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RECENT RESEARCH ACHIEVEMENT, project B8

How bacteria protect themselves from plasma treatment 

© Daniel Sadrowski

Plasmas are applied in the treatment of wounds to combat pathogens that are resistant against antibiotics. But bacteria know how to defend themselves.

Considering the ever-growing percentage of bacteria that are resistant to antibiotics, interest in medical use of plasma is increasing. In collaboration with colleagues from Kiel, researchers at Ruhr-Universität Bochum (RUB) investigated if bacteria may become impervious to plasmas, too. They identified 87 genes of the bacterium Escherichia coli, which potentially protect against effective components of plasma. “These genes provide insights into the antibacterial mechanisms of plasmas,” says Marco Krewing. He is the lead author of two articles that were published in the Journal of the Royal Society Interface this year.

A cocktail of harmful components stresses pathogens

Plasmas are created from gas that is pumped with energy. Today, plasmas are already used against multi-resistant pathogens in clinical applications, for example to treat chronic wounds. “Plasmas provide a complex cocktail of components, many of which act as disinfectants in their own right,” explains Professor Julia Bandow, Head of the RUB research group Applied Microbiology. UV radiation, electric fields, atomic oxygen, superoxide, nitric oxides, ozone, and excited oxygen or nitrogen affect the pathogens simultaneously, generating considerable stress. Typically, the pathogens survive merely several seconds or minutes.

In order to find out if bacteria, may develop resistance against the effects of plasmas, like they do against antibiotics, the researchers analysed the entire genome of the model bacterium Escherichia coli, short E. coli, to identify existing protective mechanisms. “Resistance means that a genetic change causes organisms to be better adapted to certain environmental conditions. Such a trait can be passed on from one generation to the next,” explains Julia Bandow.

Mutants missing single genes

For their study, the researchers made use of so-called knockout strains of E. coli. These are bacteria that are missing one specific gene in their genome, which contains approximately 4,000 genes. The researchers exposed each mutant to the plasma and monitored if the cells kept proliferating following the exposure.

“We demonstrated that 87 of the knockout strains were more sensitive to plasma treatment than the wild type that has a complete genome,” says Marco Krewing. Subsequently, the researchers analysed the genes missing in these 87 strains and determined that most of those genes protected bacteria against the effects of hydrogen peroxide, superoxide, and/or nitric oxide. “This means that these plasma components are particularly effective against bacteria,” elaborates Julia Bandow. However, it also means that genetic changes that result in an increase in the number or activity of the respective gene products are more capable of protecting bacteria from the effects of plasma treatment.

Heat shock protein boosts plasma resistance

The research team, in collaboration with a group headed by Professor Ursula Jakob from the University of Michigan in Ann Arbor (USA), demonstrated that this is indeed the case: the heat shock protein Hsp33, encoded by the hslO gene, protects E. coli proteins from aggregation when exposed to oxidative stress. “During plasma treatment, this protein is activated and protects the other E. coliproteins – and consequently the bacterial cell,” Bandow points out. An increased volume of this protein alone results in a slightly increased plasma resistance. Considerably stronger plasma resistance can be expected when the levels of several protective proteins are increased simultaneously.

By Meike Drießen, Translated by Donata Zuber
Awards

Poster Prize for Christoph Stewig (A3) at the Conference for Plasma Technology 19 in Cottbus

Christoph Stewig was awarded with one of the three poster prizes at the bi-annual conference on plasma technology in Cottbus. 

Conference

International Workshop on Microplasmas in Kyoto 5/2019

Several projects of the SFB 1316 presented their reseach at the International Workshop on Microplasmas in Kyoto in May 2019 as two oral and six poster presentations. 

 
MERCATOR FELLOWS

New Mercator fellow - Prof. Dr. Satoshi Hamaguchi, University of Osaka

Prof. Satoshi Hamaguchis research focus on plasma-material interactions in general, including their industrial applications. The aim of research is to understand fundamental mechanics of plasma-material interactions under various conditions. To achieve this, we combine plasma/beam experiments with numerical simulation/modeling. More specifically our current research topics include 1) etching, deposition, and surface modification processes for micro/nano electronics device manufacturing, 2) surface modification and functionalization of biomaterials by plasmas, 3) processing of water and biological systems by atmospheric-pressure plasmas mainly for applications in plasma medicine and plasma agriculture, and 4) dynamics and chemical reactions in plasmas under various conditions, including atmospheric-pressure plasmas.

Prof. Hamaguchi is also coordinator of the JSPS core-to-core program "Establishment of the Center for Collaborative Research in Data-Driven Plasma Science " that connects Osaka university with Ruhr University Bochum, and the universities in Bologna, Aix-Marseille, and York. In the framework of this program the sending side covers international airfare and the receiving side covers maintenance and the domestic travel costs. The hosting side covers the cost of holding the seminars.

MEETING

Project Meeting at the Beckmanns Hof

The spring project meeting of the SFB 1316 took place at the Beckmanns Hof between the 25.03.- 27.03.2019. The first day was devoted to a workshop about Plasma Modeling and Simulation. The project meeting itself covered all projects and general items regarding the scientific progress of the consortium.