Evaluation of cell disruption for partial isolation of intracellular pyruvate decarboxylase enzyme by silver nanoparticles method

Abstract

Candida tropicalis TISTR 5350 was used in the comparison of seven concentration levels of silver nanoparticles (0, 5, 10, 15, 20, 25, and 30 μg ml -1 ) for cell disruption methods. The optimized cell disruption strategy was selected based on the optimal protein yield and biological activity. The maximum volumetric and specifi c pyruvate decarboxylase (PDC, EC 4.1.1.1) activities (0.53±0.05 U ml -1 and 0.17±0.02 U mg -1 protein, respectively) were observed at 15 μg ml -1 silver nanoparticles. The silver nanoparticle concentration level of 15 μg ml -1 was investigated further by comparing the reaction mixtures at different time intervals of 0, 1, 2, 3, 4, 5, and 6 min. The result showed that the highest specifi c PDC activity of 0.39±0.01 U mg -1 protein was obtained from mixing for 3 min. This was not signifi cantly different (P≤0.05) from other mixing time intervals.

Batch and continuous cultivation processes of Candida tropicalis TISTR 5306 for ethanol and pyruvate decarboxylase production in fresh longan juice with optimal carbon to nitrogen molar ratio

“…The cultivation of C. tropicalis TISTR 5306 in FLJ‐C with supplemented AMS and C/N molar ratio of 39.07 ± 0.54 would yield a lower specific PDC activity of 0.049 ± 0.005 U/mg (Nunta et al, ). This was equivalent to 12.6 ± 1.3% of reported specific PDC activity by Tangtua et al () who employed a much more expensive (193.4 ± 0.4 times costlier in term of nitrogen source being used) YM medium. The lower C/N molar ratios in the range of 15.88 ± 0.21–21.88 ± 0.20 from the current study generated higher scores of ethanol concentration by only 9.8–12.0% but the specific PDC activity scores were higher by 59.9–64.7% when compared with C/N molar ratio of 39.07 ± 0.54 (Nunta et al, ) as shown in Table .…”

“…In fact, this score was not significantly different (p > .05) from the cultivation medium with C/N molar ratio of 15.88 ± 0.21 which even utilized higher quantity of AMS by 35.2 ± 0.7%. In addition, the C/N molar ratio of 21.88 ± 0.20 also yielded 35.4 ± 0.9% of reported specific PDC activity by Tangtua et al (2015) and 2.81 ± 0.30 times improvement in specific PDC activity reported by Nunta et al (2018). These should be sufficient to counteract the rising AMS cost of only 1.41 ± 0.01 times that utilized previously by Nunta et al (2018).…”

“…However, this specific PDC activity was only directly related to PAC production and did not necessarily reflect the level of ethanol or dried biomass concentration being produced. Tangtua et al () reported the highest specific PDC activity of 0.39 ± 0.01 U/mg when cultivated whole cells of C. tropicalis TISTR 5350 from YM medium was disrupted by 15 μg/ml silver nanoparticle for 3 min. Further purification process of PDC crude extract (0.62 ± 0.03–0.98 ± 0.04 U/mg) from Tangtua et al () by a cold 60% (vol/vol) acetone precipitation technique yielded the highest specific PDC activity of 2.00 ± 0.10 U/mg (Tangtua et al, ).…”

“…Tangtua et al () reported the highest specific PDC activity of 0.39 ± 0.01 U/mg when cultivated whole cells of C. tropicalis TISTR 5350 from YM medium was disrupted by 15 μg/ml silver nanoparticle for 3 min. Further purification process of PDC crude extract (0.62 ± 0.03–0.98 ± 0.04 U/mg) from Tangtua et al () by a cold 60% (vol/vol) acetone precipitation technique yielded the highest specific PDC activity of 2.00 ± 0.10 U/mg (Tangtua et al, ). In addition, Khemacheewakul et al () discovered that 1 M phosphate buffer could provide a better activation effect to specific PDC activity of C. tropicalis TISTR 5350 than 20 mM phosphate buffer by 9,050 times.…”

“…also revealed that microorganisms capable of producing ethanol such as S. cerevisiae (TISTR 5606) and C. tropicalis (TISTR 5306 and 5350) would possess certain levels of specific PDC carboligase activity. However, this specific PDC activity was only directly related to PAC production and did not necessarily reflect the level of ethanol or dried biomass concentration being produced Tangtua et al (2015). reported the highest specific PDC activity of 0.39 ± 0.01 U/mg when cultivated whole cells of C. tropicalis TISTR 5350 from YM medium was disrupted by 15 μg/ml silver nanoparticle for 3 min.…”