Antifungal spectrum determination of the K5 type yeast killer protein on fungi causing spoilage in citrus fruits

Download

index.pdf

Date

2006

Author

Kepekçi, Remziye Aysun

Metadata

Show full item record

Item Usage Stats

296
views

125
downloads

Some yeast strains under certain conditions secrete polypeptide toxins which are inhibitory to sensitive fungal cells into the medium. These yeast strains are termed as killer yeasts and their toxins are designated as killer proteins or killer toxins. Killer proteins are classified into 11 typical types (K1-K11). These toxins have different killing mechanisms on sensitive cells. Some of them hydrolyze major cell wall component, beta-1,3- glucans. As mammalian cells lack cell walls research and development of novel highly selective antifungals are mostly focused on the agents which target the components of the fungal cell wall. K5 type killer protein was characterized in our labarotory previously. This protein is an exo beta-1,3-glucanase which is stable at pH’s and temperatures appropriate for its biocontrol usage. Beta-1,3-glucan hydrolyzing activity of the K5 type killer protein highlighted the potential use of this protein as a selective antifungal agent. According to CLSI methodology, antifungal activity of the K5 type yeast killer protein was tested against 6 fungal strains causing postharvest spoilage in citrus fruits and found to be effective on Botrytis cinerea, Penicillium digitatum, Penicillium italicum whereas non effective on Colletotrichum gloeosporoides, Phythophythora citrophthora, Alternaria citri. The MIC values of the toxin for B.cinerea, P.digitatum, P.italicum were found to be 16 mikrogram/ml while IC 50 values of the toxin were 2.12, 3.31, 2.57 mikrogram/ml respectively. The results showed that K5 type yeast killer protein would be used as a novel and selective agent against B.cinerea, P.digitatum and P.italicum.

Subject Keywords

Pathogenic Micro-Organisms, By Disease.

URI

http://etd.lib.metu.edu.tr/upload/12607858/index.pdf
https://hdl.handle.net/11511/16450

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Antimicrobial spectrum determination of the K5 type yeast killer protein and its kinetics of cell killing Türel, Akif Emre; İzgü, Kadri Fatih; Department of Biology (2005) Some yeast strains under certain conditions secrete into the medium polypeptide toxins which are inhibitory to sensitive cells. These yeast strains are termed as killer yeasts and their toxins are designated as killer proteins or killer toxins. Killer proteins are classified into 11 typical types (K1-K11). These toxins have different killing mechanisms on sensitive cells. Some of them hydrolyze major cell wall component β-1,3- glucans. As mammalian cells lack cell walls research and development of novel hig...
Analysis of polyphenol oxidase production by southern pine beetle associated fungi Valiev, Abduvali; Ögel, Zümrüt Begüm; Department of Food Engineering (2007) In this study, two symbiotic fungi of Southern Pine Beetle (SPB), Entomocorticium peryii and Entomocorticium sp.A were evaluated in terms of polyphenol oxidase (PPO) production. The effect of different inhibitors, inducers and assay parameters such as temperature and pH on enzyme activity were investigated and maximum PPO activity was observed at 30°C, pH 8.0 and when tannic acid was used as an inducer. Copper-chelator salicyl hydroxamic acid (SHAM) and pcoumaric acid, both indicated as inhibitors of tyrosi...
Antimicrobial spectrum determination of the K5 type yeast killer protein on bacteria causing skin infections and its cell killing activity Gönen, Tuğçe; İzgü, Kadri Fatih; Department of Biology (2006) Some yeast strains secrete extracellular polypeptide toxins known to have potential growth inhibitory activity on sensitive yeast cells. These yeast strains are known as killer yeasts and their toxins are named as killer toxins or killer proteins. Yeast killer proteins are found inhibitory to Gram-positive bacteria in several studies which were based on microbial interactions of the producer strains tested with sensitive strains. K5 type yeast killer protein produced by Pichia anomala NCYC 434 was previousl...
Determination of antimicrobial spectrum of K9 type yeast killer toxin and its cell killing activity Yener, Burcu; İzgü, Kadri Fatih; Department of Biology (2006) Some yeast strains secrete extracellular polypeptide toxins known to have potential growth inhibitory activity on other sensitive yeast genera but are immune to their own toxins. These yeast strains are termed as killer yeasts and their toxins are designated as killer proteins or killer toxins. Killer phenotypes are classified into 11 typical types (K1-K11). The toxic actions of yeast killer proteins on sensitive cells show differences and one of the most important toxic actions involves the selective funct...
Investigation of cytocidal effect of K5 type yeast killer protein on sensitive microbial cells Sertkaya, Abdullah; İzgü, Kadri Fatih; Department of Biology (2005) Some yeasts secrete polypeptide toxins, which are lethal to other sensitive yeast cells, gram-positive pathogenic bacteria and pathogenic fungi. Therefore these are designated as killer toxins. Killer toxins are suggested as potent antimicrobial agents especially for the protection of fermentation process against contaminating yeasts, biological control of undesirable yeasts in the preservation of foods. Moreover they are promising antimicrobial agents in the medical field; due to immune system suppressing ...

Citation Formats

R. A. Kepekçi, “Antifungal spectrum determination of the K5 type yeast killer protein on fungi causing spoilage in citrus fruits,” M.S. - Master of Science, Middle East Technical University, 2006.