A molecular perspective on ciliates as soil bioindicators

► Despite of the fact that their importance in the soil ecosystem has been recognized since more than twenty five years, protists have been relatively scarcely studied in the field of bioindication in comparison to other soil organisms. ► One of the main reasons was the difficulty faced in observing and enumerating them. ► Molecular methods have brought new perspectives to screen the ciliate communities for bioindication purposes as their price and difficulty to use have considerably decreased. ► They make possible the detection of ciliates whose presence indicates precise environmental conditions (such as pollution, intermittent anoxia, relative amount of nutrients).