Bacterial diversity and enzymatic activity in a soil recently treated with tebuconazole

Abstract Tebuconazole is one of the most commonly used active substances from the group of triazoles, that exhibits high efficacy in plant protection against fungal diseases. It’s too frequent use may, however, pose risk to soil ecosystems, leading to changes in their biological diversity. This study was aimed at evaluating the effect of tebuconazole on population numbers, diversity, and structure of bacterial communities, and on the enzymatic activity of soil. Tebuconazole was introduced into the soil (sandy loam with pH 7.0) in the following doses in mg kg−1 DM (dry matter) of soil: 0.00 (C), 0.02 (O), and 10.0 (T). It caused changes in the population numbers of diversity of bacteria as well as in the biochemical activity of soil. It stimulated the proliferation of organotrophic bacteria and inhibited that of actinobacteria. The r-strategists were found to predominate among both the organotrophs and actinobacteria in the soil with tebuconazole addition. The amplicon sequencing of the 16S encoding gene (SSU rRNA) demonstrated tebuconazole to elicit changes in the structure of bacterial communities. In all soil samples, the prevailing taxon at the Phylum level turned out to be Proteobacteria, followed by Firmicutes and Actinobacteria, whereas the lowest counts were noted for Verrucomicrobia. The relative abundance of the bacteria at the Phylum level decreased in the soil under the influence of tebuconazole. The most sensitive to the effect of tebuconazole applied in a dose of 10.0 mg kg−1 turned out to be Acidobacteria, whereas the most resistant were Verrucomicrobia. The predominating taxon at the class level was Alphaproteobacteria, followed by Bacilli. Tebuconazole ensured favorable conditions for the development of bacteria from Kaistobacter and Bacillus genera as their OTUs were the highest in the soil treated with tebuconazole at 10.0 mg kg−1. In turn, Phenylobacterium and Rhodoplanes were sensitive to soil treatment with tebuconazole at doses of 0.02 mg kg−1 and 10.0 mg kg−1. Tebuconazole proved to be a strong inhibitor of urease and catalase activities, while in turn it enhanced activities of dehydrogenases, acid phosphatase, alkaline phosphatase, and arylsulfatase.