Increased Activity of Wall Hydrolytic Enzymes May Explain the Phenotype of Saccharomyces cerevisiae Fragile Mutants

1998 ◽  
Vol 37 (6) ◽  
pp. 365-367 ◽  
Author(s):  
José Ruiz-Herrera ◽  
Claudia León-Ramírez ◽  
P. Elizabeth Alvarez ◽  
Pencho Venkov
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Hydrolytic Enzymes ◽  
Increased Activity

scholarly journals Catalase Overexpression Reduces Lactic Acid-Induced Oxidative Stress in Saccharomyces cerevisiae

2009 ◽  
Vol 75 (8) ◽  
pp. 2320-2325 ◽  
Author(s):  
Derek A. Abbott ◽  
Erwin Suir ◽  
Giang-Huong Duong ◽  
Erik de Hulster ◽  
Jack T. Pronk ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Lactic Acid ◽  
Reference Strain ◽  
Specific Growth ◽  
Pyruvate Decarboxylase ◽  
Additional Stress ◽  
Batch Cultures ◽  
Native Promoter ◽  
Specific Growth Rates ◽  
Increased Activity

ABSTRACT Industrial production of lactic acid with the current pyruvate decarboxylase-negative Saccharomyces cerevisiae strains requires aeration to allow for respiratory generation of ATP to facilitate growth and, even under nongrowing conditions, cellular maintenance. In the current study, we observed an inhibition of aerobic growth in the presence of lactic acid. Unexpectedly, the cyb2Δ reference strain, used to avoid aerobic consumption of lactic acid, had a specific growth rate of 0.25 h−1 in anaerobic batch cultures containing lactic acid but only 0.16 h−1 in identical aerobic cultures. Measurements of aerobic cultures of S. cerevisiae showed that the addition of lactic acid to the growth medium resulted in elevated levels of reactive oxygen species (ROS). To reduce the accumulation of lactic acid-induced ROS, cytosolic catalase (CTT1) was overexpressed by replacing the native promoter with the strong constitutive TPI1 promoter. Increased activity of catalase was confirmed and later correlated with decreased levels of ROS and increased specific growth rates in the presence of high lactic acid concentrations. The increased fitness of this genetically modified strain demonstrates the successful attenuation of additional stress that is derived from aerobic metabolism and may provide the basis for enhanced (micro)aerobic production of organic acids in S. cerevisiae.

Carbon nutrition and hydrolytic and cellulolytic activities in the ectomycorrhizal fungus Pisolithus tinctorius

1993 ◽  
Vol 39 (5) ◽  
pp. 529-535 ◽  
Author(s):  
Weiguo Cao ◽  
Don L. Crawford
Keyword(s):  
Hydrolytic Enzymes ◽  
Ectomycorrhizal Fungus ◽  
Isozyme Pattern ◽  
Pisolithus Tinctorius ◽  
Cellulolytic Enzymes ◽  
Cellulolytic Activity ◽  
Gradient Gel Electrophoresis ◽  
Carbon Nutrition ◽  
High Concentrations ◽  
Increased Activity

Four strains of an ectomycorrhizal fungus, Pisolithus tinctorius, were investigated for carbon nutrition, and for production of hydrolytic and cellulolytic enzymes. Glucose, mannose, and cellobiose supported rapid mycelial growth of all four strains. Fructose was utilized by two strains, SMF and S359. Of the 10 hydrolytic enzymes examined, acid phosphatase, acid α-galactosidase, acid esterase, and acid β-glucosidase were found in all four strains. β-Galactosidase was only observed in strain S359. α-Mannosidase, β-mannosidase, α-glucosidase, β-xylosidase, and proteinase were not detected in any of the four strains. Isozyme patterns of β-glucosidase and esterase in the four strains were compared by activity staining after native gradient gel electrophoresis. The isozyme pattern of β-glucosidase showed three major forms in all four strains. In addition, two more isoforms were found in strain S370. All strains shared two esterase bands, while strain S370 had three more isoforms. Study on strain SMF indicated that acid β-glucosidase was expressed constitutively, with increased activity in cellobiose-containing media. Under nitrogen-limiting conditions, a low level of endoglucanase and exoglucanase activity was observed in strains SMF and S359. Further study on S359 showed that high concentrations of nitrogen repressed the cellulolytic activity. When cellobiose served as carbon source, higher cellulolytic activity was observed. Cellulose did not induce higher activity.Key words: Pisolithus, ectomycorrhizal, β-glucosidase, hydrolytic enzymes, cellulolytic enzymes.

scholarly journals PROSPECTING CYANOBACTERIA-FORTIFIED COMPOSTS AS PLANT GROWTH PROMOTING AND BIOCONTROL AGENTS IN COTTON

2014 ◽  
Vol 51 (1) ◽  
pp. 42-65 ◽  
Author(s):  
RADHA PRASANNA ◽  
SANTOSH BABU ◽  
NGANGOM BIDYARANI ◽  
ARUN KUMAR ◽  
SODIMALLA TRIVENI ◽  
...  
Keyword(s):  
Plant Growth ◽  
Management Strategies ◽  
Hydrolytic Enzymes ◽  
Biocontrol Agents ◽  
Fresh Weight ◽  
Available Nitrogen ◽  
Cotton Crop ◽  
Plant Growth Promoting ◽  
Growth Promoting ◽  
Increased Activity

SUMMARYThe potential of cyanobacteria-based compost formulations was evaluated in cotton crop at two agro-ecological locations (Nagpur and Sirsa) as plant growth promoting (PGP) and biocontrol agents. Compost-based formulations fortified withCalothrixsp. orAnabaenasp. enhanced germination and fresh weight of plants, and microbiological activity by 10–15%, besides increased available nitrogen (by 20–50%) in soil at Nagpur. In the fungi-infected fields at Sirsa,Anabaena–T. viridebiofilmed formulation performed the best, recording 11.1% lower plant mortality than commercialTrichodermaformulation. Scanning electron microscopy confirmed the colonisation of inoculated cyanobacteria/biofilms on roots. Significant correlation between mortality, increased activity of hydrolytic enzymes and fresh weight of plant roots were recorded.Calothrixsp. andAnabaenasp. proved promising as both PGP and biocontrol agents, while biofilmed formulations substantially reduced mortality of cotton plants in sick plots. This study illustrates the promise of cyanobacteria as viable inoculation option for integrated nutrient and pest management strategies of cotton.

scholarly journals Lignocellulosic Fermentation of Wild Grass Employing Recombinant Hydrolytic Enzymes and Fermentative Microbes with Effective Bioethanol Recovery

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Saprativ P. Das ◽  
Arabinda Ghosh ◽  
Ashutosh Gupta ◽  
Arun Goyal ◽  
Debasish Das
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Hydrolytic Enzymes ◽  
Batch Mode ◽  
E Coli ◽  
Wild Grass ◽  
Cell Biomass ◽  
Single Culture ◽  
Leafy Biomass ◽  
Single Enzyme ◽  
Simultaneous Saccharification

Simultaneous saccharification and fermentation (SSF) studies of steam exploded and alkali pretreated different leafy biomass were accomplished by recombinantClostridium thermocellumhydrolytic enzymes and fermentative microbes for bioethanol production. The recombinantC. thermocellumGH5 cellulase and GH43 hemicellulase genes expressed inEscherichia colicells were grown in repetitive batch mode, with the aim of enhancing the cell biomass production and enzyme activity. In batch mode, the cell biomass (A600 nm) ofE. colicells and enzyme activities of GH5 cellulase and GH43 hemicellulase were 1.4 and 1.6 with 2.8 and 2.2 U·mg−1, which were augmented to 2.8 and 2.9 with 5.6 and 3.8 U·mg−1in repetitive batch mode, respectively. Steam exploded wild grass (Achnatherum hymenoides) provided the best ethanol titres as compared to other biomasses. Mixed enzyme (GH5 cellulase, GH43 hemicellulase) mixed culture (Saccharomyces cerevisiae, Candida shehatae) system gave 2-fold higher ethanol titre than single enzyme (GH5 cellulase) single culture (Saccharomyces cerevisiae) system employing 1% (w/v) pretreated substrate. 5% (w/v) substrate gave 11.2 g·L−1of ethanol at shake flask level which on scaling up to 2 L bioreactor resulted in 23 g·L−1ethanol. 91.6% (v/v) ethanol was recovered by rotary evaporator with 21.2% purification efficiency.

Bioethanol production from alkaline hydrogen peroxide pretreated Populus deltoides wood using hydrolytic enzymes of Bacillus stratosphericus N12(M) and Bacillus altitudinis Kd1(M) under different modes of separate hydrolysis and fermentation by monoculture and co-culture combinations of ethanologens

2016 ◽  
Vol 5 (02) ◽  
pp. 4810
Author(s):  
Nisha Sharma* ◽  
Nivedita Sharma
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Populus Deltoides ◽  
Ethanol Yield ◽  
Hydrolytic Enzyme ◽  
Xylanase Activity ◽  
Hydrolytic Enzymes ◽  
Cellulase Activity ◽  
Integrated Approach ◽  
Xylanase Production ◽  
Bacillus Altitudinis

An integrated approach was studied for in-house cellulase and xylanase production, from novel hyper hydrolytic enzyme producers and enzymatic hydrolysis of pretreated Populus deltoides wood into bioethanol. A xylanase producer Bacillus altitudinis Kd1 (M) and cellulase producerBacillus stratosphericus N12 (M) was isolated from soil. Optimization of process parameters led to an optimal xylanase activity of 96.25 IU at 300C and pH 5.5 and cellulase activity of 5.98 IU at 300C and pH 8.0. The NaOH+H2O2 pretreated biomass was hydrolysed using cellulase and xylanase producing 12.45 mg/g of reducing sugars. Further fermentation of lignocellulosic hydrolysate was performed using different yeasts viz. Saccharomyces cerevisiae I, Saccharomyces cerevisiae II, Pichia stipitis, Candida shehatae and Zymomonas mobilis and maximum 11.10 g/l ethanol yield achieved with co-culture of S. cerevisiae II + P. stipitis with fermentation efficiency of 43.52% under method IV of SHF. The results have significant implications and further applications regarding production of fuel ethanol from agricultural lignocellulosic waste.

Activation of chitin synthetase in permeabilized cells of a Saccharomyces cerevisiae mutant lacking proteinase B

1982 ◽  
Vol 152 (3) ◽  
pp. 1255-1264
Author(s):  
M P Fernandez ◽  
J U Correa ◽  
E Cabib
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chelating Agent ◽  
Metal Chelators ◽  
Trypsin Treatment ◽  
Permeabilized Cells ◽  
Chitin Synthetase ◽  
Activity Curve ◽  
Subsequent Step ◽  
Increased Activity

Digitonin treatment at 30 degrees C of a Saccharomyces cerevisiae mutant lacking proteinase B permeabilized the cells and caused rapid and extensive activation of chitin synthetase in situ. The same result was obtained with a mutant generally defective in vacuolar proteases. By lowering the temperature and using different permeabilization procedures, we showed that increases in permeability and activation are distinct processes. Activation was inhibited by the protease inhibitors antipain and leupeptin, but by pepstatin or chymostatin. Metal chelators were also inhibitory, and their effect was reversed by the addition of Ca2+ but not by Mg2+. Antipain added together with Ca2+ after incubation of the cells in the presence of a chelating agent prevented reversal of inhibition, a result that was interpreted as indicating that antipain acts either on the same step affected by Ca2+ or on a subsequent step. Efforts to obtain activation in cell-free extracts were unsuccessful, but it was possible to extract the synthetase, once activated, by breaking permeabilized cells with glass beads. Treatment of the cell-free extracts with trypsin led not only to increased activity of chitin synthetase, but also to a change in the pH-activity curve and a diminished requirement by the enzyme for free N-acetylglucosamine. These observations suggest that the modification undergone by the synthetase during endogenous activation is different from that brought about by trypsin treatment.

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