TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preparation (Claimed): The recombinant host cell is produced by transforming a host cell comprising at least one deletion, mutation and/or substitution in an endogenous gene with a heterologous polynucleotide. Preferred Host: The host cell further comprises (iii) a heterologous polynucleotide encoding a polypeptide having phosphotransacetylase activity. The host cell requires reduced amount of the exogenous two-carbon substrate for its growth in culture compared to a recombinant eukaryotic host cell comprising (i), and not (ii) or (iii). The host cell has improved growth as compared to a host cell comprising (i), and not (ii) or (iii) in culture media which is not supplemented with an exogenous carbon substrate. The host cell further comprises a pyruvate-utilizing biosynthetic pathway to form a product chosen from 2,3-butanediol, 2-butanol, 2-butanone, valine, leucine, lactic acid, malate and isoamyl alcohol. The pyruvate-utilizing biosynthetic pathway is an isobutanol biosynthetic pathway converts (a) pyruvate to acetolactate, (b) acetolactate to 2,3-dihydroxyisovalerate, (c) 2,3-dihydroxyisovalerate to 2-ketoisovalerate, (d) 2-ketoisovalerate to isobutyraldehyde, and (e) isobutyraldehyde to isobutanol, where the recombinant host cell produces isobutanol. The pyruvate-utilizing biosynthetic pathway is 2-butanone biosynthetic pathway converts (a) pyruvate to acetolactate, (b) acetolactate to acetoin, (c) acetoin to 2,3-butanediol, and (d) 2,3-butanediol to 2-butanone where the host cell produces 2-butanone. The pyruvate-utilizing biosynthetic pathway is 2-butanol biosynthetic pathway converts (a) pyruvate to acetolactate, (b) acetolactate to acetoin, (c) acetoin to 2,3-butanediol, (d) 2,3-butanediol to 2-butanone, and (e) 2-butanone to 2-butanol, where the recombinant host cell produces 2-butanol. The host cell comprises 2-butanone or 2-butanol biosynthetic pathway utilizes at least one DNA molecule encoding a polypeptide which catalyzes a substrate to product conversion. Preferred Gene: The endogenous gene encoding a polypeptide having pyruvate decarboxylase activity is PDC1, PDC5, PDC6 or their combinations. The deletion, mutation and/or substitution are results in reduced or eliminated pyruvate decarboxylase activity. The heterologous polynucleotide is phosphoketolase 1 (xpk1) derived from Lactobacillus plantarum, xpkA derived from L.pentosus MD363 or 6-phosphate phosphoketolase from Bifidobacterium lactis. The heterologous polynucleotide encoding a polypeptide having phosphotransacetylase activity is ethanolamine utilization protein (EutD) derived from L.plantarum or phosphotransacetylase from B.subtilis. Preferred Polypeptide: The polypeptide which converts pyruvate to acetaldehyde, acetyl phosphate or acetyl-CoA is pyruvate decarboxylase, pyruvate formate lyase, pyruvate dehydrogenase, pyruvate oxidase or pyruvate:ferredoxin oxidoreductase. The polypeptide having phosphoketolase activity exhibits at least 85% sequence homology to amino acid sequence of SEQ ID NO: 481 or 1472 or its active fragment. Preferred Method: The host cell is grown in media containing limited carbon substrate. Preferred Components: The exogenous two-carbon substrate is ethanol or acetate. The phosphoketolase matches with profile HMM given in tables 6, 7, 8 and 9 of patent specification, where the phosphoketolase has E values of 7.5E-242, 1.1E-124, 2.1E-49 and 7.8E-37 or less, respectively. The phosphotransacetylase matches with profile HMM given in table 14 of patent specification, where the phosphotransacetylase has E value of 5E-34 or less. Sequences not defined here may be found at ftp://ftp.wipo.int/pub/published_pct_sequences/publication. EXAMPLE - No suitable example given.