Microbial biofilm formation during space flight (Micro-2A) - 07.29.14
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Microbial biofilm formation during space flight (Micro-2A) studies how gravity alters biofilm formation. Biofilms are groups of microorganisms that form on surfaces. One goal of this experiment is to develop new strategies to reduce the impact of biofilms on crew health and to minimize the harmful effects of them on materials in space and on Earth.
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This investigation sought new strategies to minimize harmful effects of microgravity-induced formation of biofilm, or groups of microorganisms that form on surfaces. Microbe cultures grown under constant mixing have indicated that space flight can increase growth and virulence. To better understand the effects of space flight on biofilm development, researchers cultured Pseudomonas aeruginosa in space and characterized the biofilms formed. They observed an increased number of viable cells, increased biomass, and increased thickness in space biofilms, regardless of phosphate concentration or carbon source. Biofilm production during space flight could therefore have detrimental impacts during long-term space flight missions.
University of Colorado at Boulder, BioServe Space Technologies, Boulder, CO, United States
Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)
Human Exploration and Operations Mission Directorate (HEOMD)
ISS Expedition Duration
March 2011 - September 2011
Previous ISS Missions
Micro-2A builds on the results obtained from Micro-2 on STS-132, in the methods of cultivation of the organisms, the anti-microbial surfaces tested, and the mutant strains of the organisms used. The results from the STS-135 experiment not only complement the results obtained from STS-132 but also provide new data on the anti-biofilm action of additional surface coatings.
- The Microbial biofilm formation during space flight (Micro-2A) investigation aims to understand the different responses and physical effects of reduced gravitational force on biofilm formation (complex aggregates of microorganisms attached to a surface). Cells grown in microgravity are compared to cells grown in normal gravity. The amount of biomass formed is measured and confocal microscopy (an optical imaging technique used to increase optical resolution and contrast) is used to identify changes in the three-dimensional structures of the biofilms. This study also tests a number of newly developed antimicrobial surfaces for their potential to reduce biofilm formation.
- Understanding the different responses and physical effects of microgravity on biofilm formation may provide new insights into combating biofilm formation in space. Furthermore, this work may also lead to better management and treatment of infections in space and on Earth.
The goal of Microbial biofilm formation during space flight (Micro-2A) is to understand the effects of microgravity on the growth, cellular physiology, and cell-cell interactions in microbial biofilms. It focuses on two model microorganisms that form biofilms both inside and outside of the human body, Pseudomonas aeruginosa and Staphylococcus aureus (S. aureus). These microbes can switch between benign (not harmful) and pathogenic (able to cause disease) interactions with humans and may be relevant to crew health during extended missions. This experiment also tests the ability of novel antimicrobial surfaces to reduce biofilm formation.
When cells form biofilms they have a number of potentially harmful properties, including increased potential for infection and increased resistance to antimicrobial compounds. Biofilms have the potential to cause significant damage to both spacecraft and their crew; numerous problems caused by biofilms were documented on Mir. A greater understanding of the effects of spaceflight on biofilms is critical.
The Micro-2A experiment makes use of Group Activation Packs (GAPs) stored in a Commercial Generic Bioprocessing Apparatus (CGBA). The CGBA is a flight certified incubator capable of controlling the temperature between 8ºC and 37ºC. Each GAP holds eight Fluid Processing Apparatus (FPA) inserts. The FPA is composed of a glass barrel divided into three chambers that are separated from one another by rubber septa. Each FPA contains growth medium with membranes in the first chamber, a microbial culture suspended in stasis medium in the second chamber, and a termination reagent in the last chamber.
Micro-2A builds on the results obtained in the Micro-2 experiment flown on STS-132. Micro-2A utilizes new methods of cultivation of the organisms that should enhance the growth of S. aureus. In addition, the results from the STS-135 Micro-2A experiment also provide new data on the anti-biofilm action of additional surface coatings not used for Micro-2.
Understanding the different effects of microgravity on biofilm formation may provide new insights into combating biofilm formation in space and may lead to better management and treatment of infections if they occur. Also, novel antimicrobial surfaces are tested for their potential to reduce the impact of biofilms in future spacecraft design.
According to the Center for Disease Control (CDC), hospital-acquired infections are the fourth leading cause of death in the United States behind stroke, cancer and heart disease. Furthermore, it is estimated that greater than 65 percent of all bacterial infections are associated with biofilms. A greater understanding of biofilms is essential if we are to find effective methods to combat their formation. Furthermore, the low-shear conditions microbes experience in microgravity are similar to those found in the human body that are difficult to study. This work may provide new insights into the role of shear and other physical effects, such as convection, on biofilm formation.
The Micro-2A experiment consists of 63 samples housed in 8 GAPs. The temperature profile of the CGBA and the temperature logger (HOBO) are required for the post-flight analysis of the data.
The samples are stowed in the CGBA at 8ºC until as late in the mission as possible then CGBA temperature is set to 37ºC and all GAPs are activated. To activate the samples, a crewmember must remove the CGBA from its middeck stowage location, take out each GAP and install the hand crank. The hand crank is then turned until the cell suspension in the second chamber is introduced to the growth media in the first chamber. Following the 72-hour growth period, a crewmember installs the hand crank again and terminates the GAPs by adding the termination reagent in the last chamber to the cells. Only a subset of the GAPs needs to be terminated. All GAPs are returned to the CGBA and the CGBA is set to 8ºC where it will remain until recovery.
While planktonic cultures (grown under constant mixing) of microbes have indicated that space flight can lead to increases in growth and virulence, the effects of space flight on biofilm development and physiology remain unclear. To address this issue, Pseudomonas aeruginosa was cultured during two Atlantis space shuttle missions: STS-132 and STS-135, and the biofilms formed during space flight were characterized. Micro-2 reveals the first evidence of space flight affecting the biofilm formation of P. aeruginosa. An increased number of viable cells, increased biomass, and increased thickness were observed in space flight biofilms when compared to ground controls regardless of phosphate concentration or carbon source. Results also show P. aeruginosa forming column-and-canopy shaped biofilms during space flight and flagella-driven motility plays a key role in the formation of this unique structure, where flagella are structures that enable cells to move in liquids by "swimming". The findings indicate that altered biofilm production during space flight may have detrimental impacts on long-term space flight missions, where increases in biofouling and microbial-induced corrosion could have profound impacts on mission success. Furthermore, it will be important to explore the effects of such changes on human health through pathogenic and beneficial interactions between humans and microbes during space flight (Kim 2013).
Kim W, Tengra FK, Shong J, Marchand N, Chan HK, Young Z, Pangule RC, Parra MP, Dordick JS, Plawsky JL, Collins CH. Effect of spaceflight on Pseudomonas aeruginosa final cell density is modulated by nutrient and oxygen availability. BMC Microbiology. 2013 November 6; 13(1): 241.
Kim W, Tengra FK, Young Z, Shong J, Marchand N, Chan HK, Pangule RC, Parra MP, Dordick JS, Plawsky JL, Collins CH. Spaceflight Promotes Biofilm Formation by Pseudomonas aeruginosa. PLOS ONE. 2013 April 29; 8(4): e62437. DOI: 10.1371/journal.pone.0062437.
Ground Based Results Publications
Lynch SV, Mukundakrishnan K, Benoit MR, Ayyaswamy PS, Matin A. Escherichia coli biofilms formed under low-shear modeled microgravity in a ground-based system. Applied and Environmental Microbiology. 2006; 72: 7701-7710.
Rensselaer Polytechnic Institute – Collins Research Group
Space Biosciences Division – Micro2 (STS-132)
Dr. Cynthia Collins, Rensselaer Polytechnic Institute, prepares samples for Microbial biofilm formation during space flight (Micro-2A). Image courtesy of NASA.
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Commercial Generic Bioprocessing Apparatus (CGBA) that houses the Microbial biofilm formation during space flight (Micro-2A) samples. Image courtesy of NASA.
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Group activation Pack (GAP) containing Fluid Processing Apparatus (FPA) for Microbial biofilm formation during space flight (Micro-2A). Image courtesy of NASA.
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