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Biosurfactant Production by Bacillus salmalaya for Lubricating Oil Solubilization and Biodegradation.

Dadrasnia A, Ismail S - Int J Environ Res Public Health (2015)

Bottom Line: The biosurfactant exhibited a high emulsification index and a positive result in the drop collapse test, with the results demonstrating the wetting activity of the biosurfactant and its potential to produce surface-active molecules.Furthermore, the biosurfactant demonstrated high stability at different ranges of salinity, pH, and temperature.Overall, the results indicated the potential use of B. salmalaya 139SI in environmental remediation processes.

View Article: PubMed Central - PubMed

Affiliation: Department of Biohealth Science, Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia. are.dadrasnia@gmail.com.

ABSTRACT
This study investigated the capability of a biosurfactant produced by a novel strain of Bacillus salmalaya to enhance the biodegradation rates and bioavailability of organic contaminants. The biosurfactant produced by cultured strain 139SI showed high physicochemical properties and surface activity in the selected medium. The biosurfactant exhibited a high emulsification index and a positive result in the drop collapse test, with the results demonstrating the wetting activity of the biosurfactant and its potential to produce surface-active molecules. Strain 139SI can significantly reduce the surface tension (ST) from 70.5 to 27 mN/m, with a critical micelle concentration of 0.4%. Moreover, lubricating oil at 2% (v/v) was degraded on Day 20 (71.5). Furthermore, the biosurfactant demonstrated high stability at different ranges of salinity, pH, and temperature. Overall, the results indicated the potential use of B. salmalaya 139SI in environmental remediation processes.

No MeSH data available.


Related in: MedlinePlus

(A) Surface tension reduction and time course of cell growth in brain–heart infusion (BHI) medium. (B) Surface tension versus concentration of biosurfactant produced by B. salmalaya 139SI. Vertical bars indicate SE (n = 3).
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ijerph-12-09848-f001: (A) Surface tension reduction and time course of cell growth in brain–heart infusion (BHI) medium. (B) Surface tension versus concentration of biosurfactant produced by B. salmalaya 139SI. Vertical bars indicate SE (n = 3).

Mentions: Drop collapse and oil spreading techniques were used because of their low cost, simplicity, and quick implementation. The positive result obtained in the drop collapse test revealed the wetting activity of the biosurfactant and its potential to produce surface-active molecules. The oil displacement test is an index to predict the surfactant production caused by the decrease in the oil-water interfacial tension [2], and the area of oil displacement (75 cm2) indicated high activity of the biosurfactant produced by B. salmalaya 139SI. The emulsification index (% E24) of 139SI decreased at low pH, and the highest emulsification (65 ± 1.1%) was observed between pH 5 and 8. Cunha et al., [17] used gasoline as a carbon source to produce a biosurfactant during fermentation at pH 6.0. Each microorganism is adapted to a specific pH, depending on the relevant type of biosurfactant, and such specificity facilitates the bioavailability of organic compounds to bacteria, accelerating hydrocarbon degradation. Additionally, the emulsion activity of strain 139SI was stable for two weeks at room temperature. The profiles of biomass at 600 nm and ST during five days of incubation time are shown in Figure 1A; growth was carried out at 32 °C and 150 rpm. The ST of the biosurfactant rapidly decreased after cultivation and became constant after 48 h (36.5 mN/m). Maximum growth was observed after two days, followed by a steady decrease until the end of the incubation (120 h). Furthermore, several authors have reported that the fluid ST did not vary once micelle formation began. Ruggeri et al., [18] indicated that quantitative analyses, including ST determination, are reliable methods for determining the solubility of biosurfactants in media. If ST is reduced to <40 mN/m and/or at least 50% emulsification is observed after 24 h, the strain can be considered to be a biosurfactant producer. Nitschke and Pastore [19] reported that B. subtilis is one of the most effective Bacillus species in this regard because it can reduce ST from 72 to 27 mN/m. In the present study, B. salmalaya 139SI showed positive results in all the quantitative tests. The carbohydrate and protein contents of strain 139SI were 0.72 g/L and 1.9 g/L, respectively.


Biosurfactant Production by Bacillus salmalaya for Lubricating Oil Solubilization and Biodegradation.

Dadrasnia A, Ismail S - Int J Environ Res Public Health (2015)

(A) Surface tension reduction and time course of cell growth in brain–heart infusion (BHI) medium. (B) Surface tension versus concentration of biosurfactant produced by B. salmalaya 139SI. Vertical bars indicate SE (n = 3).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4555315&req=5

ijerph-12-09848-f001: (A) Surface tension reduction and time course of cell growth in brain–heart infusion (BHI) medium. (B) Surface tension versus concentration of biosurfactant produced by B. salmalaya 139SI. Vertical bars indicate SE (n = 3).
Mentions: Drop collapse and oil spreading techniques were used because of their low cost, simplicity, and quick implementation. The positive result obtained in the drop collapse test revealed the wetting activity of the biosurfactant and its potential to produce surface-active molecules. The oil displacement test is an index to predict the surfactant production caused by the decrease in the oil-water interfacial tension [2], and the area of oil displacement (75 cm2) indicated high activity of the biosurfactant produced by B. salmalaya 139SI. The emulsification index (% E24) of 139SI decreased at low pH, and the highest emulsification (65 ± 1.1%) was observed between pH 5 and 8. Cunha et al., [17] used gasoline as a carbon source to produce a biosurfactant during fermentation at pH 6.0. Each microorganism is adapted to a specific pH, depending on the relevant type of biosurfactant, and such specificity facilitates the bioavailability of organic compounds to bacteria, accelerating hydrocarbon degradation. Additionally, the emulsion activity of strain 139SI was stable for two weeks at room temperature. The profiles of biomass at 600 nm and ST during five days of incubation time are shown in Figure 1A; growth was carried out at 32 °C and 150 rpm. The ST of the biosurfactant rapidly decreased after cultivation and became constant after 48 h (36.5 mN/m). Maximum growth was observed after two days, followed by a steady decrease until the end of the incubation (120 h). Furthermore, several authors have reported that the fluid ST did not vary once micelle formation began. Ruggeri et al., [18] indicated that quantitative analyses, including ST determination, are reliable methods for determining the solubility of biosurfactants in media. If ST is reduced to <40 mN/m and/or at least 50% emulsification is observed after 24 h, the strain can be considered to be a biosurfactant producer. Nitschke and Pastore [19] reported that B. subtilis is one of the most effective Bacillus species in this regard because it can reduce ST from 72 to 27 mN/m. In the present study, B. salmalaya 139SI showed positive results in all the quantitative tests. The carbohydrate and protein contents of strain 139SI were 0.72 g/L and 1.9 g/L, respectively.

Bottom Line: The biosurfactant exhibited a high emulsification index and a positive result in the drop collapse test, with the results demonstrating the wetting activity of the biosurfactant and its potential to produce surface-active molecules.Furthermore, the biosurfactant demonstrated high stability at different ranges of salinity, pH, and temperature.Overall, the results indicated the potential use of B. salmalaya 139SI in environmental remediation processes.

View Article: PubMed Central - PubMed

Affiliation: Department of Biohealth Science, Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur 50603, Malaysia. are.dadrasnia@gmail.com.

ABSTRACT
This study investigated the capability of a biosurfactant produced by a novel strain of Bacillus salmalaya to enhance the biodegradation rates and bioavailability of organic contaminants. The biosurfactant produced by cultured strain 139SI showed high physicochemical properties and surface activity in the selected medium. The biosurfactant exhibited a high emulsification index and a positive result in the drop collapse test, with the results demonstrating the wetting activity of the biosurfactant and its potential to produce surface-active molecules. Strain 139SI can significantly reduce the surface tension (ST) from 70.5 to 27 mN/m, with a critical micelle concentration of 0.4%. Moreover, lubricating oil at 2% (v/v) was degraded on Day 20 (71.5). Furthermore, the biosurfactant demonstrated high stability at different ranges of salinity, pH, and temperature. Overall, the results indicated the potential use of B. salmalaya 139SI in environmental remediation processes.

No MeSH data available.


Related in: MedlinePlus