Biosurfactant by <i>Serratia</i> sp. BR13816: Fermentation Optimization and Nanoemulsion Formation

Oliveira, Elisa Maria de; Sales, Victor Hugo Gomes; Dias, Elora Dannan Corrêa; Andrade, Marcelo Silva; Araújo, Raquel Silva; Borges, Wardsson Lustrino; Souza, Tiago Marcolino de

doi:10.1590/1678-4324-2024220225

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Article - Agriculture, Agribusiness and Biotechnology • Braz. arch. biol. technol. 67 • 2024 • https://doi.org/10.1590/1678-4324-2024220225 copy

Biosurfactant by Serratia sp. BR13816: Fermentation Optimization and Nanoemulsion Formation

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

The main objective of this study was to optimize the fermentation process using Serratia sp. BR13816, a bacterial isolate from Amazonian soil, and to evaluate the formation of nanoemulsions. Submerged fermentation was carried out with different carbon and nitrogen sources. Based on the emulsification index and surface tension results, we selected a hydrophobic (corn oil) and a hydrophilic (glycerol) carbon source, and a nitrogen one (urea). For fermentation using corn oil/urea greater emulsification indexes and lower surface tensions were verified at pH 8, 25 °C, and 48 h, whereas for glycerol/urea-supplemented medium the best conditions were attained at pH 7, 30 °C, and 96 h. These pre-selected factors (pH, temperature, and time) were used in a central composite rotatable design (CCRD) for an additional fermentation optimization of the two carbon/nitrogen mediums, corn oil/urea and glycerol/urea. The two best nutritional systems based on corn oil/urea and glycerol/urea were selected using a central composite rotatable design (CCRD). The mathematical models using the response surface methodology showed adequate adjustment. The best run of the experimental design for corn oil/urea (6.00% /0.60%) and glycerol/urea (3.00% /1.40%) systems presented surface tension values of 35.70 mN/m and 37.10 mN/m, respectively. The nanoemulsions produced by a low-energy method presented average sizes by dynamic light scattering varying from 453.1 nm to 667.3 nm when 0.1% of the oil was employed. Therefore, Serratia sp. BR13816 showed promising biosurfactant-producing potential for future industrial applications.

Keywords:
Natural surfactant; Serratia; Surface Tension; Response surface methodology; Nanosystems

HIGHLIGHTS

Biosurfactant producer Serratia sp. BR13816 was isolated from Amazonian soils

Experimental design approach was applied for optimization of medium components.

Nanoemulsions with the cell-free crude extracts were prepared with success.

Run	Coded Variables		Hydrophobic carbon-source (oil corn) containing system		Hydrophilic carbon source (glycerol) containing system
	Coded Variables		Hydrophobic carbon-source (oil corn) containing system		First design		Second design
	Carbon source concentration	Nitrogen source concentration	Carbon (g/L)	Nitrogen (g/L)	Carbon (g/L)	Nitrogen (g/L)	Carbon (g/L)	Nitrogen (g/L)
1	-1	-1	6.00	0.40	2.50	0.25	1.00	0.60
2	+1	-1	8.00	0.40	7.50	0.25	3.00	0.60
3	-1	+1	6.00	0.60	2.50	0.75	1.00	1.40
4	+1	+1	8.00	0.60	7.50	0.75	3.00	1.40
5	-1.41	0	5.58	0.50	1.46	0.50	0.58	1.00
6	+1.41	0	8.41	0.50	8.53	0.50	3.41	1.00
7	0	-1.41	7.00	0.35	5.00	0.15	2.00	0.43
8	0	+1.41	7.00	0.64	5.00	0.85	2.00	1.56
9	0	0	7.00	0.50	5.00	0.50	2.00	1.00
10	0	0	7.00	0.50	5.00	0.50	2.00	1.00
11	0	0	7.00	0.50	5.00	0.50	2.00	1.00
12	0	0	7.00	0.50	5.00	0.50	2.00	1.00

Run	Surface Tension (mN/m)
	Corn oil/urea system		Glycerol/urea system
			First design		Second design
	Observed	Predicted	Observed	Predicted	Observed	Predicted
1	43.4 ± 0.1	44.4	37.3 ± 0.5	37.5	39.0 ± 0.4	39.2
2	48.0 ± 0.5	45.0	38.1 ± 0.3	38.7	38.5 ± 0.3	38.2
3	35.7 ± 0.4	38.4	37.1 ± 0.4	37.5	39.8 ± 0.5	40.3
4	50.5 ± 0.5	49.2	39.5 ± 0.4	40.4	37.1 ± 0.3	37.2
5	43.5 ± 0.3	40.8	37.0 ± 0.4	36.8	40.8 ± 0.4	40.4
6	45.8 ± 0.4	48.8	40.6 ± 0.5	39.7	37.3 ± 0.3	37.5
7	42.9 ± 0.4	44.3	38.5 ± 0.4	38.2	38.4 ± 0.4	38.5
8	44.0 ± 0.5	43.0	40.1±0.5	38.4	38.9 ± 0.5	38.5
9	39.1 ± 0.5	38.8	39.4±0.4	38.5	38.3 ± 0.4	38.4
10	38.5 ± 0.6	38.8	38.7±0.4	38.5	38.4 ± 0.5	38.4
11	38.9 ± 0.4	38.8	38.4±0.5	38.5	38.1 ± 0.4	38.4
12	38.7 ± 0.4	38.8	37.3±0.3	38.5	38.6 ± 0.4	38.4

Source	DF	PC	Adj. SS	Adj. MS	F-value	P-value
Design of the corn oil/urea system
Model	5	81.59%	171.735	34.3470	5.32	0.033
Linear	2	31.26%	65.803	32.9016	5.10	0.051
C (Corn oil)	1	30.48%	64.143	64.1431	9.93	0.020
U (Glycerol)	1	0.79%	1.660	1.6602	0.26	0.630
Square	2	37.97%	79.922	39.9608	6.19	0.035
C*C	1	20.27%	58.081	58.0810	9.00	0.024
U*U	1	17.70%	37.249	37.2490	5.77	0.053
2-Way Interaction	1	12.36%	26.010	26.0100	4.03	0.092
C*U	1	12.36%	26.010	26.0100	4.03	0.092
Error	6	18.41%	38.742	6.4570	-	-
Lack-of-Fit	3	18.31%	38.542	12.8473	192.71	0.001
Pure Error	3	0.10%	0.200	0.0667	-	-
Total	11	100.00%	-	-	-	-
First design of the glycerol/urea system
Model	5	68.39%	9.58132	1.91626	2.49	0.149
Linear	2	62.76%	9.13465	4.56733	5.94	0.038
Glycerol (G)	1	53.44%	6.64514	6.64514	8.64	0.026
Urea (U)	1	9.32%	2.48951	2.48951	3.24	0.122
Square	2	1.65%	0.35667	0.17833	0.23	0.800
G*G	1	0.60%	0.00400	0.00400	0.01	0.945
U*U	1	1.05%	0.32400	0.32400	0.42	0.540
2-Way Interaction	1	3.98%	0.09000	0.09000	0.12	0.744
GL*UR	1	3.98%	0.09000	0.09000	0.12	0.744
Error	6	31.61%	4.61535	0.76922	-	-
Lack-of-Fit	3	17.37%	2.32535	0.77512	1.02	0.495
Pure Error	3	14.24%	2.29000	0.76333	-	-
Total	11	100.00%	-	-	-	-
Second design of the glycerol/urea system
Model	5	92.19%	10.0487	2.00975	14.17	0.003
Linear	2	76.18%	8.3037	4.15187	29.26	0.001
Glycerol (G)	1	76.17%	8.3023	8.30230	58.52	0.000
Urea (U)	1	0.01%	0.0014	0.00143	0.01	0.923
Square	2	4.91%	0.5350	0.26750	1.89	0.232
G*G	1	4.46%	0.5290	0.52900	3.73	0.102
U*U	1	0.45%	0.0490	0.04900	0.35	0.578
2-Way Interaction	1	11.10%	1.2100	1.21000	8.53	0.027
GL*UR	1	11.10%	1.2100	1.21000	8.53	0.027
Error	6	7.81%	0.8513	0.14188	-	-
Lack-of-Fit	3	6.62%	0.7213	0.24042	5.55	0.097
Pure Error	3	1.19%	0.1300	0.04333	-	-
Total	11	100.00%	10.9000	-	-	-

Trials (first design)	Glycerol	Urea	Surface tension (mN/m)
1	8.53	0.50	40.6
2	7.50	0.75	39.5
3	5.00	0.85	40.1
4	2.50	0.75	37.1
5	1.46	0.50	37.0

Nanoemulsions	Average Particle Size ± SD* (nm)	Polydispersity Index ± SD*	Zeta Potential ± SD* (mV)
CO-01	453.10^b ± 10.69	0.594^b ± 0.002	-47.5^a ± 1.0
CO-05	1004.47^a ± 174.61	0.765^a ± 0.033	-47.5^a ± 0.8
CO-1	791.90^a ± 153.99	0.745^a ± 0.032	-47.0^a ± 0.8
GL-01	667.43^b ± 41.52	0.532^a ± 0.123	-44.3^a ± 1.3
GL-05	930.90^a ± 49.80	0.628^a ± 0.057	-45.7^a ± 1.2
GL-1	926.97^a ± 93.70	0.660^a ± 0.084	-45.4^a ± 0.8

Instituto de Tecnologia do Paraná - Tecpar Rua Prof. Algacyr Munhoz Mader, 3775 - CIC, 81350-010 Curitiba PR Brazil, Tel.: +55 41 3316-3052/3054, Fax: +55 41 3346-2872 - Curitiba - PR - Brazil
E-mail: babt@tecpar.br

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[1] *Correspondence: elisa.oliveira@ueap.edu.br; Tel.: +55-96-99162-7006 (EMO)