Marine cyanolichens from different littoral zones are associated with distinct bacterial communities

Abstract

The microbial diversity and function of terrestrial lichens has been well studied, but knowledge about the non-photosynthetic bacteria associated with marine lichens is still scarce. 16S rRNA gene Illumina sequencing was used to assess the culture-independent bacterial diversity in the strictly marine cyanolichen species Lichina pygmaea and Lichina confinis, and the maritime chlorolichen species Xanthoria aureola which occupy different areas on the littoral zone. Inland terrestrial cyanolichens from Austria were also analysed as for the marine lichens to examine further the impact of habitat/lichen species on the associated bacterial communities. The L. confinis and L. pygmaea communities were significantly different from those of the maritime Xanthoria aureola lichen found higher up on the littoral zone and these latter communities were more similar to those of the inland terrestrial lichens. The strictly marine lichens were dominated by the Bacteroidetes phylum accounting for 50% of the sequences, whereas Alphaproteobacteria, notably Sphingomonas, dominated the maritime and the inland terrestrial lichens. Bacterial communities associated with the two Lichina species were significantly different sharing only 33 core OTUs, half of which were affiliated to the Bacteroidetes genera Rubricoccus, Tunicatimonas and Lewinella, suggesting an important role of these species in the marine Lichina lichen symbiosis. Marine cyanolichens showed a higher abundance of OTUs likely affiliated to moderately thermophilic and/or radiation resistant bacteria belonging to the Phyla Chloroflexi, Thermi, and the families Rhodothermaceae and Rubrobacteraceae when compared to those of inland terrestrial lichens. This most likely reflects the exposed and highly variable conditions to which they are subjected daily.

Artificial light at night erases positive interactions across trophic levels

“…This conclusion is more obvious when considering that some of these families include photoheterotrophic bacteria (e.g. the aerobic anoxygenic phototrophic Erythrobacteraceae and Rhodobacteraceae, or the rhodopsin‐containing Deinococcus) and possess carotenoids that may have a photoprotective role (West et al, and references therein).…”

“…Analyses on the carotenoids/chl a ratio (calculated at the level of the whole bacterial community) seem to corroborate our mechanistic interpretation of results. Carotenoids are present as key components of the antenna complexes in autotrophs; as such, they are expected to increase at decreasing light intensity; however, they may play photoprotective roles under stressful conditions, both in autotrophic and in heterotrophic bacteria (Cogdell & Frank, ; West et al, and references therein). At unlit sites, the observed increase of the carotenoids/chl a ratio when herbivores were excluded suggests a rise in the synthesis of these light‐harvesting pigments, likely in response to a reduction of light penetration into the biofilm due to the accumulation of a canopy of dead cells (Skov et al, ).…”

Coastal Lichens

“…Suzuki et al (2015) reported that they produce secondary metabolites, and some of these compounds have pronounced bioactive properties. A study of the microbiota of other littoral species Lichina confinis and L. pygmaea (West et al 2018) revealed differences between the bacterial communities associated with marine and terrestrial lichens and even between marine lichens inhabiting different coastal zones. The authors emphasized the importance of these studies for understanding the role of associated bacteria in the symbiosis of marine lichens and in adaptation of this association to coastal environment.…”

Rhizocarpon geographicumlichen discloses a highly diversified microbiota carrying antibiotic resistance and Persistent Organic Pollutants tolerance

“…In order to dissect the ecological functions behind the microbe-lichen interaction, the culturable and the unculturable microbiota needs to be deeply explored. Studies on the lichen microbiota are mostly based on molecular fingerprints [5, 19, 20], molecular cloning approaches [21] or 16S rRNA gene Illumina sequencing [22]. High-throughput sequencing methodologies (i.e.…”