# Biological Control of Phototrophic Biofilms in a Show Cave: The Case of Nerja Cave
## 3 Results
This pattern also occurred for the family _Chroococcidiopsaceae_, which was absent in sample 2, as well as for _Aphanotheaceae_, which was lacking in sample 1 (Figure 5). The class _Alphaproteobacteria_ was mainly composed of the orders: _Rhizobiales_, _Caulobacterales_, _Rhodospirillales_, and members of an uncultured order (Figure 4). In this class, only two genera were identified: _Brevundomonas_ and _Mesorhizobium_ (Figure 5). The class _Gammaproteobacteria_ was represented by the orders _Lysobacterales_, _Oceanospirillales_ and _Chromatiles_, with high abundance in all samples, and by _Nevskiales_, solely present in sample 1 (Figure 4). The most representative genera within the _Gammaproteobacteria_ were: _Lysobacter_, _Halomonas_, _Woeseia_ and _Luteomonas_. _Thioalbus_, _Salinisphera_ and _Halopettonella_ were identified in low abundance (Figure 5). The phylum _Actinobacteria_ was composed of three classes (_Acidimicrobia_, _Actinobacteria_ and _Rubbacteria_). However, only the class _Actinobacteria_ attained a remarkable abundance in sample 2, with a noticeable richness of the order _Pseudonocardiales_. Regarding the genus level, _Annycolatopsis_, present in the samples 2B and 1B, and an uncultured genus of the family _Nocardioidaceae_, in samples 2C and 2A, showed relative abundance. The rest of genera (_Crosiella_, _Yuhushiella_, _Pseudonocardia_, _Actinophytocola_, _Glycomyces_ and _Halactinopolypora_) reached low abundances. Figure 4: Heat-map analysis of Nerja Cave biofilms. Taxonomic identifications of _Bacteria_ at order level. The orders are described in the right column and their respective abundances included in the boxes. Within the _Chloroflexi_ phylum, the class _Thermonicrobia_ showed relatively high abundance in sample 2B. The orders _Phycishareales_ and _Platcomyectales_, within the phylum _Platcomyectes_, reached scarce representation in the biofilm samples (Figure 4). A new phylum separated from _Bacteroidetes_ is _Rhodothermaeota_[16], represented by the class _Rhodothermaeota_ in sample 1A. This class comprises the genus _Salinibacter_, only found in sample 1A, together with other uncultured genera. The phylum _Bacteroidetes_ includes the class _Cythophagia_ and the order _Flavobacteriales_, with uncultured genera, except for _Roseivirga_, with poor representation in all samples. The new phylum _Balneolaeta_[17], recently separated from _Bacteroidetes_, which includes the class _Balneolia_, only reached a representative abundance in sample 1. The phyla _'Candidatus_ Dadabacteria', _Gemmatimonadetes_ and the superphylum _Patescibacteria_ were commonly represented by uncultured bacteria, in low percentages of abundance which can only be identified using NGS. The abundance of the order _Dadabacteriales_ was remarkable in sample 1C (Figure 4). Most of the eukaryotic sequences retrieved in sample 1 were unknown, while in sample 2 the percentage of unassigned sequences was notably lower (Table 2). Figure 5: Heat-map analysis of Nerja Cave biofilms. Taxonomic identifications of _Bacteria_ at families and genera level. The groups are described in the right column and their respective abundances included in the boxes. The eukaryotic organisms identified in the four samples were affiliated to _Amoebozoa_, _Opishtokotta_ and SAR. Table 2 shows the taxonomic composition of the samples where only the taxa represented with values greater than 1% were included. Sample 1 was characterized by the abundance of _Amoebozoa_ belonging to the order _Dactylopodida_, with uncultured members in sample 1A, an uncultured order in 1A and 1B, and members of the family _Echinamoeba_ in 1A. The genus _Gregarina_ (SAR) was relatively abundant in samples 1A and 1B. The sampling site 2 showed very high abundances in samples 2A and 2B for uncultured _Schizophreniadiida_ of the _Amoebozoa_ supergroup, followed by uncultured members of the order _Rhabditida_. The genus _Heteromita_ (_Rhizaria_) also appeared with significant abundance in samples 2A and 2B.