title: Engineering strategies for the design of plant nutrient delivery systems for use in space:  approaches to countering microbiological contamination.
abstract: Microbiological contamination of crops within space-based plant growth research chambers has been postulated as a potentially significant problem.  Microbial infestations; fouling of Nutrient Delivery System (NDS) fluid loops; and the formation of biofilms have been suggested as the most obvious and important manifestations of the problem.  Strict sanitation and quarantine procedures will reduce, but not eliminate, microbial species introduced into plant growth systems in space habitats.  Microorganisms transported into space most likely will occur as surface contaminants on spacecraft components, equipment, the crew, and plant-propagative materials.  Illustrations of the potential magnitude of the microbiological contamination issue will be drawn from the literature and from documentation of laboratory and commercial field experience.  Engineering strategies for limiting contamination and for the development of countermeasures will be described.  Microbiological control technologies and NDS hardware will be discussed.  Configurations appropriate for microgravity research facilities, as well as anticipated bio-regenerative life support system implementations, will be explored.  An efficiently designed NDS, capable of adequately meeting the environmental needs of crop plants in space, is considered to be critical in both the research and operational domains.  Recommended experiments, tests, and technology developments, structured to allow the development of prudent engineering solutions also will be presented.
authors.affiliation: NASA/Ames Research Center, Advanced Life Support Division, Moffett Field, CA 94035-1000, USA.
authors.forename: A A
authors.initials: AA
authors.lastname: Gonzales
authors.forename: A C
authors.initials: AC
authors.lastname: Schuerger
authors.forename: C
authors.initials: C
authors.lastname: Barford
authors.forename: R
authors.initials: R
authors.lastname: Mitchell
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D018504:Ecological Systems, Closed; D004783:Environmental Microbiology; D004867:Equipment Design; D005658:Fungi; D018527:Hydroponics / Q000295:instrumentation* / Q000379:methods; D008021:Life Support Systems / Q000295:instrumentation*; D063245:Plant Development; D018517:Plant Roots / Q000382:microbiology; D011790:Quarantine / Q000379:methods; D012499:Sanitation / Q000379:methods; D013026:Space Flight / Q000295:instrumentation*