Transfer of Plasmid DNA During Conjugation in Spaceflight (Plazmida) (Plazmida (Plasmid)) - 06.27.18

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The transfer of Plasmid DNA During Conjugation in Spaceflight (Plazmida) investigation examines the microgravity effect on the rate of transfer and mobilization of bacteria plasmids. It is well known that the sensitivity of crewmember microflora to antibiotics undergoes significant changes during spaceflight. This manifests in the formation of strains with signs of increased resistance to many antibiotics. By spreading among crewmembers, these strains can decrease the effectiveness of the antibiotics used to provide medical treatment to crewmembers. It is hypothesized that the main mechanism of the formation of dangerous bacterial strains is related to the recombining of plasmids (molecules of DNA encoding different bacterial properties, including pathogenicity and antibiotic resistance, that exist, reproduce, and multiply independently of chromosomes), which are determined both by the frequency of autonomous plasmid transfer and their capability to be mobilized by different genetic factors. It is hypothesized that the main mechanism of polyresistant strain formation is linked to plasmid recombination which are determined by both the frequency of conjugative plasmid transfer and mobilization in the changed environment. In addition, it is well known that changing living environment factors (gas composition, pressure, etc.) has a significant impact on R-plasmid transfer
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The following content was provided by Vyacheslav Constantinovich Ilyin, and is maintained in a database by the ISS Program Science Office.
Experiment Details


Principal Investigator(s)
Vyacheslav Constantinovich Ilyin, Institute of Medical and Biological Problems of Russian Academy of Sciences (IMBP RAS), Russia

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Sponsoring Space Agency
Russian Federal Space Agency (Roscosmos)

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Research Benefits
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ISS Expedition Duration
April 2004 - October 2004; April 2007 - October 2008; September 2011 - September 2012; March 2013 - September 2013

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Experiment Description

Research Overview
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Space Applications
The investigation results could be used to comprehensively study the effect of extreme factors of a changed living environment on the formation of antibiotic resistance in infectious agents. The results obtained have great theoretical value for all fields of gravitational biology, including for fundamental research in the fields of physiology and medicine

Earth Applications
Microorganism plasmids could be used as biological indicators to determine the level of impact of spaceflight factors on microbial communities in terms of assessing the risk of growth of the potential pathogenicity of human and environmental microflora. Thus, in flights of varying duration and radius, the plasmid transfer frequency may be different, as could be the corresponding risk of formation of drug-resistant bacteria. This aspect is potentially dangerous because poly-resistant strains of potentially pathogenic microorganisms formed in enclosed living spaces such as an orbiting space station are a type of depository for plasmids of multiple drug resistance, and consuming antibiotics could lead to their selective growth.

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Operational Requirements and Protocols
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Decadal Survey Recommendations

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Results/More Information

Strains of Bacillus thuringiensis were used as the donor and the recipient: Bacillus thuringiensis GBJ085 (donor) x Bacillus thuringiensis 4Q7 (recipient). The donor contained a plasmid resistant to tetracycline and with the nalidixic acid resistance associated with the gene chromosome. The recipient was resistant to streptomycin. During the experiment on the ISS, Rekomb-K equipment was used, in which donor and recipient liquid cultures were transferred and mixed for conjugation.

The results of the studies conducted point to the suppression of plasmid transfer frequency in gram-negative microorganisms. This was particularly clear for the mobilization of bacterial genes, where the difference in the production of transconjugants was 1000 times less than in the control. The conditions for the preliminary adaptation of donor and recipient strains to space-flight facilitated the suppression of conjugation transfer frequency and did not affect the frequency of plasmid mobilization, which in both cases remained extremely low. However, gram-negative microorganisms strains adapted to spaceflight demonstrated an increase in plasmid transfer frequency during conjugation in flight and an increase in plasmid mobilization activity on Earth.

As regards plasmid stability, the flight plasmids were much more stable than the controls. The increase in the average number of determinants of antibiotic resistance in strains was observed in virtually all the groups. This was most clearly noted for the mobilization of strains adapted to space conditions when conjugation was done on Earth. This circumstance points to the fact that in spaceflight there is the risk of strain formation with signs of resistance, despite the decrease in plasmid transfer frequency in some microorganism groups in spaceflight. The research confirmed the possibility of using plasmid transfer frequency as a biological indicator for the status of microbial communities in changed living conditions. Based on the results of the research, a mathematical model was created of the impact of microgravity on conjugation processes, and as a result on the formation of strains with signs of resistance.

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