Limits...
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

Effects of different PCS blends on the weight of bacteria biomass on the PCS in test tube systems without pH control after 120 h (n = 3). (S, soybean hulls; F, soybean flour; Y, yeast extract; R, drued bovine RBC; B, dried bovine albumin; +, mineral salts).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2724407&req=5

Figure 2: Effects of different PCS blends on the weight of bacteria biomass on the PCS in test tube systems without pH control after 120 h (n = 3). (S, soybean hulls; F, soybean flour; Y, yeast extract; R, drued bovine RBC; B, dried bovine albumin; +, mineral salts).

Mentions: BC production (g/l) and biomass formation (g/g-PCS) in flask fermentation from three replicates of each PCS types are presented in Figures 2 and 3. When biomass vs. BC was plotted (not shown), the result showed no specific relationship between biomass attached on PCS and BC production as the correlation coefficients between these values were extremely low: R-squared values of 0.01 for biomass versus BC production. This pattern was also observed in the PCS biofilm fermentation of succinic acid and nisin [24,26]. Comparable levels of biomass were attached on each PCS, ranging from 1.1 to 3.3 g/g-PCS. In an attempt to select an optimal PCS for BC production, the means of BC produced (g/l) were ranked as follow according to the results from Tukey's multiple comparisons: SY+ > SFR, SFYR+, SR+, SFYBR > S, SB+, SFY, SYB+ > SFYB+ > SFYB and the ranking of biomass produced (g/g) on PCS was: SFYR+, SYB+, SFYB > SF+, SR+, SY+ > S, SB+, SFB, SFR, SFY, SFYB+, SFYBR. Overall, after considering other factors such as nitrogen content per g of PCS, nitrogen leaching rate, and amounts of biomass attached on PCS, 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 [22-24], and high biomass attachment (Figure 2).


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)

Effects of different PCS blends on the weight of bacteria biomass on the PCS in test tube systems without pH control after 120 h (n = 3). (S, soybean hulls; F, soybean flour; Y, yeast extract; R, drued bovine RBC; B, dried bovine albumin; +, mineral salts).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 2: Effects of different PCS blends on the weight of bacteria biomass on the PCS in test tube systems without pH control after 120 h (n = 3). (S, soybean hulls; F, soybean flour; Y, yeast extract; R, drued bovine RBC; B, dried bovine albumin; +, mineral salts).
Mentions: BC production (g/l) and biomass formation (g/g-PCS) in flask fermentation from three replicates of each PCS types are presented in Figures 2 and 3. When biomass vs. BC was plotted (not shown), the result showed no specific relationship between biomass attached on PCS and BC production as the correlation coefficients between these values were extremely low: R-squared values of 0.01 for biomass versus BC production. This pattern was also observed in the PCS biofilm fermentation of succinic acid and nisin [24,26]. Comparable levels of biomass were attached on each PCS, ranging from 1.1 to 3.3 g/g-PCS. In an attempt to select an optimal PCS for BC production, the means of BC produced (g/l) were ranked as follow according to the results from Tukey's multiple comparisons: SY+ > SFR, SFYR+, SR+, SFYBR > S, SB+, SFY, SYB+ > SFYB+ > SFYB and the ranking of biomass produced (g/g) on PCS was: SFYR+, SYB+, SFYB > SF+, SR+, SY+ > S, SB+, SFB, SFR, SFY, SFYB+, SFYBR. Overall, after considering other factors such as nitrogen content per g of PCS, nitrogen leaching rate, and amounts of biomass attached on PCS, 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 [22-24], and high biomass attachment (Figure 2).

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