Polycyclic aromatic hydrocarbons (PAHs) are organic compounds with mutagenic, genotoxic and carcinogenic properties. Although PAHs in soil can cause toxicity to microorganisms, the microbial community is able to degrade these compounds through the synthesis of extracellular enzymes with oxi-reductase activity. Since the use of indigenous microorganisms in bioremediation processes can reduce the risks associated with hydrocarbon contaminated soils, a better understanding of the effect of hydrocarbon contaminants on soil microorganisms may be of help in assessing the recovery potential of a soil. The aim of the research was to study the microbial community responses to PAH contamination of soils belonging to three different Mediterranean ecosystems: holm oak, black pine and beech woods. Each soil was divided in three aliquots subjected to different treatments: spike with phenanthrene, pyrene and benzo[a]pyrene. The soils were incubated in unlit mesocosms under controlled conditions. After 4, 108 and 360 days PAH concentrations (microwave extraction and GC- MS/MS quantification), microbial growth rates (radioactive tracer incorporation techniques) and structure of microbial community (PLFA and ergosterol content) were measured. A permutational MANOVA (Multivariate Analysis of Variance) was performed to test the differences in PLFAs, ergosterol and microbial growth among treatments and sampling times. Along 360 days of incubation, PAH contents decreased in all the mesocosm types. Benzo[a]pyrene showed a slower decrease due to its low water solubility and high tendency to sorb to soil organic fraction, that make it scantly available for microbial community. The NMDS (Non-metric multidimensional scaling) results showed a clear separation among sampling times but not among the added PAHs for the three investigated soils. After 360 days from contamination no effects on the microbial community structure was observable, probably thanks to the high percentage (26.4% in holm oak, 38.0% in black pine and 31.5% in beech woods) of organic matter present in the investigated soils.
Microbial biomass and growth rate in three forest soils contaminated with PAHs
Baldantoni D.;
2019-01-01
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are organic compounds with mutagenic, genotoxic and carcinogenic properties. Although PAHs in soil can cause toxicity to microorganisms, the microbial community is able to degrade these compounds through the synthesis of extracellular enzymes with oxi-reductase activity. Since the use of indigenous microorganisms in bioremediation processes can reduce the risks associated with hydrocarbon contaminated soils, a better understanding of the effect of hydrocarbon contaminants on soil microorganisms may be of help in assessing the recovery potential of a soil. The aim of the research was to study the microbial community responses to PAH contamination of soils belonging to three different Mediterranean ecosystems: holm oak, black pine and beech woods. Each soil was divided in three aliquots subjected to different treatments: spike with phenanthrene, pyrene and benzo[a]pyrene. The soils were incubated in unlit mesocosms under controlled conditions. After 4, 108 and 360 days PAH concentrations (microwave extraction and GC- MS/MS quantification), microbial growth rates (radioactive tracer incorporation techniques) and structure of microbial community (PLFA and ergosterol content) were measured. A permutational MANOVA (Multivariate Analysis of Variance) was performed to test the differences in PLFAs, ergosterol and microbial growth among treatments and sampling times. Along 360 days of incubation, PAH contents decreased in all the mesocosm types. Benzo[a]pyrene showed a slower decrease due to its low water solubility and high tendency to sorb to soil organic fraction, that make it scantly available for microbial community. The NMDS (Non-metric multidimensional scaling) results showed a clear separation among sampling times but not among the added PAHs for the three investigated soils. After 360 days from contamination no effects on the microbial community structure was observable, probably thanks to the high percentage (26.4% in holm oak, 38.0% in black pine and 31.5% in beech woods) of organic matter present in the investigated soils.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
