Microorganisms, surfactants produced properties

Microorganisms are capable to produce a great variety of products with excellent surface-active properties. However, its use in certain applications depends on the production and purification costs for specific activities, if compared to the corresponding synthetic surfactants. Thus, the last works are concentrated in the identification of potentials surfactants, in the evaluation of their properties, and in the optimization of the fermentative processes for their production [4]. 

Most of the physicochemical investigations were carried out with surfactant foams. However, in biotechnology, protein foams in combination with surfactants play a role. The properties of these protein and protein/surfactant foams differ considerably from those of pure surfactant foams. Therefore, the results evaluated by surfactant foams can only be partially applied to protein foams. Since proteins adsorb at interfaces at very low concentrations, protein concentrations of as little as Imgl can influence foaming [2]. Protein concentration in industrial cultivation media are far above this limit, because of the high protein content of complex nutrient media and because the microorganisms produce proteins and excrete them into the cultivation medium. In this chapter model protein foams and protein/surfactant foams formed in cultivation media, and their effect on flotation of proteins and microorganisms, are discussed. The results with model protein foams are compared with those of cultivation foams. 

Biobased surfactants are surface-active compounds, which are produced extra-cellularly by microorganisms from carbon sources such as hydrocarbons, crude oil, glucose, sucrose, glycerin, olive oil or fructose. Biobased surfactants have special advantages over their chemically manufactured counterparts because of lower toxicity, biodegradability, and effectiveness at extreme conditions. In addition, they possess surface-active properties differing in many cases from synthetic surfactants. 

The question what is the natural role of microbial surfactants would appear to be of fundamental significance in microbial physiology and of practical value in designing selection methods for improved molecules. However, the question has a basic flaw. There is no reason to suspect that surfactants have one natural role. As described in this chapter, microbial surfactants have very different structures, are produced by a wide variety of microorganisms, and have very different surface properties. Thus, it will be necessary to analyze each surfactant, or group of surfactants, separately. Only then may it be possible to draw any generalizations. 

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