Effective degradation of organic pollutants in aqueous media by microbial strains isolated from soil of a contaminated industrial site

Filomena Sannino,Assunta Nuzzo,Alessandro Piccolo,Valeria Ventorino,Olimpia Pepe

doi:10.1186/s40538-016-0052-x

Abstract

Bioremediation is a low-cost technology, whose efficacy is often enhanced with preliminary mild physical–chemical remediation methods. A further advantage of bioremediation resides in its eco-compatibility and, thus, sustainability. Two autochthonous microbial strains, Methylobacterium populi VP2 and Aspergillus sydowii VP4, were isolated from a soil of a highly contaminated industrial site and used to degrade the aqueous extract of contaminants (AEC) obtained from the same polluted soil. The AEC incubation with both strains produced a significant removal of most organic pollutants, although the degradation capacity decreased with increasing AEC concentration in the minimal selective liquid medium (MSML) of the experiments. At 30 % of AEC, M. populi VP2 determined the removal of most pollutants and the appearance of new products due to oxidation and enzymatic degradation. Incubation of A. sydowii VP4 at the same AEC concentration in MSML removed the same pollutants but also the derived degradation products. Our results showed that the strains isolated from a highly contaminated soil maintained the capacity to use organic contaminants as metabolic carbon in aqueous extracts from the same soil. The greater biodegradation efficiency of the fungal strain in comparison to M. populi VP2 may be caused by a modification of the A. sydowii VP4 cell surface that increases cell permeability to hydrophobic compounds and thus enhances the extent of pollutants degradation. This work indicates that two specific strains, M. populi VP2 and A. sydowii VP4, isolated from the soil of a highly contaminated site are not only useful in the treatment of leaching polluted waters but may also be used in bioaugmentation practices during remediation of contaminated soils.

Highlights

Bioremediation is a low-cost technology, whose efficacy is often enhanced with preliminary mild physical–chemical remediation methods
The two microbial strains used in this study were able to grow in the minimal selective liquid medium (MSLM) containing different aqueous extract of contaminants (AEC) concentrations
After 15 days of incubation at 28 °C, both M. populi VP2 and A. sydowii VP4 increased over 2 log CFU/mL in the presence of AEC, reaching values of about 7.3 and 5.3 log CFU/mL, respectively (Table 1)

Summary

Introduction

Bioremediation is a low-cost technology, whose efficacy is often enhanced with preliminary mild physical–chemical remediation methods. Waste management policies are often inadequate to keep the pace with increased industrialization and lead to a significant environmental degradation by toxic and hazardous pollutants. Several contaminants, such as heavy metals, radionuclides, and recalcitrant organic compounds, including pesticides, dyes, Polycyclic Aromatic Hydrocarbons (PAHs) and PoliChlorinated Bihenyls (PCBs), may persistently accumulate in soils and sediments, potentially menacing health security and environment quality. Despite its long-time requirement, bioremediation is an alternative low-cost technology, whose efficacy is often enhanced with preliminary mild physical–chemical remediation methods [4, 5]. A further advantage of bioremediation resides in its eco-compatibility and, sustainability

Objectives

Methods

Results

Conclusion