Genetically Modified Photoautotrophic Ethanol Producing Host Cells, Method For Producing The Host Cells, Constructs For The Transformation Of The Host Cells, Method For Testing A Photoautotrophic Strain For A Desired Growth Property And Method Of Producing Ethanol Using The Host Cells

Abstract

The invention provides genetically modified photoautotrophic ethanol producing host cells. Ethanol production is controlled by an inducible promoter. Promoters utilized may be endogenous or heterologous, and genetic modification may be obtained by extrachromosomal means or chromosomal insertion.

1 . A genetically modified photoautotrophic, ethanol producing host cell comprising:
 a coding nucleic acid sequence comprising a promoter and a gene encoding at least one overexpressed enzyme for the formation of ethanol under the transcriptional control of the promoter, wherein   the promoter can be induced by nutrient starvation, oxidative stress, darkness, heat shock, cold shock, salt stress or stationary growth of the host cell.   
     
     
         2 . The genetically modified host cell according to  claim 1 , wherein
 the promoter is selected from a group of promoters consisting of:   ntcA, nblA, isiA, petJ, petE, sigB, lrtA, htpG, ggpS, psaA, psbA2, hspA, clpB1, hliB and crhC, psbA.   
     
     
         3 . The genetically modified host cell according to  claim 1 , wherein the promoter is a heterologous promoter. 
     
     
         4 . The genetically modified host cell according to  claim 1 , wherein the promoter is an endogenous promoter. 
     
     
         5 . The genetically modified host cell according to  claim 1 , wherein the promoter is  synechocystis  PpetJ. 
     
     
         6 . The genetically modified host cell according to  claim 1 , wherein the promoter is Anabena PpetE. 
     
     
         7 . The genetically modified host cell according to  claim 1 , wherein the promoter is a heterologous promoter and one overexpressed enzyme for the formation of ethanol is a gene encoding an alcohol dehydrogenase, which directly converts acetyl-CoA to ethanol, wherein the gene is under the transcriptional control of the heterologous promoter. 
     
     
         8 . The genetically modified host cell according to  claim 1 , wherein the promoter is PpetJ and induction occurs at night time. 
     
     
         9 . A construct for the transformation of a photoautotrophic host cell, comprising:
 a coding nucleic acid sequence comprising a promoter, which can be induced by nutrient starvation of the host cell, and   a gene encoding at least one overexpressed enzyme for the formation of ethanol under the transcriptional control of the promoter.   
     
     
         10 . The construct according to  claim 8 , wherein
 the coding nucleic acid sequence is flanked at its 5′ and 3′ end by nucleic acid sequences, which are able to bind to at least parts of said host genome for integration of the coding sequence into the host genome.