Mock community (16S rRNA gene)
The mock community consisted of genomic DNA of the following 12  strains: Arthrobacter chlorophenolicus A6, Achromobacter xylosoxidans A8, Bacillus pumillus SAFR-032, Micrococcus luteus NCTC 2665, Methylobacterium radiotolerans JCM 2831, Pseudomonas alcaliphila JAB1, Pseudomonas veronii 20a2, Rhodobacter jostii RHA1, Burkholderia xenovorans LB400, Cupriavidus necator H850, Pandoraea pnomenusa B-356, and Rhizobium  radiobacter  C58. The genomic DNA from both bacterial cultures was isolated with a DNeasy Plant Mini Kit (Qiagen, Germany), and DNA concentration was  measured  using  a  Qubit  uorimeter  and  Qubit  dsDNA  HS  Assay  Kit  (both  Life Technologies, USA). The final mock community was prepared by mixing the genomic DNA from the cultures in equal concentrations. Amplicons were prepared using two sequential polymerase chain reactions (PCRs) with specific primers. For 16S rRNA gene amplicons, 515 forward (5-GTGYCAGCMGCNGCGG-3) and 926 reverse (5-CCGYCAATTYMTTTRAGTTT-3) primers were used targeting the hypervariable regions V4-V5. For the second PCR, the primers were modified with adaptor tags and internal barcodes. Resultant amplicons of 16S rRNA genes and ITS regions were purified using SPRIselect magnetic beads (Beckman Coulter, USA) and sent to the Core Facility for Nucleic Acid at the University of Alaska Fairbanks (AK, USA), where the sequencing analysis was performed using Illumina Miseq platform.