Provided is a method for preparing Rebaudioside J using an enzymatic method, comprising using rebaudioside A as a substrate, and making the substrate, in the presence of a glycosyl donor, react under the catalysis of a UDP-glycosyltransferase-con-taining recombinant cell and/or UDP-glycosyltransferase prepared therefrom to generate Rebaudioside J.

A DNA sequence encoding Der p1 protein having a particular base sequence is codon-optimized for the Pichia pastoris expression system, which is conducive to expressing Der p1 in Pichia pastoris. After gene optimization and adding an activating element to increase the expression of Der p1 in molecular level, it was found that Der p1 is expressed at a higher level as compared with the prior art and has biological activity similar to the natural protein.

Provided is a Pichia pastoris mutant strain for expressing an exogenous gene. Specifically, provided is a Pichia pastoris mutant strain comprising, with respect to Pichia pastoris mutant strain GS115 or CICC32806, one or more of the following six mutations: BQ9382_C1-2260, EKK deletions at positions 308-310, a hypothetical protein; BQ9382_C1-3800, E129K, 60S ribosomal subunit assembly/exported protein LOC1; BQ9382_C1-5700, I312M, mitochondrial external NADH dehydrogenase, type II NAD(P)H:quinone oxidoreductase; BQ9382_C2-3950, Q145X, an essential protein having a binding partner Psr1p and used for completely activating a general stress response; BQ9382_C3-2220, E188K, a hypothetical protein; and BQ9382_C3-4370, W196X, orotidine 5\′-phosphate decarboxylase. The provided Pichia pastoris mutant strain is an effective commonly employed host for exogenous expression, and can efficiently express different proteins, especially phospholipase and lipase.

This application describes transcriptional units, synthetic expression systems, and host cells comprising transcriptional units and synthetic expression systems, wherein the synthetic expression system is capable of expressing a gene of interest. Also described are methods for the production of bioproducts (including, but not limited to, proteins or RNA expressed from the gene of interest). In some embodiments, bioproducts are produced from host cells under culture conditions without addition of methanol.

A process for the preparation of bio-based malonic acid and crystalline calcium malonate is provided. The calcium malonate is highly pure and provides a source of malonic acid made from a renewable carbon source rather than existing processes which rely on the use of petroleum-based products. The calcium malonate provides an improved source of malonic acid, which is important to many industrial processes.

A novel isolated Pichia stipitis strain is provided. The strain is capable of fermenting at least a pentose sugar in the presence of one or more inhibitory substances to produce ethanol. A method of utilizing the strain to produce ethanol is also provided.

Strains of yeast genetically engineered to produce increased amounts of non-hydroxylated collagen or hydroxylated collagen are described. An all-in-one vector including the DNA necessary to produce collagen, promotors, and hydroxylating enzymes is also described. Methods for producing non-hydroxylated or hydroxylated collagen are also provided.

The present disclosure provides methods for producing consumable recombinant proteins that are substantially free from herein-disclosed undesired byproducts.

The invention relates to preparation of fermented food products, including dairy or dairy analogue products, with Pichia kluyveri and lactic acid bacteria in the presence of carbohydrate(s) which is sucrose, fructose, glucose or mixtures thereof. Fermentation of such products can be made using a starter culture composition comprising Pichia kluyveri strain(s) and lactic acid bacteria strain(s). The composition optionally comprises carbohydrate(s) which is sucrose, fructose and/or glucose.

The present disclosure relates to a novel yeast mutant strain for producing a ceramide precursor, and a method for preparing the same, and more specifically, to a Pichia ciferrii mutant strain genetically engineered to overexpress sphingolipid metabolites prepared through the reconstruction of metabolic pathways for ceramide production in Pichia ciferrii, or a method for preparing the mutant strain.