Production of acetone, butanol, and ethanol from biomass of the green seaweed Ulva lactuca

Green seaweed Ulva lactuca harvested from the North Sea near Zeeland (The Netherlands) was characterized as feedstock for acetone, ethanol and ethanol fermentation. Solubilization of over 90% of sugars was achieved by hot-water treatment followed by hydrolysis using commercial cellulases. A hydrolysate was used for the production of acetone, butanol and ethanol (ABE) by Clostridium acetobutylicum and Clostridium beijerinckii. Hydrolysate-based media were fermentable without nutrient supplementation. C. beijerinckii utilized all sugars in the hydrolysate and produced ABE at high yields (0.35 g ABE/g sugar consumed), while C. acetobutylicum produced mostly organic acids (acetic and butyric acids). These results demonstrate the great potential of U. lactuca as feedstock for fermentation. Interestingly, in control cultures of C. beijerinckii on rhamnose and glucose, 1,2 propanediol was the main fermentation product (9.7 g/L)

RNA-seq analysis of Clostridium beijerinckii DSM 6423 at early exponential, acetogenic, and solventogenic growth phase on rhamnose compared to glucose

This experiment aim was to characterize the catabolism of L-rhamnose of Clostridium beijerinckii DSM 6423 by transcriptomic analysis, generating new insights and knowledge on utilization of L-rhamnose for production of chemicals, including Isopropanol, Butanol, Ethanol (IBE) and 1,2-propandiol. These analysis on cultures grown on L-rhamnose compared to D-glucose grown cultures showed upregulation of the L-rhamnose-related clusters and genes, and lower expression of the solventogenic genes, which was reflected in the products formed

Downstream Processing of Isochrysis galbana using Wet Biomass

In the present work, wet Isochrysis galbana biomass has been processed directly after harvesting to obtain high added-value compounds. A three-step sequential process has been designed to extract soluble proteins, lipids and pigments, leaving an exhausted residue. With this process, based on the use of compressed fluids, we were able to lower the energetic requirements, obtain higher extraction efficiency and lower generation of residues (while using environmentally benign solvents), compared to a similar procedure developed using dry microalgae biomass. The three-step sequential process started using subcritical water (employing mainly the residual water contained in the wet biomass) at 10-100 bar and 30-50 ºC to recover soluble proteins; the second step consisted on a pigments extraction using carbon dioxide expanded ethanol (CXE) (pressures between 50-100 bar, 40-60 ºC and ethanol percentages 40-80%); later on, a supercritical fluid extraction using pure CO2 is used to recover lipids (conditions between 250-400 bar and 40-70 ºC). By using this integrated process, we were able to recover around 70-80% of valuable lipids and pigments while proteins and sugars were mainly left in the residue. Life Cycle Assessment (LCA) has been measured and compared with results previously obtained in our research group working with Isochrysis galbana after freeze drying of the biomass. Results obtained demonstrated that energy requirements and associated costs of the developed process were much lower, therefore increasing the possibilities for biorefinery development at large scale

Downstream Processing of Isochrysis galbana using Wet Biomass

In the present work, wet Isochrysis galbana biomass has been processed directly after harvesting to obtain high added-value compounds. A three-step sequential process has been designed to extract soluble proteins, lipids and pigments, leaving an exhausted residue. With this process, based on the use of compressed fluids, we were able to lower the energetic requirements, obtain higher extraction efficiency and lower generation of residues (while using environmentally benign solvents), compared to a similar procedure developed using dry microalgae biomass. The three-step sequential process started using subcritical water (employing mainly the residual water contained in the wet biomass) at 10-100 bar and 30-50 ºC to recover soluble proteins; the second step consisted on a pigments extraction using carbon dioxide expanded ethanol (CXE) (pressures between 50-100 bar, 40-60 ºC and ethanol percentages 40-80%); later on, a supercritical fluid extraction using pure CO2 is used to recover lipids (conditions between 250-400 bar and 40-70 ºC). By using this integrated process, we were able to recover around 70-80% of valuable lipids and pigments while proteins and sugars were mainly left in the residue. Life Cycle Assessment (LCA) has been measured and compared with results previously obtained in our research group working with Isochrysis galbana after freeze drying of the biomass. Results obtained demonstrated that energy requirements and associated costs of the developed process were much lower, therefore increasing the possibilities for biorefinery development at large scale

Monascus ruber as cell factory for lactic acid production at low pH

A Monascus ruber strain was isolated that was able to grow on mineral medium at high sugar concentrations and 175 g/l lactic acid at pH 2.8

Monascus ruber as cell factory for lactic acid production at low pH

A Monascus ruber strain was isolated that was able to grow on mineral medium at high sugar concentrations and 175 g/l lactic acid at pH 2.8