A Intermediate Products During the Aerobic Degradation of Sweetpotato Plants by Serratia Marcescens 2003-01-2684
Sustaining long-duration human exploration and development of space requires ensuring that there is a continuous supply of vital resources and maximum utilization of wastes evolving from human habitation and crop biomass production. The products of waste treatment potentially constitute a valuable source of nutrients and utilizable materials. A clear profile of organics derived from aerobic biodegradation would enable the expansion of the list of potential organic species to be considered when examining the sustaining of long-duration, human space exploration. In laboratory studies, a survey was conducted of the products of aerobic degradation of sweetpotato biomass where Serratia marcescens a soil microbial isolate was used as the biological agent. Use of a pure culture ensured that the introduction of the microbial population in a controlled environment can be monitored and that any changes in the population can be readily determined to be due either to contamination or to changes in the population of the specific culture. Two Kontes glass bioreactors of 5-liter capacity, each containing sweetpotato foliar biomass (500 g) was inoculated with fresh bacterial culture and incubated in a shaker at 30°C for 31 days. Two fifteen-milliliter samples from each reactor were taken twice each week and analyzed for organic species. The analytical procedures were established to determine what organic compounds predominate when sweetpotato biomass was composted. A survey of the significant organic species was completed using gas chromatography and mass spectroscopy. For this study of composted material, the major organic species identified included anthraquinone, 4-chloro-6-methoxyauron, phenanthrene, naphthalene and claviculine (a dopamine receptor). Further mass reduction at defined intervals, in repeated thirty-day studies, measured up to 40%. The results of this work will enable researchers to further refine analytical methods that will enable researchers to quantify organics derived from aerobic biodegradation. The resulting profiles of organic species may be included in model development of the aerobic composter process. The significance of the results of this work can be found in the providing of information to be considered as decisions and alternatives are presented for consideration of the possible systems that will ensure mission success. Also, this work makes clear more of the “unknown species” related to potential use of bioregenerative approaches for space missions.