(750a) Glycerol Fermentation from Glucose By Osmotolerant Yeast Wickerhamomyces Anomalus

Glycerol is considered as one of the top 12 biobased platform chemicals. In the present study, Wickerhamomyces anomalus BKK11-4, an in-house isolate was used for glycerol production from glucose. The fermentation kinetics were compared with those from other commercial glycerol producers reported in literatures, i.e., Saccharomyces cerevisiaeATCC^® 64236^TM and Millerozyma farinosa ATCC^® 20210^TM. The results showed that under high initial glucose concentration present in the rich medium containing yeast extract and peptone, W. anomalus BKK11-4 consumed glucose for glycerol as the major product while S. cerevisiae ATCC 64236 and M. farinosa ATCC 20210 grew slowly and produced ethanol as the major product. Although S. cerevisiae ATCC 64236 and M. farinosa ATCC 20210 are claimed as the osmotolerant strains that possessed the ability to produce ethanol, both of them require the specific process conditions such as the operation with the presence of sulfite ions which are considered as toxic substances and required an intensive product recovery and purification steps. Further medium optimization was conducted in the shake flask fermentation. It was observed that glycerol production was enhanced with lower ethanol accumulation when cultivating W. anomalusBKK11-4 in the mineral salt medium with high glucose concentration. The effect of C:N ratio was also investigated. The results suggested that cultivating W. anomalus BKK11-4 in the mineral salt medium with the C:N ratio of 133:1 gave the final glycerol concentration of 58 g/L with the corresponding yield of 0.28 g/g that was equivalent to 55% of theoretical conversion yield. Therefore, these medium compositions were selected for further process optimization in the 7 L stirred fermentor where the agitation and aeration were varied. Glycerol production performance was improved when cultivated in the stirred fermentor as observed from no ethanol accumulation. As a result, the product yield was increased to 0.38 g/g (75% of theoretical conversion yield) with the final glycerol concentration of 70 g/L and the productivity of 0.32 g/L×h when operating the fermentor at 700 rpm and 1.0 vvm. As mentioned above, W. anomalus BKK11-4 possesses the osmotolerant characteristics as it can ferment high concentration of glucose to glycerol. In addition, its nutrient requirements seem low as it can grow and produce glycerol well in the low-cost mineral salt medium. Therefore, we can claim W. anomalus BKK11-4 as the potential glycerol producer from sugar platform.