European Journal of Soil Biology
Evaluating T-RFLP protocols to sensitively analyze the genetic diversity
and community changes of soil alkane degrading bacteria
Methods
2.1. Evaluation of restriction enzymes for alkB T-RFLP
The BLAST database was searched for either complete or partial
alkB gene sequences with Pseudomonas putida P1 alkB (AJ233397)
and Rhodococcus sp. Q15 alkB1 (AF388182) sequences as references
using the blastn Basic Search Alignment Tool [22]. Results were
counterchecked with the blastx protein database search [23] to
account for nucleotide sequences related to the alkane monooxygenase.
Suitable sequences were aligned with BioEdit [24] using
the ClustalW alignment tool [25]. Only sequences having the
binding sites for the experimentally applied alkB primers (see
section PCR-amplification) were included for further restriction
enzyme selection. The retrieved alignment included 83 sequences
and was manually checked and uploaded to the online program
Restriction Enzyme Picker (REPK) Online v.1.2 [26]. The alignment
was checked for restriction sites of the restriction enzymes giving
highest REPK scores and for the correctness of the proposed fragment
length using the NEB cutter V2.0 online search tool [27]. The
enzymes were ranked as proposed by Engebretson and Moyer [28]
according to (i) the number of total terminal restriction fragments
(i.e. richness of T-RFs) with the constraints that the fragment length
ranged between 50 and 550 bp and a minimum discriminating
length difference of at least three basepairs to account for the
resolution power of the capillary electrophoresis, (ii) the percentage
of sequences with no restriction site for the respective enzyme
as well as (iii) the percentage of sequences with T-RFs < 50 bp.