**Jadwiga Wyszkowska 1,\*, Agata Borowik 1, Jacek Olszewski <sup>2</sup> and Jan Kucharski <sup>1</sup>**


Received: 19 November 2019; Accepted: 15 December 2019; Published: 17 December 2019

**Abstract:** This study aims to determine the effects of crops and their cultivation regimes on changes in the soil microbiome. Three plant species were selected for the study: *Triticum aestivum, Brassica napus*, and *Pisum sativum* ssp. *arvense*, that were cultivated in soils with a similar particle size fraction. Field experiments were performed on the area of the Iławski Lake District (north-eastern Poland) at the Production and Experimental Station 'Bałcyny' (53◦35 49" N, 19◦51 20" E). In soil samples counts, organotrophic bacteria and actinobacteria were quantified, and the colony development index (CD) and ecophysiological diversity index (EP) were computed. In addition, a 16S amplicon sequencing encoding gene was conducted based on the hypervariable region V3–V4. Further analyses included an evaluation of the basic physiochemical properties of the soil and the activities of dehydrogenases, catalase, urease, acid phosphatase, alkaline phosphatase, arylsulfatase, and β-glucosidase. Analyses carried out in the study demonstrated that the rhizosphere of *Triticum aestivum* had a more beneficial effect on bacteria development than those of *Brassica napus* and *Pisum sativum* ssp. *arvense*, as indicated by the values of the ecophysiological diversity index (EP) and operational taxonomic unit (OTU) abundance calculated for individual taxa in the soils in which the studied crops were grown. More OTUs of the taxa *Alphaproteobacteria, Gammaproteobacteria, Clostridia, Sphingomonadales, Rhodospirillales*, *Xanthomonadales*, *Streptomycetaceae, Pseudonocardiaceae, Acetobacteraceae*, *Solibacteraceae, Kaistobacter, Cohnella, Azospirillum, Cryptosporangium, Rhodoplanes*, and *Saccharopolyspora* were determined in the bacteriome structure of the soil from *Triticum aestivum* cultivation than in the soils from the cultivation of *Brassica napus* and *Pisum sativum* ssp. *arvense*. Also, the activities of most of the analyzed enzymes, including urease, catalase, alkaline phosphatase, β-glucosidase, and arylsulfatase, were the higher in the soil sown with *Triticum aestivum* than in those with the other two plant species.

**Keywords:** bacteria; diversity; operational taxonomic unit (OTU); enzymes activity
