scholarly journals Expression of 17 Genes in Clostridium thermocellum ATCC 27405 during Fermentation of Cellulose or Cellobiose in Continuous Culture

2005 ◽  
Vol 71 (8) ◽  
pp. 4672-4678 ◽  
Author(s):  
David M. Stevenson ◽  
Paul J. Weimer
Keyword(s):  
Growth Rate ◽  
Acetic Acid ◽  
Alcohol Dehydrogenase ◽  
Continuous Culture ◽  
Clostridium Thermocellum ◽  
Product Distribution ◽  
Scaffolding Protein ◽  
Rrna Gene ◽  
Cellulolytic Bacterium ◽  
Type Iv

ABSTRACT Clostridium thermocellum is a thermophilic, anaerobic, cellulolytic bacterium that produces ethanol and acetic acid as major fermentation end products. The effect of growth conditions on gene expression in C. thermocellum ATCC 27405 was studied using cells grown in continuous culture under cellobiose or cellulose limitation over a ∼10-fold range of dilution rates (0.013 to 0.16 h−1). Fermentation product distribution displayed similar patterns in cellobiose- or cellulose-grown cultures, including substantial shifts in the proportion of ethanol and acetic acid with changes in growth rate. Expression of 17 genes involved or potentially involved in cellulose degradation, intracellular phosphorylation, catabolite repression, and fermentation end product formation was quantified by real-time PCR, with normalization to two calibrator genes (recA and the 16S rRNA gene) to determine relative expression. Thirteen genes displayed modest (fivefold or less) differences in expression with growth rate or substrate type: sdbA (cellulosomal scaffoldin-dockerin binding protein), cdp (cellodextrin phosphorylase), cbp (cellobiose phosphorylase), hydA (hydrogenase), ldh (lactate dehydrogenase), ack (acetate kinase), one putative type IV alcohol dehydrogenase, two putative cyclic AMP binding proteins, three putative Hpr-like proteins, and a putative Hpr serine kinase. By contrast, four genes displayed >10-fold-reduced levels of expression when grown on cellobiose at dilution rates of >0.05 h−1: cipA (cellulosomal scaffolding protein), celS (exoglucanase), manA (mannanase), and a second type IV alcohol dehydrogenase. The data suggest that at least some cellulosomal components are transcriptionally regulated but that differences in expression with growth rate or among substrates do not directly account for observed changes in fermentation end product distribution.

scholarly journals Form and Function of Clostridium thermocellum Biofilms

2012 ◽  
Vol 79 (1) ◽  
pp. 231-239 ◽  
Author(s):  
Alexandru Dumitrache ◽  
Gideon Wolfaardt ◽  
Grant Allen ◽  
Steven N. Liss ◽  
Lee R. Lynd
Keyword(s):  
Acetic Acid ◽  
Clostridium Thermocellum ◽  
Cell Attachment ◽  
Cell Structure ◽  
Hydrolysis Rate ◽  
Cellulolytic Bacterium ◽  
Biofilm Growth ◽  
Content Type ◽  
Lignocellulose Conversion ◽  
Continuous Flow Reactors

ABSTRACTThe importance of bacterial adherence has been acknowledged in microbial lignocellulose conversion studies; however, few reports have described the function and structure of biofilms supported by cellulosic substrates. We investigated the organization, dynamic formation, and carbon flow associated with biofilms of the obligately anaerobic cellulolytic bacteriumClostridium thermocellum27405. Using noninvasive,in situfluorescence imaging, we showed biofilms capable of near complete substrate conversion with a characteristic monolayered cell structure without an extracellular polymeric matrix typically seen in biofilms. Cell division at the interface and terminal endospores appeared throughout all stages of biofilm growth. Using continuous-flow reactors with a rate of dilution (2 h−1) 12-fold higher than the bacterium's maximum growth rate, we compared biofilm activity under low (44 g/liter) and high (202 g/liter) initial cellulose loading. The average hydrolysis rate was over 3-fold higher in the latter case, while the proportions of oligomeric cellulose hydrolysis products lost from the biofilm were 13.7% and 29.1% of the total substrate carbon hydrolyzed, respectively. Fermentative catabolism was comparable between the two cellulose loadings, with ca. 4% of metabolized sugar carbon being utilized for cell production, while 75.4% and 66.7% of the two cellulose loadings, respectively, were converted to primary carbon metabolites (ethanol, acetic acid, lactic acid, carbon dioxide). However, there was a notable difference in the ethanol-to-acetic acid ratio (g/g), measured to be 0.91 for the low cellulose loading and 0.41 for the high cellulose loading. The results suggest that substrate availability for cell attachment rather than biofilm colonization rates govern the efficiency of cellulose conversion.

scholarly journals Metabolome Analysis of Constituents in Membrane Vesicles for Clostridium thermocellum Growth Stimulation

2021 ◽  
Vol 9 (3) ◽  
pp. 593
Author(s):  
Shunsuke Ichikawa ◽  
Yoichiro Tsuge ◽  
Shuichi Karita
Keyword(s):  
Growth Rate ◽  
Clostridium Thermocellum ◽  
Consolidated Bioprocessing ◽  
Membrane Vesicle ◽  
Single Gene ◽  
Membrane Vesicles ◽  
Growth Stimulation ◽  
Cellulosic Biomass ◽  
Cellulolytic Bacterium ◽  
Metabolome Analysis

The cultivation of the cellulolytic bacterium, Clostridium thermocellum, can have cost-effective cellulosic biomass utilizations, such as consolidated bioprocessing, simultaneous biological enzyme production and saccharification. However, these processes require a longer cultivation term of approximately 1 week. We demonstrate that constituents of the C. thermocellum membrane vesicle fraction significantly promoted the growth rate of C. thermocellum. Similarly, cell-free Bacillus subtilis broth was able to increase C. thermocellum growth rate, while several B. subtilis single-gene deletion mutants, e.g., yxeJ, yxeH, ahpC, yxdK, iolF, decreased the growth stimulation ability. Metabolome analysis revealed signal compounds for cell–cell communication in the C. thermocellum membrane vesicle fraction (ethyl 2-decenoate, ethyl 4-decenoate, and 2-dodecenoic acid) and B. subtilis broth (nicotinamide, indole-3-carboxaldehyde, urocanic acid, nopaline, and 6-paradol). These findings suggest that the constituents in membrane vesicles from C. thermocellum and B. subtilis could promote C. thermocellum growth, leading to improved efficiency of cellulosic biomass utilization.

CONTINUOUS CULTURE OF BRUCELLA ABORTUS S.19

1961 ◽  
Vol 7 (4) ◽  
pp. 491-505 ◽  
Author(s):  
Andreas H. W. Hauschild ◽  
Hilliard Pivnick
Keyword(s):  
Growth Rate ◽  
Continuous Culture ◽  
Dilution Rate ◽  
Brucella Abortus ◽  
Specific Growth ◽  
Limiting Factor ◽  
Continuous Growth ◽  
Viable Cells ◽  
Metabolic Products ◽  
Growth Of Bacteria

An apparatus is described for the continuous growth of bacteria. Brucella abortus S.19 has been grown in continuous culture for periods up to 3 weeks with populations up to 2 × 1011viable cells per ml and without the establishment of nonsmooth variants.Concentrations between 3 × 109and 2 × 1011cells per ml could be maintained as a function of the dilution rate without the requirement of a known limiting factor in the medium. In a series of steady-state conditions, the specific growth rate increased steadily up to 0.28 hour−1with decreasing population levels.Incidence of mutants was governed by the dilution rate and could also be reduced by various chelating substances.In continuous growth combined with continuous dialysis, population levels were approximately twice those obtained in continuous growth without dialysis. The effect of dialysis appears to be the continuous removal of growth-limiting metabolic products.

scholarly journals Improved growth rate in Clostridium thermocellum hydrogenase mutant via perturbed sulfur metabolism

2017 ◽  
Vol 10 (1) ◽  
Author(s):  
Ranjita Biswas ◽  
Charlotte M. Wilson ◽  
Richard J. Giannone ◽  
Dawn M. Klingeman ◽  
Thomas Rydzak ◽  
...  
Keyword(s):  
Growth Rate ◽  
Clostridium Thermocellum ◽  
Sulfur Metabolism

An X-ray structural study of organic ligands of the complexone type. IV. Crystal and molecular structure of rac-2,3-dihydroxybutane-1,4-diamine-N,N,N?,N?-tetra-acetic acid

1983 ◽  
Vol 24 (3) ◽  
pp. 400-407
Author(s):  
A. E. Obodovskaya ◽  
L. M. Shkol'nikova ◽  
L. O. Atovmyan ◽  
I. A. Seliverstova ◽  
V. G. Yashunskii ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Acetic Acid ◽  
Structural Study ◽  
Crystal And Molecular Structure ◽  
Organic Ligands ◽  
X Ray ◽  
Type Iv

scholarly journals Endogenous hormonal content during grain development in hexaploid and tetraploid wheat

1970 ◽  
Vol 33 (3) ◽  
pp. 493-502 ◽  
Author(s):  
Sridhar Gutam ◽  
Virendra Nath ◽  
GC Srivastava
Keyword(s):  
Growth Rate ◽  
Acetic Acid ◽  
Abscisic Acid ◽  
Gibberellic Acid ◽  
Grain Growth ◽  
Indole Acetic Acid ◽  
Tetraploid Wheat ◽  
Weight Basis ◽  
Ploidy Levels ◽  
Hormonal Content

A pot experiment was conducted in the rabi (post rainy) seasons of 2001 and 2002 to study the genotypic differences in grain growth rate and endogenous hormonal content in the developing grains of hexaploid and tetraploid wheat. The endogenous hormonal contents of grains in both the ploidy levels had changed in sequence. At 5 days after anthesis (DAA), gibberellic acid (GA3); at 15 DAA (rapid growth phase), indole-acetic acid (IAA); at 25 DAA (dough stage), abscisic acid (ABA) were maximum. At 35 DAA, all the endogenous hormonal level decreased and among the hormones, ABA was highest followed by IAA and GA3. Hexaploids recorded higher concentrations of endogenous hormones (13.38% IAA, 17.89% GA3, and 14.7% ABA) on fresh weight basis and resulted in higher seed weight (56.99 mg/grain) and grain growth rate (0.009 g/g/day) compared to tetraploids (49.08 mg/grain; 0.008 g/g/day) on dry weight basis by better mobilization of photosynthates during grain filling. Key Words: Grain growth rate, hormones, indole-acetic acid, gibberellic acid, abscisic acid. doi:10.3329/bjar.v33i3.1608 Bangladesh J. Agril. Res. 33(3) : 493-502, September 2008

scholarly journals Regulation of Major Cellulosomal Endoglucanases of Clostridium thermocellum Differs from That of a Prominent Cellulosomal Xylanase

2005 ◽  
Vol 187 (7) ◽  
pp. 2261-2266 ◽  
Author(s):  
Tali W. Dror ◽  
Adi Rolider ◽  
Edward A. Bayer ◽  
Raphael Lamed ◽  
Yuval Shoham
Keyword(s):  
Growth Rate ◽  
Clostridium Thermocellum ◽  
Transcript Level ◽  
Clear Correlation ◽  
Transcript Levels ◽  
Batch Cultures ◽  
Processive Endoglucanase ◽  
The Family ◽  
Genes Encoding ◽  
Family 10 Xylanase

ABSTRACT The expression of scaffoldin-anchoring genes and one of the major processive endoglucanases (CelS) from the cellulosome of Clostridium thermocellum has been shown to be dependent on the growth rate. For the present work, we studied the gene regulation of selected cellulosomal endoglucanases and a major xylanase in order to examine the previously observed substrate-linked alterations in cellulosome composition. For this purpose, the transcript levels of genes encoding endoglucanases CelB, CelG, and CelD and the family 10 xylanase XynC were determined in batch cultures, grown on either cellobiose or cellulose, and in carbon-limited continuous cultures at different dilution rates. Under all conditions tested, the transcript levels of celB and celG were at least 10-fold higher than that of celD. Like the major processive endoglucanase CelS, the transcript levels of these endoglucanase genes were also dependent on the growth rate. Thus, at a rate of 0.04 h−1, the levels of celB, celG, and celD were threefold higher than those obtained in cultures grown at maximal rates (0.35 h−1) on cellobiose. In contrast, no clear correlation was observed between the transcript level of xynC and the growth rate—the levels remained relatively high, fluctuating between 30 and 50 transcripts per cell. The results suggest that the regulation of C. thermocellum endoglucanases is similar to that of the processive endoglucanase celS but differs from that of a major cellulosomal xylanase in that expression of the latter enzyme is independent of the growth rate.

scholarly journals Statistically Guided Synthesis of MoV-Based Mixed-Oxide Catalysts for Ethane Partial Oxidation

Catalysts ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 370
Author(s):  
Juan Jimenez ◽  
Kathleen Mingle ◽  
Teeraya Bureerug ◽  
Cun Wen ◽  
Jochen Lauterbach
Keyword(s):  
Acetic Acid ◽  
Partial Oxidation ◽  
Mixed Oxide ◽  
Structural Integrity ◽  
Product Distribution ◽  
Catalytic Performance ◽  
Oxide Catalysts ◽  
Acid Yield ◽  
Mixed Oxide Catalysts ◽  
Catalyst Composition

The catalytic performance of Mo8V2Nb1-based mixed-oxide catalysts for ethane partial oxidation is highly sensitive to the doping of elements with redox and acid functionality. Specifically, control over product distributions to ethylene and acetic acid can be afforded via the specific pairing of redox elements (Pd, Ni, Ti) and acid elements (K, Cs, Te) and the levels at which these elements are doped. The redox element, acid element, redox/acid ratio, and dopant/host ratio were investigated using a three-level, four-factor factorial screening design to establish relationships between catalyst composition, structure, and product distribution for ethane partial oxidation. Results show that the balance between redox and acid functionality and overall dopant level is important for maximizing the formation of each product while maintaining the structural integrity of the host metal oxide. Overall, ethylene yield was maximized for a Mo8V2Nb1Ni0.0025Te0.5 composition, while acetic acid yield was maximized for a Mo8V2Nb1Ti0.005Te1 catalyst.

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