Cloud point extraction of microalgae cultures

Improving Product Specificity of Whole-Cell Alkane Oxidation in Nonconventional Media: A Multivariate Analysis Approach

Two-liquid-phase reaction media have long been used in bioconversions to supply or remove hydrophobic organic reaction substrates and products to reduce inhibitory and toxic effects on biocatalysts. In case of the terminal oxyfunctionalization of linear alkanes by the AlkBGT monooxygenase the excess alkane substrate is often used as a second phase to extract the alcohol, aldehyde, and acid products. However, the selection of other carrier phases or surfactants is complex due to a large number of parameters that are involved, such as biocompatibility, substrate bioavailability, and product extraction selectivity. This study combines systematic high-throughput screening with chemometrics to correlate physicochemical parameters of a range of cosolvents to product specificity and yield using a multivariate regression model. Partial least-squares regression shows that the defining factor for product specificity is the solubility properties of the reaction substrate and product in the cosolvent, as measured by Hansen solubility parameters. Thus the polarity of cosolvents determines the accumulation of either alcohol or acid products. Whereas usually the acid product accumulates during the reaction, by choosing a more polar cosolvent the 1-alcohol product can be accumulated. Especially with Tergitol as a cosolvent, a 3.2-fold improvement in the 1-octanol yield to 18.3  mmol  L^-1 is achieved relative to the control reaction without cosolvents.

Efficient Extraction of Carotenoids from Sargassum muticum Using Aqueous Solutions of Tween 20

The replacement of synthetic compounds by natural products witnesses an increasing demand from the pharmaceutical, cosmetic, food and nutraceutical industries. Included in the set of natural raw materials that are poorly explored are the macroalgae. Despite the detailed characterization and identification of most relevant biomolecules that are present in the main macroalgae species, there remains a lack of efficient and economically viable processes available to meet the needs of the markets. In this work, an efficient and single-step process, based on aqueous solutions of Tween 20, to recover carotenoids from Sargassum muticum, an invasive brown macroalgae species present in the Portuguese coast, is proposed and optimized allowing an extraction yield of 2.78 ± 0.4 mgcarotenoids.gdried mass-1, which is shown to increase the extraction efficiency by 38% when compared with traditional methods.

Perstraction of Intracellular Pigments through Submerged Fermentation of Talaromyces spp. in a Surfactant Rich Media: A Novel Approach for Enhanced Pigment Recovery

A high percentage of the pigments produced by Talaromyces spp. remains inside the cell, which could lead to a high product concentration inhibition. To overcome this issue an extractive fermentation process, perstraction, was suggested, which involves the extraction of the intracellular products out of the cell by using a two-phase system during the fermentation. The present work studied the effect of various surfactants on secretion of intracellular pigments produced by Talaromyces spp. in submerged fermentation. Surfactants used were: non-ionic surfactants (Tween 80, Span 20 and Triton X-100) and a polyethylene glycerol polymer 8000, at different concentrations (5, 20, 35 g/L). The highest extracellular pigment yield (16 OD500nm) was reached using Triton X-100 (35 g/L), which was 44% higher than the control (no surfactant added). The effect of addition time of the selected surfactant was further studied. The highest extracellular pigment concentration (22 OD500nm) was achieved when the surfactant was added at 120 h of fermentation. Kinetics of extracellular and intracellular pigments were examined. Total pigment at the end of the fermentation using Triton X-100 was 27.7% higher than the control, confirming that the use of surfactants partially alleviated the product inhibition during the pigment production culture.

Cell disruption for microalgae biorefineries

Microalgae are a potential source for various valuable chemicals for commercial applications ranging from nutraceuticals to fuels. Objective in a biorefinery is to utilize biomass ingredients efficiently similarly to petroleum refineries in which oil is fractionated in fuels and a variety of products with higher value. Downstream processes in microalgae biorefineries consist of different steps whereof cell disruption is the most crucial part. To maintain the functionality of algae biochemicals during cell disruption while obtaining high disruption yields is an important challenge. Despite this need, studies on mild disruption of microalgae cells are limited. This review article focuses on the evaluation of conventional and emerging cell disruption technologies, and a comparison thereof with respect to their potential for the future microalgae biorefineries. The discussed techniques are bead milling, high pressure homogenization, high speed homogenization, ultrasonication, microwave treatment, pulsed electric field treatment, non-mechanical cell disruption and some emerging technologies.

Solubilization of phenanthrene above cloud point of Brij 30: a new application in biodegradation

In the present study a new application of solubilization of phenanthrene above cloud point of Brij 30 in biodegradation was developed. It was shown that a temporal solubilization of phenanthrene above cloud point of Brij 30 (5wt%) permitted to obtain a stable increase of the solubility of phenanthrene even when the temperature was decreased to culture conditions of used microorganism Pseudomonas putida (28°C). A higher initial concentration of soluble phenanthrene was obtained after the cloud point treatment: 200 against 120μM without treatment. All soluble phenanthrene was metabolized and a higher final concentration of its major metabolite - 1-hydroxy-2-naphthoic acid - (160 against 85μM) was measured in the culture medium in the case of a preliminary cloud point treatment. Therefore a temporary solubilization at cloud point might have a perspective application in the enhancement of biodegradation of polycyclic aromatic hydrocarbons.

Solubilization capacity of nonionic surfactant micelles exhibiting strong influence on export of intracellular pigments in Monascus fermentation

In this study, perstractive fermentation of intracellular Monascus pigments in nonionic surfactant micelle aqueous solution had been studied. The permeability of cell membrane modified by nonionic surfactant might have influence on the rate of export of intracellular pigments into its extracellular broth while nearly no effect on the final extracellular pigment concentration. However, the solubilization of pigments in nonionic surfactant micelles strongly affected the final extracellular pigment concentration. The solubilization capacity of micelles depended on the kind of nonionic surfactant, the super-molecule assembly structure of nonionic surfactant in an aqueous solution, and the nonionic surfactant concentration. Elimination of pigment degradation by export of intracellular Monascus pigments and solubilizing them into nonionic surfactant micelles was also confirmed experimentally. Thus, nonionic surfactant micelle aqueous solution is potential for replacement of organic solvent for perstractive fermentation of intracellular product.