Production of a biosurfactant by Bacillus subtilis ICA56 aiming bioremediation of impacted soils

• B. subtilis ICA56 isolated from a Brazilian mangrove produced an effective tensoative.
• The biosurfactants were stable under extreme conditions (pH, temperature and salinity).
• It was capable to remove hydrocarbons and heavy metals from contaminated systems.
• The biosurfactant presented low toxicity.
• Biosurfactant concentration was 1.29 g L−1 when glycerol was used as substrate.

This work aimed to study the production of a biosurfactant by a new strain of Bacillus subtilis ICA56 isolated from a Brazilian mangrove and to evaluate its functional properties and applicability for bioremediation. The use of agro-industrial wastes (glycerol, sunflower oil, cheese whey and cashew apple juice) as alternative substrates for biosurfactant production was tested as this may lead to a reduction in the cost of the bioprocess. Glycerol was the best carbon source yielding 1290 mg L−1 of crude biosurfactant. The critical micellar concentration of the crude biosurfactant produced by ICA56 was 25 mg L−1 and, at this concentration, it was able to reduce the surface tension of the water from 72 to 30 mN m−1 and to reduce the interfacial tension on a water/gasoline system from 15 to 3 mN m−1. Furthermore, the crude biosurfactant retained its tensoative properties in a broad range of pH, temperature and salinity and it was not toxic to Artemia salina. In this work, model experiments were conducted to simulate the removal of hydrocarbons and heavy metals from contaminated environmental systems in the laboratory by the crude biosurfactant produced by ICA56. Results showed that it was very efficient, highlighting its potential for bioremediation.

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