Bioconversion of Sugarcane Vinasse into High-Added Value Products and Energy.

Vinasse, a residue from bioethanol production containing high organic matter concentration, was used as substrate in submerged fermentation of Pseudomonas aeruginosa PA1 for biosurfactant production. About 2.7 g/L of rhamnolipids was obtained, with surface tension of 29.2 mN/m and critical micelle concentration of 80.3 mg/L. After separation of rhamnolipid and biomass, residual fermentation media were submitted to anaerobic biodegradation in mesophilic conditions. The residual medium derived from fermentation with vinasse diluted to 1 : 1, without addition of nitrogen, C : N 21, and for 168 h, led to 63.2% chemical oxygen demand (COD) removal and 97.6 mL CH4/g CODremoved. Compared to results obtained with fresh vinasse (73.7% COD removal and 112.4 mL CH4/g CODremoved), it could be concluded that both processes can be integrated in order to add value to the residue and obtain energy, reducing production costs and at the same time environmental impacts related to vinasse disposal.

Displaying Lipase B from Candida antarctica in Pichia pastoris Using the Yeast Surface Display Approach: Prospection of a New Anchor and Characterization of the Whole Cell Biocatalyst.

Yeast Surface Display (YSD) is a strategy to anchor proteins on the yeast cell wall which has been employed to increase enzyme stability thus decreasing production costs. Lipase B from Candida antarctica (LipB) is one of the most studied enzymes in the context of industrial biotechnology. This study aimed to assess the biochemical features of this important biocatalyst when immobilized on the cell surface of the methylotrophic yeast Pichia pastoris using the YSD approach. For that purpose, two anchors were tested. The first (Flo9) was identified after a prospection of the P. pastoris genome being related to the family of flocculins similar to Flo1 but significantly smaller. The second is the Protein with Internal Repeats (Pir1) from P. pastoris. An immunolocalization assay showed that both anchor proteins were able to display the reporter protein EGFP in the yeast outer cell wall. LipB was expressed in P. pastoris fused either to Flo9 (FLOLIPB) or Pir1 (PIRLIPB). Both constructions showed hydrolytic activity towards tributyrin (>100 U/mgdcw and >80 U/mgdcw, respectively), optimal hydrolytic activity around 45°C and pH 7.0, higher thermostability at 45°C and stability in organic solvents when compared to a free lipase.