Development of xylose-fermenting yeast Pichia stipitis for ethanol production through adaptation on hardwood hemicellulose acid prehydrolysate.
OBJECTIVE
The objective of this study was to develop a mutant from Pichia stipitis NRRL Y-7124, tolerant of high concentrations of acetic acid and other inhibitory components present in acid hydrolysates, to improve ethanol yield and productivity.


RESULTS
The mutant was developed through adaptation in acid hydrolysate supplemented with nutrients and minerals at 30 +/- 0.5 degrees C. When it was tested for its ability to ferment acid hydrolysate, it showed shorter fermentation time, better tolerance to acid and could ferment at lower pH. The ethanol yield (Yp/s) and productivity (Qp) were increased 1.6- and 2.1-fold, respectively.


CONCLUSIONS
The development of a mutant and its tolerance to acetic acid present in hydrolysates is described. The selected mutant is capable of fermenting both hexoses and pentoses present in hydrolysate at lower pH in comparison with the parent strain.


CONCLUSIONS
The mutant could play a significant role in reducing environmental pollution by using sugars present in pulp mill effluent and, at the same time, could produce a marketable liquid fuel ethanol.
Nigam
J N
JN
Biochemistry Division, Regional Research Laboratory, Jorhat 785 006, Assam, India. jnnbio@yahoo.com
D019342:Acetic Acid / Q000494:pharmacology*; D000222:Adaptation, Physiological; D002482:Cellulose / Q000737:chemistry; D003470:Culture Media; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation / Q000187:drug effects; D006868:Hydrolysis; D009154:Mutation; D010843:Pichia / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D013464:Sulfuric Acids / Q000737:chemistry; D014197:Trees; D014994:Xylose / Q000378:metabolism*
D003470:Culture Media; D013464:Sulfuric Acids; D000431:Ethanol; D002482:Cellulose; D014994:Xylose; C033158:sulfuric acid; D019342:Acetic Acid