A kinetics modeling study on the inhibition of glucose on cellulosome of Clostridium thermocellum

Zhang, Pengcheng; Wang, Buyun; Xiao, Qunfang; Wu, Shan

doi:10.1016/j.biortech.2015.04.037

Cited by 15 publications

(13 citation statements)

References 24 publications

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“…Surprisingly, the lowest cellulosomal enzyme activities were found in GCs1, even though H. thermocellum growing on glucose is not subject to carbon catabolite repression [30]. The observed GAs1 enzyme activities were in agreement with a study by Zhang et al [59], who used kinetic models and empirical experiments to prove that glucose was an inhibitor of the H. thermocellum cellulosome. Other reports also indicated that cellobiose was a strong inhibitor of cellulosome and cellulase [41,42].…”

Section: Growth Patterns Sugar Utilization Cellulosomal Enzyme Actisupporting

confidence: 89%

Utilization of Monosaccharides by <em>Hungateiclostridium thermocellum</em> ATCC 27405 Through Adaptive Evolution

Ha-Tran¹,

Nguyen²,

Lo³

et al. 2020

Preprint

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Hungateiclostridium thermocellum ATCC 27405 is a promising bacterium with a robust ability to degrade lignocellulosic biomass complexes, including crystalline cellulose components, through a multienzyme cellulosomal system. In contrast, it exhibits poor growth on simple monosaccharides such as fructose and glucose. This phenomenon raises many important questions concerning its glycolytic pathways and sugar transport systems. Until now, the detailed mechanisms of H. thermocellum adaptation to growth on monosaccharides have been poorly explored. In this study, adaptive laboratory evolution was applied to train the bacterium on monosaccharides, and genome resequencing was used to detect the genes that had mutated during adaptation. RNA-seq data of the 1st-generation culture growing on either fructose or glucose revealed that several glycolytic genes in the EMP pathway were expressed at lower levels in these cells than in cellobiose-grown cells. After 8 generations of culture on fructose and glucose, the evolved H. thermocellum strains grew faster and yielded greater biomass than the nonadapted strains. Genomic screening also revealed several mutation events in the genomes of the evolved strains, especially in genes responsible for sugar transport and central carbon metabolism. Consequently, these genes could be applied as targets for further metabolic engineering to improve this bacterium for bioindustrial usage.

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Section: Growth Patterns Sugar Utilization Cellulosomal Enzyme Actisupporting

confidence: 89%

Utilization of Monosaccharides by <em>Hungateiclostridium thermocellum</em> ATCC 27405 Through Adaptive Evolution

Ha-Tran¹,

Nguyen²,

Lo³

et al. 2020

Preprint

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“…However, the final cell biomass of FAs1 and GAs1 was still lower than that of CGs1, in contrast to the results obtained in the work of Johnson et al [ 29 ], who found that the final H. thermocellum cell density of FAs1, GAs1 and CGs1 was comparable. As the most powerful hydrolytic machinery that has been identified in a microorganism to date, H. thermocellum cellulosomal function, composition, and regulation patterns have been a popular research topic for decades [ 1 , 2 , 3 , 4 , 7 , 12 , 14 , 17 , 18 , 25 , 26 , 28 , 29 , 43 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 ]. Regarding cellulosomal enzyme activities, FAs1 cellulosomes expressed the highest exoglucanase, endoglucanase, and xylanase activities, followed by CGs1 cellulosomes ( Figure 2 B).…”

Section: Resultsmentioning

confidence: 99%

Utilization of Monosaccharides by Hungateiclostridium thermocellum ATCC 27405 through Adaptive Evolution

Ha-Tran

Nguyen

et al. 2021

Microorganisms

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Hungateiclostridium thermocellum ATCC 27405 is a promising bacterium for consolidated bioprocessing with a robust ability to degrade lignocellulosic biomass through a multienzyme cellulosomal complex. The bacterium uses the released cellodextrins, glucose polymers of different lengths, as its primary carbon source and energy. In contrast, the bacterium exhibits poor growth on monosaccharides such as fructose and glucose. This phenomenon raises many important questions concerning its glycolytic pathways and sugar transport systems. Until now, the detailed mechanisms of H. thermocellum adaptation to growth on hexose sugars have been relatively poorly explored. In this study, adaptive laboratory evolution was applied to train the bacterium in hexose sugars-based media, and genome resequencing was used to detect the genes that got mutated during adaptation period. RNA-seq data of the first culture growing on either fructose or glucose revealed that several glycolytic genes in the Embden–Mayerhof–Parnas pathway were expressed at lower levels in these cells than in cellobiose-grown cells. After seven consecutive transfer events on fructose and glucose (~42 generations for fructose-adapted cells and ~40 generations for glucose-adapted cells), several genes in the EMP glycolysis of the evolved strains increased the levels of mRNA expression, accompanied by a faster growth, a greater biomass yield, a higher ethanol titer than those in their parent strains. Genomic screening also revealed several mutation events in the genomes of the evolved strains, especially in those responsible for sugar transport and central carbon metabolism. Consequently, these genes could be applied as potential targets for further metabolic engineering to improve this bacterium for bio-industrial usage.

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“…The kinetics parameters of maximum reaction rate ( V max ) and the Michaelis–Menten constant ( K m ) values displayed a prevailing effect when the cellulosome obtained in the supernatant as compared to the whole cells. Recently, a mathematical model was developed to estimate the inhibitory effect of glucose on cellulosome by using C. thermocellum (Equation (1)) [92] C=K−K·Av where C was the glucose concentration, K was the inhibition constant for glucose on cellulosome, v was the rate of the hydrolytic action of cellulosome, and constant A could be deduced from the slope of the straight line, which plotted based on C versus 1/ v . It described the relationship between glucose concentration and saccharification rate at a specific glucose concentration or a specific time.…”

Section: Effects Of Several Substrate-related Factors On Cellulosomentioning

confidence: 99%

“…Hence, methods that can decrease the glucose-induced inhibition on cellulosome should be effective in enhancing cellulose saccharification by the anaerobic cellulosome-producing bacteria [93]. Attempts to eliminate side reactions such as ethanol and CO 2 fermentation proved the utilization of certain adsorbents (i.e., activated carbon and biochar) could lower the inhibition of glucose and improve the adsorption of substrates onto cellulosome [92].…”

Section: Effects Of Several Substrate-related Factors On Cellulosomentioning

confidence: 99%

Substrate-Related Factors Affecting Cellulosome-Induced Hydrolysis for Lignocellulose Valorization

Wang

Leng

Islam

et al. 2019

IJMS

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Cellulosomes are an extracellular supramolecular multienzyme complex that can efficiently degrade cellulose and hemicelluloses in plant cell walls. The structural and unique subunit arrangement of cellulosomes can promote its adhesion to the insoluble substrates, thus providing individual microbial cells with a direct competence in the utilization of cellulosic biomass. Significant progress has been achieved in revealing the structures and functions of cellulosomes, but a knowledge gap still exists in understanding the interaction between cellulosome and lignocellulosic substrate for those derived from biorefinery pretreatment of agricultural crops. The cellulosomic saccharification of lignocellulose is affected by various substrate-related physical and chemical factors, including native (untreated) wood lignin content, the extent of lignin and xylan removal by pretreatment, lignin structure, substrate size, and of course substrate pore surface area or substrate accessibility to cellulose. Herein, we summarize the cellulosome structure, substrate-related factors, and regulatory mechanisms in the host cells. We discuss the latest advances in specific strategies of cellulosome-induced hydrolysis, which can function in the reaction kinetics and the overall progress of biorefineries based on lignocellulosic feedstocks.

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A kinetics modeling study on the inhibition of glucose on cellulosome of Clostridium thermocellum

Cited by 15 publications

References 24 publications

Utilization of Monosaccharides by <em>Hungateiclostridium thermocellum</em> ATCC 27405 Through Adaptive Evolution

Utilization of Monosaccharides by <em>Hungateiclostridium thermocellum</em> ATCC 27405 Through Adaptive Evolution

Utilization of Monosaccharides by Hungateiclostridium thermocellum ATCC 27405 through Adaptive Evolution

Substrate-Related Factors Affecting Cellulosome-Induced Hydrolysis for Lignocellulose Valorization

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