Influence of earthworm activity on microbial communities related with the degradation of persistent pollutants.
Earthworms may promote the biodegradation of polycyclic aromatic hydrocarbons (PAHs) in soil, but the mechanism through which they exert such influence is still unknown. To determine if the stimulation of PAH degradation by earthworms is related to changes in microbial communities, a microcosm experiment was conducted consisting of columns with natural uncontaminated soil covered with PAH-contaminated dredge sediment. Columns without and with low and high Eisenia andrei densities were prepared. Organic matter and PAH content, microbial biomass, and dehydrogenase activity (DHA) were measured in soil and sediment over time. Biolog Ecoplate™ and polymerase chain reaction using denaturing gradient gel electrophoresis were used to evaluate changes in metabolic and structural diversity of the microbial community, respectively. Earthworm activity promoted PAH degradation in soil, which was significant for biphenyl, benzo[a]pyrene, and benzo[e]pyrene. Microbial biomass and DHA activity generally did not change over the experiment. Earthworm activity did change microbial community structure, but this did not affect its functioning in terms of carbon substrate consumption. Results suggest no relationship between changes in the microbial community by earthworm activity and increased PAH disappearance. The role of shifts in soil microbial community structure induced by earthworms in PAH removal needs further investigation.
Institute of Marine Research-Marine and Environmental Research Centre, Department of Life Sciences, University of Coimbra, Coimbra, Portugal. tiagonluz@iav.uc.pt
Tiago
T
Natal-da-Luz
Iwa
I
Lee
Rudo A
RA
Verweij
Paula V
PV
Morais
Martin J M
MJ
Van Velzen
José Paulo
JP
Sousa
Cornelis A M
CA
Van Gestel
D000818:Animals; D001580:Benzopyrenes / Q000378:metabolism; D001673:Biodegradation, Environmental; D018533:Biomass; D019015:Geologic Sediments / Q000032:analysis; D009835:Oligochaeta / Q000378:metabolism*; D010088:Oxidoreductases / Q000032:analysis; D011084:Polycyclic Aromatic Hydrocarbons / Q000378:metabolism*; D012987:Soil / Q000032:analysis; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism*
D001580:Benzopyrenes; D011084:Polycyclic Aromatic Hydrocarbons; D012987:Soil; D012989:Soil Pollutants; D010088:Oxidoreductases