Anaerobic utilization of phosphite/phosphine as a sole source of phosphorus: implication to growth in the Jovian environment

Abstract

The objective of the investigation was to isolate anaerobic micro-organisms which had the ability to utilize inorganic phosphorus in forms other than phosphate. The first part of this investigation was to isolate from Cape Canaveral soil micro-organisms capable of utilizing phosphite as their phosphorus source under anaerobic conditions. In an attempt to demonstrate this ability, a medium was prepared which contained hypophosphite as the phosphorus source. This was inoculated with soil samples, and growth was subcultured at least four times. To verify that these isolates could use hypophosphite, they were inoculated into defined hypophosphite medium, and samples were removed periodically and killed with formalin. Growth was determined by turbidity measurements and the sample was then filtered. The filtrate was separated by chromatography and the total amounts of hypophosphite, phosphate and phosphate in the filtrate were measured. By this procedure it appeared that the hypophosphite level began decreasing after 14 hr of incubation suggesting utilization of the hypophosphite under anaerobic conditions. The third part of this investigation used labeled (32P) hypophosphite in a defined medium; the cells were then lysed and the metabolic compounds separated by the use of paper chromatography and autoradiograms, demonstrating the presence of 32P in intermediate metabolic compounds. Similar investigations are now being performed with phosphine as the phosphorus source.