TECHNOLOGY FOCUS - BIOLOGY - Preferred Components: The host cell is a phototroph, which is a cyanobacterium, prokaryotes, eukaryotes, yeasts, filamentous fungi, protozoa, algae or synthetic cells, where the host cell produces carbon-based products.    TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Method: In the method of improving pyruvate decarboxylase activity, alcohol dehydrogenase activity, screening for pyruvate decarboxylase activity, alcohol dehydrogenase activity or bi-functional alcohol dehydrogenase comprises any one of the group consisting of growing host cells with pararosaniline, isolating the pyruvate decarboxylase enzyme, alcohol dehydrogenase enzyme or bi-functional alcohol dehydrogenase from the host cell and analyzing enzyme biophysical characteristics, batch culturing the host cell expressing the pyruvate decarboxylase, alcohol dehydrogenase or bi-functional alcohol dehydrogenase, and culturing the host cell in a turbidostat. Preferred Components: In the isolated or recombinant polynucleotide: the nucleic acid sequence encodes a polypeptide having the activity of any one of the polypeptide sequences as in table 16; the nucleic acid sequence and the sequence of interest are operably linked to at least one expression control sequence. The vector comprising the isolated or recombinant polynucleotide expresses the polypeptide. The isolated polynucleotide comprises at least one of SEQ ID NOs: 3, 6, 9, 12, 15, 16, 18, 19, 21, 23, 29, or 33. The nucleotide codon encoding amino acid positions 574 of SEQ ID NO: 17 and 568 of SEQ ID NO: 20 is cysteine, glutamine, isoleucine, methionine, phenylalanine, proline, threonine, tryptophan, tyrosine or valine. The pyruvate decarboxylase (pdc) gene comprises SEQ ID NO: 3 or 6. The pdc gene is from Gluconacetobacter diazotrophicus, Beijerinckia indica, Gluconobacter oxydans, Acetobacter pasteurianus, Zymomonas mobilis, Zymobacter palmae, Schizosaccharomyces pombe, Podospora anserina, Aspergillus fumigatus, Neurospora crassa, Gibberella zeae, Planctomyces maris, Oryza sativa, Oryza punctata, Zea mays, Arabidopsis thaliana, Petunia x hybrida, Lotus corniculatus, Physcomitrella patens subsp. patens, Lycoris aurea, Dianthus caryophyllus, Citrus sinensis, Fragaria x ananassa, Vitis vinifera, Pisum sativum, Lotus japonicus, Prunus armeniaca, Nicotiana tabacum, Solanum tuberosum, Legionella pneumophila, Aspergillus clavatus, Aspergillus terreus, Aspergillus niger, Clostridium acetobutylicum, Nostoc punctiforme, Geobacter lovleyi, Cyanothece sp. PCC 8801, Microcystis aeruginosa, Lactococcus lactis, Chlamydomonas reinhardtii, Triticum aestivum, Bacillus cereus, Bacillus anthracis, Bacillus thuringiensis, Lyngbya spp. PC8106, Saccharum officinarum, Coix lacryma-jobi, Echinochloa crus-galli, Oryza glaberrima, or Aspergillus nidulans. The gene for an alcohol dehydrogenase comprises SEQ ID NOs: 9, 12, 15 or 23. The gene for an alcohol dehydrogenase (adh) is adh1 or adh2. The adh1 is from Shigella dysenteriae 1012 (accession number ZP-03064170), Escherichia coli (accession number YP-002292842), Enterobacter cancerogenus ATCC 35316, accession number ZP-03282582), Salmonella enterica (accession number YP-001587957), Serratia proteamaculans 568 (accession number YP-001478632), Klebsiella pneumoniae subsp. pneumonia (accession number YP-001335514), Shigella flexneri 2a strain 301 (accession number NP-707612), Pseudomonas putida (accession number YP-001267259), Erwinia tasmaniensis Et1/99 (accession number YP-001908360), Bacillus amyloliquefaciens FZB42 (accession number YP 001421338), Bacillus coagulans 36D1 (accession number ZP 01695986), Neisseria meningitidis (accession number YP-974586), Staphylococcus aureus MW2 (accession number NP-645385), Actinobacillus pleuropneumoniae serovar (accession number ZP-00134308), Bacillus cereus subsp. cytotoxis (accession number YP-001374103), Bacillus thuringiensis (accession number YP-036379), Bacillus weihenstephanensis (accession number YP-001644942), Bacillus anthracis strain Ames (accession number NP-844655), Exiguobacterium sp. AT1b (accession number ZP-02989690), Streptococcus pneumoniae (accession number ZP-01817011), Streptococcus sanguinis SK36 (accession number YP-001035842), Streptococcus gordonii (accession number YP-001449881), Neisseria gonorrhoeae (accession number YP-208496), Lactobacillus brevis (accession number YP-794451), Staphylococcus epidermidis (accession number YP-187853), Streptococcus suis (accession number YP-001197647), Streptococcus pyogenes (accession number NP-606374), Enterococcus faecalis V583 (accession number NP-815523), Lactococcus lactis (accession number NP-267964), Streptococcus equi subsp. zooepidemicus (accession number YP-002122442), Streptococcus agalactiae (accession number NP-687090), Lactobacillus reuteri (accession number ZP-03072955), Entamoeba dispar SAW760 (accession number XM-001741780 or XM-001733263), Arcobacter butzleri RM4018 (accession number CP-000361), Clostridium beijerinckii strain NRRL B593 (accession number AF-157307), Trichomonas vaginalis (accession number XM-001314150), Methanocorpusculum labreanum Z (accession number CP-000559), Malassezia globosa CBS 7966 (accession number XM-001729044), Lactobacillus fermentum IFO 3956 (accession number AP-008937), Brachyspira hyodysenteriae strain WA1 (accession number EF-488203), Brachyspira pilosicoli strain 95/1000 (accession number EF-488210), Thermoanaerobacter pseudethanolicus ATCC 33223 (accession number CP000924), Thermoanaerobacter brockii (accession number X64841), Thermoanaerobacter ethanolicus (accession number U49975), Thermoanaerobacter sp. X514 (accession number CP000923), Methanosarcina barkeri strain Fusaro (accession number CP000099), Thermoanaerobacter ethanolicus (accession number DQ323135), Thermoanaerobacter tengcongensis MB4 (accession number AE013038), Methanosarcina acetivorans strain C2A (accession number AE010299). The adh2 gene is from 93 microorganisms e.g. Phytomonas sp. ADU-2003 (accession number AAP39869), Xanthobacter autotrophicus (accession number YP-001415578), Methylibium petroleiphilum (YP-001021255), Alkalilimnicola ehrlichei (YP-742969), Sinorhizobium meliloti (NP-435872), Azotobacter vinelandii, Proteus mirabilis, Rhodoferax ferrireducens, Pseudomonas fluorescens, Rhodospirillum rubrum, Pseudomonas syringae, Shewanella putrefaciens, Salmonella enterica, Psychromonas, Pseudomonas entomophila, Shewanella pealeana, Vibrio angustum, Vibrio sp. Ex25, Shewanella halifaxensis, Idiomarina loihiensis, Vibrionales bacterium, Vibrio campbellii, Vibrio splendidus, Shewanella woodyi, Vibrio sp. MED222, Vibrio alginolyticus, Photobacterium sp. SKA34, Shewanella baltica, Escherichia coli, Vibrio fischeri, Escherichia albertii, Shewanella benthica, Shewanella loihica, Vibrio vulnificus, Shewanella frigidimarina, Shewanella denitrificans, Shigella boydii, Photobacterium profundum, Vibrio parahaemolyticus, Serratia proteamaculans, Citrobacter koseri, Enterobacter sp. 638, Shigella flexneri, Shigella dysenteriae, Shewanella sp. MR-4, Shewanella sp. ANA-3, Enterobacter sakazakii, Vibrio harveyi, Azoarcus sp. EbN1, Shewanella oneidensis, Rhodopseudomonas palustris. The gene for a bi-functional alcohol dehydrogenase comprises SEQ ID NO: 18 or 21. The gene for a bi-functional alcohol dehydrogenase is from Synechococcus sp. JA-3-Ab, Synechococcus sp. JA-2-3B'a, Acaryochloris marina MBIC11017, Chromobacterium violaceum, Chlamydomonas reinhardtii, Aeromonas hydrophila, Aeromonas salmonicida, Microcystis aeruginosa, Shewanella loihica, Shewanella amazonensis, Enterobacter sakazakii, Citrobacter koseri, Sodalis glossinidius, Klebsiella pneumoniae, Rhodopseudomonas palustris, Shigella dysenteriae, Escherichia coli, Shigella flexneri, Shigella sonnei, Shigella boydii, Klebsiella oxytoca, Salmonella enterica, Salmonella typhimurium, Serratia proteamaculans, Erwinia tasmaniensis, Erwinia carotovora, Shewanella oneidensis, Enterobacter sp. 638, Shewanella, Photobacterium profundum, Photorhabdus luminescens, Vibrio cholerae, Yersinia enterocolitica, Shewanella baltica, Yersinia pseudotuberculosis, Yersinia pestis, Vibrio parahaemolyticus, Elusimicrobium minutum, Shewanella putrefaciens, Shewanella pealeana, Mastigamoeba balamuthi, Shewanella frigidimarina, Xenorhabdus nematophila, Proteus mirabilis, Chromobacterium violaceum, Vibrio harveyi, Shewanella woodyi, Aliivibrio salmonicida, Shewanella piezotolerans, Shewanella halifaxensis, Shewanella sediminis, Shewanella frigidimarina, Psychromonas ingrahamii or Salmonella typhi. EXAMPLE - Recombinant strains were generated by using plasmid DNA (2-5 mu g) bearing the pyruvate decarboxylase (pdc)-alcohol dehydrogenase (adh) construct and antibiotic marker gene, which were linearized with XbaI and added to Synechococcus sp. PCC 7002 or Synechococcus sp. PCC 7002 pAQ7(ldh):P(cI)-adhA kan (0.5-1 ml). The cell-DNA mixture was incubated with gentle rotation at 37 degrees C in the dark for 4 hours and then plated onto an A+ agar plate and incubated at 37 degrees C (~50 mu E) in air. After 24 hours, the plates were underlaid with kanamycin to a final concentration of 50 mu g/ml or spectinomycin to 25 mu g/ml as appropriate and incubated. After 5 days, background growth was diminished and Km(R) colonies began to be visible, at which point the plates were transferred to 37 degrees C (~50 mu E) and carbon dioxide (1%). After 3 additional days, two antibiotic resistant colonies from each transformation were streaked onto A+ 100 mu g/ml kanamycin or 100 mu g/ml spectinomycin agar plates for single colony segregation. The streaked plates were incubated for 4 days at 37 degrees C in air and transferred to 37 degrees C (50 mu E), carbon dioxide (1%) for an additional 3 days. The colonies from these plates were used to inoculate seed cultures. A single colony of one clone from the original streak plate from each transformation was inoculated into 5 ml A+ and either kanamycin or spectinomycin broth (5-1000 mu g/ml) in a 16mmx 150 mm plastic-capped culture tube and incubated at a 60 degrees angle. After 3 days, the cultures were transferred into foam-plugged unbaffled Erlenmeyer flasks (125 ml) containing JB2.1 (30 ml) with antibiotic concentrations that were used in the initial test-tube seed cultures at an initial optical density (OD) of 0.1 at 730 nm. The initial weight of each flask culture was determined so that sterile distilled water could be added at sampling times to account for evaporation. At each sampling point, culture (300 mu l) was removed and the cultures were replenished with an equal amount of fresh JB2.1 medium. At roughly 24 hour intervals, samples were taken and their OD730 was measured. In addition, cell-free samples (100 mu l) was used to determine the liquid ethanol concentration by gas chromatography/flame ionization detection.