Biomolecules from Natural Sources. Группа авторов

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Figure 1.1 The chemical structures of the most common glycolipids.

      The amphiphilic character triggers them to aggregate at liquid interfaces with different degrees of polarity and hydrogen bridges, giving them the ability to reduce surface- and interfacial-tension between solids, liquids and gases.

      Furthermore most biosurfactants exhibit characteristics such as tolerance to pH, temperature and ionic strength, biodegradability, low toxicity, detergency, emulsification, de-emulsification and foaming. There is considerable interest in potential applications, due to their environmental friendly character and sustainability (Geys et al. 2014; Makkar et al. 2011; Santos et al. 2016; Smyth et al. 2010). Nowadays the preservation of the Earth as a sustainable planet is one of humanities greatest concerns. In line with this concern about the environment, many industries are changing to a global viewpoint on the future of manufacturing. In fact, they have recognized the potential of living cells in the pre-treatment of raw materials, processing operations, product modifications, selective waste management, energy recycling and conservation.

      Biosurfactants are quite adaptable, their performance is versatile in a wide range of applications, in different areas, such as pharmaceutics, cosmetics, agronomy, food, beverages, metallurgy, agrochemicals, organic chemicals, petrochemicals, fertilizers, and others (Abdel-Mawgoud and Stephanopoulos 2018). The main applications in the pharmaceutical field are as anti-microbial, anti-cancer, anti-viral and anti-adhesive agents, immunological adjuvants, and in drug and gene delivery (Abdel-Mawgoud and Stephanopoulos 2018).

      1.1.1 Application of Biosurfactants

      The most commonly used surfactants are chemically produced from petroleum, these synthetic derived agents are generally toxic and not biodegradable. This problem motivates the search for more environmentally friendly surfactants, such as biosurfactants produced by microorganisms, which provides a wide range of applications (Santos et al. 2016; Vijayakumar and Saravanan 2015).

      Biosurfactants have several advantages over petroleum based surfactants, such as structural diversity, low toxicity, greater biodegradability, the ability to function in wide ranges of pH, temperature and salinity, as well as greater selectivity, lower protein denaturing potency and lower critical micellar concentration (CMC). The wide range of industrial applications include the field of petroleum industry as well as bioremediation, agricultural, food processing, health, chemical, and cosmetic industries (Abdel-Mawgoud and Stephanopoulos 2018; Santos et al. 2016). The following sections present an overview of the most investigated application fields for biosurfactants.

      1.1.1.1 Petroleum Industry

      The major accruing market for biosurfactants is currently the petroleum industry, which offers different applications for them (Santos et al. 2016).

      Petroleum, also known as crude oil is a natural energy source found beneath the earth´s surface. It is a resource that is in great demand, and has become the leading raw material for development and the economy in the past century. It basically consists of two to three phases (liquid/solid and gas), the industry uses several mechanisms to separate these (Almeida et al. 2016). Biosurfactants have shown promising applications in this industry, such as extraction, transportation or petrochemical manufacturing (Makkar et al. 2011).

Approximately 50–65% of oil residues are found in porous rocks, caused by high forces of capillarity, interfacial tension between the aqueous and the hydrocarbon phases and the high viscosity of the crude oil. These residues can often not be recovered by conventional oil recovery methods (Almeida et al. 2016; Santos et al. 2016). Biosurfactants can lower the interfacial tension between oil/rock and oil/water interfaces, in that way the oil-recovery can be enhanced. A mixture containing the producing microorganism can be injected into the porous rock, which will be sealed for a certain time to allow microbial growth. Therefore, the production of biosurfactants allows the breakdown of the oil film in the rocks and oil flow can be re-established. Experiments have shown that the use of indigenous microorganisms Arthobacter sp, Pseudomonas sp and Bacillus sp resulted in a reduction of paraffin from 29.8 to 25.5 % in 9 months (Bachmann et al. 2014).

      Because of their amphipilic structure, biosurfactants have highly emulsifying properties which are important for the extraction of oil, to form stable water–oil emulsions (Bachmann et al. 2014).

      1.1.1.2 Bioremediation

      Oil spills during the СКАЧАТЬ