The impact on the soil microbial community and enzyme activity of two earthworm species during the bioremediation of pentachlorophenol-contaminated soils

Abstract

The ecological effect of earthworms on the fate of soil pentachlorophenol (PCP) differs with species. This study addressed the roles and mechanisms by which two earthworm species (epigeic Eisenia fetida and endogeic Amynthas robustus E. Perrier) affect the soil microbial community and enzyme activity during the bioremediation of PCP-contaminated soils. A. robustus removed more soil PCP than did E. foetida. A. robustus improved nitrogen utilisation efficiency and soil oxidation more than did E. foetida, whereas the latter promoted the organic matter cycle in the soil. Both earthworm species significantly increased the amount of cultivable bacteria and actinomyces in soils, enhancing the utilisation rate of the carbon source (i.e. carbohydrates, carboxyl acids, and amino acids) and improving the richness and evenness of the soil microbial community. Additionally, earthworm treatment optimized the soil microbial community and increased the amount of the PCP-4-monooxygenase gene. Phylogenic classification revealed stimulation of indigenous PCP bacterial degraders, as assigned to the families Flavobacteriaceae, Pseudomonadaceae and Sphingobacteriacea, by both earthworms. A. robustus and E. foetida specifically promoted Comamonadaceae and Moraxellaceae PCP degraders, respectively.

Effects of two ecological earthworm species on atrazine degradation performance and bacterial community structure in red soil

“…between microorganisms and reactants (Lin et al, 2016b). Additionally, earthworms also increase soil microbial activities via digesting organic matters and improving nutrient availability (Lin et al, 2016a).…”

Monitoring the Activated Sludge Activities Affected by Industrial Toxins via an Early-Warning System Based on the Relative Oxygen Uptake Rate (ROUR) Index

“…However, the biochemical treatment units in WWTPs are sensitive to high-level of toxic emerging substances or PTEs in influents and the paralysis often occurs in case of a shock load. It is reported that the spill of cyanide and other illegal chemical dumping can cause the shutdown of WWTPs and consequently release contaminants to the surrounding environment [14]. Toxicity assessment methods require development for monitoring the change of influent toxicity and guiding the rapid response strategies to protect WWTPs from the shock load [15].…”

“…Additionally, most of these approaches are still in laboratory test, leaving a huge gap between the state-of-art concept and industrial practices. Besides, these biological measurements are indirect methods as the indicator organisms are exogenous to the activated sludge and unable to represent the real domestication and adaptability of the activated sludge during wastewater treatment process [14]. An early-warning system directly monitoring the change of the activated sludge activities can represent the real performance of WWTPs and provide a basis for emergency measures of toxic substances in industrial wastewater, for effectively evaluating the influent toxicity and alarming the shock load of industrial wastewater [3,40].…”

“…The oxygen uptake rate (OUR) is a theoretical indicator for characterizing the activated sludge activities, representing the in situ changes of microbial activities in removing pollutants [41][42][43]. The OUR has been used for several cases of toxicity assessment like organic compounds, PTEs, and complex wastewater [14,44]. For instance, the OUR is able to estimate the kinetic parameters in a model including substrate hydrolysis, biomass growth and endogenous metabolism [45].…”

Efectos de la lombriz roja californiana (Eisenia foetida), sobre el crecimiento de microorganismos en suelos contaminados con mercurio de Segovia, Antoquia

“…La implementación de lombrices para la biorremediación es una técnica novedosa que ha mostrado que las capacidades de asimilación de metales por vía digestiva es prácticamente independiente del pH del suelo [27]. A través de las secreciones mucilaginosas y la transformación de materia orgánica, las lombrices incrementan la actividad microbial y la disponibilidad de los nutrientes, de igual manera se ha reportado que las lombrices pueden estimular las bacterias, hongos y especies relacionadas con la degradación del pentaclorofenol [28][29][30][31][32].…”