Title: Environmental applications of the biosurfactant produced by Candida sphaerica cultivated in low-cost substrates
Author: Juliana M. Luna Raquel D. Rufino Alı´cia Maria A.T.
Jara Pedro P.F. Brasileiro Leonie A. Sarubbo
Reference: COLSUA 19594
To appear in: Colloids and Surfaces A: Physicochem. Eng. Aspects
Received date: 2-6-2014
Revised date: 4-12-2014
Accepted date: 6-12-2014
Please cite this article as: J.M. Luna, R.D. Rufino, A.M.A.T. Jara, P.P.F. Brasileiro,
L.A. Sarubbo, Environmental applications of the biosurfactant produced by Candida sphaerica cultivated in low-cost substrates, Colloids and Surfaces A: Physicochemical and Engineering Aspects (2014), http://dx.doi.org/10.1016/j.colsurfa.2014.12.014
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Ac ce pte d M an us cri pt*Graphical Abstract (for review)
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Ac ce pte d M an us cri pt
HIGHLIGHTS 1. The biosurfactant produced in bioreactor reduced the surface tension for 27 mN/m. 2. The biosurfactant yield in shake flasks was 8 g/L. 3. The biosurfactant yield in bioreactor was 21 g/L. 4. The biosurfactant demulsified 40% of motor oil in seawater. 5. The crude biosurfactant dispersed 90% of oil droplets in seawater. 6. The biosurfactant proved to be non-toxic to indigenous marine microbiota.
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Ac ce pte d M an us cri pt
Environmental applications of the biosurfactant produced by Candida sphaerica cultivated in low-cost substrates
Juliana M. Lunaa,b, Raquel D. Rufinoa,b, Alícia Maria A.T. Jaraa,b, Pedro P.F. Brasileiroa,b,
Leonie A. Sarubboa,b,* aCentro de Ciências e Tecnologia, Universidade Católica de Pernambuco, Rua do Príncipe, n. 526, Boa Vista, Cep: 50050-900, Recife-Pernambuco, Brazil bCentro de Gestão de Tecnologia e Inovação (CGTI), Rua da Praia, n.11, São José, CEP: 50000-000, Recife, Pernambuco, Brazil * Corresponding author. Tel.: +55 81 21194048; fax: +55 81 21194043.
E-mail address: firstname.lastname@example.org (L. Sarubbo)
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Ac ce pte d M an us cri pt
Surfactants are amphipathic molecules that accumulate at interfaces, decrease interfacial tensions, and form aggregate structures such as micelles. Biosurfactants constitute one of the main classes of natural surfactants produced by microorganisms, being classified in accordance with their chemical composition or microbial origin. These polymers had attracted, in the last few years, considerable interest due to biodegradable nature, low toxicity and diversity of applications. In this paper the biosurfactant from Candida sphaerica UCP 0995 grown in distilled water supplemented with 9 % ground-nut oil refinery residue plus and 9 % corn steep liquor was first produced in shake flasks and in a bioreactor. The biosurfactant decreased the surface tension of water from 72 to 25 mN/m with a yield of 8.0 g/L when produced in shake flasks while the biosurfactant produced in the bioreactor reduced the surface tension for 27 mN/m with a yield of 21 g/L after 144 h. The biosurfactant was then tested for demulsification of motor oil emulsions, showing values around 40%. The crude biosurfactant was capable of dispersing approximately 90 % of oil droplets in seawater and proved to be non-toxic to indigenous marine microbiota. The biosurfactant acted as a solubilizer of motor oil in sea water as demonstrated by the acceleration and growth of the indigenous microorganisms throughout the 30 days of cultivation. The present findings indicate the application potential of the biosurfactant produced by C. sphaerica in the oil industry as a complement to remediation processes involving contaminated water.
Keywords: biosurfactant, Candida, petroleum, emulsification, demulsification, bioremediation.
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Ac ce pte d M an us cri pt 1. Introduction
Environmental contamination caused by petroleum and oil derivative spills is a contemporary concern. Storing and transport operations of crude-oil and derivatives have been recognized as critical to controlling pollution in some countries due to the number of cases reported in which leaking tanks and pipelines led to pollution .
Demands from society and government and the issues of the environmental sustainability of the operations concerning transportation and storage of hydrocarbons have impelled the development of new product storage technologies and pipeline inspections. Also, other factors related to minimizing the release of chemicals into the environment are investigated, thus providing new incentives for researchers to develop clean products and processes as well as technologies for the treatment of areas contaminated by these contaminants [ 2 ] .
The properties of superficial and interfacial tension reduction between solids, liquids and gases make natural surfactants an important class of substances . From an environmental standpoint, this class of biomolecules, known as biosurfactants, presents a series of advantages in comparison to synthetic surfactants, such as low toxicity, biodegradability and effectiveness in a wide range of pH and temperature values .
Biosurfactants are produced by a number of microorganisms including bacteria (e.g.
Bacillus subtilis and Pseudomonas aeruginosa), yeasts (e.g. Wickerhamiella domercqiae and
Candida batistae) and some filamentous fungi (e.g. Aspergillus, Ustilago maydis and
Pseudozyma flocculosa during the growth on water-immiscible substrates . However, some microorganisms can produce biosurfactants in the presence of different types of substrates, such as carbohydrates. The use of different carbon sources changes the structure and properties of the biosurfactant produced, which can be useful in particular applications.