Response of ammonia-oxidizing archaea and bacteria to long-term industrial effluent-polluted soils, Gujarat, Western India

Abstract

Soil nitrifiers have been showing an important role in assessing environmental pollution as sensitive biomarkers. In this study, the abundance and diversity of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) were investigated in long-term industrial waste effluent (IWE) polluted soils. Three different IWE polluted soils characterized as uncontaminated (R1), moderately contaminated (R2), and highly contaminated (R3) were collected in triplicate along Mahi River basin, Gujarat, Western India. Quantitative numbers of ammonia monooxygenase α-subunit (amoA) genes as well as 16S rRNA genes indicated apparent deleterious effect of IWE on abundance of soil AOA, AOB, bacteria, and archaeal populations. Relatively, AOB was more abundant than AOA in the highly contaminated soil R3, while predominance of AOA was noticed in uncontaminated (R1) and moderately contaminated (R2) soils. Soil potential nitrification rate (PNR) significantly (P<0.05) decreased in polluted soils R2 and R3. Reduced diversity accompanied by apparent community shifts of both AOB and AOA populations was detected in R2 and R3 soils. AOB were dominated with Nitrosospira-like sequences, whereas AOA were dominated by Thaumarchaeal "group 1.1b (Nitrososphaera clusters)." We suggest that the significant reduction in abundance and diversity AOA and AOB could serve as relevant bioindicators for soil quality monitoring of polluted sites. These results could be further useful for better understanding of AOB and AOA communities in polluted soils.

Effect of long-term industrial waste effluent pollution on soil enzyme activities and bacterial community composition

“…However, due to the long-term industrial waste effluent contamination, the chemical properties of R2 and R3 have changed considerably. Soil samples at R2 and R3 sites have been receiving mixed contamination of organic (primarily organohalogens, polyaromatic hydrocarbons, phenolic and aliphatic compounds) and varying degrees of heavy metal pollutants for more than 20 years through IWE (Labunska et al 1999;Subrahmanyam et al 2014c). The uncontaminated soil R1, as a control, was collected from the nearest unpolluted area within the vicinity of the R2 site.…”

“…The uncontaminated soil R1, as a control, was collected from the nearest unpolluted area within the vicinity of the R2 site. Details about the site location, soil sampling, and soil physicochemical properties including heavy metal analysis have been reported in our earlier study (Subrahmanyam et al 2014c) and also listed in Tables 1 and 2. In all these sites, the landscape is covered with Calotrophis procera, Acasia, Digitaria sp., Brachiaria sp., Datura stramonium, Parthenium sp., Brasssica sp., and Cynodon dactylon.…”

“…Then, the soil samples were gently crumbled, mixed thoroughly, and passed through a 2.0-mm sieve. Processed soil samples were stored at 4°C for analysis of soil characteristics and at −80°C for DNA extraction (Subrahmanyam et al 2014c). …”

“…Heavy metals adversely affect the activity and diversity of soil microbial communities associating with elemental cycling (Wang et al 2007;Subrahmanyam et al 2014a, c). A significant decrease in bacterial diversity has been observed with increased soil pollution (Subrahmanyam et al 2014c). Therefore, soil microbial activity and community structure are accepted as indicators of overall soil environmental quality (Winding et al 2005;Igbinosa 2015).…”

“…In our previous study, we found that long-term industrial waste effluent (IWE) pollution resulted in a significant decrease in both soil potential nitrification and diversity of nitrifiers, and that the archaeal 16S rRNA gene and functional amoA gene abundance were greatly reduced by IWE pollution (Subrahmanyam et al 2014c). However, the study just concentrated on the influence of long-term IWE pollution on soil nitrifiers, the knowledge on how the IWE pollution affect the soil enzymes and general bacterial community is hardly known.…”