Marine Biofilms – platforms on a give-and take basis

Over the past years an important focus in the field of marine microbial ecology has been the study of marine biofilms. These multi-cultural communities adhered to surfaces are beneficial for their members. Embedded in a self-produced matrix consisting of extracellular polymeric substances the microbes profit from a stable and more stress-resistant environment (Xavier and Foster, 2007).

In 2018 an article was published by a group of French marine microbiologists. The main aim of the study was to get a better insight in marine biofilms. They wanted to distinguish the key members of these communities, their interactions and any dynamical changes regarding the composition and abundance.

The study was conducted in a Mediterranean bay in France over a period of 75 days.

Plastic panels were used as substrates. You may wonder why scientists would do research on biofilms? Throughout your course of studies you probably have learned about this topic. But the scientist questioned previous studies. Earlier investigations do not show the actual diversity of the marine microbial communities because of the chosen primers. Previous primer sets exhibit small coverage ranges for bacterial communities and even smaller or no coverage for Archaea. So in fact little is known about the true life of these communities.

The researches underline that the choice of primers should not be underestimated. To obtain correct data with high resolution and high accuracy, suitable primer sets should be used.

The study stands out by a multiple use of scientific approaches. With the help of computer software the most suitable primer was found, covering 88% of main bacterial groups and 83% of main Archaea groups. 16S rRNA sequence analyses were undertaken with the generalist primer. Additionally flow cytometry, network and cluster testing was applied. The gene comparisons allowed the researches to identify 7012 OTUs in total indicating the impressive diversity of biofilms. The pioneer communities, so the first microbes growing on the plastic panel, were mainly Gamma-proteobacteria. Archaea did not really grow in these microbial communities (only <0.4%).

With the most abundant OTUs cluster analyses were conducted showing strong changes in the composition of the communities. Biofilms are highly dynamic, expressed by rapid changes in the abundance of bacterial taxa. 90 % of the taxonomic units were short lived. Alpha-proteobacteria and Flavobacteriia dominated the pioneer communities rapidly. Interesting is that even if there are some negative interactions, biofilms do not exist because of competitive reasons between microbes but mainly because of intra-and interspecific cooperation. I would describe it as a platform on a give-and take basis, where everyone can share and provide something and profit in return by others. Another key finding of the study was that environmental conditions influence the dynamics in biofilms more than previously thought. Temperature as a physical variable has the strongest impact, silicate the lowest. 

Conclusion

The presented study gave a new insight in the world of marine microbial communities showing that things aren’t always as simple as we might think. The level of diversity and interactions hardly can be imagined in its entirety. An important head finding is that Flavobacteriia might play one of the main roles in the functioning of these marine ecosystems.

Article Reviewed:

Pollet, T., Berdjeb, L., Garnier, C., Durrieu, G., Le Poupon, C., Misson, B., & Jean-François, B. (2018). Prokaryotic community successions and interactions in marine biofilms: the key role of Flavobacteriia. FEMS microbiology ecology, 94(6), fiy083.

Reference: 
Xavier, J. B., & Foster, K. R. (2007). Cooperation and conflict in microbial biofilms. Proceedings of the National Academy of Sciences, 104(3), 876-881.