Kinetics of Whole Cells and Ethanol Production from Candida tropicalis TISTR 5306 Cultivation in Batch and Fed-batch Modes Using Assorted Grade Fresh Longan Juice

Abstract

The kinetic profiles of Candida tropicalis TISTR 5306 cultivation based on modified yeast-malt (MYM), assorted grade fresh longan juice (AsgLG) and longan solid waste extract (LSWE) medium were evaluated in 1 l batch mode. The highest ethanol concentration level (25.5 ± 0.8 g/l) and ethanol yield -Y p/s of 0.491 ± 0.017 g ethanol/g consumed substrate, dried biomass concentration level (9.44 ± 0.05 g/l) and dried biomass yield -Y x/s of 0.533 ± 0.170 g dried biomass/g consumed substrate, specific pyruvate decarboxylase (PDC) activity (0.037 ± 0.003 U/mg protein) were achieved (p ≤ 0.05) in AsgLG medium. Scores ranking strategy were employed and AsgLG medium was subsequently selected with in the highest total score (p ≤ 0.05) of 698 ± 7 at 48 h. The cultivation in fed-batch mode with three rounds of pulse feeding (PF) in 1 l AsgLG medium was carried out. The apparent highest ethanol and dried biomass concentration levels with corresponding yields relative to time zero were (28.3 ± 0.5 g/l, 0.482 ± 0.012 g/g) at 120 h of PF2 and (9.39 ± 0.04 g/l, 0.110 ± 0.001 g/g) at 192 h of PF3. The maximum specific PDC activity was 0.057 ± 0.006 U/mg protein during PF1 feeding.

Validation of mathematical model with phosphate activation effect by batch (R)-phenylacetylcarbinol biotransformation process utilizing Candida tropicalis pyruvate decarboxylase in phosphate buffer

“…Phosphate buffer also offers cost-saving advantage. Leksawasdi et al 17 proposed that utilization of phosphate buffer in a 1 kg PAC production system would maintain the cost ratio of reaction buffer to total production at 25.9%, which is much lower than a cost ratio of 94.9% for MOPS buffer 34 . Evidently, the developed PAC biotransformation model provided good fitting within the investigated range of 30/36 to 100/120 mM initial benzaldehyde/pyruvate concentration levels for partially purified C. tropicalis TISTR 5350 PDC.…”

“…Although chemocatalysts can offer the relatively high catalytic activity and selectivity for some reactions 6,7 , a number of organic compounds transformation processes still rely heavily on biocatalysts to achieve the desired level of enantioselectivity [8][9][10] . Thus, biocatalysts including enzymes, cells organelles, and whole cells in either native or artificially constructed forms 11 have been widely used in the production of both high-volume/low-value compounds such as ethanol [12][13][14][15][16][17] and low-volume/high-value chemical species including (R)-phenylacetylcarbinol (PAC) 2,15,[18][19][20][21][22][23][24] .…”

“…PAC could be produced through in vivo direct microbial transformation process with some strategies of benzaldehyde feeding using growing cells of yeasts, fungi, and bacteria [28][29][30] . This biotransformation process can be conducted in vitro by using non-viable whole cells 15,17,24 and partially purified pyruvate decarboxylase (PDC) enzyme 18,20,28,29,[31][32][33][34] . The detailed reaction mechanism of PAC biotransformation was clearly elucidated 18 (Fig.…”

Valorization of rice straw, sugarcane bagasse and sweet sorghum bagasse for the production of bioethanol and phenylacetylcarbinol

“…The results were expressed as mean ± standard error and analyses were performed with Statistical Packages for the Social Sciences (SPSS, version 17.0) using one-way analyses of variance (ANOVA). Statistical differences among means were determined using Duncan's multiple comparisons and considered signi cant at p ≤ 0.05 42,43 .…”

“…NF 200, Ankara, Turkey) at 2,822 × g for 15 min to separate supernatant and cells pellet. The cells pellet was then washed with distilled water and dried in a hot air oven (Daihan Lab Co., Ltd., Gangwon, Korea) at 105°C until a constant weight was obtained to determine the dried biomass concentration 42 . The supernatant was analyzed for pH, total soluble solids, sugars (cellobiose, glucose, xylose, arabinose), ethanol, and acetic acid concentration.…”