Obtenção de Imagens de Algas por Microscopia de Força Atômica.

bitstream/CNPDIA/10457/1/CT63_2004.pd

Production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) P(3HB-co-3HV) with a broad range of 3HV content at high yields by Burkholderia sacchari IPT 189

The biosynthesis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) from sucrose and propionic acid by Burkholderia sacchari IPT 189 was studied using a two-stage bioreactor process. In the first stage, this bacterium was cultivated in a balanced culture medium until sucrose exhaustion. In the second stage, a solution containing sucrose and propionic acid as carbon source was fed to the bioreactor at various sucrose/propionic acid (s/p) ratios at a constant specific flow rate. Copolymers with 3HV content ranging from 40 down to 6.5 (mol%) were obtained with 3HV yield from propionic acid (Y-3HV/prop) increasing from 1.10 to 1.34 g g(-1). Copolymer productivity of 1 g l(-1) h(-1) was obtained with polymer biomass content rising up to 60% by increasing a specific flow rate at a constant s/p ratio. Increasing values of 3HV content were obtained by varying the s/p ratios. A simulation of production costs considering Y-3HV/prop obtained in the present work indicated that a reduction of up to 73% can be reached, approximating US$1.00 per kg which is closer to the value to produce P3HB from sucrose (US$ 0.75 per kg)

Increasing PHB production with an industrially scalable hardwood hydrolysate as a carbon source

In this study, we report an industrially feasible conversion of wood hydrolysate from a pilot-scale forest biorefinery. The wood hydrolysate was compared to a synthetic hydrolysate with a similar content of carbon sources (glucose, xylose, and acetate). To maximize the PHB concentration, high-cell density cultivations were conducted in bioreactors for 52 h using the bacterium Paraburkholderia sacchari IPT 101 LMG 19450. The conversion of wood hydrolysate yielded a maximum PHB concentration of 34.5 g/L, which is among the highest reported for lignocellulose hydrolysates. In comparison, the use of a synthetic hydrolysate resulted in substantially lower PHB concentration (22.0 g/L). This could be attributed to a higher maximum specific growth rate of 0.36 vs. 0.33 per h for cells grown in wood hydrolysate vs. synthetic hydrolysate. For the wood hydrolysate, the final PHB content per cell mass reached 58 % g/g and a maximum PHB productivity of 0.72 g/(Lh), while the synthetic hydrolysate reached 55 % g/g and 0.46 g/(Lh) respectively. Given the increase in bacterial growth and PHB productivity when using the wood hydrolysate, the chosen lignocellulose conversion process is beneficial for subsequent biotechnological conversion to key bioproducts