Effect of soil contamination with petroleum products on esterase activity in earthworm Lumbricus terrestris

Abstract

Among biomarkers of exposure the suitability of esterases especially carboxylesterases (CarE), metabolizing wide array of xenobiotics being important for organismal functioning, was very often underlined. Moreover, neurotoxic effects of constituents of petroleum products may be exert by inhibition of cholinesterase (ChE) isozymes in animals. Here, we examined esterase activity toward acetylthiocholine iodide and ρ-nitrophenyl acetate in earthworms Lumbricus terrestris reared through four weeks on loamy sand soil contaminated with petroleum products (unleaded petrol, used engine oil), in two weeks intervals. Such contamination was simulated in one m3 volume soil containers, at a dose of 6 g . kg–1 of dry soil (experimental field in Mydlniki, Krakow suburb, Poland; 50.0815oN, 19.84730oE). We compared the effects of these contaminants action in soil collected in the year of treatment and one year later. We evaluated also effects of animals rearing on soil unremediated and remediated with "cocktail" of microorganism, and also checked the enzymatic activities response in two weeks intervals. We found lower ChE activity in animals reared on petroleum derivatives contaminated soil when compared with control animals, but only in the case of four weeks rearing on soil collected in the year of treatment. Similar response of ChE in animals reared on soil collected a year after the treatment, but estimated in earlier period of time – after two weeks exposure to petrol unleaded contamination was observed. CarE activity characterized higher variability with time than ChE activity. Generally, the activity of CarE lowered from the beginning to the end of the rearing (in all experimental groups). Animals reared on remediated soil, in most cases, had higher ChE activity than those reared on unremediated soil (control and diesel oil exposed animals).