Impact of ionic liquids on extreme microbial biotypes from soil

Abstract

This work aims at identifying, amongst extreme soil biotypes at locations of high salinity and high hydrocarbon load, microbial strains able to survive short or long-term exposure to the presence of selected ionic liquids. We have evaluated the impact of ionic liquids on the diversity of the soil microbiota to identify which microbial strains have higher survival rates towards ionic liquids, and consequently those which might possibly play a major role in their biotic fate. To the best of our knowledge, this is the first study of this kind. Soils, from a region in Portugal (Aveiro) were sampled and the bacterial and fungal strains able to survive after exposure to high concentrations of selected ionic liquids were isolated and further characterised. We have mainly focused on two types of cations: imidazolium – the most commonly used; and cholinium – generally perceived as benign. The surviving microbial strains were isolated and taxonomically identified, and the ionic liquid degradation was analysed during their cultivation. The continuing exposure of the microbial strains to petroleum hydrocarbons is likely to be the basis for their acquired resistance to some imidazolium salts; also, the higher capacity of fungi – compared to bacteria – to grow, even during their exposure to these liquid salts, became evident in this study.