Heavy metal tolerance and production of surfactant by Pseudomonas fluorescens Slim15

Abstract

Inadequate disposal of industrial waste or environmental accidents has caused major environmental impacts, such as the heavy metal contamination. Biotechnological processes involving microorganisms have been used as a strategy to recover impacted environments. The aim of this study was to evaluate the influence of essential and non-essential heavy metals on the growth and the surfactant production from Pseudomonas fluorescens Slim15 strain. Minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) tests were used to evaluate the tolerance to metals Pb and Zn. Emulsifying activity and surface tension tests were carried out to evaluate the influence of the metals on the biosurfactant production. P. fluorescens Slim15 strain presented growth in presence up to 31.25 mg/L of Zn and 1000 mg/L of Pb in the MIC test, and of 4000 mg/L in the MBC test for tested metals. The metals did not have a significant influence on the biosurfactant production. This research showed that P. fluorescens Slim15 strain had satisfactory yield in the tolerance and surfactant production tests, even in high concentrations of metals. This bacterium strain is a promising bioremediation agent of environments contaminated by heavy metals.