Described herein are devices and methods for increasing the production of steviol glycosides, which have industrial and economic value. The steviol glycosides produced by the devices and methods disclosed herein do not require the ultra purification that is common in conventional or commercial methods and do not have a bitter aftertaste, making them better suited as flavor-enhancing additives to food, pharmaceutical, and nutritional supplement products.

Described is a method for the incorporation of formaldehyde into biomass comprising the following enzymatically catalyzed steps (1) condensation of pyruvate with formaldehyde into 4-hydroxy-2-oxobutanoic acid (HOB); (2) amination of the thus produced 4-hydroxy-2-oxobutanoic acid (HOB) to produce homoserine; (3) conversion of thus produced homoserine to threonine; (4) conversion of the thus produced threonine into glycine and acetaldehyde or acetyl-CoA; (5) condensation of the thus produced glycine with formaldehyde to produce serine; and (6) conversion of the thus produced serine to produce pyruvate, wherein said pyruvate can then be used as a substrate in step (1).

Described is a method for the incorporation of formaldehyde into biomass comprising the following enzymatically catalyzed steps (1) condensation of pyruvate with formaldehyde into 4-hydroxy-2-oxobutanoic acid (HOB); (2) amination of the thus produced 4-hydroxy-2-oxobutanoic acid (HOB) to produce homoserine; (3) conversion of thus produced homoserine to threonine; (4) conversion of the thus produced threonine into glycine and acetaldehyde or acetyl-CoA; (5) condensation of the thus produced glycine with formaldehyde to produce serine; and (6) conversion of the thus produced serine to produce pyruvate, wherein said pyruvate can then be used as a substrate in step (1).

The present invention is in the technical field of synthetic biology and metabolic engineering. More particularly, the present invention is in the technical field of fermentation of metabolically engineered host cells. The present invention describes a method of making sialylated oligosaccharide by fermentation with a genetically modified cell, as well as to the genetically modified cell used in the method. The genetically modified cell comprises at least one nucleic acid sequence coding for an enzyme involved in sialylated oligosaccharide synthesis and at least one nucleic acid expressing a membrane protein.

Provided is a method of producing a product by culturing a carboxydotrophic acetogenic bacterium with a disrupting mutation in a lactate dehydrogenase enzyme in the presence of a substrate comprising CO, CO.sub.2, and/or H.sub.2. Preferably, the disrupting mutation reduces or eliminates the expression or activity of the enzyme such that the bacterium produces a reduced amount of lactate or no lactate.

Provided is a method of producing a product by culturing a carboxydotrophic acetogenic bacterium with a disrupting mutation in a lactate dehydrogenase enzyme in the presence of a substrate comprising CO, CO.sub.2, and/or H.sub.2. Preferably, the disrupting mutation reduces or eliminates the expression or activity of the enzyme such that the bacterium produces a reduced amount of lactate or no lactate.

Provided is a mutant hydroxyphenylpyruvate dioxygenase (HPPD) polypeptide, an encoding gene thereof and a use thereof. The mutant HPPD polypeptide retains the activity of catalyzing the conversion of hydroxyphenylpyruvate acid into homogentisic acid or homogentisate, and the sensitivity to HPPD inhibitor herbicides is lower than that of original unmutated HPPD. On position 372 corresponding to the amino acid sequence represented by SEQ ID NO: 1, the mutant HPPD polypeptide comprises the following mutations: F372A, F372G, F372V, F372P, F372S, F372T, F372C, F372M, F372Q, F372D or F372 deletion. The described mutant can provide plants with high tolerance to HPPD inhibitor herbicides, and can be used to cultivate plants that are tolerant to HPPD inhibitor herbicides.

Provided is a mutant hydroxyphenylpyruvate dioxygenase (HPPD) polypeptide, an encoding gene thereof and a use thereof. The mutant HPPD polypeptide retains the activity of catalyzing the conversion of hydroxyphenylpyruvate acid into homogentisic acid or homogentisate, and the sensitivity to HPPD inhibitor herbicides is lower than that of original unmutated HPPD. On position 372 corresponding to the amino acid sequence represented by SEQ ID NO: 1, the mutant HPPD polypeptide comprises the following mutations: F372A, F372G, F372V, F372P, F372S, F372T, F372C, F372M, F372Q, F372D or F372 deletion. The described mutant can provide plants with high tolerance to HPPD inhibitor herbicides, and can be used to cultivate plants that are tolerant to HPPD inhibitor herbicides.

Provided is a genome editing system and method for gene editing at least one target sequence in a cell genome. The genome editing system comprises: (1) an expression construct comprising a Cas12f nuclease; and (2) an expression DNA sequence comprising a guide RNA corresponding to the Cas12f nuclease, and an expression construct of the targeting sequence of the target sequence. The gene editing system or method can accurately knock out a target gene from within a cell; in addition, in an in vitro cutting experiment, the target gene can be accurately cut.

The disclosure provides variants of nicotine oxidoreductase and methods to select such variants that are unexpectedly active in the catabolic destruction of nicotine by oxidation using oxygen as electron acceptor, and catabolically active fragments thereof. Also disclosed are compositions comprising the CycN cytochrome c protein and at least one of the variant nicotine oxidoreductase holoenzymes, the fragments thereof, or a naturally occurring nicotine oxidoreductase, as well as fusion proteins comprising catalytically active nicotine oxidoreductase fragments or holoenzymes and CycN cytochrome c fragments or holoenzymes. Additionally, variants of L-6-hydroxynicotine oxidase, or catalytically active fragments thereof, are provided. Further disclosed are polynucleotides encoding such proteins, vectors comprising such polynucleotides, and host cells comprising such polynucleotides or vectors. Also provided are methods of using any of the disclosed compositions or formulations to treat nicotine dependence or reduce the risk of relapse to nicotine dependence.