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Cellulosic ethanol production by natural bacterial consortia is enhanced by Pseudoxanthomonas taiwanensis.

Du R, Yan J, Li S, Zhang L, Zhang S, Li J, Zhao G, Qi P - Biotechnol Biofuels (2015)

Bottom Line: In the present study, we analyzed 16 different natural bacterial consortia from a variety of habitats in China and found that the HP consortium exhibited relatively high ethanol production (2.06 g/L ethanol titer from 7 g/L α-cellulose at 55°C in 6 days).The ethanol conversion ratio reached 78%, with ethanol titers up to 2.5 g/L.In the present study, we found a natural bacterial consortium with outstanding ethanol production performance, and revealed an efficient method with potentially broad applicability for further improving the ethanol production of natural bacterial consortia.

View Article: PubMed Central - PubMed

Affiliation: Institute of New Nuclear and New Energy Technology, Tsinghua University, Beijing, 100084 China ; Beijing Engineering Research Center for Biofuels, Tsinghua University, Beijing, 100084 China.

ABSTRACT

Background: Natural bacterial consortia are considered a promising solution for one-step production of ethanol from lignocellulose because of their adaptation to a wide range of natural lignocellulosic substrates and their capacity for efficient cellulose degradation. However, their low ethanol conversion efficiency has greatly limited the development and application of natural bacterial consortia.

Results: In the present study, we analyzed 16 different natural bacterial consortia from a variety of habitats in China and found that the HP consortium exhibited relatively high ethanol production (2.06 g/L ethanol titer from 7 g/L α-cellulose at 55°C in 6 days). Further studies showed that Pseudoxanthomonas taiwanensis played an important role in the high ethanol productivity of HP and that this strain effectively boosted the ethanol production of various other natural bacterial consortia. Finally, we developed a new consortium, termed HPP, by optimizing the proportion of P. taiwanensis in the HP consortium to achieve the highest ethanol production reported for natural consortia. The ethanol conversion ratio reached 78%, with ethanol titers up to 2.5 g/L.

Conclusions: In the present study, we found a natural bacterial consortium with outstanding ethanol production performance, and revealed an efficient method with potentially broad applicability for further improving the ethanol production of natural bacterial consortia.

No MeSH data available.


Related in: MedlinePlus

The strengthened consortium HP withP. taiwanensis(HPP) exhibits increased ethanol production capability. (A)P. taiwanensis boosts ethanol production by consortium HP in a dose-dependent manner. Co-fermentations were conducted with different proportions of P. taiwanensis and with α-cellulose as a carbon source at 55°C for 7 days, with HP as a control. The ratio in the legend represents the biomass ratio between the consortium and the single strain. The error bars represent SD (n = 3). (B) Cellulase enzyme activity of HP and HPP. Fermentation was conducted with α-cellulose at 55°C for 7 days, and the cellulase enzyme activities of the consortium with and without P. taiwanensis co-culture at a 17:1 biomass ratio were measured; the highest activities are shown. FPase, filter paper activity; EG, endoglucanase; CBH, exoglucanase; BG, β-glucosidase. HPP represents the new consortium obtained by co-culture of HP and P. taiwanensis. The error bars represent the SD (n = 3). (C) PCR-DGGE analysis of HP and HPP at two stages, including the highest filter paper activity (represented as FPase) and highest ethanol titer (represented as EtOH). (D) Principal component analysis (PCA) of the PCR-DGGE data in C. PC1 and PC2 explained 57.5% and 30.6% of the total variance, respectively.
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Fig4: The strengthened consortium HP withP. taiwanensis(HPP) exhibits increased ethanol production capability. (A)P. taiwanensis boosts ethanol production by consortium HP in a dose-dependent manner. Co-fermentations were conducted with different proportions of P. taiwanensis and with α-cellulose as a carbon source at 55°C for 7 days, with HP as a control. The ratio in the legend represents the biomass ratio between the consortium and the single strain. The error bars represent SD (n = 3). (B) Cellulase enzyme activity of HP and HPP. Fermentation was conducted with α-cellulose at 55°C for 7 days, and the cellulase enzyme activities of the consortium with and without P. taiwanensis co-culture at a 17:1 biomass ratio were measured; the highest activities are shown. FPase, filter paper activity; EG, endoglucanase; CBH, exoglucanase; BG, β-glucosidase. HPP represents the new consortium obtained by co-culture of HP and P. taiwanensis. The error bars represent the SD (n = 3). (C) PCR-DGGE analysis of HP and HPP at two stages, including the highest filter paper activity (represented as FPase) and highest ethanol titer (represented as EtOH). (D) Principal component analysis (PCA) of the PCR-DGGE data in C. PC1 and PC2 explained 57.5% and 30.6% of the total variance, respectively.

Mentions: Based on this idea, we further optimized the HP consortium and found that the highest ethanol titer, 2.5 g/L from α-cellulose, was achieved at a biomass ratio of 17:1 between the HP consortium and P. taiwanensis (Figure 4A). Compared with the original HP consortium, the optimized HP that contained P. taiwanensis (HPP consortium) showed a 21.5% increase in β-glucosidase activity and slight improvements in exoglucanase and filter paper activities (Figure 4B). A community structure analysis (Figure 4C and D) further revealed an 18% difference between HP and HPP at the point of the highest ethanol titer. Given that the HP consortium alone included a certain amount of P. taiwanensis, these results demonstrated that addition of P. taiwanensis at the correct biomass ratio could further improve the cellulose utilization of natural consortia that already possessed the strain. Moreover, the HPP consortium, with an optimized P. taiwanensis concentration, exhibited significant improvement in cellulose degradation and conversion of filter paper and sweet sorghum stalks (Table 1), suggesting that HPP has potential for industrial ethanol production utilizing natural lignocellulosic substrates.Figure 4


Cellulosic ethanol production by natural bacterial consortia is enhanced by Pseudoxanthomonas taiwanensis.

Du R, Yan J, Li S, Zhang L, Zhang S, Li J, Zhao G, Qi P - Biotechnol Biofuels (2015)

The strengthened consortium HP withP. taiwanensis(HPP) exhibits increased ethanol production capability. (A)P. taiwanensis boosts ethanol production by consortium HP in a dose-dependent manner. Co-fermentations were conducted with different proportions of P. taiwanensis and with α-cellulose as a carbon source at 55°C for 7 days, with HP as a control. The ratio in the legend represents the biomass ratio between the consortium and the single strain. The error bars represent SD (n = 3). (B) Cellulase enzyme activity of HP and HPP. Fermentation was conducted with α-cellulose at 55°C for 7 days, and the cellulase enzyme activities of the consortium with and without P. taiwanensis co-culture at a 17:1 biomass ratio were measured; the highest activities are shown. FPase, filter paper activity; EG, endoglucanase; CBH, exoglucanase; BG, β-glucosidase. HPP represents the new consortium obtained by co-culture of HP and P. taiwanensis. The error bars represent the SD (n = 3). (C) PCR-DGGE analysis of HP and HPP at two stages, including the highest filter paper activity (represented as FPase) and highest ethanol titer (represented as EtOH). (D) Principal component analysis (PCA) of the PCR-DGGE data in C. PC1 and PC2 explained 57.5% and 30.6% of the total variance, respectively.
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Related In: Results  -  Collection

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Fig4: The strengthened consortium HP withP. taiwanensis(HPP) exhibits increased ethanol production capability. (A)P. taiwanensis boosts ethanol production by consortium HP in a dose-dependent manner. Co-fermentations were conducted with different proportions of P. taiwanensis and with α-cellulose as a carbon source at 55°C for 7 days, with HP as a control. The ratio in the legend represents the biomass ratio between the consortium and the single strain. The error bars represent SD (n = 3). (B) Cellulase enzyme activity of HP and HPP. Fermentation was conducted with α-cellulose at 55°C for 7 days, and the cellulase enzyme activities of the consortium with and without P. taiwanensis co-culture at a 17:1 biomass ratio were measured; the highest activities are shown. FPase, filter paper activity; EG, endoglucanase; CBH, exoglucanase; BG, β-glucosidase. HPP represents the new consortium obtained by co-culture of HP and P. taiwanensis. The error bars represent the SD (n = 3). (C) PCR-DGGE analysis of HP and HPP at two stages, including the highest filter paper activity (represented as FPase) and highest ethanol titer (represented as EtOH). (D) Principal component analysis (PCA) of the PCR-DGGE data in C. PC1 and PC2 explained 57.5% and 30.6% of the total variance, respectively.
Mentions: Based on this idea, we further optimized the HP consortium and found that the highest ethanol titer, 2.5 g/L from α-cellulose, was achieved at a biomass ratio of 17:1 between the HP consortium and P. taiwanensis (Figure 4A). Compared with the original HP consortium, the optimized HP that contained P. taiwanensis (HPP consortium) showed a 21.5% increase in β-glucosidase activity and slight improvements in exoglucanase and filter paper activities (Figure 4B). A community structure analysis (Figure 4C and D) further revealed an 18% difference between HP and HPP at the point of the highest ethanol titer. Given that the HP consortium alone included a certain amount of P. taiwanensis, these results demonstrated that addition of P. taiwanensis at the correct biomass ratio could further improve the cellulose utilization of natural consortia that already possessed the strain. Moreover, the HPP consortium, with an optimized P. taiwanensis concentration, exhibited significant improvement in cellulose degradation and conversion of filter paper and sweet sorghum stalks (Table 1), suggesting that HPP has potential for industrial ethanol production utilizing natural lignocellulosic substrates.Figure 4

Bottom Line: In the present study, we analyzed 16 different natural bacterial consortia from a variety of habitats in China and found that the HP consortium exhibited relatively high ethanol production (2.06 g/L ethanol titer from 7 g/L α-cellulose at 55°C in 6 days).The ethanol conversion ratio reached 78%, with ethanol titers up to 2.5 g/L.In the present study, we found a natural bacterial consortium with outstanding ethanol production performance, and revealed an efficient method with potentially broad applicability for further improving the ethanol production of natural bacterial consortia.

View Article: PubMed Central - PubMed

Affiliation: Institute of New Nuclear and New Energy Technology, Tsinghua University, Beijing, 100084 China ; Beijing Engineering Research Center for Biofuels, Tsinghua University, Beijing, 100084 China.

ABSTRACT

Background: Natural bacterial consortia are considered a promising solution for one-step production of ethanol from lignocellulose because of their adaptation to a wide range of natural lignocellulosic substrates and their capacity for efficient cellulose degradation. However, their low ethanol conversion efficiency has greatly limited the development and application of natural bacterial consortia.

Results: In the present study, we analyzed 16 different natural bacterial consortia from a variety of habitats in China and found that the HP consortium exhibited relatively high ethanol production (2.06 g/L ethanol titer from 7 g/L α-cellulose at 55°C in 6 days). Further studies showed that Pseudoxanthomonas taiwanensis played an important role in the high ethanol productivity of HP and that this strain effectively boosted the ethanol production of various other natural bacterial consortia. Finally, we developed a new consortium, termed HPP, by optimizing the proportion of P. taiwanensis in the HP consortium to achieve the highest ethanol production reported for natural consortia. The ethanol conversion ratio reached 78%, with ethanol titers up to 2.5 g/L.

Conclusions: In the present study, we found a natural bacterial consortium with outstanding ethanol production performance, and revealed an efficient method with potentially broad applicability for further improving the ethanol production of natural bacterial consortia.

No MeSH data available.


Related in: MedlinePlus