Aqueous Fermentation Media Research Articles

An Investigation on the Removal of High Concentrations of PAHs Using Two-Liquid Phase System

Two-liquid phase systems consisting of two insoluble liquids can be effective in removing high concentrations of hydrocarbons from aqueous environments. In this study, the removal efficiencies of Naphthalene (Nap), Acenaphthene (Acn), Fluorene (Flu), Fluoranthene (Flr), Anthracene (Ant), and Pyrene (Pyr) at high concentrations in the two-liquid phase system were investigated. Two-liquid phase systems were constituted using Bis (2-Ethylhexyl) sebacate (BES) and aqueous fermentation media. Nutrient Broth (NB) and Bushnell Haas Yeast (BHY) medium were used as aqueous fermentation media. Acn, Flu, Flr, Ant, Pyr, and Nap were degraded at a rate of 93.1%, 80.8%, 57.6%, 68.5%, 63.8%, and 100%, respectively with BES/NB system. In the BES/BHY system, Acn, Flu, Flr, Ant, Pyr, and Nap, were degraded at a rate of 29.6%, 44.3%, 22.8%, 68.1%, and 19.7%, 45.4%, respectively. When both systems are compared, it has been shown that the BES/NB system can be effective under specified conditions.

Enhancing Lignin Dispersion and Bioconversion by Eliminating Thermal Sterilization

Thermal sterilization is widely applied in fermentation to ensure a pure culture. In this study, a facile and energy-efficient strategy by eliminating thermal sterilization (ETS) was unveiled for upgrading lignin bioconversion. Through alkaline solubilization and neutralization, lignin dispersion in aqueous fermentation media was significantly enhanced by ETS. Small-angle X-ray scattering and dynamic light scattering analyses indicated that the lignin colloid size was dramatically reduced. Compared to 20.5 wt % lignin precipitation during the conventional thermal sterilization, precipitated lignin was not observed within the ETS medium. 31P NMR characterization demonstrated an 11.7% increase of phenolic OH in ETS lignin. Ionization of phenolic OH presented more negatively charged groups, strengthening electrostatic repulsion, resulting in smaller colloidal particles. Interestingly, the pure culture of Rhodococcus opacus PD630 was achieved within the ETS medium due to the lack of lignin degradation ability with most natural microbes. R. opacus PD630 cell amount, lignin degradation, and lipid production by ETS increased by 330, 16.6, and 20.7%, respectively. Overall, an energy-efficient ETS strategy that promoted lignin dispersion and bioconversion significantly is reported in this study.

Separation of water/butan-1-ol with ionic liquids in ternary liquid-liquid phase equilibrium

In this work ionic liquids (ILs) as a novel popular solvents are proposed for removing butan-1-ol from the aqueous fermentation media. Ternary liquid-liquid phase equilibrium data are presented for mixtures of {ionic liquid (1) + butan-1-ol (2) + water (3)} at T = 328.15 K and ambient pressure. The ILs with long alkane chains such as hexadecyltrimethylammonium bis{(trifluomethyl)sulfonyl}imide, [N16,1,1,1][NTf2], 1,3-didecyl-2-methylimidazolium dicyanamide, [D2MIM][DCA] and tetrabutylphosphonium bis{(trifluomethyl)sulfonyl}imide, [P4,4,4,4][NTf2] have been tested. The results are discussed in terms of the selectivity and solute distribution ratio of separation of related systems. The complete miscibility in the binary liquid systems of butan-1-ol with three used ILs was observed. The ammonium-based IL in comparison with phosphonium-based IL shows lower selectivity and solute distribution ratio. The non-random two liquid NRTL model was used successfully to correlate the experimental tie-lines and to calculate the phase composition error in mole fraction in the ternary systems.

Extraction of butan-1-ol from water with ionic liquids at T = 308.15 K

Ionic liquids (ILs) are novel green solvents that can be proposed for removing butan-1-ol from the aqueous fermentation media. Ternary (liquid+liquid) equilibrium data are presented for {ionic liquid (1)+butan-1-ol (2)+water (3)} at T=308.15K and ambient pressure to analyze the performance of the ionic liquid (IL) in the extraction of butan-1-ol from aqueous phase. The tetracyanoborate-based ILs have been studied: 1-hexyl-3-methylimidazolium tetracyanoborate, ([HMIM][TCB]), 1-decyl-3-methylimidazolium tetracyanoborate, ([DMIM][TCB]) and trihexyltetradecylphosphonium tetracyanoborate, ([P14,6,6,6][TCB]). The results are discussed in terms of the selectivity and distribution ratio of separation of related systems. The complete miscibility in the binary liquid systems of butan-1-ol with all used ILs was observed. The imidazolium cation in comparison with phosphonium cation shows lower selectivity and distribution ratio. The IL with the longer alkyl chain at the cation shows higher selectivity and distribution ratio in this process. The non-random two liquid NRTL model was used successfully to correlate the experimental tie-lines and to calculate the phase composition error in mole fraction in the ternary systems. The average root mean square deviation (RMSD) of the phase composition was 0.0027. The data presented here indicates the usefulness of [P14,6,6,6][TCB] as a solvent for the separation of butan-1-ol from water using solvent extraction. The density of [P14,6,6,6][TCB] was measured as a function of temperature.

Investigation of Ionic Liquids for the Separation of Butanol and Water

With the continual rise in the cost of fossil fuel based energy, research into economic and sustainable alternatives is of increasing importance. One significant source of increased cost and demand is the consumption of fossil fuels for automotive fuels. While ethanol has received the most attention as a fuel additive; butanol could be a better direct fuel alternative owing to its physical properties and energy value when compared to ethanol. Commercial butanol is nearly exclusively produced from petroleum feedstocks currently; however, some recent interest has begun to refocus on its generation via fermentation. Unfortunately, this production is limited due to the nature of the process and the use of energy-intensive separation techniques. Ionic liquids are novel green solvents that have the potential to be employed as an extraction agent to remove butanol from the aqueous fermentation media. A hurdle to this potential is the limited availability of solubility data for ionic liquids. This research investigates the phase behavior of two ionic liquids, butanol, and water. Additionally, issues related to the implementation of the investigated ionic liquids are discussed.

Extraction of penicillin G from aqueous solutions: Analysis of reaction equilibrium and mass transfer

Analysis of the reaction equilibrium and mass transfer in the extraction of penicillin G (Pen G) into an organic phase is an important research area to develop a cost-effective process for its separation from an aqueous fermentation media. In order to evaluate this, equilibrium experiments were first carried out to select the organic phase (composed of the carrier and solvent) that gives good values for the distribution of penicillin G between the aqueous and organic phases. An organic phase of Amberlite LA-2 in any of the solvents (Shellsol TK/butyl acetate/tributyl phosphate) gave high distribution coefficient and the stoichiometry of the reaction has been shown to follow a simple ratio of 2:2. The performance of the organic phases was evaluated in a membrane contactor and very high percentage extraction was achieved. The extraction was performed by contacting a “feed” solution containing penicillin G (flowing in the fiber side) with an “organic phase” of Amberlite LA-2 in one of the solvents (flowing on the shell side) of the contactor. The antibiotic solutes formed complex with the Amberlite LA-2 molecules which were transported across the fiber wall to the shell side and extracted in the organic phase. The extraction in once-through mode was low and the feed/organic solutions need to be recycled to increase the percentage extraction. In the recycle mode operated at flow rates of 3.6–4.4 mL/s, an extraction of 90–98% was achieved. A simple mathematical model and its semi-analytical solution presented here can be used to determine the overall mass transfer coefficient using the experimental values of the distribution coefficient, operating parameters and the dimensions of the membrane module.

Measuring oxygen diffusion coefficients with polarographic oxygen electrodes. II. Fermentation Media

Fermentation media consist of a large number of chemicals which composition undergoes alteration during the course of fermentations. In consequence, the conventional methods and correlations for gas diffusion coefficient measurement and prediction cannot be easily applied to such systems. Oxygen diffusion coefficients have been measured in simulated chemical systems as well as in complex solutions of nutrient broth, using the polarographic technique introduced in a previous article. It is identified that sugars and salts are the major factors influencing oxygen diffusion coefficients in these aqueous fermentation media. The effect of salts on oxygen diffusion coefficients in electrolyte solutions has been found to be well correlated with the square root of total ionic strength of electrolyte solutions. The individual effect of glucose and its combined effect with salts are explored in order to reach rational correlations capable of predicting oxygen diffusion coefficients in synthetic fermentation media. For aqueous solutions of glucose plus salts, it is observed that the log-additive relationship can be used to account for the combined effect. Finally, a linear correlation has been established in measuring oxygen diffusion coefficients in aqueous solutions having different concentrations of nutrient broth.

Microbial transformations of natural antitumor agents: use of solubilizing agents to improve yields of hydroxylated ellipticines.

Aromatic hydroxylation of the antitumor alkaloid ellipticine by Aspergillus alliaceus results in the formation of both 8- and 9-hydroxyellipticines. Experiments designed to increase yields of microbial hydroxylation focused on enhancing the water solubility of ellipticine in aqueous fermentation media by use of wetting agents or solubilizing polymers, or both. Yields of hydroxylated metabolites were determined by high-performance liquid chromatography with the use of a mu-Bondapak-phenyl column and a mobile phase of acetonitrile--0.1% (NH4)2CO3 (1:1). Polyvinylpyrrolidone (molecular weight, 40,000) and polyoxyethylated vegetable oil (Emulphor 620) increased the water solubility of ellipticine and the yield of hydroxylated metabolites.