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Table 6 Comparison of the kinetic parameters for caffeine degradation in different pH (1200 mg/L of caffeine, 30 °C,15d.)a

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

pH

Fungal dry mass (g)

Ccaffeine,f (mg/L)

Ctheophylline,f (mg/L)

C3-methylxanthine,f (mg/L)

Qcaffeine

(mg/L d)

Qtheophylline

(mg/L d)

Ytheophylline/caffeine

% of caffeine degraded

5

0.14 ± 0.01A

508.5 ± 45.4C

245.3 ± 17.5A

87.8 ± 12.5A

46.1 ± 3.0A

16.4 ± 1.2A

0.35 ± 0.01A

57.6 ± 3.8A

6

0.22 ± 0.02B

41.7 ± 5.9A

776.5 ± 35.8C

125.1 ± 10.9B

77.2 ± 0.4C

51.8 ± 2.4C

0.67 ± 0.03C

96.5 ± 0.5C

7

0.22 ± 0.03B

105.0 ± 16.9B

549.4 ± 29.3B

178.7 ± 10.8C

73.0 ± 1.1B

36.6 ± 2.0B

0.50 ± 0.03B

91.3 ± 1.4A

  1. aAll kinetic parameters were calculated according to Sirisansaneeyakul and others (2013) [34]
  2. All data are presented as mean ± SD, A-Cp < 0.05 in the same column
  3. Concentrations of caffeine, theophylline and 3-methylxanthine determined by HPLC
  4. C caffeine,f the final caffeine concentration (mg/L), Ctheophylline,f the final theophylline concentration (mg/L), C3-methylxanthine,f the final 3-methylxanthine 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)