Design Challenges for Biosynthetics in Space

Jackson LeeASEN 5519 Payload Design

12/9/03

Engineered PHB in cressleafhttp://www.firstscience.com/site/articles/sykes.asp

PHB poly-b-hydroxybutyratehttp://wine1.sb.fsu.edu/bch5425/lect09/lect09.htm

Why Plastics in Space?In space, packaging can account for up to 40% dry weight of food. Advances will reduce this, but large amounts of plastic waste remain1.No current ability to produce petroleum based plastics on a mars/ lunar base, so no plastic bags, no containers, bottles, etc.No current ability to process plastic wastesLong duration missions (10 year+)

BiosyntheticsPlastics, proteins, biopolymers produced as a natural part of biological function or by genetic modification and are generally biodegradable7.• Insulin, ethyl alcohol, fabrics, Bt, sutures

Plastics (Many forms)• Certain biopolymers are produced that are currently on

the market as “envi-friendly” plastic substitutes (Nodax, Biopol7)

• Natural byproduct of starches by bacteria. Carbon/ energy storage, biofilm formation2,3.

PHB PHA

How do we do it?How do you provide biodegradable plastics on a mars/ lunar base? Microbes or plants

R. Sphaeroides, a commonly studied bacterium

Cressleaf with engineered chloroplasts to produce PHA vacuoles

Differentiated cellsundifferentiated

Encapsulated vacuolesExtracellular secretion

Gene insertion and expression difficult

Simpler genetic manipulation

Difficult to monitorDifficult to quantify2

GreenhouseLarge bioreactors

Hormone sensitive5Easily poisoned or soured2

Control parameters:Light, pH, T, gas composition, nutrients (N/P)5

Wastes: CO2

Control parameters:pH, T, salts, C/N/P2

Wastes: nasty stuff

Lignified cell wallPeptidoglycan wall2

Slower growth (days, months)5

Rapid growth, (minutes)4

PlantsBacteria

This sucks!• How can we combine the few advantages of

each to make a better “bio-bioreactor”?• In nature, many internal bacterial-plant

symbiosis exists. The plant provides a controlled environment, the bacteria provides a function the plant is unable to do.8

• Can we use this to make plants host bacteria we want and have the bacteria produce things for us?

Examples

Rhizobiumhttp://www.science.uwaterloo.ca/~tcharles/rhizobium.html

Mycorrhizalhttp://www.ecol.kvl.dk/~sto/gf/orglist.htm

AdvantagesIf nodule forming bacteria can be coaxed into forming PHAs or PHBs, they can be harvested and processed into biodegradable plastic products on a mars/lunar greenhouse.

Easy genetic manipulationIn Situ plastics production NO theoretical infrastructure mass(*)Fast response of bacteria shielded by slower growing plants.Plants provide nutrients as part of symbiosisBacteria excrete product into intercellular space, forming nodules that can be easily harvested, avoiding plant lignin processingPerfect for poor countries on earth with few resources

Needs work• Never been tried• Internal response/ control parameters of plants

poorly understood• Inoculation of plants with opportunistic

pathogens• Harvesting and processing

Take home lesson1. Biosynthetics and biodegradable plastics can

be a tool for mass savings and functionality on a mars / lunar base

2. A hybrid bioreactor involving plant-microbial symbiosis can overcome many of the disadvantages of using individual plant or microbial biotechnology

3. This technology is only a few years away, and will be of incredible benefit for remote locations on earth and elsewhere.

Fin

Questions?

Bibliography1. Solid Waste Processing and Resource Recovery Workshop Report –EDCTSD CTSD-ADV-474 Rev A July 1, 20022. CVEN 5484 Environmental Microbiology, Mark Hernandez3. Wolfrum, E, and P. Weaver. “Quantitative measurement of the growth rate of the PHA-Producing Photosynthetic Bacterium R. gelatinosus CBS-2” Proceedings of the Renewable and Advanced Energy Systems for the 21st Century. RAES99-7690. 1999.4. Personal Correspondence, Dave Klaus5. Personal Correspondence, Alex Hoehn6. ME!7. http://www.bact.wisc.edu:81/ScienceEd/discuss/msgReader$108. N. Amarger. “Genetically Modified Bacteria in Agriculture.” Biochimie. 84: 1061-1072. 2002