Microbial torularhodin – a comprehensive review

The demand for food, feed, cosmeceutical, and nutraceutical supplements/additives from natural sources has been rapidly increasing, with expectations for a faster expansion than the growth of the global markets in the coming years. In this framework, a particular interest is given to carotenoids due to their outstanding antioxidant activities, particularly the xanthophylls class. Torularhodin is one of these carotenoids that stands out for its multifunctional role as: antioxidant, anticancer and antimicrobial, yet its commercial potential is still unexplored. Although most xanthophylls can be naturally found in: microbial, plant and animal sources, torularhodin is only produced by microbial species, especially red oleaginous yeast. The microbial production of xanthophylls has many advantages as compared to other natural sources, such as: the need for low production area, easier extraction, high yields (at optimum operating conditions), and low (or no) seasonal, climatic, and geographic variation dependency. Due to the importance of natural products and their relevance to the market, this review provides a comprehensive overview of the: properties, characteristics and potential health benefits of torularhodin. Moreover, the most promising developments in both upstream and downstream processing to obtain this colorant from microbial sources are considered. For this purpose, the main microorganisms used for torularhodin production are firstly reviewed, including biosynthesis pathway and torularhodin properties. Following, an overall analysis of the processing aspects related with its: extraction, separation and purification is provided. Lastly, current status and future trends of torularhodin-based processes and products such as therapeutic agents or biomaterials are discussed, indicating promising directions toward biorefinery and circular economy.

Rapeseed meal valorization strategies via nitrogen- and oxygen-limited production of polyhydroxyalkanoates with Pseudomonas putida

Rapeseed meal (RSM) is a candidate for biopolymer production due to its abundance, low cost and potential integration with other rapeseed-derived products. However, existing studies pursuing such schemes are limited. The feasibility of different strategies for RSM valorization via protein extraction and polyhydroxyalkanoate production were evaluated. Nitrogen-limited RSM media was produced from hydrolysis of residues which had undergone extensive protein extraction using sodium hydroxide. A study of oxygen-limited fermentation was also performed on hydrolysate of untreated RSM via batch feeding. The typical strategy of using a high carbon-to-nitrogen ratio may not be the most suitable route for polyhydroxyalkanoate (PHA) production using nitrogen-rich biomass as a feedstock. Central composite design-based experiments show that due to mass transfer limitations protein extraction at 1-L scale could only achieve yields around 50% and 69%, at room temperature and 60 °C, respectively. Protein extraction yields reduced with successive extractions, meaning that whilst the RSM hydrolysate is viable for growth, designing a valorization scheme which has the fermentation step dictated by the protein extraction may not be practical/economical. A better route which utilizes oxygen-limitation to initially induce stationary phase was identified, giving accumulation of polyhydroxyalkanoate once the oxygen levels began to recover; 8.93% and 1.75% PHA accumulation in fed-batch cultures of synthetic and RSM media, respectively. The findings demonstrate that decoupling of protein extraction performance from PHA synthesis is feasible. This study provides important insight into the degrees of freedom available in the design of a holistic valorization scheme of rapeseed meal, and high protein lignocellulosic biomass in general.

Highlights from the Faraday Discussion on Ionic Liquids: From Fundamental Properties to Practical Applications, Cambridge, UK, September 2017

For the third time, a Faraday Discussion addressed ionic liquids. Encompassing the wealth of research in this field, the contributions ranged from fundamental insights to the diverse applications of ionic liquids. Lively discussions initiated in the lecture hall and during poster sessions then seamlessly continued during the social program.

Recovery of tyrosol from aqueous streams using hydrophobic ionic liquids: a first step towards developing sustainable processes for olive mill wastewater (OMW) management

Hydrophobic ILs have been proposed as VOCs replacements for tyrosol recovery from aqueous solutions, revealing promising extraction efficiency and regeneration capacity. This will help developing sustainable processes for olive mill waste management.

Solubility of CO2 in [1-n-butylthiolanium][Tf2N]+toluene mixtures: liquid-liquid phase split separation and modelling

Carbon dioxide has been shown to be an effective antisolvent gas for separating organic compounds from ionic liquids (ILs) by inducing a liquid-vapour to liquid-liquid-vapour transition. Using carbon dioxide, toluene can be separated from imidazolium, phosphonium and pyridinum cation-based ILs with the bis(trifluoromethylsulfonyl)imide anion, which is relatively hydrophobic and has a high toluene solubility. A new IL with relatively low viscosity is tested here for the same toluene separation process: 1-n-butylthiolanium bis(trifluoromethylsulfonyl)imide. Carbon dioxide solubility in binary and ternary systems containing toluene and 1-n-butylthiolanium bis(trifluoromethylsulfonyl)imide is measured at 298.15 and 313.15 K up to 7.4 MPa. Solubility behaviour in this IL is similar to imidazolium-based ILs with the same anion. However, phase split pressures are lower when 1-n-butylthiolanium bis (trifluoromethylsulfonyl)imide is used instead of 1- n-hexyl-3-methylimidazolium bis(trifluoromethylsu- lfonyl)imide at the same conditions of temperature and initial composition of toluene in the IL. Solubility data are modelled with the conductor-like screening model for real solvents combined with the Soave-Redlich-Kwong equation of state, which provides good qualitative results.