NOVELTY - Production (m1) of a thraustochytrid cell culture involves transforming a thraustochytrid cell with a nucleic acid molecule comprising a polynucleotide sequence encoding a polypeptide (p1) associated with xylose import, conversion of xylose to xylulose, and/or phosphorylation of xylulose; and growing the transformed thraustochytrid cell in a culture medium comprising xylose as a carbon source.    USE - For the production of a thraustochytrid cell culture which is useful for producing biomass, microbial oil, biofuel, and food product, cosmetic, industrial composition or pharmaceutical composition for an animal or human. The food product is an infant formula for premature infants; a milk, beverage, therapeutic drink, and/or nutritional drink; an additive for animal or human food; a nutritional supplement; and an animal feed (i.e. an aquaculture feed, or a domestic animal feed, zoological animal feed, work animal feed and/or livestock feed). The biofuel is produced by transesterifying the oil, cracking the oil, processing the oil by thermal depolymerization or adding the oil to a petroleum refining process; and is biodiesel, jet biofuel, renewable diesel or co-processed renewable diesel (all claimed). The pharmaceutical composition including e.g. an anti-inflammatory composition, a drug for treatment of coronary heart disease, a drug for treatment of arteriosclerosis, a chemotherapeutic agent, an active excipient, an osteoporosis drug, an anti-depressant, an anticonvulsant, an anti-Helicobacter pylori drug, a drug for treatment of neurodegenerative disease, a drug for treatment of degenerative liver disease, an antibiotic, a cholesterol lowering composition, and a triglyceride lowering composition.    ADVANTAGE - The method produces thraustochytrids with the ability to grow on alternative carbon sources such as xylose for use in commercial and industrial applications.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a thraustochytrid cell culture produced by the method (m1);    (2) a thraustochytrid cell (c1) comprising a nucleic acid molecule comprising a polynucleotide sequence encoding a polypeptide associated with xylose import, conversion of xylose to xylulose, and/or phosphorylation of xylulose;    (3) a thraustochytrid culture comprising: the thraustochytrid cell (c1), and a cell culture medium comprising xylose as a carbon source;    (4) production of a thraustochytrid biomass, involving: growing the thraustochytrid cell (c1) in a culture medium comprising xylose as a carbon source, and harvesting the biomass from the culture medium;    (5) production of a microbial oil involving: growing the thraustochytrid cell (c1) in a culture medium comprising xylose as a carbon source to produce a biomass, and extracting an oil from the biomass;    (6) production (m2) of a food product, cosmetic, industrial composition or pharmaceutical composition for an animal or human, involving: growing the thraustochytrid cell (c1) in a culture medium comprising xylose as a carbon source, harvesting a biomass from the culture medium, and preparing the food product, cosmetic, industrial composition, or pharmaceutical composition from the biomass; and    (7) production of a biofuel, involving: growing the thraustochytrid cell (c1) in a culture medium comprising xylose as a carbon source to produce a biomass, extracting an oil from the biomass, and producing a biofuel by transesterifying the oil, cracking the oil, processing the oil by thermal depolymerization and/or adding the oil to a petroleum refining process.