13Polyhydroxyalkanoates (PHAs) are bioplastics that can replace conventional 14 petroleum derived products in various applications. One of the major barriers for 15 their widespread introduction in the market is the higher production costs when 16 compared with their petrochemical counterparts. In this work, a process was 17 successfully implemented with high productivity based on wheat straw, a cheap 18 and readily available agricultural residue, as raw material. The strain 19Burkholderia sacchari DSM 17165 which is able to metabolize glucose, xylose 20 and arabinose, the main sugars present in wheat straw hydrolysates (WSH), 21 was used. Results in shake flask showed that B. sacchari cells accumulated ca 22 * Corresponding author. Tel.: +351 21 8419137; fax: +351 21 8419062.e-mail address: teresa.cesario@ist.utl.pt 2 70 % g P(3HB)/g cell-dry-weight with a yield of polymer on sugars (Y P/S ) of 0.18 23 g/g when grown on a mixture of commercial C6 and C5 sugars (control), while 24 these values reached ca 60 % g P(3HB)/g cell-dry-weight and 0.19 g/g, 25 respectively, when WSHs were used as carbon source. In fed-batch cultures 26 carried out in 2L stirred tank reactors on WSH, a maximum polymer 27 concentration of 105 g/L was reached after 61 h of cultivation corresponding to 28 an accumulation of 72% of CDW. Polymer yield and productivity were 0.22 g 29 P(3HB)/g total sugar consumed and 1.6 g/L . h, respectively. The selected 30 feeding strategy successfully overcame the carbon catabolite repression 31 phenomenon observed in sugar mixtures containing hexoses and pentoses. 32 This is the first work describing fed-batch cultivations aiming at PHA production 33 using real lignocellulosic hydrolysates. Additionally, the P(3HB) volumetric 34 productivities attained are, by far, the highest achieved ever on agricultural 35 wastes hydrolysates. 36 Keywords 37Wheat straw hydrolysates ; poly 3-hydroxybutyrate; Burkholderia sacchari; carbon

A carotenoid-accumulating bacterium isolated from soil, identified as a Sphingomonas sp., grew at 0.18 h(-1) and produced 1.7 mg carotenoids g(-1) dry cell, among which beta-carotene (29% of total carotenoids) and nostoxanthin (36%). A mutant strain, obtained by treatment with ethyl methanesulfonate, accumulated up to 3.5 mg carotenoids g(-1) dry cell. Accumulation of beta-carotene by this strain depended on the oxygenation of the growth medium, with maximal accumulation (89%) occurring under limiting conditions. Beta-carotene accumulation could be further enhanced by incubating the cells in the presence of glycerol (either not or only slowly assimilated) and yeast extract resulting in an accumulation of 5.7 mg beta-carotene g(-1) dry cell wt. The strain used lactose as carbon source with similar biomass and carotenoid production, providing a viable alternative use for cheese whey ultra-filtrate.

Burkholderia sacchari DSM 17165 is able to grow and produce poly(3-hydroxybutyrate) both on hexoses and pentoses. In a previous study, wheat straw lignocellulosic hydrolysates (WSH) containing high C6 and C5 sugar concentrations were shown to be excellent carbon sources for P(3HB) production.Using a similar feeding strategy developed for P(3HB) production based on WSH, fedbatch cultures were developed aiming at the production of the copolymer P(3HB-co-4HB) (poly(3-hydroxybutyrate-co-4-hydroxybutyrate)) by B. sacchari. The ability of this * Corresponding author. Tel.: +351 21 8419137; Fax: +351 21 8419062.e-mail address: teresa.cesario@tecnico.ulisboa.pt 2 strain to synthesize P(3HB-co-4HB) was first shown in shake flasks using gammabutyrolactone (GBL) as precursor of the 4HB units.Fed-batch cultures using glucose as carbon source (control) and GBL were developed to achieve high copolymer productivities and 4HB incorporations. The attained P(3HB-co-4HB) productivity and 4HB molar % were 0.7 g/(L·h) and 4.7 molar %, respectively.The 4HB incorporation was improved to 6.3 and 11.8 molar % by addition of 2 g/L propionic and acetic acid, respectively. When WSH were used as carbon source under the same feeding conditions, the values achieved were 0.5 g/(L·h) and 5.0 molar %, respectively. Burkholderia sacchari, a strain able to produce biopolymers based on xylose-rich lignocellulosic hydrolysates, is for the first time reported to produce P(3HB-co-4HB) using gamma butyrolactone as precursor.