Phytate mineralizing bacteria and their phytase activity from different matrices of tropical floodplain wetlands

Phytic acid constitutes a significant part of total phosphorus (P) load in aquatic sediments, with potential for P release to water. The present study harnessed phytase producing bacteria from different matrices of two floodplain wetlands of West Bengal, India and examined their phytate mineralization activity. Prominent phytate degrading bacterial isolates were identified from 16S rDNA sequences as Bacillus megaterium, Arthrobacter sp., Klebsiella oxytoca, Methylobaderium gregans, and Fidibacillus sp. The bacteria from gut of Cirrhinus mrigala had much higher phytase activity than those from sediment and water. Requirements of pH for optimum phytase enzyme activity varied widely, in sync with the pH of respective niche, with highest activity at pH 3-4 for gut bacteria and pH 6-7 for sediment isolates, suggesting their P release potential. Although the sediment bacteria had moderate phytase enzyme activity, presence of large amount of organic matter of plant origin, and congenial physio-chemical environments such as temperature and pH might make the wetland sediment an important site of phytate degradation towards phosphorus cycling for primary production.