Statistical optimization of kojic acid production by a UV-induced mutant strain of <i>Aspergillus terreus</i>

Shakibaie, Mojtaba; Ameri, Atefeh; Ghazanfarian, Roya; Adeli-Sardou, Mahboubeh; Amirpour-Rostami, Sahar; Torkzadeh-Mahani, Masoud; Imani, Mehdi; Forootanfar, Hamid

doi:10.1016/j.bjm.2018.03.009

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Brazilian Journal of Microbiology

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Biotechnology and Industrial Microbiology • Braz. J. Microbiol. 49 (4) • Oct-Dec 2018 • https://doi.org/10.1016/j.bjm.2018.03.009 copy

Statistical optimization of kojic acid production by a UV-induced mutant strain of Aspergillus terreus

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

The ability of four Aspergillus strains for biosynthesis of kojic acid was evaluated among which Aspergillus terreus represented the highest level (2.21 g/L) of kojic acid production. Improvement kojic acid production ability of A. terreus by random mutagenesis using different exposure time to ultraviolet light (5–40 min) was then performed to obtain a suitable mutant of kojic acid production (designated as C_5-10, 7.63 g/L). Thereafter, design of experiment protocol was employed to find medium components (glucose, yeast extract, KH₂PO₄ (NH₄)₂SO₄, and pH) influences on kojic acid production by the C_5-10 mutant. A 2^5-1 fractional factorial design augmented to central composite design showed that glucose, yeast extract, and KH₂PO₄ were the most considerable factors within the tested levels (p < 0.05). The optimum medium composition for the kojic acid production by the C_5-10 mutant was found to be glucose, 98.4 g/L; yeast extract, 1.0 g/L; and KH₂PO₄, 10.3 mM which was theoretically able to produce 120.2 g/L of kojic acid based on the obtained response surface model for medium optimization. Using these medium compositions an experimental maximum Kojic acid production (109.0 ± 10 g/L) was acquired which verified the efficiency of the applied method.

Keywords:
Kojic acid; Aspergillus terreus; UV mutagenesis; Medium optimization

Variable	Component	Unit	Low level (-1)	High level (+1)
X ₁	Glucose	g/L	50	100
X ₂	Yeast extract	g/L	0.5	1
X ₃	KH₂PO₄	mM	0.5	14
X ₄	pH	-	2	5
X ₅	(NH₄)₂SO₄	g/L	0.5	2

Run	Coded levels					KA concentration (g/L)
	x ₁	x ₂	x ₃	x ₄	x ₅	Experimental	Predicted
1	-1	-1	-1	-1	+1	12.1	13.7
2	+1	-1	-1	-1	-1	12.3	16.0
3	-1	+1	-1	-1	-1	25.2	40.5
4	+1	+1	-1	-1	+1	36	51
5	-1	-1	+1	-1	-1	1.0	1.5
6	+1	-1	+1	-1	+1	10.5	2.4
7	-1	+1	+1	-1	+1	1.5	2.3
8	+1	+1	+1	-1	-1	98.2	122.5
9	+1	-1	-1	+1	-1	19.9	39.4
10	+1	-1	-1	+1	+1	12.2	19.4
11	-1	+1	-1	+1	+1	14.9	17.8
12	+1	+1	-1	+1	-1	22.2	33.5
13	-1	-1	+1	+1	+1	5	6.2
14	+1	-1	+1	+1	-1	15.6	17.1
15	-1	+1	+1	+1	-1	3.7	5.3
16	+1	+1	+1	+1	+1	9.5	15.6
17	0	0	0	0	0	15.1	24.7
18	0	0	0	0	0	16.4	24.7
19	0	0	0	0	0	28.9	24.7
20	0	0	0	0	0	10.75	24.7
21	0	0	0	0	0	28.6	24.7
22	-2	0	0	0	0	10	8.1
23	2	0	0	0	0	97	76
24	0	-2	0	0	0	14.4	8.6
25	0	+2	0	0	0	118.2	70.9
26	0	0	-2	0	0	5.2	3.5
27	0	0	2	0	0	20.3	13.8
28	0	0	0	-2	0	24.5	14.7
29	0	0	0	+2	0	19.2	14.7
30	0	0	0	0	-2	27.1	24.7
31	0	0	0	0	+2	33.5	24.7
32	0	0	0	0	0	27.4	24.7
33	0	0	0	0	0	47.5	24.7

Source of variation	Sum of square	df	Mean of square	F value	Prob > F
Model	5.35	13	0.41	24.98	<0.0001
x ₁	1.43	1	1.43	86.56	<0.0001
x ₂	0.42	1	0.42	25.35	<0.0001
x ₃	0.17	1	0.17	10.61	0.0044
x ₁ x ₂	0.095	1	0.095	5.74	0.0277
x ₁ x ₃	0.82	1	0.82	50.03	<0.0001
x ₁ x ₄	0.29	1	0.29	17.44	0.0006
x ₂ x ₄	0.29	1	0.29	17.73	0.0005
x ₂ x ₅	0.19	1	0.19	11.51	0.0032
x32	0.57	1	0.57	34.77	<0.0001
x42	0.096	1	0.096	5.82	0.0267
x12x2	0.078	1	0.078	4.71	0.0436
x12x3	0.70	1	0.70	42.44	<0.0001
x12x5	0.076	1	0.076	4.59	0.0461
Residual	0.3	18	0.016
Lack of fit	0.13	13	0.0099	0.29	0.9655
Pure error	0.17	5	0.034
Cor total^a a p < 0.001	6.44	32

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E-mail: bjm@sbmicrobiologia.org.br

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[1] Conflicts of interest

The authors declare no conflicts of interest.