Table 5.
Algal community composition based on the ITS2 data set and comprising the 10 most abundant OTUs that made up >88% of the community. Table shows the discrepancies between OTU assignments using (1) Qiime and a custom database downloaded from NCBI, (2) Qiime and additional reference sequences of the locally abundant taxa (underlined), and (3) the manual verification of taxa assignments. The latter one comprised the comparison of the representative sequences of the OTUs with their respective reference sequences in terms of sequence identities (≥94.0% similarity required) and their secondary structures (absence of compensatory base changes (CBC) in homology positions required. A more comprehensive list comprising the 38 most abundant taxa with their corresponding OTU identification numbers can be found in the Table S7. Our results reveal that the manual verification including secondary structure prediction and CBC search is essential, and thus, highly recommended
| OTU ID | WP79 [%] | WP99 [%] | (1) Qiime + NCBI database | (2) Qiime + NCBI database + local references | (3) Qiime + NCBI database + local references + manual verification (sequence similarity [%], sequence cover [%]) |
|---|---|---|---|---|---|
| denovo 99 | 1.8 | 59.1 | Chloromonas sp. CCCryo289-06 HQ404893.1 | Chloromonas brevispina K-2 | No blast hit (88%, 83%, 6 CBC when compared denovo99 and Chloromonas brevispina K-2 – one CBC out of it is located in the most conserved part of structure, i.e. in top close to the 5´end of III helix, see Fig. 4) |
| denovo 20 | 5.5 | 28.2 | Chlamydomonas nivalis GU117577.1 | Chlamydomonas nivalis DL07 | Chlamydomonas nivalis DL07 (100%, 100%) |
| denovo 107 | 39.8 | <0.1 | Chloromonas sp. CCCryo289-06 HQ404893.1 | Chloromonas brevispina K-2 | Chloromonas brevispina K-2 (100% identical except for one nucleotide - instead of ʿRʿ in reference sequence, there was ’G’, 100%) |
| denovo 100 | 13.7 | <0.1 | Chloromonas pichinchae HQ404889.1 | Chloromonas pichinchae HQ404889.1 | no blast hit |
| denovo 63 | 10.9 | 0.2 | No blast hit | Scotte Ila cryophila K-1 | Scotiella cryophila K-1 (100%, 100%) |
| denovo 142 | 8.2 | 1.7 | Chloromonas rostafinskii HQ404863.1 | Chloromonas rostafinskii HQ404863.1 | No blast hit |
| denovo 130 | 1.4 | 3.5 | No blast hit | No blast hit | No blast hit |
| denovo 181 | 4.1 | 0 | No blast hit | No blast hit | No blast hit |
| denovo 254 | 3.1 | 0.1 | Chloromonas rostafinskii HQ404863.1 | Chloromonas rostafinskii HQ404863.1 | No blast hit |
| denovo 23 | 0.1 | 2.2 | No blast hit | No blast hit | No blast hit |
| 11.4 | 5.0 | Other | Other | Other |