Carbohydrate Polymers 83 (2011) 1582–1590 Contents lists available at ScienceDirect Carbohydrate Polymers journal homepage: www.elsevier.com/locate/carbpol Characterization of biodegradable films from the extracellular polysaccharide produced by Pseudomonas oleovorans grown on glycerol byproduct Vítor D. Alves a,∗ , Ana R. Ferreira b , Nuno Costa b , Filomena Freitas b , Maria A.M. Reis b , Isabel M. Coelhoso b a CEER-Biosystems Engineering, Institute of Agronomy, Technical University of Lisbon, Tapada da Ajuda, 1349-017 Lisbon, Portugal b REQUIMTE/CQFB, Chemistry Department, FCT/Universidade Nova de Lisboa, 2829-516 Caparica, Portugal article info Article history: Received 21 July 2010 Received in revised form 7 September 2010 Accepted 7 October 2010 Available online 13 October 2010 Keywords: Biodegradable films Microbial polysaccharide Glycerol by-product Barrier properties abstract In this work, the film-forming capacity of the new microbial exopolysaccharide (EPS) composed by sugars and acyl groups, produced by Pseudomonas oleovorans NRRL B-14682, was studied. The films were trans- parent and quite flexible and tough when handled, but showed to be stiff under tensile and puncture tests. They presented a high water vapour permeability but a quite low permeability to carbon diox- ide, which are typical of hydrophilic polysaccharide films. Furthermore, they showed good stability in contact with liquid water, after auto-crosslinking reactions at low pH, upon or after drying. Preliminary biodegradability tests indicated an easy biological degradation when exposed to soil microorganisms. The results obtained are rather promising regarding the film-forming capacity of the new EPS, as they were obtained only with the biopolymer itself. The films formulation may be complemented with additives (e.g. plasticizers, emulsifiers, nanocomposites), to design films for specific applications. © 2010 Elsevier Ltd. All rights reserved. 1. Introduction For a long time traditional polymers have supplied most of common packaging materials because they present several desired features like softness, lightness and transparency. However, increased use of synthetic packaging films has led to serious eco- logical problems due to their total non-biodegradability (Siracusa, Rocculi, Romani, & Dalla Rosa, 2008). Consequently, the interest on replacing conventional polymers in some packaging applications by biopolymers, has greatly increased, as they are biodegradable and can be produced or recovered from renewable resources. Water soluble polysaccharides, such as starch, pectin, alginate, carrageenan, chitosan and cellulose derivates, are known for their film-forming properties which have been intensively investigated (Aider, 2010; Alves, Costa, & Coelhoso, 2010; Bertuzzi, Vidaurre, Armada, & Gottifredi, 2007; da Silva, Bierhalz, & Kieckbusch, 2009; de Moura et al., 2009; Fabra, Talens, & Chiralt, 2008; Lafargue, Lourdin, & Doublier, 2007). Due to the large diversity of available polysaccharides, a wide range of films properties can be obtained (Nisperos-Carriedo, 1994). The referred polymers are commonly extracted from natural resources, such as plants and algae, as well as from agro-industrial by-products. However, the recovery process is generally based on ∗ Corresponding author. Tel.: +351 213653546; fax: +351 213653195. E-mail address: vitoralves@isa.utl.pt (V.D. Alves). the use of chemicals (Hilliou et al., 2006). Furthermore, the avail- ability and quality of the biopolymer sources are dependent on climate and on the season of the year. As a consequence, the proper- ties of the polymer recovered present a significant variability over time. Microbial polysaccharides represent an alternative to those obtained by other processes. Hyaluronan, kefiran and gellan are examples of microbial polysacharides that have been tested to pro- duce biodegradable films (Piermaria, Pinotti, García, & Abraham, 2009; Sun & Zhitomirsky, 2009; Xu, Li, Kennedy, Xie, & Huang, 2007). Xanthan gum has also been used in blends with other biopolymers (Soares, Lima, Oliveira, Pires, & Soldi, 2005). In microbial processes, after process optimization, the cultivation parameters (e.g. stirring rate, temperature, pH, nutrients concen- tration) are easily controlled over time, enabling the production of biopolymers with rather stable chemical and physical characteris- tics. Nevertheless, the potential market of these biopolymers is still conditioned by the production costs, which are quite dependent on the high price of the carbon sources commonly used, such as sucrose and glucose (García-Ochoa, Santos, Casas, & Gómez, 2000; Singh, Saini, & Kennedy, 2008). As such, the attention has been driven to search viable low-cost carbon sources, namely among agro-industrial wastes and industrial by-products. Glycerol rich by- product from the biodiesel production is an example. It is generated in large quantities, far beyond current consumption in traditional applications, and the development of new routes to convert crude glycerol into higher value products is an urgent need. 0144-8617/$ – see front matter © 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.carbpol.2010.10.010