| Molecular    Techniques | Target region    and primers/probes used | references | 
      
        | T-RFLP | 16S rRNA (27f-1389r) | [99,100] | 
      
        | RFLP | AlkB (alkH1F2/alkH3R) | [56] | 
      
        | Dot-Blot | nahH (nahH-F/nahH-R; C23OeF/C23OeR) nahAc (nahAc-F/nahAc-RP/nahAc-RR ;Ac114-F/Ac114-R)alkB (alkB-F/alkB-R) | [99,100] | 
      
        | Southern-blot | nahH (nahH-F/nahH-R; C23OeF/C23OeR) nahAc (nahAc-F/nahAc-RP/nahAc-RR ;Ac114-F/Ac114-R)alkB (alkB-F/alkB-R) | [100] | 
      
        | RISA | ITS (1387f/23Sr) | [100] | 
      
        | DGGE | 16S rRNA(341F-GC/520R) | [69] | 
      
        | DGGE | 16S rRNA(357F-GC/518R) | [100] | 
      
        | DGGE | 16S rRNA(341-F-GC/907-R) | [43] | 
      
        | DGGE | 16S rRNA(357F-CG/907R) | [95] | 
      
        | DGGE | AlkB (alkH1F2-CG/alkH3R) | [56] | 
      
        | DGGE | 16S rRNA (907R-341F) | [76] | 
      
        | DGGE | Bacterial SSU rRNA (BAC27Fa/BAC518R); Archaeal SSU rRNA    (Arch21f/Arch958r; Arch344fa/Arch519r) Microeukaryotic SSU rRNA (EK7F-EK516R) | [39] | 
      
        | DGGE | PAH-RHDαGP (PAH-RHDαGP-F ; PAH-RHDαGP-R) | [39] | 
      
        | Clone libraries | 16S rRNA (341-F/907-R) | [42] | 
      
        | Clone libraries | 16S rRNA (519f-1392r) | [76] | 
      
        | Clone libraries | alkB (alk-H1F ; alk-H3R) | [39] | 
      
        | Clone libraries | PAH-RHDα(PAH-RHDαGP-F/PAH-RHDαGP-R); PAH-RHDα[GN] (PAH-RHDαGN-F/PAH-RHDαGN-R) | [55] | 
      
        | Clone libraries | 16S rRNA(27F/1492R) | [50] | 
      
        | Clone libraries | PAH-RHDαGP (PAH-RHDαGP-F ; PAH-RHDαGP-R); xylE (xylE-F/xylE-R) | [69] | 
      
        | Real time PCR | 16S rRNA (341F/534R); phoA ( phoA F/phoA R) | [50] | 
      
        | Real time PCR | alkB (alkBFd-alkBRd) | [77] | 
      
        | Real time PCR | 16S rRNA gene (968F-1401R) ; PAH-RHDα (GPF-GPR/GNF-GNR) | [69] | 
      
        | Sequencing | alkB (alkH3R) | [56] | 
      
        | Conventional PCR | alkB (alk-H1F/alk-H3R);    PAH-RHDα(PAH-RHDαGP-F/PAH-RHDαGP-R); PAH-RHDαGN (PAH-RHDαGN-F/PAH-RHDαGN-R); bamA (BamSP9F/BamASP1R); assA/bssA (ass/bssF/ass/bssR) | [39] | 
      
        | Conventional PCR | PAH-RHDα (GPF/GPR; GNF/GNR); xylE (xylE-F/xylE-R) bph (bphC-F/bphC-R) | [69] | 
      
        | Conventional PCR | alk (L-alkB/R-alkB; L-alkB870G/R-alkB870G; L-TS2S/L-TS2Smod/L-TS2Smod2;    R-deg1RE/R-deg1RE2; RH L-alkB1/RH R-alkB1; RH L-alkB2/RH R-alkB2; RH    L-alkB194/RH R-alkB194; (Ac) alkM-F/(Ac) alkM-R); ndoB (L-ndoB/R-ndoB); C23DO (L-cat238/R-cat238; xylEb-F/xylEb-R; cat2,3    1a-F/cat2,3 6a-R); tod (todC1-F/todC1-R); bph (bphA1-F/bphA1-R) | [72] | 
      
        | Competitive PCR | cndoB (L-ndoB/R-cndoB) | [72] | 
      
        | RT-PCR | alkB2 (RH L-alkB2/RH R-alkB2); C23DO (cat2,3 1a-F/cat2,3 6a-R); ndoB (L-ndoB/R-ndoB) | [72] | 
      
        | Operational Protein Families (ORFs) analysis | PAH-RHDα(PAH-RHDαGP-F/PAH-RHDαGP-R); PAH-RHDα[GN] (PAH-RHDαGN-F/PAH-RHDαGN-R) | [55] |