Isolation and assessment of phytate-hydrolysing bacteria from the DelMarVa Peninsula.

The Delaware-Maryland-Virginia (DelMarVa) Peninsula, flanking one side of the Chesapeake Bay, is home to a substantial broiler chicken industry. As such, it produces a significant amount of manure that is typically composted and spread onto local croplands as a fertilizer. Phytate (myo inositol hexakisphosphate), the major form of organic phosphorus in the manure, can be hydrolysed by microorganisms to produce orthophosphate. Orthophosphate is a eutrophication agent which can lead to algal blooms, hypoxia and fish kills in the Chesapeake Bay and its tributaries. This transect study reveals a subpopulation of heterotrophic, thiosulfate-utilizing bacteria that can degrade phytate within the watershed as well as its receiving water sediment. Aerobic isolates were typical soil bacteria, e.g. Pseudomonad, Bacillus and Arthrobacter species, as well as a less common Staphylococcus inhabitant. Bacillus pumilus, Staphyloccocus equorum, Arthrobacter bergei and Pseudomonas marginalis strains have not been previously described as phytate-degrading. Each site along the transect - from manure pile to receiving sediment - was host to a population of bacteria that can degrade phytate and hence, each is a possible non-point source of orthophosphate pollution. Each new isolate could provide an enzyme additive for monogastric feed, thus reducing the impact of excessive phytate load on the environment.