Syngas fermentation process and medium

Abstract

A process for fermenting syngas and a fermentation medium provides high ethanol productivity while removing medium components that were previously thought to be essential. The process is effective for providing a specific STY of at least about 1 g ethanol/(L-day-gram cells). In this aspect, the fermentation medium has a weight ratio of NH 4+ to B of about 625:1 or more, or a weight ratio of NH4+ to Mn of about 4050:1 or more, or a weight ratio of NH/ to Mo of about 2500:I or more, or a ratio of NH4+ to Cu of about 4050:I or more; or the fermentation medium has a weight ratio of P to B of about 30:1 or more, or a weight ratio of P to Mn of about 190:1 or more, or a weight ratio of P to Mo of about 120:1 or more, or a weight ratio of Mn to Cu of about 190:1 or more; or the fermentation medium has a weight ratio of K to B of about 35:1 or more, or a weight ratio of K to Mn of about 245:1 or more, or a weight ratio of K to Mo of about 150:1 or more, or a weight ratio of K to Cu of about 245:1 or more.

1 - 7 . (canceled) 
     
     
         8 . A fermentation process comprising fermenting syngas in a fermentation medium, the process effective for providing a specific STY of at least about 1 gram of ethanol/(L-day·gram cells), wherein the fermentation medium has a weight ratio of NH 4   +  to B of about 625:1 or more, or a weight ratio of NH 4   +  to Mn of about 4050:1 or more, or a weight ratio of NH 4   +  to Mo of about 2500:1 or more, or a ratio of NH 4   +  to Cu of about 4050:1 or more; or
 wherein the fermentation medium has a weight ratio of P to B of about 30:1 or more, or a weight ratio of P to Mn of about 190:1 or more, or a weight ratio of P to Mo of about 120:1 or more, or a weight ratio of Mn to Cu of about 190:1 or more; or 
 wherein the fermentation medium has a weight ratio of K to B of about 35:1 or more, or a weight ratio of K to Mn of about 245:1 or more, or a weight ratio of K to Mo of about 150:1 or more, or a weight ratio of K to Cu of about 245:1 or more. 
 
     
     
         9 . The fermentation process of  claim 8  wherein the fermentation medium includes at least one or more of
 at least about 112 mg of nitrogen per gram of cells, 
 at least about 10.5 mg of phosphorous per gram of cells, or 
 at least about 26 mg of potassium per gram of cells. 
 
     
     
         10 . The fermentation process of  claim 9  wherein the fermentation medium includes at least one or more of
 about 112 to about 125 mg of nitrogen per gram of cells, 
 about 10.5 to about 15 mg of phosphorous per gram of cells, 
 or about 26 to about 36 mg of potassium per gram of cell. 
 
     
     
         11 . The fermentation process of  claim 9  wherein the nitrogen is provided from a nitrogen source selected from the group consisting of ammonium chloride, ammonium phosphate, ammonium sulfate, ammonium nitrate, and mixtures thereof, the phosphorous is provided from a phosphorous source selected from the group consisting of phosphoric acid, ammonium phosphate, potassium phosphate, and mixtures thereof, and the potassium is provided from a potassium source selected from the group consisting of potassium chloride, potassium phosphate, potassium nitrate, potassium sulfate, and mixtures thereof. 
     
     
         12 . The fermentation process of  claim 8  wherein the fermentation medium includes one or more of
 at least about 2.7 mg of iron per gram of cells, 
 at least about 10 μg of tungsten per gram of cells, 
 at least about 34 μg of nickel per gram of cells, 
 at least about 9 μg of cobalt per gram of cells, 
 at least about 4.5 mg of magnesium per gram of cells, 
 at least about 11 mg of sulfur per gram of cells, and 
 at least about 6.5 μg of thiamine per gram of cells. 
 
     
     
         13 . The fermentation process of  claim 12  wherein the fermentation medium includes one or more of
 about 2.7 to about 5 mg of iron per gram of cells, 
 about 10 to about 30 μg of tungsten per gram of cells, 
 about 34 to about 40 μg of nickel per gram of cells, 
 about 9 to about 30 μg of cobalt per gram of cells, 
 about 4.5 to about 10 mg of magnesium per gram of cells, 
 about 11 to about 20 mg of sulfur per gram of cells, and 
 about 6.5 to about 20 μg of thiamine per gram of cells. 
 
     
     
         14 . The fermentation process of  claim 12  wherein the iron is provided from an iron source selected from the group consisting of ferrous chloride, ferrous sulfate, and mixtures thereof, the tungsten is provided from a tungsten source selected from the group consisting of sodium tungstate, calcium tungstate, potassium tungstate, and mixtures thereof, the nickel is provided from a nickel source selected from the group consisting of nickel chloride, nickel sulfate, nickel nitrate, and mixtures thereof, the cobalt is provided from a cobalt source selected from the group consisting of cobalt chloride, cobalt fluoride, cobalt bromide, cobalt iodide, and mixtures thereof, the magnesium is provided from a magnesium source selected from the group consisting of magnesium chloride, magnesium sulfate, magnesium phosphate, and the sulfur is provided from a sulfur source selected from the group consisting of cysteine, sodium sulfide, and mixtures thereof. 
     
     
         15 . The fermentation process of  claim 8  wherein a pH of the fermentation medium is maintained in a range of about 4.2 to about 4.8. 
     
     
         16 . The fermentation process of  claim 8  wherein the syngas has a CO/CO 2  ratio of at least about 0.75. 
     
     
         17 . The fermentation process of  claim 8  wherein the fermentation includes contacting the syngas with one or more acetogenic bacteria. 
     
     
         18 . The fermentation process of  claim 17  wherein the acetogenic bacteria is selected from the group consisting of  Acetogenium kivui, Acetoanaerobium noterae, Acetobacterium woodii, Alkalibaculum bacchi  CP 11 (ATCC BAA-1772),  Blautia producta, Butyribacterium methylotrophicum, Caldanaerobacter subterraneous, Caldanaerobacter subterraneous pacificus, Carboxydothermus hydrogenoformans, Clostridium aceticum, Clostridium acetobutylicum, Clostridium acetobutylicum  P262 (DSM 19630 of DSMZ Germany),  Clostridium autoethanogenum  (DSM 19630 of DSMZ Germany),  Clostridium autoethanogenum  (DSM 10061 of DSMZ Germany),  Clostridium autoethanogenum  (DSM 23693 of DSMZ Germany),  Clostridium autoethanogenum  (DSM 24138 of DSMZ Germany),  Clostridium carboxidivorans  P7 (ATCC PTA-7827),  Clostridium coskatii  (ATCC PTA-10522),  Clostridium drakei, Clostridium ljungdahlii  PETC (ATCC 49587),  Clostridium ljungdahlii  ERI2 (ATCC 55380),  Clostridium ljungdahlii  C-01 (ATCC 55988),  Clostridium jungdahlii  0-52 (ATCC 55889),  Clostridium magnum, Clostridium pasteurianum  (DSM 525 of DSMZ Germany),  Clostridium ragsdali  P11 (ATCC BAA-622),  Clostridium scatologenes, Clostridium thermoaceticum, Clostridium ultunense, Desulfotomaculum kuznetsovii, Eubacterium limosum, Geobacter sulfarreducens, Methanosarcina acetivorans, Methanosarcina barkeri, Morrella thermoacetica, Morrella thermoautotrophica, Oxobacter pfennigii, Peptostreptococcus productus, Ruminococcus productus, Thermoanaerobacter kivui,  and mixtures thereof. 
     
     
         19 . The fermentation process of  claim 8  wherein the process is effective for providing a cell density of at least about 1.0 g/L. 
     
     
         20 . The fermentation process of  claim 8  wherein the process is effective for providing a CO conversion of at least about 5 to about 99%.