(582h) Production of Biosurfactant By a Microorganism Isolated From a Brazilian Mangrove: Influence of Oxygen Transfer On the Bioreactor

The aim of this work is to evaluate the agitation and oxygen rate, on order of optimize the biosurfactant production for a scale-up operation. Biosurfactants are surface-active agents which are amphiphilic biological compounds produced extracellularly or as part of the cell membrane by a variety of yeast, bacteria and filamentous fungi.  Advantageously they can be produced from renewable resource substrates or industrial waste products. One of the most important properties of biosurfactants is the reduction of surface tension. These materials show low critical micelle concentration (CMC) values, surface tension reduction of the fermentation broth to less than 30 mN/m, and interfacial tension below 1 mN/m. In addition, several biosurfactants have been reported to have manifold biological activities covering antibiotics, fungicides, insecticides, antiviral and antitumoral agents, immunomodulators or specific toxins or enzyme inhibitors, which make them also interesting for pharmaceutical applications. In comparison to their chemically synthesized equivalents they have many advantages. They are environmentally friendly, biodegradable, less toxic and non-hazardous. They have better foaming properties and higher selectivity. They are active at extreme temperatures, pH and salinity as well, and can be produced from industrial wastes and from by-products. This last feature makes cheap production of biosurfactants possible and allows utilizing waste substrates and reducing their polluting effect at the same time. Nevertheless, one of the major obstacles in the biosurfactant commercial production is high production costs. However, the cost can be reduced by strain improvement, medium composition optimization by statistical methods, using alternative inexpensive substrates, or through the bioreactor operation and design. There is a lack of fundamental knowledge about biosurfactant production scaling up. The most utilized criterion in scaling up of aerobic fermentations is maintaining similarity between the volumetric oxygen transfer coefficient (KLa) at both analyzed systems. In order to develop suitable technology of commercialization, carrying out tests in bioreactors is essential. Therefore, a reactor with an integrated foam collector was designed for biosurfactant production using a microorganism (ICA 56) isolated from a brazilian mangrove. Previous works have showed that the aeration rate and agitation increases the oxygen transfer on the bioreactor, favoring biosurfactant production by a Bacillus strain. At 200 rpm and 1 L.min^-1 O₂, the biosurfactant production was around 200 mg/L, and the surface tension of the foam collected was about 30 dyna.cm^-1.