Abstract
Clostridium thermocellum is an anaerobic thermophilic bacterium which degrades cellulose and ferments the resulting glucose, cellobiose, and cellodextrins predominantly to ethanol. However, relatively little information was available on carbohydrate uptake by this bacterium. Washed cells internalized intact oligomers as large as cellopentaose. Since cellobiose and cellodextrin phosphorylase activities were detected in the cytosol and were not associated with cell membranes, phosphorylation of carbohydrates occurred intracellularly. Kinetic studies indicated that cellobiose and larger cellodextrins were taken up by a common uptake system while glucose entered via a separate mechanism. When cells were treated with metabolic inhibitors including iodoacetate and arsenate, the uptake of radiolabeled glucose or cellobiose was reduced by as much as 90%, and this reduction was associated with a 95% decline in intracellular ATP content. A combination of the ionophores nigericin and valinomycin abolished the proton-motive force but only slightly decreased transport and ATP. These results suggested that the two modes of carbohydrate transport in C. thermocellum were ATP dependent. This work is the first demonstration of cellodextrin transport by a cellulolytic bacterium.
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- Alexander J. K. Purification and specificity of cellobiose phosphorylase from Clostridium thermocellum. J Biol Chem. 1968 Jun 10;243(11):2899–2904. [PubMed] [Google Scholar]
- Aït N., Creuzet N., Cattanéo J. Characterization and purification of thermostable beta-glucosidase from Clostridium thermocellum. Biochem Biophys Res Commun. 1979 Sep 27;90(2):537–546. doi: 10.1016/0006-291x(79)91269-5. [DOI] [PubMed] [Google Scholar]
- Béguin P., Aubert J. P. The biological degradation of cellulose. FEMS Microbiol Rev. 1994 Jan;13(1):25–58. doi: 10.1111/j.1574-6976.1994.tb00033.x. [DOI] [PubMed] [Google Scholar]
- Cook G. M., Janssen P. H., Morgan H. W. Uncoupler-Resistant Glucose Uptake by the Thermophilic Glycolytic Anaerobe Thermoanaerobacter thermosulfuricus (Clostridium thermohydrosulfuricum). Appl Environ Microbiol. 1993 Sep;59(9):2984–2990. doi: 10.1128/aem.59.9.2984-2990.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Felix C. R., Ljungdahl L. G. The cellulosome: the exocellular organelle of Clostridium. Annu Rev Microbiol. 1993;47:791–819. doi: 10.1146/annurev.mi.47.100193.004043. [DOI] [PubMed] [Google Scholar]
- Helaszek C. T., White B. A. Cellobiose uptake and metabolism by Ruminococcus flavefaciens. Appl Environ Microbiol. 1991 Jan;57(1):64–68. doi: 10.1128/aem.57.1.64-68.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
- LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
- Lowe S. E., Jain M. K., Zeikus J. G. Biology, ecology, and biotechnological applications of anaerobic bacteria adapted to environmental stresses in temperature, pH, salinity, or substrates. Microbiol Rev. 1993 Jun;57(2):451–509. doi: 10.1128/mr.57.2.451-509.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lundin A., Richardsson A., Thore A. Continous monitoring of ATP-converting reactions by purified firefly luciferase. Anal Biochem. 1976 Oct;75(2):611–620. doi: 10.1016/0003-2697(76)90116-0. [DOI] [PubMed] [Google Scholar]
- Maas L. K., Glass T. L. Cellobiose uptake by the cellulolytic ruminal anaerobe Fibrobacter (Bacteroides) succinogenes. Can J Microbiol. 1991 Feb;37(2):141–147. doi: 10.1139/m91-021. [DOI] [PubMed] [Google Scholar]
- Martin S. A., Russell J. B. Transport and phosphorylation of disaccharides by the ruminal bacterium Streptococcus bovis. Appl Environ Microbiol. 1987 Oct;53(10):2388–2393. doi: 10.1128/aem.53.10.2388-2393.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Muir M., Williams L., Ferenci T. Influence of transport energization on the growth yield of Escherichia coli. J Bacteriol. 1985 Sep;163(3):1237–1242. doi: 10.1128/jb.163.3.1237-1242.1985. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ng T. K., Zeikus J. G. Differential metabolism of cellobiose and glucose by Clostridium thermocellum and Clostridium thermohydrosulfuricum. J Bacteriol. 1982 Jun;150(3):1391–1399. doi: 10.1128/jb.150.3.1391-1399.1982. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ng T. K., Zeikus J. G. Synthesis of [C]Cellobiose with Clostridium thermocellum Cellobiose Phosphorylase. Appl Environ Microbiol. 1986 Oct;52(4):902–904. doi: 10.1128/aem.52.4.902-904.1986. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Riebeling V., Thauer R. K., Jungermann K. The internal-alkaline pH gradient, sensitive to uncoupler and ATPase inhibitor, in growing Clostridium pasteurianum. Eur J Biochem. 1975 Jul 1;55(2):445–453. doi: 10.1111/j.1432-1033.1975.tb02181.x. [DOI] [PubMed] [Google Scholar]
- Speelmans G., Poolman B., Konings W. N. Amino acid transport in the thermophilic anaerobe Clostridium fervidus is driven by an electrochemical sodium gradient. J Bacteriol. 1993 Apr;175(7):2060–2066. doi: 10.1128/jb.175.7.2060-2066.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Thurston B., Dawson K. A., Strobel H. J. Cellobiose versus glucose utilization by the ruminal bacterium Ruminococcus albus. Appl Environ Microbiol. 1993 Aug;59(8):2631–2637. doi: 10.1128/aem.59.8.2631-2637.1993. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Zeikus J. G. Chemical and fuel production by anaerobic bacteria. Annu Rev Microbiol. 1980;34:423–464. doi: 10.1146/annurev.mi.34.100180.002231. [DOI] [PubMed] [Google Scholar]