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Effects of aromatic compounds on the production of bacterial nanocellulose by Gluconacetobacter xylinus.

Zhang S, Winestrand S, Guo X, Chen L, Hong F, Jönsson LJ - Microb. Cell Fact. (2014)

Bottom Line: However, very little is known about the effect on G. xylinus of specific lignocellulose-derived inhibitors.Vanillin was reduced to vanillyl alcohol with a yield of up to 80%.This is the first investigation of the effect of specific phenolics on the production of BC by G. xylinus, and is also the first demonstration of the ability of G. xylinus to convert phenolic compounds.

View Article: PubMed Central - HTML - PubMed

Affiliation: China-Sweden Associated Research Laboratory in Industrial Biotechnology, College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China. fhong@dhu.edu.cn.

ABSTRACT

Background: Bacterial cellulose (BC) is a polymeric nanostructured fibrillar network produced by certain microorganisms, principally Gluconacetobacter xylinus. BC has a great potential of application in many fields. Lignocellulosic biomass has been investigated as a cost-effective feedstock for BC production through pretreatment and hydrolysis. It is well known that detoxification of lignocellulosic hydrolysates may be required to achieve efficient production of BC. Recent results suggest that phenolic compounds contribute to the inhibition of G. xylinus. However, very little is known about the effect on G. xylinus of specific lignocellulose-derived inhibitors. In this study, the inhibitory effects of four phenolic model compounds (coniferyl aldehyde, ferulic acid, vanillin and 4-hydroxybenzoic acid) on the growth of G. xylinus, the pH of the culture medium, and the production of BC were investigated in detail. The stability of the phenolics in the bacterial cultures was investigated and the main bioconversion products were identified and quantified.

Results: Coniferyl aldehyde was the most potent inhibitor, followed by vanillin, ferulic acid, and 4-hydroxybenzoic acid. There was no BC produced even with coniferyl aldehyde concentrations as low as 2 mM. Vanillin displayed a negative effect on the bacteria and when the vanillin concentration was raised to 2.5 mM the volumetric yield of BC decreased to ~40% of that obtained in control medium without inhibitors. The phenolic acids, ferulic acid and 4-hydroxybenzoic acid, showed almost no toxic effects when less than 2.5 mM. The bacterial cultures oxidized coniferyl aldehyde to ferulic acid with a yield of up to 81%. Vanillin was reduced to vanillyl alcohol with a yield of up to 80%.

Conclusions: This is the first investigation of the effect of specific phenolics on the production of BC by G. xylinus, and is also the first demonstration of the ability of G. xylinus to convert phenolic compounds. This study gives a better understanding of how phenolic compounds and G. xylinus cultures are affected by each other. Investigations in this area are useful for elucidating the mechanism behind inhibition of G. xylinus in lignocellulosic hydrolysates and for understanding how production of BC using lignocellulosic feedstocks can be performed in an efficient way.

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Cultivation of G. xylinus in medium containingvanillin. The figure shows changes in (A) the glucose concentrationof the culture medium, (B) the pH value of the culture medium, (C)the concentration of living cells, and (D) the concentration of vanillin.Vanillin was added on day one. Error bars show standard errors of means of threereplicates.
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Figure 4: Cultivation of G. xylinus in medium containingvanillin. The figure shows changes in (A) the glucose concentrationof the culture medium, (B) the pH value of the culture medium, (C)the concentration of living cells, and (D) the concentration of vanillin.Vanillin was added on day one. Error bars show standard errors of means of threereplicates.

Mentions: Results obtained with vanillin are shown in Figure 4 and inTable 1. Figure 4 indicatesthat vanillin did not severely inhibit the growth of G. xylinus until theconcentration exceeded 2.5 mM (Figure 4A-C). An initialvanillin concentration of 0.5 mM hardly affected glucose consumption, pH value orBC yield (Figure 4 and Table 1).With an initial vanillin concentration of 2.5 mM, the glucose consumption ratedeclined from 3.5 g/(L∙d) to 1.7 g/(L∙d) (Table 1A). The concentration of living bacteria at the end of thecultivation was 4.0 × 106 cells/mL, much lower than in thecultures with reference medium, which reached 23.4 × 106cells/mL (Figure 4C). The volumetric yield of BC declined asthe concentration of vanillin increased (Table 1B). When theinitial concentration of vanillin was 5 mM or higher, the glucose consumption ratewas <0.4 g/(L∙d) (Table 1A), the concentrationof living bacteria in the cultures was very low (Figure 4C),and the yield of BC was <0.4 g/L (Table 1B).


Effects of aromatic compounds on the production of bacterial nanocellulose by Gluconacetobacter xylinus.

Zhang S, Winestrand S, Guo X, Chen L, Hong F, Jönsson LJ - Microb. Cell Fact. (2014)

Cultivation of G. xylinus in medium containingvanillin. The figure shows changes in (A) the glucose concentrationof the culture medium, (B) the pH value of the culture medium, (C)the concentration of living cells, and (D) the concentration of vanillin.Vanillin was added on day one. Error bars show standard errors of means of threereplicates.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4126184&req=5

Figure 4: Cultivation of G. xylinus in medium containingvanillin. The figure shows changes in (A) the glucose concentrationof the culture medium, (B) the pH value of the culture medium, (C)the concentration of living cells, and (D) the concentration of vanillin.Vanillin was added on day one. Error bars show standard errors of means of threereplicates.
Mentions: Results obtained with vanillin are shown in Figure 4 and inTable 1. Figure 4 indicatesthat vanillin did not severely inhibit the growth of G. xylinus until theconcentration exceeded 2.5 mM (Figure 4A-C). An initialvanillin concentration of 0.5 mM hardly affected glucose consumption, pH value orBC yield (Figure 4 and Table 1).With an initial vanillin concentration of 2.5 mM, the glucose consumption ratedeclined from 3.5 g/(L∙d) to 1.7 g/(L∙d) (Table 1A). The concentration of living bacteria at the end of thecultivation was 4.0 × 106 cells/mL, much lower than in thecultures with reference medium, which reached 23.4 × 106cells/mL (Figure 4C). The volumetric yield of BC declined asthe concentration of vanillin increased (Table 1B). When theinitial concentration of vanillin was 5 mM or higher, the glucose consumption ratewas <0.4 g/(L∙d) (Table 1A), the concentrationof living bacteria in the cultures was very low (Figure 4C),and the yield of BC was <0.4 g/L (Table 1B).

Bottom Line: However, very little is known about the effect on G. xylinus of specific lignocellulose-derived inhibitors.Vanillin was reduced to vanillyl alcohol with a yield of up to 80%.This is the first investigation of the effect of specific phenolics on the production of BC by G. xylinus, and is also the first demonstration of the ability of G. xylinus to convert phenolic compounds.

View Article: PubMed Central - HTML - PubMed

Affiliation: China-Sweden Associated Research Laboratory in Industrial Biotechnology, College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai 201620, China. fhong@dhu.edu.cn.

ABSTRACT

Background: Bacterial cellulose (BC) is a polymeric nanostructured fibrillar network produced by certain microorganisms, principally Gluconacetobacter xylinus. BC has a great potential of application in many fields. Lignocellulosic biomass has been investigated as a cost-effective feedstock for BC production through pretreatment and hydrolysis. It is well known that detoxification of lignocellulosic hydrolysates may be required to achieve efficient production of BC. Recent results suggest that phenolic compounds contribute to the inhibition of G. xylinus. However, very little is known about the effect on G. xylinus of specific lignocellulose-derived inhibitors. In this study, the inhibitory effects of four phenolic model compounds (coniferyl aldehyde, ferulic acid, vanillin and 4-hydroxybenzoic acid) on the growth of G. xylinus, the pH of the culture medium, and the production of BC were investigated in detail. The stability of the phenolics in the bacterial cultures was investigated and the main bioconversion products were identified and quantified.

Results: Coniferyl aldehyde was the most potent inhibitor, followed by vanillin, ferulic acid, and 4-hydroxybenzoic acid. There was no BC produced even with coniferyl aldehyde concentrations as low as 2 mM. Vanillin displayed a negative effect on the bacteria and when the vanillin concentration was raised to 2.5 mM the volumetric yield of BC decreased to ~40% of that obtained in control medium without inhibitors. The phenolic acids, ferulic acid and 4-hydroxybenzoic acid, showed almost no toxic effects when less than 2.5 mM. The bacterial cultures oxidized coniferyl aldehyde to ferulic acid with a yield of up to 81%. Vanillin was reduced to vanillyl alcohol with a yield of up to 80%.

Conclusions: This is the first investigation of the effect of specific phenolics on the production of BC by G. xylinus, and is also the first demonstration of the ability of G. xylinus to convert phenolic compounds. This study gives a better understanding of how phenolic compounds and G. xylinus cultures are affected by each other. Investigations in this area are useful for elucidating the mechanism behind inhibition of G. xylinus in lignocellulosic hydrolysates and for understanding how production of BC using lignocellulosic feedstocks can be performed in an efficient way.

Show MeSH
Related in: MedlinePlus