Growth and cellulolytic activity of Cellulomonas flavigena

1981 ◽  
Vol 27 (12) ◽  
pp. 1260-1266 ◽  
Author(s):  
B. H. Kim ◽  
J. W. T. Wimpenny
Keyword(s):  
Free Enzyme ◽  
Crystalline Cellulose ◽  
Exponential Growth Phase ◽  
Cellulolytic Bacterium ◽  
Cellulolytic Activity ◽  
Mineral Salts ◽  
Cellulomonas Flavigena ◽  
Rate Limiting Step ◽  
Rate Limiting ◽  
Hydrolysis Of

Growth factor requirements, growth kinetics, and the ability to produce the enzyme cellulase were examined in the cellulolytic bacterium Cellulomonas flavigena KIST 321. The organism was found to require only thiamine for growth in mineral salts medium containing simple sugars or cellulose. Growth rates on various carbohydrates suggested that disruption of the crystalline structure was the rate-limiting step in the utilization of crystalline cellulose, and hydrolysis of the polymer itself was as rapid as the uptake of the hydrolytic product. When the organism was grown on cellulose the cellulolytic activity appeared to be bound to the cell at the beginning of the exponential growth phase: only after this did cell-free enzyme activity appear. The cell-free enzyme appeared to be unstable, and its activity decreased at the beginning of the stationary phase.

scholarly journals The necessity of magnesium cation for acid assistance aglycone departure in catalysis by Escherichia coli (lacZ) β-galactosidase

1978 ◽  
Vol 175 (2) ◽  
pp. 539-546 ◽  
Author(s):  
M L Sinnott ◽  
S G Withers
Keyword(s):  
Escherichia Coli ◽  
Isotope Effects ◽  
Free Enzyme ◽  
Pyridinium Salts ◽  
Kinetic Isotope ◽  
Rate Limiting Step ◽  
Magnesium Cation ◽  
Rate Of Hydrolysis ◽  
Rate Limiting ◽  
Hydrolysis Of

1. Removal of Mg2+ from Escherichia coli (lacZ) beta-galactosidase slightly increases the rate of hydrolysis of galactosyl pyridinium salts, but decreases the rate of hydrolysis of arylgalactosides. 2. Fair correlation of logkcat. and log (Km) with the pKa of aglycone is now observed for arglygalactosides, as well as for glycosyl pyridinium salts. 3. Degalactosylation of Mg2+-free enzyme is the rate-limiting step in the hydrolysis of 2,4-dinitrophenyl galactoside. 4. alpha-Deuterium kinetic isotope effects for both sets of substrates are consistent with the rate-determining generation of a glycosyl cation. 5. The pH-independent, SNl hydrolysis of 3,4-dinitrophenyl galactoside has been measured: it is as fast as that of the galactosyl 3-chloropyridinium ion. 6. Hydrolysis of these two substrates by Mg2+-free enzyme proceeds at very similar rates. 7. It is concluded that loss of both types of aglycone takes place, without acid catalysis, from the first ES complex of substrate and apoenzyme. 8. Data for galactosyl azide and thiopicrate confirm that neither charge nor change of atom is the cause of the differences in behavior between aryl galactosides and galactosylpyridinium salts.

The hydrolysis and biogas production of complex cellulosic substrates using three anaerobic biomass sources

2013 ◽  
Vol 67 (2) ◽  
pp. 293-298 ◽  
Author(s):  
C. Keating ◽  
D. Cysneiros ◽  
T. Mahony ◽  
V. O'Flaherty
Keyword(s):  
Biogas Production ◽  
Positive Role ◽  
Diverse Range ◽  
Factors Affecting ◽  
Rate Limiting Step ◽  
Solid Substrates ◽  
Different Temperatures ◽  
Anaerobic Biomass ◽  
Rate Limiting ◽  
Hydrolysis Of

In this study, the ability of various sludges to digest a diverse range of cellulose and cellulose-derived substrates was assessed at different temperatures to elucidate the factors affecting hydrolysis. For this purpose, the biogas production was monitored and the specific biogas activity (SBA) of the sludges was employed to compare the performance of three anaerobic sludges on the degradation of a variety of complex cellulose sources, across a range of temperatures. The sludge with the highest performance on complex substrates was derived from a full-scale bioreactor treating sewage at 37 °C. Hydrolysis was the rate-limiting step during the degradation of complex substrates. No activity was recorded for the synthetic cellulose compound carboxymethylcellulose (CMC) using any of the sludges tested. Increased temperature led to an increase in hydrolysis rates and thus SBA values. The non-granular nature of the mesophilic sludge played a positive role in the hydrolysis of solid substrates, while the granular sludges proved more effective on the degradation of soluble compounds.

Potential of anaerobic digestion of complex waste(water)

2001 ◽  
Vol 44 (8) ◽  
pp. 115-122 ◽  
Author(s):  
G. Zeeman ◽  
W. Sanders
Keyword(s):  
Waste Water ◽  
Anaerobic Digestion ◽  
Order Relation ◽  
Organic Substrates ◽  
Reactor Technology ◽  
Rate Limiting Step ◽  
Treatment Technologies ◽  
Transport Complex ◽  
Rate Limiting ◽  
Hydrolysis Of

Although they differ greatly in origin complex waste(water)s mainly consist of proteins, lipids, carbohydrates and sometimes lignin in addition. Hydrolysis is the first and generally rate-limiting step in the process of anaerobic digestion of particulate organic substrates. Hydrolysis of particulate polymers can be described by Surface Based Kinetics, but for use in practice the empirical first order relation is advised. Unlike the hydrolysis of protein and carbohydrate, lipid hydrolysis is hardly occurring in the absence of methanogenesis. The latter is probably a physical rather than a biological process and affects the choice for either a one- or a two-step (phase) anaerobic reactor. In the chain of collection and transport, complex wastes often become complex wastewaters simply because of dilution. Dilution not only changes the reactor technology to be applied but also complicates the post-treatment and possibilities for resource recovery. Combining concentrated with diluted waste streams will almost always end up in much more complicated treatment technologies.

Biological treatability of a corn wet mill effluent

2002 ◽  
Vol 45 (12) ◽  
pp. 339-346 ◽  
Author(s):  
G. Eremektar ◽  
O. Karahan-Gul ◽  
F. Germirli-Babuna ◽  
S. Ovez ◽  
H. Uner ◽  
...  
Keyword(s):  
Biological Treatment ◽  
Rate Coefficient ◽  
Activated Sludge Process ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Metabolic Products ◽  
High Level ◽  
Biological Treatability ◽  
Rate Limiting ◽  
Hydrolysis Of

Corn wet mill effluents are studied in terms of their characteristics relevant for biological treatment. They have a high COD of mainly soluble and biodegradable nature, with practically no soluble inert components. They generate a relatively high level of soluble residual metabolic products, which affects the choice of the appropriate biological treatment and favors aerobic activated sludge process. Experimental assessment of process kinetics yields typical values. Hydrolysis of the slowly biodegradable COD, the rate limiting step for the utilization of substrate, is characterized by an overall rate coefficient, which is within the range commonly associated for the hydrolysis of starch.

scholarly journals The kinetics of hydrolysis of some extended N-aminoacyl-l-arginine methyl esters by human plasma kallikrein. Evidence for subsites S2 and S3

1982 ◽  
Vol 203 (1) ◽  
pp. 149-153 ◽  
Author(s):  
P R Levison ◽  
G Tomalin
Keyword(s):  
Human Plasma ◽  
Methyl Esters ◽  
Plasma Kallikrein ◽  
Substrate Complex ◽  
Enzyme Substrate ◽  
Rate Limiting Step ◽  
Kinetics Of Hydrolysis ◽  
Rate Limiting ◽  
Kinetics Of ◽  
Hydrolysis Of

Subsites in the S2-S4 region were identified in human plasma kallikrein. Kinetic constants (kcat., Km) were determined for a series of seven extended N-aminoacyl-L-arginine methyl esters based on the C-terminal sequence of bradykinin (-Pro-Phe-Arg) or (Gly)n-Arg. The rate-limiting step for the enzyme-catalysed reaction was found to be deacylation of the enzyme. It was possible to infer that hydrogen-bonded interactions occur between substrate and the S2-S4 region of kallikrein. Insertion of L-phenylalanine at residue P2 demonstrates that there is also a hydrophobic interaction with subsite S2, which stabilizes the enzyme-substrate complex. The strong interaction demonstrated between L-proline at residue P3 and subsite S3 is of greatest importance in the selectivity of human plasma kallikrein. The purification of kallikrein from Cohn fraction IV of human plasma is described making use of endogenous Factor XIIf to activate the prekallikrein. Kallikreins I (Mr 91 000) and II (Mr 85 000) were purified 170- and 110-fold respectively. Kallikrein I was used for the kinetic work.

Cellulosomes localise on the surface of membrane vesicles from the cellulolytic bacterium Clostridium thermocellum

2019 ◽  
Vol 366 (12) ◽  
Author(s):  
Shunsuke Ichikawa ◽  
Satoru Ogawa ◽  
Ayami Nishida ◽  
Yuzuki Kobayashi ◽  
Toshihito Kurosawa ◽  
...  
Keyword(s):  
Clostridium Thermocellum ◽  
Cell Communication ◽  
Membrane Vesicles ◽  
Cellulolytic Enzymes ◽  
Crystalline Cellulose ◽  
Cellulolytic Bacterium ◽  
Cellulolytic Activity ◽  
Cellulolytic Bacteria ◽  
Degradation Activity ◽  
Enzyme Complexes

ABSTRACTMembrane vesicles released from bacteria contribute to cell–cell communication by carrying various cargos such as proteins, nucleic acids and signaling molecules. Cellulolytic bacteria have been isolated from many environments, yet the function of membrane vesicles for cellulolytic ability has been rarely described. Here, we show that a Gram-positive cellulolytic bacterium Clostridium thermocellum released membrane vesicles, each approximately 50–300 nm in diameter, into the broth. The observations with immunoelectron microscopy also revealed that cellulosomes, which are carbohydrate-active enzyme complexes that give C. thermocellum high cellulolytic activity, localized on the surface of the membrane vesicles. The membrane vesicles collected by ultracentrifugation maintained the cellulolytic activity. Supplementation with the biosurfactant surfactin or sonication treatment disrupted the membrane vesicles in the exoproteome of C. thermocellum and significantly decreased the degradation activity of the exoproteome for microcrystalline cellulose. However, these did not affect the degradation activity for soluble carboxymethyl cellulose. These results suggest a novel function of membrane vesicles: C. thermocellum releases cellulolytic enzymes on the surface of membrane vesicles to enhance the cellulolytic activity of C. thermocellum for crystalline cellulose.

scholarly journals Studies of the esterase activity of cytosolic aldehyde dehydrogenase with resorufin acetate as substrate

1997 ◽  
Vol 322 (3) ◽  
pp. 701-708 ◽  
Author(s):  
Trevor M. KITSON ◽  
Kathryn E. KITSON
Keyword(s):  
Aldehyde Dehydrogenase ◽  
Point Of View ◽  
Ph Profile ◽  
Rate Limiting Step ◽  
The Common ◽  
Aldehyde Oxidation ◽  
Rate Limiting ◽  
Hydrolysis Of ◽  
Very High ◽  
Putative Catalytic Residue

Resorufin acetate is a very good substrate for sheep liver cytosolic aldehyde dehydrogenase, both from the point of view of practical spectrophotometry and in terms of information provided about the nature of the catalysis shown by this enzyme. p-Nitrophenyl (PNP) acetate competes against resorufin acetate for the enzyme's active site (although relatively weakly as the latter substrate has the lower Michaelis constant), but acetaldehyde (in the presence of NAD+) inhibits the hydrolysis of resorufin acetate only at very high aldehyde concentration. In the absence of cofactor, the rate-limiting step in the hydrolysis of resorufin acetate and of PNP acetate is hydrolysis of the common acetyl-enzyme, as shown by the observation of bursts of chromophoric product and very similar values of kcat. In the presence of NAD+ or NADH, however, the deacylation step with resorufin acetate is greatly accelerated until acylation seems to become rate-limiting, because no burst is seen under these conditions. Millimolar concentrations of Mg2+ activate the hydrolyis of resorufin acetate both in the presence and absence of cofactors. With both Mg2+ and cofactor the kcat for hydrolysis of resorufin acetate is 30–35 s-1; this is three orders of magnitude higher than the kcat for aldehyde oxidation in the presence of Mg2+, showing that the enzyme's potential catalytic efficency is very much hampered by the slowness with which NADH dissociates from its binding site. The pH profile for the hydrolysis of resorufin acetate in the presence of NAD+ or NADH fits well to a theoretical ionization curve of pKa approx. 8.2; it is suggested that this might belong to the enzyme's putative catalytic residue (Cys-302).

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