%0 Journal Article
%T Biosurfactant-Producing Lactobacilli: Screening, Production Profiles, and Effect of Medium Composition
%A Eduardo J. Gudi£¿a
%A Jos¨¦ A. Teixeira
%A L¨ªgia R. Rodrigues
%J Applied and Environmental Soil Science
%D 2011
%I Hindawi Publishing Corporation
%R 10.1155/2011/201254
%X Biosurfactant production was screened in four lactobacilli strains. The highest biosurfactant production (excreted and cell-bound biosurfactants) was achieved with Lactobacillus paracasei ssp. paracasei A20, a strain isolated from a Portuguese dairy plant, with a decrease in the surface tension of 6.4£¿mN£¿m£¿1 and 22.0£¿mN£¿m£¿1, respectively. Biosurfactant production by this strain was evaluated under different culture broth compositions. The use of different nitrogen sources revealed that yeast extract is essential for bacterial growth, while peptone is crucial for biosurfactant synthesis. For biosurfactant production, the use of peptone and meat extract yielded a higher production when compared to the standard medium, with a surface tension reduction of 24.5£¿mN£¿m£¿1. Furthermore, experiments were also conducted in a reactor with pH and temperature control. Biomass and biosurfactant production in bioreactor was higher comparing with the experiments conducted in shake flaks. The optimization procedure adopted in the current work was found to improve the biosurfactant production and opened new perspectives for the use of L. paracasei ssp. paracasei A20 as a promising biosurfactant-producer. 1. Introduction Biosurfactants are surface-active compounds synthesized by microorganisms with pronounced surface and emulsifying activities [1, 2]. Several properties and physiological functions in the producer organisms have been described for different groups of biosurfactants, that include solubility of hydrophobic compounds, heavy metal binding, bacterial pathogenesis, cell adhesion and aggregation, quorum sensing, and biofilm formation [2, 3]. Bacteria are the main group of biosurfactant-producing microorganisms, although they are also produced by some yeasts and filamentous fungi [4]. These compounds can be synthesized by microorganisms growing on water-immiscible hydrocarbons, as well as on water-soluble compounds such as glucose, sucrose, glycerol, or ethanol, and can be excreted or remain attached to the cell wall [5]. Diversity existing among the biosurfactant-producing microorganisms suggests that their production represents an important survival strategy and appears to have evolved in an independent, yet parallel fashion [6, 7]. A number of studies have reported the potential of lactobacilli as biosurfactant-producers [8¨C16]. Biosurfactants isolated from several lactobacilli have been characterized as multicomponent mixtures, consisting of protein and polysaccharides [13, 14, 17, 18]; in other cases, the surface active compounds were identified as glycolipids
%U http://www.hindawi.com/journals/aess/2011/201254/