Ant nests as a microbial hot spots in a long-term heavy metal-contaminated soils

Abstract

Interactions between soil fauna and soil microorganisms are not fully recognized, especially in extreme environments, such as long-term metal-polluted soils. The purpose of the study was to assess how the presence of Lasius niger ants affected soil microbial characteristics in a long-term metal-polluted area (Upper Silesia in Poland). Paired soil samples were taken from bulk soil and from ant nests and analysed for a range of soil physicochemical properties, including metal content (zinc, cadmium, and lead). Microbial analysis included soil microbial activity (soil respiration rate), microbial biomass (substrate-induced respiration rate), and bacteria catabolic properties (Biolog® ECO plates). Soil collected from ant nests was drier and was characterized by a lower content of organic matter, carbon and nitrogen contents, and also lower metal content than bulk soil. Soil microbial respiration rate was positively related to soil pH (p = 0.01) and negatively to water-soluble metal content, integrated into TIws index (p = 0.01). Soil microbial biomass was negatively related to TIws index (p = 0.04). Neither soil microbial activity and biomass nor bacteria catabolic activity and diversity indices differed between bulk soil and ant nests. Taken together, ant activity reduced soil contamination by metals in a microscale which support microbial community activity and biomass but did not affect Biolog® culturable bacteria.

Diversity and activity of soil biota at a post‐mining site highly contaminated with Zn and Cd are enhanced by metallicolous compared to non‐metallicolous Arabidopsis halleri ecotypes

“…We noted that independently on plant ecotype amino acids and carboxylic acids were used the most among other chemical groups of substrates. This is in line with earlier studies (Klimek et al, 2022; Kuźniar et al, 2018) and can be associated with the fact that these groups are numerously represented on Biolog® ECO plates (6 amino acids and 9 carboxylic acids within 31 substrates) and they are particularly vital components of root exudates, which are known to favor bacterial community growth and development. Further, carboxylic acids differentiation between the experimental treatments was frequently reported in earlier studies (Furtak et al, 2020; Yao et al, 2006), however, it is not a rule Jezierska Tys, et al, 2021).…”

“…The field experiment was conducted in a metalliferous location M_PL22 near Bukowno—a small town in the vicinity of Olkusz in the Upper Silesia region, where ore deposits and intensive mining and smelting have resulted in high soil metal contents. This region is known as one of the most contaminated areas in Europe (Klimek et al, 2022; Pawlowski, 1990). Plants were located within three plots in a randomized block design, on each plot 40 different A. halleri genotypes were planted – 10 from the local M_PL22 population and 30 from the three foreign populations.…”

“…Due to mortality of some plant genotypes during the experiment, 23 soil samples were collected for this test. Biolog® ECO plates contained three sets of 31 carbon substrates and tetrazolium dye as the substrate utilization indicator (http://www.biolog.com) (Klimek et al, 2022; Preston‐Mafham et al, 2002). The substrates were classified into six organic substrate guilds based on their chemical structure: amines (e.g., putrescine), amino acids (e.g., L‐asparagine, L‐threonine), carbohydrates (e.g., D‐xylose, D‐mannitol), carboxylic acids (e.g., D‐malic acid, D‐galacturonic acid), polymers (e.g., tween 80 and tween 40), and miscellaneous (compounds which do not fit to any previous category, e.g., pyruvic acid methyl ester, D,L‐α‐glycerol phosphate) (Campbell et al, 1997).…”

Morphological and elemental analysis of termite mound and ant nest in agriculturally prominent area

“…10). Ants are common in metal polluted areas due to their metal resistant behavior ( Klimek et al, 2022). Reports are available on the rare earth elements and trace elements in termite mound.…”