-FL/glucose or glycerol) are still far from meeting the requirements of industrial production. The sufficient carbon flux for 2'-FL biosynthesis is a major challenge. As such, it is of great significance for the construction of recombinant strains with a high stoichiometric yield.

RESULTS

In the present study, we designed a 2'-FL biosynthesis pathway from fructose with a theoretical stoichiometric yield of 0.5 mol 2'-FL/mol fructose. The biosynthesis of 2'-FL involves five key enzymes: phosphomannomutase (ManB), mannose-1-phosphate guanylytransferase (ManC), GDP-D-mannose 4,6-dehydratase (Gmd), and GDP-L-fucose synthase (WcaG), and α-1,2-fucosyltransferase (FucT). Based on starting strain SG104, we constructed a series of metabolically engineered E. coli strains by deleting the key genes pfkA, pfkB and pgi, and replacing the original promoter of lacY. The co-expression systems for ManB, ManC, Gmd, WcaG, and FucT were optimized, and nine FucT enzymes were screened to improve the stoichiometric yields of 2'-FL. Furthermore, the gene gapA was regulated to further enhance 2'-FL production, and the highest stoichiometric yield (0.498 mol 2'-FL/mol fructose) was achieved by using recombinant strain RFL38 (SG104ΔpfkAΔpfkBΔpgi119-lacYΔwcaF::119-gmd-wcaG-manC-manB, 119-AGGAGGAGG-gapA, harboring plasmid P30). In the scaled-up reaction, 41.6 g/L (85.2 mM) 2'-FL was produced by a fed-batch bioconversion, corresponding to a stoichiometric yield of 0.482 mol 2'-FL/mol fructose and 0.986 mol 2'-FL/mol lactose.

CONCLUSIONS

The biosynthesis of 2'-FL using recombinant E. coli from fructose was optimized by metabolic engineering strategies. This is the first time to realize the biological production of 2'-FL production from fructose with high stoichiometric yields. This study also provides an important reference to obtain a suitable distribution of carbon flux between 2'-FL synthesis and glycolysis.

Safety of 3-fucosyllactose (3-FL) produced by a derivative strain of Escherichia coli K-12 DH1 as a novel food pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on 3-fucosyllactose (3-FL) as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is mainly composed of the human-identical milk oligosaccharide (HiMO) 3-FL, but it also contains d-lactose, l-fucose, 3-fucosyllactulose and a small fraction of other related saccharides. The NF is produced by fermentation by a genetically modified strain (Escherichia coli K-12 DH1 MDO MAP1834) of E. coli K-12 DH1 (DSM 4235). The information provided on the manufacturing process, composition and specifications of the NF does not raise safety concerns. The applicant intends to add the NF to a variety of foods, including infant formula and follow-on formula, food for special medical purposes and food supplements (FS). The target population is the general population. The anticipated daily intake of 3-FL from both proposed and combined (authorised and proposed) uses at their respective maximum use levels in all population categories does not exceed the highest intake level of 3-FL from human milk in infants on a body weight basis. The intake of 3-FL in breastfed infants on a body weight basis is expected to be safe also for other population groups. The intake of other carbohydrate-type compounds structurally related to 3-FL is also considered of no safety concern. FS are not intended to be used if other foods with added 3-FL or human milk are consumed on the same day. The Panel concludes that the NF is safe under the proposed conditions of use.

Safety of 6'-sialyllactose (6'-SL) sodium salt produced by derivative strains of Escherichia coli BL21 (DE3) as a novel food pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on 6'-sialyllactose (6'-SL) sodium salt as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is mainly composed of the human-identical milk oligosaccharide (HiMO) 6'-SL, but it also contains d-lactose, 6'-sialyllactulose, sialic acid, N-acetyl-d-glucosamine and a small fraction of other related oligosaccharides. The NF is produced by fermentation with two genetically modified strains of Escherichia coli BL21 (DE3), the production strain and the optional degradation strain. The information provided on the identity, manufacturing process, composition and specifications of the NF does not raise safety concerns. The applicant intends to add the NF to a variety of foods, including infant formula and follow-on formula, food for special medical purposes and food supplements. The target population is the general population. In some scenarios at the maximum use levels, the estimated intakes per kg body weight were higher than the high average natural intake of 6'-SL from human milk. However, given the intrinsic nature of human milk oligosaccharides (HMOs), the wide range of intakes from human milk, and considering that infants are naturally exposed to similar amounts of these substances, the Panel considers that the consumption of the NF at the proposed conditions of use does not raise safety concerns. The intake of 6'-SL in breastfed infants on a body weight basis is also expected to be safe for other population groups. The intake of other carbohydrate-type compounds structurally related to 6'-SL is also considered of no safety concern. Food supplements are not intended to be used if other foods with added 6'-SL or human milk are consumed on the same day. The Panel concludes that the NF is safe under the proposed conditions of use.

Safety of 2'-fucosyllactose (2'-FL) produced by a derivative strain (APC199) of Corynebacterium glutamicumATCC 13032 as a novel food pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on 2'-fucosyllactose (2'-FL) as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is mainly composed of the human-identical milk oligosaccharide (HiMO) 2'-FL, but it also contains d-lactose, l-fucose, 3-fucosyllactose, difucosyllactose, d-glucose and d-galactose. The NF is produced by fermentation with a genetically modified strain (APC199) of Corynebacterium glutamicum ATCC 13032. 2'-FL, when chemically synthesised or produced by fermentation with derivative strains of Escherichia coli K-12 DH1 or E. coli BL21 (DE3), is already authorised and included in the EU list of NFs. This application refers to a change in the production process and specifications, while target population, conditions of use and consequently, the anticipated intake remain unchanged. The information provided on the identity, production process, composition and specifications of the NF does not raise safety concerns. The intake of other carbohydrate-type compounds structurally related to 2'-FL is also considered of no safety concern. In line with other milk oligosaccharides that are natural components of human milk, the safety assessment of this NF is mainly based on the comparison between the intake of breastfed infants and the estimated intake as NF. Given that the NF would be consumed at the same extent as the already authorised 2'-FL, the Panel considers that the consumption of the NF at the proposed uses and use levels does not raise safety concerns. The Panel concludes that the NF is safe under the proposed conditions of use.

Safety of 3-fucosyllactose (3-FL) produced by a derivative strain of Escherichia coli BL21 (DE3) as a Novel Food pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on 3-fucosyllactose (3-FL) as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is mainly composed of the human-identical milk oligosaccharide (HiMO) 3-FL, but it also contains d-lactose, l-fucose, d-glucose and d-galactose, and a small fraction of other related saccharides. The NF is produced by fermentation with a genetically modified strain of Escherichia coli BL21 (DE3). The information provided on the manufacturing process, composition and specifications of the NF does not raise safety concerns. The applicant intends to add the NF to a variety of foods, including infant formula and follow-on formula, food for infants and young children, food for special medical purposes and food supplements. The target population is the general population. The anticipated daily intake of 3-FL from both proposed and combined (authorised and proposed) uses at their respective maximum use levels in all population categories does not exceed the highest intake level of 3-FL from human milk in infants on a body weight basis. The intake of 3-FL in breastfed infants on a body weight basis is expected to be safe also for other population groups. The intake of other carbohydrate-type compounds structurally related to 3-FL is also considered of no safety concern. Food supplements are not intended to be used if other foods with added 3-FL or human milk are consumed on the same day. The Panel concludes that the NF is safe under the proposed conditions of use.

Safety of lacto-N-tetraose (LNT) produced by derivative strains of Escherichia coli BL21 (DE3) as a Novel Food pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on lacto-N-tetraose (LNT) as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is a powdered mixture mainly composed of the human-identical milk oligosaccharide (HiMO) LNT, but it also contains d-lactose, lacto-N-triose II and para-lacto-N-hexaose, and a small fraction of other related saccharides. The NF is produced by fermentation with two genetically modified strains of Escherichia coli BL21 (DE3), the production strain and the optional degradation strain. The information provided on the manufacturing process, composition and specifications of the NF does not raise safety concerns. The applicant intends to add the NF to a variety of foods, including infant and follow-on formula, food for infants and young children, food for special medical purposes and food supplements. The target population is the general population. The anticipated daily intake of LNT from the NF at the maximum proposed use levels does not exceed the intake level of naturally occurring LNT in breastfed infants on a body weight basis. The intake of LNT in breastfed infants on a body weight basis is expected to be safe also for other population groups. The intake of other carbohydrate-type compounds structurally related to LNT is also considered of no safety concern. Food supplements are not intended to be used if other foods with added LNT or human milk are consumed on the same day. The Panel concludes that the NF is safe under the proposed conditions of use.

Safety of 3'-sialyllactose (3'-SL) sodium salt produced by derivative strains of Escherichia coli BL21 (DE3) as a Novel Food pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on 3'-sialyllactose (3'-SL) sodium salt as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is mainly composed of the human-identical milk oligosaccharide (HiMO) 3'-SL, but it also contains d-lactose, 3'-sialyllactulose, sialic acid, N-acetyl-d-glucosamine and a small fraction of other related oligosaccharides. The NF is produced by fermentation with two genetically modified strains of Escherichia coli BL21 (DE3), the production strain and the optional degradation strain. The information provided on the manufacturing process, composition and specifications of the NF does not raise safety concerns. The applicant intends to add the NF to a variety of foods, including infant formula and follow-on formula, food for infants and young children, food for special medical purposes and food supplements. The target population is the general population. The anticipated daily intake of 3'-SL from both proposed and combined (authorised and proposed) uses at their respective maximum use levels in all population categories does not exceed the highest intake level of 3'-SL from human milk in infants on a body weight basis. The intake of 3'-SL in breastfed infants on a body weight basis is expected to be safe also for other population groups. The intake of other carbohydrate-type compounds structurally related to 3'-SL is also considered of no safety concern. Food supplements are not intended to be used if other foods with added 3'-SL or human milk are consumed on the same day. The Panel concludes that the NF is safe under the proposed conditions of use.

Safety of the extension of use of 2'-fucosyllactose (2'-FL) and lacto-N-neotetraose (LNnT) as novel foods in food supplements for infants pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on the safety of the extensions of use of the authorised novel foods (NFs) 2'-fucosyllactose (2'-FL) and lacto-N-neotetraose (LNnT) in food supplements (FS) for infants pursuant to Regulation (EU) 2015/2283. The NFs are produced by fermentation with genetically modified strains of Escherichia coli K-12 and already included in the EU list of NFs. The applicant stated that no changes in the production process or the identity of the NFs occurred. The applicant proposes an extension of use of the NF containing 2'-FL in FS intended for infants (< 1 year), at a maximum use level of 1.2 g/day. The applicant also proposes an extension of use of LNnT in FS intended for infants, at a maximum use level of 0.6 g/day. The intake of 2'-FL per kg body weight from the proposed maximum use levels in FS for infants is lower than the lowest estimated mean intake of naturally occurring 2'-FL from human milk. Similarly, the intake of LNnT per kg body weight is lower than the highest estimated mean intake of naturally occurring 2'-FL from human milk. Furthermore, the Panel notes that the proposed uses of 2'-FL in FS for infants are lower than the estimated intake from the already authorised uses of the NF for the same population group. The Panel also notes that the proposed uses of LNnT in FS for infants are similar to the estimated intake from the already authorised uses of the NF for the same population group. The Panel concludes that the use of the NFs containing 2'-FL or LNnT in FS for infants is safe under the proposed conditions of use.