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Studies addressing for ecological compatible products have been increased along time, especially, on biosurfactant field. Biosurfactants are extracellular amphiphilic compound that are mainly produced by microorganisms and are classified into five main groups, including the glycolipids one. Rhamnolipids are included in the latter and are anionic biosurfactants produced predominantly by Pseudomonas aeruginosa being classified as mono- and di-rhamnolipids. In addition, their production may occur from different carbon sources, which may be obtained from renewable and low-cost residue. Therefore, it is possible to reduce the rhamnolipids production cost, since this has been the main bottleneck for replacing the chemical surfactants. In addition, to meeting a bona fide industrial application some limitations such as low productivity as well as recovery and/or purification that represent from 60 to 80% of total production cost should be improved. Therefore, this review covers different ways for producing rhamnolipids covering their application in many fields such as pharmaceutical, agricultural, petrochemical and so on; demonstrating the versatility of these biological compounds.

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The improvement of biotechnological processes capable of transforming agro-industrial waste into products with high added value has stood out in the area of renewable energies, promoting positive impacts to the environment. Thus, the present work evaluated the influence of nickel on the conversion of fermentable sugars, present in the green coconut shell hydrolyzate (GCSH), into butanol and other products. Fermentation assays were performed at 37 °C, starting with 19.4 g.L-1 of sugars and 1.0 g.L-1 of inoculum (C. beijerinckii). The GCSH was supplemented with tryptone, yeast extract, ammonium acetate, minerals and phosphate buffer. Two conditions were tested: with and without addition of nickel. Concentrations of sugars (glucose and xylose), intermediate products (organic acids), acetone, butanol, and ethanol were determined by high performance liquid chromatography (HPLC). The results show that the butanol production was higher from GCSH without addition of nickel, reaching a concentration of 2.14 g.L-1 of butanol. Therefore, the presence of nickel in the hydrolyzate was not favorable in the production of butanol under the studied process conditions.

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