Heterologous Expression of the Cytotoxin Restrictocin in Aspergillus nidulans and Aspergillus niger

1994 ◽  
Vol 5 (5) ◽  
pp. 486-497 ◽  
Author(s):  
T. Brandhorst ◽  
R. Yang ◽  
W.R. Kenealy
2002 ◽  
Vol 37 (1) ◽  
pp. 89-97 ◽  
Author(s):  
I Nikolaev ◽  
M Mathieu ◽  
P.J.I van de Vondervoort ◽  
J Visser ◽  
B Felenbok

1995 ◽  
Vol 41 (7) ◽  
pp. 601-611 ◽  
Author(s):  
Tristan Brandhorst ◽  
William R. Kenealy

The effects of altered leader sequences on the secretion and localization of restrictocin expression in Aspergillus nidulans and Aspergillus niger were investigated. The region encoding the leader sequence of the Aspergillus resirictus restrictocin (res) gene was altered and variants were expressed under the glucoamylase (glaA) promoter in A. nidulans and A. niger. The entire restrictocin leader sequence was replaced by the glaA leader sequence in one variant. In another, the signal sequence of restrictocin was replaced with the glaA signal, leaving a hybrid with the putative restrictocin pro region in place of the glaA pro region. The putative pro region was deleted from the restrictocin leader of a third variant. Toxic effects, such as reduced transcript levels and cellular lysis, were minimal when restrictocin was expressed with the native leader sequence, but became more pronounced as the leader sequence was varied. These toxic effects were inversely proportional to the level of restrictocin secreted. In all transformed strains, restrictocin secretion appeared at the periphery of colonies and was observed to occur at the tips of hyphae. Localization of restrictocin to differentiated structures (conidiophores), as occurs in A. resirictus, was observed only in transformed strains containing the complete restrictocin leader sequence.Key words: localization, secretion, targeting, translocation, development.


Author(s):  
سعاد محمد خليفة أبوالغيث ◽  
أحلام القمودي محمد زعيط

استهدفت هذه الدراسة عزل بعض أنواع الفطريات من التربة الملوثة بالهيدروكربون بمصفاة الزاوية لتكرير النفط، حيث تم عزل وتعريف بعض الفطريات مثل Rhizopus, Aspergillus fumigatus, Aspergillus niger, Aspergillus flavus, Aspergillus nidulans وأوضحت نتائج هذه الدراسة أن تواجد وتنوع فطر Aspergillus قد تفوق معنويا مقارنة بتواجد وتنوع فطرRhizopus. كما تم في هذه الدراسة اختبار قدرة وكفاءة الفطريات المعزولة على النمو واستغلال المركبات الهيدروكربونية المتمثلة في زيت الحمادة وزيت الشرارة بتركيز 1% و3%، حيث أوضحت النتائج بأن جنس Rhizopus سجل أعلى معدل للنمو على الوسط الغذائي Malt Extract Agar، وسجل كلا من فطر A. fumigatus وفطر A. flavus معدّل النمو القطري أعلى معنويا من النمو القطري لفطرA. niger  وفطر A. nidulans. هذه المعدّلات العالية تدل على إمكانية استخدام الفطريات المعزولة في المعالجة البيولوجية للتربة الملوّثة بالنفط.


2020 ◽  
Vol 20 (3) ◽  
Author(s):  
Jorg C de Ruijter ◽  
Kiyohiko Igarashi ◽  
Merja Penttilä

ABSTRACT Processed lignocellulosic biomass is a source of mixed sugars that can be used for microbial fermentation into fuels or higher value products, like chemicals. Previously, the yeast Saccharomyces cerevisiae was engineered to utilize its cellodextrins through the heterologous expression of sugar transporters together with an intracellular expressed β-glucosidase. In this study, we screened a selection of eight (putative) cellodextrin transporters from different yeast and fungal hosts in order to extend the catalogue of available cellobiose transporters for cellobiose fermentation in S. cerevisiae. We confirmed that several in silico predicted cellodextrin transporters from Aspergillus niger were capable of transporting cellobiose with low affinity. In addition, we found a novel cellobiose transporter from the yeast Lipomyces starkeyi, encoded by the gene Ls120451. This transporter allowed efficient growth on cellobiose, while it also grew on glucose and lactose, but not cellotriose nor cellotetraose. We characterized the transporter more in-depth together with the transporter CdtG from Penicillium oxalicum. CdtG showed to be slightly more efficient in cellobiose consumption than Ls120451 at concentrations below 1.0 g/L. Ls120451 was more efficient in cellobiose consumption at higher concentrations and strains expressing this transporter grew slightly slower, but produced up to 30% more ethanol than CdtG.


2020 ◽  
Vol 8 (9) ◽  
pp. 1447
Author(s):  
Patrick Schwarz ◽  
Elie Djenontin ◽  
Eric Dannaoui

The in vitro interactions of isavuconazole in combination with colistin were evaluated against 55 clinical Aspergillus species isolates belonging to the five most important species (Aspergillus flavus, Aspergillus fumigatus, Aspergillus nidulans, Aspergillus niger, and Aspergillus terreus) responsible for human aspergillosis by a microdilution checkerboard technique based on the European Committee on Antimicrobial Susceptibility Testing (EUCAST) reference method for antifungal susceptibility testing. Selected isolates (A. nidulans, n = 10; A. niger, n = 15) were additionally evaluated by an agar diffusion assay using isavuconazole gradient concentration strips with or without colistin incorporated Roswell Parc Memorial Institute (RPMI) agar. Interpretation of the checkerboard results was done by the fractional inhibitory concentration index. Using the checkerboard method, combination isavuconazole–colistin was synergistic for 100% of the 15 A. nidulans isolates and for 60% of the 20 A. niger isolates. No interactions were found for any of the other isolates. By agar diffusion assay, minimal inhibitory concentrations (MICs) in combination decreased compared to isavuconazole alone for 92% of the isolates. No interactions were found for any A. nidulans isolates, but synergy was observed for 40% of the A. niger isolates. A poor essential agreement of EUCAST and gradient concentration strip MICs at ± 2 log2 dilutions with 0% was obtained. Antagonistic interactions were never observed regardless of the technique used.


2006 ◽  
Vol 129 (1-3) ◽  
pp. 195-214 ◽  
Author(s):  
Christina Bohlin ◽  
Leif J. Jönsson ◽  
Robyn Roth ◽  
Willem H. van Zyl

2011 ◽  
Vol 11 (1) ◽  
pp. 2 ◽  
Author(s):  
Ondřej Kaplan ◽  
Karel Bezouška ◽  
Ondřej Plíhal ◽  
Rüdiger Ettrich ◽  
Natallia Kulik ◽  
...  

2013 ◽  
Vol 13 (1) ◽  
Author(s):  
Ondrej Kaplan ◽  
Karel Bezouska ◽  
Ondrej Plihal ◽  
Rudiger Ettrich ◽  
Natallia Kulik ◽  
...  

2001 ◽  
Vol 183 (20) ◽  
pp. 5826-5833 ◽  
Author(s):  
Soula Margelis ◽  
Cletus D'Souza ◽  
Anna J. Small ◽  
Michael J. Hynes ◽  
Thomas H. Adams ◽  
...  

ABSTRACT Glutamine synthetase (GS), EC 6.3.1.2 , is a central enzyme in the assimilation of nitrogen and the biosynthesis of glutamine. We have isolated the Aspergillus nidulans glnA gene encoding GS and have shown that glnA encodes a highly expressed but not highly regulated mRNA. Inactivation of glnA results in an absolute glutamine requirement, indicating that GS is responsible for the synthesis of this essential amino acid. Even when supplemented with high levels of glutamine, strains lacking a functionalglnA gene have an inhibited morphology, and a wide range of compounds have been shown to interfere with repair of the glutamine auxotrophy. Heterologous expression of the prokaryotic Anabaena glnA gene from the A. nidulans alcA promoter allowed full complementation of the A. nidulans glnAΔ mutation. However, the A. nidulans fluG gene, which encodes a protein with similarity to prokaryotic GS, did not replace A. nidulans glnA function when similarly expressed. Our studies with theglnAΔ mutant confirm that glutamine, and not GS, is the key effector of nitrogen metabolite repression. Additionally, ammonium and its immediate product glutamate may also act directly to signal nitrogen sufficiency.


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