Effects of Heavy Metals on Phosphatase Enzyme Activity and Indole-3-Acetic Acid (IAA) Production of Phosphate Solubilizing Bacteria
Lalmuankimi Khiangte, R. Lalfakzuala
Abstract
Phosphorus is an essential nutrient element for all life forms. Phosphate solubilizing bacteria play an important role in plant growth and development and are able to solubilize unavailable forms of phosphates by excreting organic acids and phosphatase enzymes mainly acid phosphatase through the process of solubilization and mineralization. In this study, 17 potential phosphate solubilizing bacteria were identified using 16SrRNA gene sequence from Thenzawl paddy field of Mizoram, India. Assessment of acid phosphatase (APase) activity and Indole-3-acetic acid (IAA) production under induced heavy metals stresses were done in vitro condition. APase activity was determined by performing p-nitrophenyl phosphate assay of the bacterial broth culture and IAA production was checked using Salkowski’s reagent. Maximum APase activity was seen in Burkholderia gladioli strain MZUTZ15 (35.884 µg p-NP ml−1 hr−1) while maximum IAA production was seen in Burkholderia sp. strain MZUTZ19 (31.201 µg ml −1) under control experiment. The APase activity and IAA production of all tested isolates were found to be adversely affected by the presence of different concentration of heavy metals such as copper (Cu) and iron (Fe) in the culture medium compared to control.