Table 2.

Effect of nitrogen sources on citric acid production by Candida tropicalis (F value= 107.536.) and Pichia kluyveri (F value = 44.401).

Nitrogen sources	Yeast isolates
	Candida tropicalis			Pichia kluyveri
	Citric acid (g/L)	Biomass (g/L)	Glucose consumed (%)	Citric acid (g/L)	Biomass (g/L)	Glucose consumed (%)
Diammonium hydrogen phosphate	40.90 ± 0.73	8.90 ± 0.79	82.96 ± 0.90	23.10 ± 0.92	9.36 ± 0.48	66.03 ± 0.58
Ammonium dihydrogen phosphate	30.60 ± 0.78	5.40 ± 0.51	65.60 ± 0.45	11.33 ± 0.98	8.36 ± 0.35	60.83 ± 0.99
Ammonium chloride	50.53 ± 0.83	11.40 ± 0.62	94.54 ± 0.92	26.56 ± 0.43	10.90 ± 0.37	71.50 ± 0.56
Ammonium ferrous sulfate	24.40 ± 0.72	6.43 ± 0.56	45.46 ± 0.64	14.66 ± 0.49	7.30 ± 0.52	30.43 ± 0.75
Urea	21.83 ± 0.58	3.43 ± 0.35	36.23 ± 0.84	8.43 ± 0.43	4.26 ± 0.17	22.10 ± 0.80
Ammonium phosphate monobasic	37.13 ± 0.72	9.16 ± 0.43	62.33 ± 0.99	17.36 ± 0.35	6.30 ± 0.47	37.16 ± 0.89
Ammonium sulfate	41.52 ± 0.46	10.53 ± 0.76	88.90 ± 0.46	35.40 ± 0.46	11.46 ± 0.40	81.56 ± 0.10

Mean ± standard error (n = 3) were presented.