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Impact of syringaldehyde on the growth of Clostridium beijerinckii NCIMB 8052 and butanol production

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ABSTRACT

While lignocellulosic biomass excels as a cheap, renewable resource for biofuel production, it does present some challenges such as generation of microbial inhibitory compounds. The mode of selective inhibition of acetone–butanol–ethanol (ABE) production (as opposed to cell growth) by syringaldehyde on Clostridium beijerinckii NCIMB 8052 was examined. C. beijerinckii 8052 grown in syringaldehyde-supplemented P2 medium had a comparable growth rate (μ = 0.34) at acidogenic growth phase to that of C. beijerinckii 8052 grown in control P2 medium (μ = 0.30). The addition of syringaldehyde into P2 medium inhibited solvent production by C. beijerinckii 8052 and increased butyric and acetic acid accumulation in the fermentation broth. Analysis of coenzyme A transferase (CoAT) using cell-free extracts of C. beijerinckii 8052 showed decreased expression and activity in the presence of syringaldehyde. These results indicate that C. beijerinckii 8052 CoAT is negatively affected by syringaldehyde and thus, hampers the ability of the microorganism to metabolize butyric and acetic acid for ABE production as evidenced by the accumulation of butyric and acetic acid in the fermentation broth.

No MeSH data available.


Kinetic behavior of glucose utilization (a) and cell growth (b) by C. beijerinckii NCIMB 8052 in P2 medium supplemented with different (0.2–1.0 g/L) concentrations of syringaldehyde. Data represent averages of results from at least three fermentations
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Fig1: Kinetic behavior of glucose utilization (a) and cell growth (b) by C. beijerinckii NCIMB 8052 in P2 medium supplemented with different (0.2–1.0 g/L) concentrations of syringaldehyde. Data represent averages of results from at least three fermentations

Mentions: The initial sugar level in the growth medium was 59 g/L in all treatments. Figure 1a presents the time course of glucose utilization during the growth of C. beijerinckii in P2 medium containing different concentrations of syringaldehyde. Interestingly, syringaldehyde (0.2–1.0 g/L) enhanced the growth of C. beijerinckii by 4–31% during initial 24 h of fermentation when compared to the control experiment (Fig. 1b). In contrast, syringaldehyde has been shown to reduce the growth of E. coli KO11 and E. coli LY01 by more than 75% during the first 24-h postinoculation and by 40% after 48 h of growth (Zaldivar et al. 1999). Prior reports have shown that syringaldehyde (≤2.0 g/L) had no significant effect on the overall growth of C. beijerinckii BA101 (Ezeji et al. 2007b). In view of the biphasic (acidogenic and solventogenic) life cycle nature of solventogenic Clostridium species, however, it is not clear whether syringaldehyde will have profound impact at a particular growth phase. Analysis of the impact of syringaldehyde on C. beijerinckii 8052 growth and generation time revealed that C. beijerinckii 8052 had a growth rate, μ, of 0.34 and a generation time of 2.21 h in the presence of 1.0 g/L syringaldehyde at the exponential growth phase during which acetic and butyric acid are produced predominantly (Table 1). Similarly, average generation time of 2.46 h and growth rate of 0.30 were obtained with control fermentations (Table 1). Consequently, the presence of syringaldehyde in the fermentation medium did not have significant effect on the generation time and growth rate of C. beijerinckii 8052 during exponential growth phase. As expected, the growth rate of C. beijerinckii 8052 grown in both P2 control and syringaldehyde-supplemented P2 media decreased drastically (Table 1) at the solventogenic growth phase during which previously produced acetic and butyric acid were expected to be re-assimilated for ABE production. Although the presence of syringaldehyde marginally increased the growth rate of C. beijerinckii 8052 with concomitant decrease in generation time during exponential phase, the growth rate of C. beijerinckii 8052 during the solventogenic growth phase in P2 control medium was 117% more than that of the syringaldehyde-supplemented P2 medium (Table 1). At the end of fermentation residual glucose concentration was 18.3 g/L for the control fermentation. It can be noted that the utilization of glucose by C. beijerinckii, as estimated by measurement of residual glucose concentration after fermentation, varied (17.8–44.1 g/L) during growth in syringaldehyde-supplemented P2 medium. The reduction (13–64%) in glucose utilization by C. beijerinckii during growth in syringaldehyde-supplemented P2 medium (>0.4 g/L syringaldehyde) is associated with abrupt decrease in growth after 24 h of the fermentation (Fig. 1). In contrast, the growth of C. beijerinckii in P2 medium (control) or syringaldehyde-supplemented P2 medium (≤0.4 g/L syringaldehyde) extended to 36 h after which gradual decrease ensued (Fig. 1b).Fig. 1


Impact of syringaldehyde on the growth of Clostridium beijerinckii NCIMB 8052 and butanol production
Kinetic behavior of glucose utilization (a) and cell growth (b) by C. beijerinckii NCIMB 8052 in P2 medium supplemented with different (0.2–1.0 g/L) concentrations of syringaldehyde. Data represent averages of results from at least three fermentations
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Related In: Results  -  Collection

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Fig1: Kinetic behavior of glucose utilization (a) and cell growth (b) by C. beijerinckii NCIMB 8052 in P2 medium supplemented with different (0.2–1.0 g/L) concentrations of syringaldehyde. Data represent averages of results from at least three fermentations
Mentions: The initial sugar level in the growth medium was 59 g/L in all treatments. Figure 1a presents the time course of glucose utilization during the growth of C. beijerinckii in P2 medium containing different concentrations of syringaldehyde. Interestingly, syringaldehyde (0.2–1.0 g/L) enhanced the growth of C. beijerinckii by 4–31% during initial 24 h of fermentation when compared to the control experiment (Fig. 1b). In contrast, syringaldehyde has been shown to reduce the growth of E. coli KO11 and E. coli LY01 by more than 75% during the first 24-h postinoculation and by 40% after 48 h of growth (Zaldivar et al. 1999). Prior reports have shown that syringaldehyde (≤2.0 g/L) had no significant effect on the overall growth of C. beijerinckii BA101 (Ezeji et al. 2007b). In view of the biphasic (acidogenic and solventogenic) life cycle nature of solventogenic Clostridium species, however, it is not clear whether syringaldehyde will have profound impact at a particular growth phase. Analysis of the impact of syringaldehyde on C. beijerinckii 8052 growth and generation time revealed that C. beijerinckii 8052 had a growth rate, μ, of 0.34 and a generation time of 2.21 h in the presence of 1.0 g/L syringaldehyde at the exponential growth phase during which acetic and butyric acid are produced predominantly (Table 1). Similarly, average generation time of 2.46 h and growth rate of 0.30 were obtained with control fermentations (Table 1). Consequently, the presence of syringaldehyde in the fermentation medium did not have significant effect on the generation time and growth rate of C. beijerinckii 8052 during exponential growth phase. As expected, the growth rate of C. beijerinckii 8052 grown in both P2 control and syringaldehyde-supplemented P2 media decreased drastically (Table 1) at the solventogenic growth phase during which previously produced acetic and butyric acid were expected to be re-assimilated for ABE production. Although the presence of syringaldehyde marginally increased the growth rate of C. beijerinckii 8052 with concomitant decrease in generation time during exponential phase, the growth rate of C. beijerinckii 8052 during the solventogenic growth phase in P2 control medium was 117% more than that of the syringaldehyde-supplemented P2 medium (Table 1). At the end of fermentation residual glucose concentration was 18.3 g/L for the control fermentation. It can be noted that the utilization of glucose by C. beijerinckii, as estimated by measurement of residual glucose concentration after fermentation, varied (17.8–44.1 g/L) during growth in syringaldehyde-supplemented P2 medium. The reduction (13–64%) in glucose utilization by C. beijerinckii during growth in syringaldehyde-supplemented P2 medium (>0.4 g/L syringaldehyde) is associated with abrupt decrease in growth after 24 h of the fermentation (Fig. 1). In contrast, the growth of C. beijerinckii in P2 medium (control) or syringaldehyde-supplemented P2 medium (≤0.4 g/L syringaldehyde) extended to 36 h after which gradual decrease ensued (Fig. 1b).Fig. 1

View Article: PubMed Central

ABSTRACT

While lignocellulosic biomass excels as a cheap, renewable resource for biofuel production, it does present some challenges such as generation of microbial inhibitory compounds. The mode of selective inhibition of acetone–butanol–ethanol (ABE) production (as opposed to cell growth) by syringaldehyde on Clostridium beijerinckii NCIMB 8052 was examined. C. beijerinckii 8052 grown in syringaldehyde-supplemented P2 medium had a comparable growth rate (μ = 0.34) at acidogenic growth phase to that of C. beijerinckii 8052 grown in control P2 medium (μ = 0.30). The addition of syringaldehyde into P2 medium inhibited solvent production by C. beijerinckii 8052 and increased butyric and acetic acid accumulation in the fermentation broth. Analysis of coenzyme A transferase (CoAT) using cell-free extracts of C. beijerinckii 8052 showed decreased expression and activity in the presence of syringaldehyde. These results indicate that C. beijerinckii 8052 CoAT is negatively affected by syringaldehyde and thus, hampers the ability of the microorganism to metabolize butyric and acetic acid for ABE production as evidenced by the accumulation of butyric and acetic acid in the fermentation broth.

No MeSH data available.