title: Selection and characterization of a newly isolated thermotolerant Pichia kudriavzevii strain for ethanol production at high temperature from cassava starch hydrolysate.
abstract: Pichia kudriavzevii DMKU 3-ET15 was isolated from traditional fermented pork sausage by an enrichment technique in a yeast extract peptone dextrose (YPD) broth, supplemented with 4 % (v/v) ethanol at 40 °C and selected based on its ethanol fermentation ability at 40 °C in YPD broth composed of 16 % glucose, and in a cassava starch hydrolysate medium composed of cassava starch hydrolysate adjusted to 16 % glucose. The strain produced ethanol from cassava starch hydrolysate at a high temperature up to 45 °C, but the optimal temperature for ethanol production was at 40 °C. Ethanol production by this strain using shaking flask cultivation was the highest in a medium containing cassava starch hydrolysate adjusted to 18 % glucose, 0.05 % (NH(4))(2)SO(4), 0.09 % yeast extract, 0.05 % KH(2)PO(4), and 0.05 % MgSO(4)·7H(2)O, with a pH of 5.0 at 40 °C. The highest ethanol concentration reached 7.86 % (w/v) after 24 h, with productivity of 3.28 g/l/h and yield of 85.4 % of the theoretical yield. At 42 °C, ethanol production by this strain became slightly lower, while at 45 °C only 3.82 % (w/v) of ethanol, 1.27 g/l/h productivity and 41.5 % of the theoretical yield were attained. In a study on ethanol production in a 2.5-l jar fermenter with an agitation speed of 300 rpm and an aeration rate of 0.1 vvm throughout the fermentation, P. kudriavzevii DMKU 3-ET15 yielded a final ethanol concentration of 7.35 % (w/v) after 33 h, a productivity of 2.23 g/l/h and a yield of 79.9 % of the theoretical yield.
authors.affiliation: Department of Microbiology, Faculty of Science, Kasetsart University, Bangkok, 10900, Thailand.
authors.forename: Napatchanok
authors.initials: N
authors.lastname: Yuangsaard
authors.forename: Wichien
authors.initials: W
authors.lastname: Yongmanitchai
authors.forename: Mumoru
authors.initials: M
authors.lastname: Yamada
authors.forename: Savitree
authors.initials: S
authors.lastname: Limtong
mesh_terms: D003470:Culture Media / Q000737:chemistry; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D000431:Ethanol / Q000378:metabolism*; D005516:Food Microbiology; D020459:Genes, rRNA; D006358:Hot Temperature; D002365:Manihot / Q000378:metabolism*; D008969:Molecular Sequence Data; D016533:Mycological Typing Techniques; D010843:Pichia / Q000302:isolation & purification* / Q000378:metabolism*; D012331:RNA, Fungal / Q000235:genetics; D012335:RNA, Ribosomal / Q000235:genetics; D017422:Sequence Analysis, DNA; D013213:Starch / Q000378:metabolism*
chemical_list: D003470:Culture Media; D004271:DNA, Fungal; D004275:DNA, Ribosomal; D012331:RNA, Fungal; D012335:RNA, Ribosomal; C065096:RNA, ribosomal, 26S; D000431:Ethanol; D013213:Starch