Biodegradation of caffeine by whole cells of tea-derived fungi Aspergillus sydowii, Aspergillus niger and optimization for caffeine degradation

Table 7 Comparison of the kinetic parameters for caffeine degradation in tea infusion fermentation (30 °C, 15d, natural pH)^a

Strains or treatments	Fungal dry mass (g)	C_caffeine,0 (mg/L)	C_caffeine,f (mg/L)	C_{theophylline,f} (mg/L)	Q_caffeine (mg/L d)	Q_theophylline (mg/L d)	Y_{theophylline/caffeine}	% of caffeine degraded
A. sydowii NRRL250	0.19 ± 0.02^A	1082.9 ± 65.8^A	157.8 ± 10.2^A	501.2 ± 13.5^C	61.7 ± 5.0^B	31.8 ± 0.8^B	0.52 ± 0.05^B	85.4 ± 1.7^B
A. niger NCBT110A	0.24 ± 0.01^B	1085.3 ± 64.8^A	1248.1 ± 30.5^D	27.2 ± 0.8^A	ND	ND	ND	ND
Natural treatment	0.20 ± 0.02^A	1073.9 ± 78.6^A	817.6 ± 8.6^B	74.7 ± 3.3^B	17.1 ± 5.14^A	3.3 ± 0.1^A	0.21 ± 0.06^A	23.6 ± 5.3^A
Control	ND	1101.6 ± 89.5^A	1096.4 ± 33.2^C	25.0 ± 2.1^A	ND	ND	ND	ND

^aAll kinetic parameters were calculated according to Sirisansaneeyakul and others (2013) [34]
All data are presented as mean ± SD, ^A-Dp < 0.05 in the same column
Concentrations of caffeine, theophylline and 3-methylxanthine determined by HPLC
C_caffeine,0 initial caffeine concentration (mg/L), C_caffeine,f the final caffeine concentration (mg/L), C_{theophylline,f} the final theophylline concentration (mg/L) Q_caffeine the volumetric rate of caffeine degradation (mg/L d), Q_theophylline the volumetric rate of theophylline production (mg/L d), Y_{theophylline/caffeine} theophyline yield on caffeine (mg/mg), ND not determined

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