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Enhanced production of bacterial cellulose by using a biofilm reactor and its material property analysis.

Cheng KC, Catchmark JM, Demirci A - J Biol Eng (2009)

Bottom Line: FESEM results showed the attachment of A. xylinum on PCS, producing an interweaving BC product.TGA results demonstrated that PCS-grown BC had about 95% water retention ability, which was lower than BC produced within suspended-cell reactor.Finally, DMA results showed that BC from the PCS biofilm reactor increased its mechanical property values, i.e., stress at break and Young's modulus when compared to the control BC.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Agricultural and Biological Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA. kuc141@psu.edu

ABSTRACT
Bacterial cellulose has been used in the food industry for applications such as low-calorie desserts, salads, and fabricated foods. It has also been used in the paper manufacturing industry to enhance paper strength, the electronics industry in acoustic diaphragms for audio speakers, the pharmaceutical industry as filtration membranes, and in the medical field as wound dressing and artificial skin material. In this study, different types of plastic composite support (PCS) were implemented separately within a fermentation medium in order to enhance bacterial cellulose (BC) production by Acetobacter xylinum. The optimal composition of nutritious compounds in PCS was chosen based on the amount of BC produced. The selected PCS was implemented within a bioreactor to examine the effects on BC production in a batch fermentation. The produced BC was analyzed using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA). Among thirteen types of PCS, the type SFYR+ was selected as solid support for BC production by A. xylinum in a batch biofilm reactor due to its high nitrogen content, moderate nitrogen leaching rate, and sufficient biomass attached on PCS. The PCS biofilm reactor yielded BC production (7.05 g/L) that was 2.5-fold greater than the control (2.82 g/L). The XRD results indicated that the PCS-grown BC exhibited higher crystallinity (93%) and similar crystal size (5.2 nm) to the control. FESEM results showed the attachment of A. xylinum on PCS, producing an interweaving BC product. TGA results demonstrated that PCS-grown BC had about 95% water retention ability, which was lower than BC produced within suspended-cell reactor. PCS-grown BC also exhibited higher Tmax compared to the control. Finally, DMA results showed that BC from the PCS biofilm reactor increased its mechanical property values, i.e., stress at break and Young's modulus when compared to the control BC. The results clearly demonstrated that implementation of PCS within agitated fermentation enhanced BC production and improved its mechanical properties and thermal stability.

No MeSH data available.


Related in: MedlinePlus

Stress/strain diagrams of tensile test results. (A) PCS-grown BC. (B) Control BC.
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Figure 8: Stress/strain diagrams of tensile test results. (A) PCS-grown BC. (B) Control BC.

Mentions: BC produced in either agitated or air-lifted culture is believed to lose its high polymerization property which results in low mechanical strength [35] due to the formation of small pellets. As a result, DMA analysis was performed to determine if there was any improvement in mechanical strength of PCS-grown BC as compared to control BC. Both types of BC were investigated: PCS-grown BC from a PCS biofilm reactor, and control from agitated culture. Figure 8 shows a typical stress-strain response of the PCS-grown BC (A) and control (B) samples. The extension of our testers showed a linear-elastic behavior. PCS-grown BC exhibited a longer elastic deformation around 1.4%, where a yield point was seen, which was followed by irreversible deformation. On the other hand, control BC testers showed only 0.8% elongation.


Enhanced production of bacterial cellulose by using a biofilm reactor and its material property analysis.

Cheng KC, Catchmark JM, Demirci A - J Biol Eng (2009)

Stress/strain diagrams of tensile test results. (A) PCS-grown BC. (B) Control BC.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2724407&req=5

Figure 8: Stress/strain diagrams of tensile test results. (A) PCS-grown BC. (B) Control BC.
Mentions: BC produced in either agitated or air-lifted culture is believed to lose its high polymerization property which results in low mechanical strength [35] due to the formation of small pellets. As a result, DMA analysis was performed to determine if there was any improvement in mechanical strength of PCS-grown BC as compared to control BC. Both types of BC were investigated: PCS-grown BC from a PCS biofilm reactor, and control from agitated culture. Figure 8 shows a typical stress-strain response of the PCS-grown BC (A) and control (B) samples. The extension of our testers showed a linear-elastic behavior. PCS-grown BC exhibited a longer elastic deformation around 1.4%, where a yield point was seen, which was followed by irreversible deformation. On the other hand, control BC testers showed only 0.8% elongation.

Bottom Line: FESEM results showed the attachment of A. xylinum on PCS, producing an interweaving BC product.TGA results demonstrated that PCS-grown BC had about 95% water retention ability, which was lower than BC produced within suspended-cell reactor.Finally, DMA results showed that BC from the PCS biofilm reactor increased its mechanical property values, i.e., stress at break and Young's modulus when compared to the control BC.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Agricultural and Biological Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA. kuc141@psu.edu

ABSTRACT
Bacterial cellulose has been used in the food industry for applications such as low-calorie desserts, salads, and fabricated foods. It has also been used in the paper manufacturing industry to enhance paper strength, the electronics industry in acoustic diaphragms for audio speakers, the pharmaceutical industry as filtration membranes, and in the medical field as wound dressing and artificial skin material. In this study, different types of plastic composite support (PCS) were implemented separately within a fermentation medium in order to enhance bacterial cellulose (BC) production by Acetobacter xylinum. The optimal composition of nutritious compounds in PCS was chosen based on the amount of BC produced. The selected PCS was implemented within a bioreactor to examine the effects on BC production in a batch fermentation. The produced BC was analyzed using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA). Among thirteen types of PCS, the type SFYR+ was selected as solid support for BC production by A. xylinum in a batch biofilm reactor due to its high nitrogen content, moderate nitrogen leaching rate, and sufficient biomass attached on PCS. The PCS biofilm reactor yielded BC production (7.05 g/L) that was 2.5-fold greater than the control (2.82 g/L). The XRD results indicated that the PCS-grown BC exhibited higher crystallinity (93%) and similar crystal size (5.2 nm) to the control. FESEM results showed the attachment of A. xylinum on PCS, producing an interweaving BC product. TGA results demonstrated that PCS-grown BC had about 95% water retention ability, which was lower than BC produced within suspended-cell reactor. PCS-grown BC also exhibited higher Tmax compared to the control. Finally, DMA results showed that BC from the PCS biofilm reactor increased its mechanical property values, i.e., stress at break and Young's modulus when compared to the control BC. The results clearly demonstrated that implementation of PCS within agitated fermentation enhanced BC production and improved its mechanical properties and thermal stability.

No MeSH data available.


Related in: MedlinePlus