Variation des stérols chez Kluyveromyces lactis et chez un mutant résistant par culture en présence de doses sublétales d'amphotéricine B

1988 ◽  
Vol 34 (6) ◽  
pp. 787-792 ◽  
Author(s):  
A. Hakkou ◽  
J. Coulon ◽  
M. Mpona-Minga ◽  
R. Bonaly
Keyword(s):  
Mutant Strain ◽  
Resistant Strain ◽  
Kluyveromyces Lactis ◽  
Wild Strain ◽  
Total Sterol ◽  
Sublethal Doses

A mutant strain of Kluyveromyces lactis resistant to amphothericin B and weakly to nystatin has been isolated from subcultures of the wild strain grown in the presence of sublethal doses of amphothericin B. The mutant and the wild strain were equally sensitive to pimaricin, filipin, and candicidin. The efficacy of fungizone was very low. In comparison with the wild strain the level of sterols was two times lower in the resistant strain but the composition of these sterols was about the same in the two strains. The action of sublethal doses of amphothericin B on the composition of the sterols was the same in these two yeasts and brought a 40% decrease of the total sterol level and a modification in their distribution. This variation cannot fully explain the resistance of the yeast but it may be associated to other changes of the membranes. [Journal translation]

scholarly journals Telomere Loops and Homologous Recombination-Dependent Telomeric Circles in a Kluyveromyces lactis Telomere Mutant Strain

2007 ◽  
Vol 28 (1) ◽  
pp. 20-29 ◽  
Author(s):  
Anthony J. Cesare ◽  
Cindy Groff-Vindman ◽  
Sarah A. Compton ◽  
Michael J. McEachern ◽  
Jack D. Griffith
Keyword(s):  
Electron Microscopy ◽  
Homologous Recombination ◽  
Mutant Strain ◽  
Kluyveromyces Lactis ◽  
Plant Cells ◽  
Physical Characteristics ◽  
Dna Molecules ◽  
Telomeric Dna ◽  
Strand Invasion

ABSTRACT The Kluyveromyces lactis ter1-16T strain contains mutant telomeres that are poorly bound by Rap1, resulting in a telomere-uncapping phenotype and significant elongation of the telomeric DNA. The elongated telomeres of ter1-16T allowed the isolation and examination of native yeast telomeric DNA by electron microscopy. In the telomeric DNA isolated from ter1-16T, looped molecules were observed with the physical characteristics of telomere loops (t-loops) previously described in mammalian and plant cells. ter1-16T cells were also found to contain free circular telomeric DNA molecules (t-circles) ranging up to the size of an entire telomere. When the ter1-16T uncapping phenotype was repressed by overexpression of RAP1 or recombination was inhibited by deletion of rad52, the isolated telomeric DNA contained significantly fewer t-loops and t-circles. These results suggest that disruption of Rap1 results in elevated recombination at telomeres, leading to increased strand invasion of the 3′ overhang within t-loop junctions and resolution of the t-loop junctions into free t-circles.

scholarly journals The htrA Gene Plays an Important role During Yersinia Pseudotuberculosis Growth at High Temperature

2020 ◽  
Author(s):  
Elena Escobar Garduño ◽  
Lucia Soto Urzua ◽  
Rogelio Rodriguez Sotres ◽  
Luis Javier Martinez Morales
Keyword(s):  
Growth Rate ◽  
Mutant Strain ◽  
Growth Rates ◽  
Yersinia Pseudotuberculosis ◽  
Wild Strain ◽  
Three Dimensional ◽  
Data Bank ◽  
Immunoblot Analysis ◽  
Dimensional Structure ◽  
Bacteria Growth

Abstract htrA is a gene coding for the stress inducible HtrA protein, identified as a temperature stress response protein in several Gram positive and Gram negative bacteria. Growth rates at several temperatures (30ºC, 37ºC and 42ºC) were compared for Yersinia pseudotuberculosis YPIII wild strain and the isogenic mutant 1YPIII (htrA::Km), which was obtained by insertion of a kanamycin resistance cassette into the htrA gene.Y. pseudotuberculosis 1YPIII growth rates did not differ from the Y. pseudotuberculosis wild strain growth rates when cultivated at 30°C, which is consistent with a non-essential role for the HtrA protein at this temperature. However, 1YPIII mutant strain growth rate decreased by 18.73% at 37°C, and by 60.14% at 42°C, as compared to the Y. pseudotuberculosis YPIII wild strain growth rate. HtrA complementation in the strain 1YPIII/pAHTRA46 suppressed the differences in growth rates. Immunoblot analysis confirmed the absence of the HtrA protein in the 1YPIII mutant strain at any of the growth temperatures under analysis. In silico predictions were obtained for the three-dimensional structure of amino acid sequence belonging to HtrA from Y. pseudotuberculosis YPIII, Yersinia pestis CO92, using the protein data bank structure 1KY9:B from Escherichia coli, as template. The model's quality was found to be acceptable. Southern blot analysis shows a single htrA gene signal. These data indicate that the unique htrA gene in Y. pseudotuberculosis YPIII is required for the adaptive response of this species to high temperatures and although it is not a pathogenicity factor, it can be targeted by antibiotics.

Isobutanol Production and Alcohol Tolerance by Yeast Wild Strain

2015 ◽  
Vol 1113 ◽  
pp. 334-339
Author(s):  
Azah Ramli Nor ◽  
A. Rahman Roshanida
Keyword(s):  
Climate Change ◽  
Saccharomyces Cerevisiae ◽  
Batch Fermentation ◽  
Kluyveromyces Lactis ◽  
Wild Strain ◽  
Fuel Additive ◽  
Alcohol Tolerance ◽  
Yeast Growth ◽  
Different Types ◽  
Global Movements

Recently, there have been global movements toward reducing the use of fossil resources as source of energy due to continuous depletion of petroleum fuel-reserves besides contributing to environmental problems such as greenhouse effect, global warming and climate change. Isobutanol is one of biomass-based fuels that has been recognizes for its potentiality as fuel additive or substitute due to its attractive physical properties. This paper investigates the production of isobutanol and alcohol tolerance by five different types of yeast (Saccharomyces cerevisiae,Kluyveromyces lactisGG799 andPichia pastorisKM71H, GS115 and X33) in batch fermentation. Based on the result obtained,P.pastorisX33 produced the highest concentration of isobutanol at 65 mg/l followed byP.pastorisGS115,K.lactisGG799,P.pastorisKM71H andS.cerevisiaewith concentration of 57 mg/l, 49 mg/l 49 mg/l and 46 mg/l respectively. This result proves that yeast is able to produce isobutanol naturally.S. cerevisiaehas been proven as good yeast in alcohol tolerance as it was capable to grow in more than 2% isobutanol and butanol of up to 2%. Among the different alcohols tested for alcohol tolerance, 3-methyl-1-butanol has the highest toxicity towards yeast growth as compared to isobutanol and butanol.

scholarly journals Induction and catabolite repression of alpha-amylase synthesis in Bacilluslicheniformis SKB4

2017 ◽  
Vol 7 (6) ◽  
pp. 8
Author(s):  
Saptadip Samanta ◽  
Subhajit Jana ◽  
Sanjay Kar ◽  
Pradeep Kumar Das Mohapatra ◽  
Bikash Ranjan Pati ◽  
...  
Keyword(s):  
Mutant Strain ◽  
Bacillus Licheniformis ◽  
Catabolite Repression ◽  
Wild Strain ◽  
Second Messenger ◽  
Protein Synthesis Inhibitor ◽  
Synthesis Inhibitor ◽  
Repressive Effect ◽  
Amylase Production ◽  
Messenger System

Microbial amylases have an exciting potentiality and are being used extensively in different industries. In this study, regulation of amylase biosynthesis was examined in Bacillus licheniformis SKB4 (wild type) and its mutant strain (8b). The mutant strain was developed by using UV exposure. Expression of the a-amylase gene of Bacillus licheniformis was activated by inducer and subject to catabolite repression. Addition of exogenous glucose or sucrose repressed bio-synthesis of a-amylase which was concentration (0.05-1.0% w/v) dependent. However, mutant strain could enable to overrule the glucose mediated repressive effect. Supplementation of second messenger like cyclic adenosine 3',5'-monophosphate (cAMP, 5 mM) along with glucose could a little bit improve amylase synthesis in wild strain. Antibiotics like rifampicin and tetracycline (ribonucleic acid and protein synthesis inhibitor; 100mg/ml) had stopped the release of enzyme in both wild and mutant strain. Amylase production was also inhibited in presence of respiratory inhibitor 2,4-dinitrophenol (uncoupler) at (5mM) concentration. Thus, the pattern of regulation of a-amylase production in the present strain was in multiple forms; it showed the classical glucose effect without stimulation of second messenger system. 

scholarly journals Influence of UV light exposure on mineral composition and biomass production of mycomeat produced from different agricultural substrates

2017 ◽  
Vol 62 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Isaac Adejumo ◽  
Charles Adetunji ◽  
Oluyomi Adeyemi
Keyword(s):  
Mutant Strain ◽  
Biomass Production ◽  
Waste Treatment ◽  
Uv Light ◽  
Light Exposure ◽  
Agricultural Waste ◽  
Wild Strain ◽  
Palm Kernel ◽  
Pleurotus Sajor Caju ◽  
The Rich

The wild and mutant strain of Pleurotus sajor caju was cultured on different agricultural substrates. Treatment 1 contained agricultural substrates alone. Treatment 2 contained the mutant strain of the mushroom plus agricultural waste. Treatment 3 contained the wild strain of the mushroom plus agricultural waste. The mutant strain of Pleurotus sajor caju cultured on groundnut shell had the highest iron content while the mutant strain cultured on palm kernel meal had the highest biomass production, 10.5 g/L and 17.20 g/L after 7 and 14 days respectively. The proximate analyses of the feed variety (mycomeat) revealed the rich nutritional content which may be explored for feed ingredients in livestock production. The findings do not only support the bioremediation of agricultural waste to produce high-value bio-products, but also provide evidence that improvement of microorganism strains represents a viable way to enhance the nutritional value of fermented products.

The screening of microalgae mutant strain Scenedesmus sp. Z-4 with a rich lipid content obtained by 60Co γ-ray mutation

RSC Advances ◽  
2015 ◽  
Vol 5 (64) ◽  
pp. 52057-52061 ◽  
Author(s):  
Bingfeng Liu ◽  
Chao Ma ◽  
Ruonan Xiao ◽  
Defeng Xing ◽  
Hongyu Ren ◽  
...  
Keyword(s):  
Mutant Strain ◽  
Lipid Content ◽  
Wild Strain ◽  
Lipid Productivity ◽  
Γ Ray

A microalgae mutant Scenedesmus sp. Z-4 with a lipid content of 28.86% and biomass of 2.876 g/L is obtained using 60Co γ-ray mutation. The lipid productivity and content of mutant Z-4 are greater than that of the wild strain, respectively.

Comparative mitochondrial function in two strains of Aspergillus niger

1968 ◽  
Vol 46 (12) ◽  
pp. 1515-1521 ◽  
Author(s):  
Edwin S. Higgins ◽  
Wilson H. Friend
Keyword(s):  
Aspergillus Niger ◽  
Mitochondrial Function ◽  
Resistant Strain ◽  
Simple Procedure ◽  
Wild Strain ◽  
Respiratory Control ◽  
Citrate Cycle ◽  
Functional Integrity ◽  
Oxidative Pathway ◽  
Respiratory Chains

A relatively simple procedure for isolation of mitochondria from Aspergillus niger was described. The organelles satisfied standard criteria for structural and functional integrity and were characterized by a somewhat higher degree of respiratory control than that associated with mitochondria from fungi reported by others. Mitochondria from a nitroaryl-resistant strain respired more vigorously and had higher respiratory control ratios than mitochondria from the parent wild strain. These observations may explain previous demonstrations that the former strain had high citrate cycle activity and no measurable direct oxidative pathway, whereas the wild strain metabolized glucose predominantly via gluconate and had very little citrate cycle capability. The respiratory chains in A. niger for NADH and for succinate were similar to those in mitochondria from higher organisms, although NADH was freely permeable to the organelles and was oxidized the most vigorously of all externally supplied substrates.

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