Enhanced bioproduction of poly-3-hydroxybutyrate from wheat straw lignocellulos...

• Autor(es): Cesário, M. Teresa ; Raposo, Rodrigo S. ; Almeida, M. Catarina M. D. de ; Keulen, Frederik van ; Ferreira, Bruno S. ; Fonseca, M. Manuela R. da
• Data: 2014
• Origem: Repositório Comum
• Assunto(s): Wheat straw hydrolysates; Poly 3-hydroxybutyrate; Burkholderia sacchari; Carbon catabolite repression; Agricultural lignocellulosic residues; High cell density cultures
• Tipo de Documento: Artigo
• Idioma: Inglês

Descrição

Project: EC/FP7/246449 - New tailor-made PNB-based nanocomposites for high performance applications produced from environmentally friendly production routes "Polyhydroxyalkanoates (PHAs) are bioplastics that can replace conventional petroleum derived products in various applications. One of the major barriers for their widespread introduction in the market is the higher production costs when compared with their petrochemical counterparts. In this work, a process was successfully implemented with high productivity based on wheat straw, a cheap and readily available agricultural residue, as raw material. The strain Burkholderia sacchari DSM 17165 which is able to metabolize glucose, xylose and arabinose, the main sugars present in wheat straw hydrolysates (WSH), was used. Results in shake flask showed that B. sacchari cells accumulated ca 70 % g P(3HB)/g cell-dry-weight with a yield of polymer on sugars (YP/S) of 0.18 g/g when grown on a mixture of commercial C6 and C5 sugars (control), while these values reached ca 60 % g P(3HB)/g cell-dry-weight and 0.19 g/g, respectively, when WSHs were used as carbon source. In fed-batch cultures carried out in 2L stirred tank reactors on WSH, a maximum polymer concentration of 105 g/L was reached after 61 h of cultivation corresponding to an accumulation of 72% of CDW. Polymer yield and productivity were 0.22 g P(3HB)/g total sugar consumed and 1.6 g/L. h, respectively. The selected feeding strategy successfully overcame the carbon catabolite repression phenomenon observed in sugar mixtures containing hexoses and pentoses. This is the first work describing fed-batch cultivations aiming at PHA production using real lignocellulosic hydrolysates. Additionally, the P(3HB) volumetric productivities attained are, by far, the highest achieved ever on agricultural wastes hydrolysates."