Already a short-term soils exposure to the field-rate glufosinate concentration significantly influences soil bacterial communities

The early impact of glufosinate derived herbicide Basta® 15 on bacterial communities of two different soils never exposed to this herbicide was investigated using cultivation approach and non-cultivation based denaturing gradient gel electrophoresis (DGGE) analysis of amplified 16S rRNA genes. Under the simulated laboratory conditions glufosinate treatment increased numbers of total cultivable heterotrophic bacteria in both tested soils. Surprisingly even the lowest glufosinate concentration (1 mmol) significantly affected bacterial community composition in both tested soils and original populations were replaced by new ones upon the 2 days glufosinate treatment. In nutrient rich Haniska soil the effect was dose dependent and glufosinate treatment decreased genetic diversity of bacterial population. In nutrient poor Kaľava soil the highest glufosinate concentration (16 mmol) increased the diversity of bacterial population probably as a result of carbon source supplementation. Glufosinate treatment selected Gram-negative bacteria in both soils. Two species of Enterobacter genus were found to be dominant in glufosinate treated Haniska soil and Pseudomonas beteli and Brevundimonas diminuta were found to be dominant in glufosinate treated Kaľava soil using non-cultivation based DGGE method. Our data indicated that under the simulated soil conditions the soil bacterial community was significantly affected even by a short-term exposure to glufosinate.