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Prioritizing Wild Yeast Strains for Macroalgal Bioethanol
Production
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Conclusion
The study isolated yeast strain from 100 samples (98 fruit
sources
and 2-fermented product), and 19 strains were prioritized based
on
the growth in glucose and xylose media, with the carbohydrate
fermentation capabilities. Yeast strains CY, TY, CHY, MY
exhibited
longer exponential phase during growth kinetics. Around 21% of
yeast
strains exhibited good ethanol tolerance up to 10% NaCl
concentration. Good growth was observed at 35oC for all the
yeast
strains. Synthetic sugar fermentation produced higher ethanol
conversion efficiency for two strains CY (83.5%) and TY (94.7%).
Xylose fermentation by GVY produced 28.56% conversion
efficiency.
Yeast strains CY and TY were prioritized based on higher ethanol
conversion, ethanol, and temperature tolerance and identified as
Meyerozyma caribbica (Cashew yeast: CY) and Pichia kudriavzevii
(toddy yeast: TY). Thermotolerant yeast Pichia kudriavzevii (TY)
could withstand temperature up to 45oC and Meyerozyma caribbica
(CY)
could tolerate salt concentration up to 4% and produce highest
ethanol of 2.6g/L and achieving 88.8% fermentation efficiency,
providing basis for new insights on tolerance levels for
different
stressors by these wild yeast strains. Glucose fermentation by
CY
and TY strain produced 3.45g/L and 13.6g/L ethanol with
fermentation
efficiencies of 24.69% and 60.62%, respectively. Xylose
fermentation
was achieved by CY strain producing 1.43g/L of ethanol with
10.45%
fermentation efficiency exhibiting xylose-fermenting
capabilities,
whereas TY strain was seen efficient in fermenting the
macroalgal
sugars. The cellulolytic nature of the prioritized yeast strain
revealed its activity through consolidated bioprocess.
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Citation : Hebbale, D., Mishra, R.S. & Ramachandra, T.V. 2021.
Prioritizing Wild Yeast Strains for Macroalgal Bioethanol Production. Bioenerg. Res.
(2021). https://doi.org/10.1007/s12155-021-10283-3
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