Living Composites of Electrospun Yeast Cells for Bioremediation and Ethanol Production

Abstract

The preparation of composites of living functional cells and polymers is a major challenge. We have fabricated such "living composites" by preparation of polymeric microtubes that entrap yeast cells. Our approach was the process of coaxial electrospinning in which a core containing the yeast was "spun" within a shell of nonbiodegradable polymer. We utilized the yeast Candida tropicalis, which was isolated from olive water waste. It is particularly useful since it degrades phenol and other natural polyphenols, and it is capable of accumulating ethanol. The electrospun yeast cells showed significant activity of bioremediation of phenol and produced ethanol, and, in addition, the metabolic processes remained active for a prolonged period. Comparison of electrospun cells to planktonic cells showed decreased cell activity; however, the olive water waste after treatment by the yeast was no longer toxic for Escherichia coli, suggesting that detoxification and prolonged viability and activity may outweigh the reduction of efficiency.

Engineered Living Materials: Prospects and Challenges for Using Biological Systems to Direct the Assembly of Smart Materials

“…By extension, electrospinning techniques developed for biohybrid materials could be extended to ELMs. Figure shows examples of yeast and bacterial cells encapsulated in core–shell electrospun fibers . In these examples, living cells were encapsulated in a water‐soluble biocompatible polymeric core that provides a favorable environment to maintain cell viability.…”

“…In these examples, living cells were encapsulated in a water‐soluble biocompatible polymeric core that provides a favorable environment to maintain cell viability. Simultaneously during electrospinning, a second needle can be used to form a shell around the biocompatible core fiber . A shell layer can alternatively be synthetized via chemical deposition after the spinning of the core .…”

“…This shell layer provides the structure its robustness and durability by preventing dissolution of the water‐soluble core. In these electrospun fibers, yeast cells were demonstrated to remain functional and capable of biodegrading polyphenols and producing ethanol (Figure a) . Composite fibers containing bacterial cells Micrococcus luteus and Nitrobacter winogradskyi were used to sequester gold and remove nitrate from solutions, respectively .…”

“…In the middle panel, encapsulated yeast cells are shown in purple. Reproduced with permission . Copyright 2015, American Chemical Society.…”

The Use of a Gas Chromatography/Milli-whistle Technique for the On-line Monitoring of Ethanol Production Using Microtube Array Membrane Immobilized Yeast Cells

“…Although the current techniques available for the immobilization of yeast cells have some drawbacks, we were able to use a highly porous hollow MTAM to immobilize Saccharomyces cerevisiae to form yeast-MTAMs for bioethanol fermentation. [7][8][9][10][11] The porous hollow yeastMTAMs were developed by using a coaxial electrospinning technique. They were functionalized by creating nanopores on the surface using a pore-forming agent, followed by a leachingout process, as described previously.…”