Cryo-Electron Microscopy of Polymer Particles in a High Cell Density Synthetic Biofilm

Thiagarajan, V.; Ming, Yang; Scriven, L. E.; Flickinger, Michael C.

doi:10.1016/s0921-0423(96)80040-2

Cited by 3 publications

(3 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Samples for which the top surface was to be imaged were cast on stainless steel shims and either rehydrated in distilled water or directly frozen in liquid nitrogen. Samples whose cross‐sections were to be imaged were prepared on silicon wafers, 1 cm × 1 cm (Ted Pella Inc. Redding, CA) as previously described (27, 28, 32). Rehydrated samples were soaked in distilled water on the silicon wafer for 10 min before freezing in liquid nitrogen.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Engineering the Microstructure and Permeability of Thin Multilayer Latex Biocatalytic Coatings Containing E. coli

Lyngberg

Thiagarajan

et al. 2001

Biotechnol. Prog.

Self Cite

View full text Add to dashboard Cite

The microstructure and permeability of rehydrated 20-100 microm thick partially coalesced (vinyl-actetate acrylic copolymer) SF091 latex coatings and a 118 microm thick model trilayer biocatalytic coating consisting of two sealant SF091 layers containing a middle layer of viable E. coli HB101 + latex were studied as delaminated films in a diffusion apparatus with KNO(3) as the diffussant. The permeability of the hydrated coatings is due to diffusive transport through the pore space between the partially coalesced SF091 latex particles. Coating microstructure was visualized by fast freeze cryogenic scanning electron microscopy (cryo-SEM). The effective diffusion coefficient of SF091 latex coatings (diffusive permeability/film thickness) was determined as the ratio of the effective diffusivity of KNO(3) to its diffusivity in water (D(eff)/D). Polymer particle coalescence was arrested by two methods to increase coating permeability. The first used glycerol with coating drying at 4 degrees C, near the glass transition temperature (T(g)). The second method used sucrose or trehalose as a filler to arrest coalescence; the filler was then dissolved away. D(eff)/D was measured as a function of film thickness; content of glycerol, sucrose, and trehalose; drying time; and rehydration time. D(eff)/D varied from 3 x 10(-4) for unmodified SF091 coatings to 6.8 x 10(-2) for coatings containing sucrose. D(eff)/D was reduced by the flattening of latex particles against the surface of the solid substrate, as well as by the presence of the colloid stabilizer hydroxyethylcellulose (HEC). When corrected for the flattened particle layer, D(eff)/D of HEC-free coatings was as high as 0.20, which agreed with the value predicted from analysis of cryo-SEM images of the coat surface. D(eff)/D decreased by one-half in approximately 5 days in rehydrated SF091 coatings, indicating that significant wet coalescence occurs after glycerol, sucrose, or trehalose are leached from the films. D(eff)/D of SF091 latex trilayer coatings containing viable E. coli HB101 cells decreased as cell loading was increased from 2.2 x 10(-2) for 64 g dry cell weight per liter of coat volume to 5 x 10(-3) for 151 g DCW/L of coat volume. The reduction in coating permeability with increasing cell loading is predicted by Maxwell's equation for D(eff)/D in periodic composites.

show abstract

Section: Methodsmentioning

confidence: 99%

“…Dry samples were frozen directly. Water remaining on top or inside the samples was sublimed by heating the specimens to −90 °C for 90 min at ultralow vacuum, after which the samples were sputter‐coated with gold (32).…”

Section: Methodsmentioning

confidence: 99%

Engineering the Microstructure and Permeability of Thin Multilayer Latex Biocatalytic Coatings Containing E. coli

Lyngberg

Thiagarajan

et al. 2001

Biotechnol. Prog.

Self Cite

View full text Add to dashboard Cite

show abstract

“…[10,11] The idea of encapsulating viable bacteria in a latex coating first appeared in the 1980s. [12] In 1996, landmark publications that systematically studied and characterized biocoatings were published by Flickinger and colleagues, [13][14][15] who later coined the term "biocoating" [10] to refer to an adhesive biocatalytic coating. Biocoatings or "living paints" are attracting growing interest, but there are to-date only about 50 publications on the topic.…”

mentioning

confidence: 99%

Waterborne Coatings Encapsulating Living Nitrifying Bacteria for Wastewater Treatment

Chen

Krings

Beale

et al. 2022

Advanced Sustainable Systems

View full text Add to dashboard Cite

Biofilm bioreactors are attracting growing interest in the wastewater industry, as they allow higher cell densities and thus higher reaction rates compared to conventional bioreactors. However, some commonly used nitrifying bacteria, such as Nitrosomonas europaea, are slow‐growing and need a prolonged period of time to develop a mature biofilm. Here, a biocoating or “living paint” is introduced, which is a synthetic biofilm made from a colloidal polymer (synthetic latex) binder encapsulating viable nitrifying bacteria at high density. Conventionally, the film formation of biocoatings is achieved by drying a bacteria/latex mixture. However, this fabrication is detrimental to the viability of the encapsulated bacteria because of the osmotic stress induced by desiccation. A nondesiccating film formation process is presented for biocoatings, which exploits two colloid science phenomena: coagulation and wet sintering. Desiccation‐sensitive, nitrifying bacteria are employed in the biocoatings to convert NH4+ to NO2− and then NO3−. These biocoatings have a conversion rate (NO2− and NO3− production) of 3 mg N g−1 d−1 that is five times higher than in conventionally desiccated biocoatings. The reactivity continues over a period of 1 month. The processing method for these living paints is transformative for wastewater treatment and other applications using delicate, desiccation‐sensitive microorganisms.

show abstract

Painting and Printing Living Bacteria: Engineering Nanoporous Biocatalytic Coatings to Preserve Microbial Viability and Intensify Reactivity

Flickinger

Schottel

Bond

et al. 2007

Biotechnology Progress

Self Cite

100

View full text Add to dashboard Cite

Latex biocatalytic coatings containing ∼50% by volume of microorganisms stabilize, concentrate and preserve cell viability on surfaces at ambient temperature. Coatings can be formed on a variety of surfaces, delaminated to generate stand-alone membranes or formulated as reactive inks for piezoelectric deposition of viable microbes. As the latex emulsion dries, cell preservation by partial desiccation occurs simultaneously with the formation of pores and adhesion to the substrate. The result is living cells permanently entrapped, surrounded by nanopores generated by partially coalesced polymer particles. Nanoporosity is essential for preserving microbial viability and coating reactivity. Cryo-SEM methods have been developed to visualize hydrated coating microstructure, confocal microscopy and dispersible coating methods have been developed to quantify the activity of the entrapped cells, and FTIR methods are being developed to determine the structure of vitrified biomolecules within and surrounding the cells in dry coatings. Coating microstructure, stability and reactivity are investigated using small patch or strip coatings where bacteria are concentrated 10 2 -to 10 3 -fold in 5-75 µm thick layers with pores formed by carbohydrate porogens. The carbohydrate porogens also function as osmoprotectants and are postulated to preserve microbial viability by formation of glasses inside the microbes during coat drying; however, the molecular mechanism of cell preservation by latex coatings is not known. Emerging applications include coatings for multistep oxidations, photoreactive coatings, stabilization of hyperthermophiles, environmental biosensors, microbial fuel cells, as reaction zones in microfluidic devices, or as very high intensity (>100 g‚L -1 coating volume‚h -1 ) industrial or environmental biocatalysts. We anticipate expanded use of nanoporous adhesive coatings for prokaryotic and eukaryotic cell preservation at ambient temperature and the design of highly reactive "living" paints and inks.

show abstract

Cryo-Electron Microscopy of Polymer Particles in a High Cell Density Synthetic Biofilm

Cited by 3 publications

References 6 publications

Engineering the Microstructure and Permeability of Thin Multilayer Latex Biocatalytic Coatings Containing E. coli

Engineering the Microstructure and Permeability of Thin Multilayer Latex Biocatalytic Coatings Containing E. coli

Waterborne Coatings Encapsulating Living Nitrifying Bacteria for Wastewater Treatment

Painting and Printing Living Bacteria: Engineering Nanoporous Biocatalytic Coatings to Preserve Microbial Viability and Intensify Reactivity

Contact Info

Product

Resources

About