Influence of toluene and salinity on biosurfactant production by <i>Bacillus</i> sp.: scale up from flasks to a bench-scale bioreactor

Souza, Ellen Cristina; Vessoni-Penna, Thereza Christina; Arni, Saleh Al; Domínguez, José Manuel; Converti, Attilio; Oliveira, Ricardo Pinheiro de Souza

doi:10.1590/0104-6632.20170342s20150787

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Bioprocess Engineering • Braz. J. Chem. Eng. 34 (2) • Apr 2017 • https://doi.org/10.1590/0104-6632.20170342s20150787 copy

Influence of toluene and salinity on biosurfactant production by Bacillus sp.: scale up from flasks to a bench-scale bioreactor

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

To select the best biosurfactant producer, Pseudomonas putida, Bacillus megatherium, Bacillus licheniformis and Bacillus subtilis were cultured in flasks on media with different salinity [low salinity (LS), Bushnell-Haas (BH) and artificial sea water (SW) media] supplemented or not with toluene as a model pollutant. Toluene inhibited the growth of all microorganisms and stimulated the biosurfactant production. B. subtilis exhibited the best performance, being able to lower the surface tension (ST) in the LS medium to 65.5 mN/min in the absence of toluene, and to 46.5 mN/min in the BH medium in the presence of toluene, corresponding to ST reductions of 13.0 and 27.5 mN/m, respectively. Scaling up the process to a bench-scale fermentor, the best results were obtained in the LS medium, where B. subtilis was able to reduce the toluene concentration from 26.0 to 4.3 g/L within 12 h and ST by 17.2 mN/m within 18 h. The results of this study point out that B. subtilis is an interesting biosurfactant producer, which could be used in the bioremediation of toluene-contaminated water.

Keywords
Bioreactor; Toluene; Biosurfactant; Saline media; Bacillus subtilis; Bioremediation

Medium		LS		BH		SW
Strain	Time (h)	Biomass concentration (g/L)	ST_red (mN/m)	Biomass concentration (g/L)	ST_red (mN/m)	Biomass concentration (g/L)	ST_red (mN/m)
	48	0.11±0.01^a	5.7±0.4	0.20±0.02^f	3.5±0.5	0.52±0.03ⁱ	3.6±0.3
B. subtilis	72	0.24±0.01^e	8.4±0.5	0.28±0.01ⁱ	4.4±0.5	0.80±0.03ⁿ	4.4±0.5
	96	0.24±0.02^e	3.0±0.6	0.26±0.01^h	0.6±0.6	0.40±0.03^f	13.0±0.1
	48	0.20±0.02^d	11.8±0.3	0.60±0.03^p	0.3±0.3	0.28±0.02^b	0.8±0.2
B. licheniformis	72	0.56±0.01^j	2.1±1.4	0.62±0.03^q	2.6±0.3	0.76±0.01^m	0.4±0.3
	96	0.82±0.02^k	2.2±1.1	0.35±0.02^l	0.6±0.3	0.28±0.02^b	2.8±0.3
	48	0.28±0.02^f	0.1±0.1	0.48±0.01ⁿ	5.6±0.3	0.20±0.02^a	2.6±0.5
B. megatherium	72	0.26±0.03^ef	4.7±0.4	0.60±0.02^p	2.4±0.5	0.44±0.02^h	1.7±0.4
	96	0.34±0.02^gh	1.6±0.5	0.32±0.01^k	2.6±0.54	0.32±0.03^d	1.6±0.6
	48	0.32±0.01^g	12.4±0.8	0.60±0.02^p	16.4±0.5	1.32±0.01^q	7.6±0.3
P. putida	72	0.32±0.01^g	21.2±1.1	1.01±0.02^r	9.6±0.5	0.62±0.01^k	11.8±0.3
	96	0.36±0.02^h	7.2±1.1	0.36±0.02^l	12.4±0.4	0.72±0.03^l	3.8±0.3

Medium		LS		BH		SW
Strain	Time (h)	Biomass concentration (g/L)	ST_red (mN/m)	Biomass concentration (g/L)	ST_red (mN/m)	Biomass concentration (g/L)	ST_red (mN/m)
	48	0.16±0.02^c	23.5±0.7	0.08±0.01^a	20.5±0.7	0.34±0.03^e	21.7±0.4
B. subtilis	72	0.16±0.01^c	23.5±0.7	0.14±0.01^c	27.3±0.3	0.40±0.02^f	20.6±0.3
	96	0.11±0.01^a	22.3±0.5	0.10±0.01^b	27.5±0.5	0.40±0.02^f	23.4±0.3
	48	0.11±0.02^a	24.6±0.6	0.46±0.03^m	24.5±0.6	0.28±0.02^b	19.7±0.3
B. licheniformis	72	0.12±0.03^ab	23.3±0.5	0.26±0.02^h	24.5±0.5	0.30±0.01^c	19.7±0.4
	96	0.11±0.02^a	22.2±1.1	0.16±0.03^d	12.6±0.3	0.28±0.01^b	17.6±0.6
	48	0.14±0.03^bc	19.5±0.6	0.52±0.01^o	20.5±0.6	0.30±0.02^c	20.7±0.3
B. megatherium	72	0.12±0.03^ab	25.6±0.6	0.22±0.01^g	20.6±0.5	0.54±0.02^j	19.9±0.1
	96	0.14±0.02^bc	18.8±0.4	0.08±0.02^a	17.6±0.5	0.28±0.03^b	17.0±0.2
	48	0.48±0.02ⁱ	25.8±0.9	0.35±0.03^l	33.6±0.4	1.02±0.01^p	25.4±0.2
P. putida	72	0.12±0.02^ab	15.1±1.2	0.30±0.03^j	23.7±0.4	0.42±0.01^g	21.7±0.4
	96	0.28±0.01^f	0.8±0.3	0.18±0.01^e	21.5±0.6	0.82±0.02^o	22.0±0.3

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