Functional Seasonality of Free-Living and Particle-Associated Prokaryotic Communities in the Coastal Adriatic Sea

Abstract

Marine snow is an important habitat for microbes, characterized by chemical and physical properties contrasting those of the ambient water. The higher nutrient concentrations in marine snow lead to compositional differences between the ambient water and the marine snow-associated prokaryotic community. Whether these compositional differences vary due to seasonal environmental changes, however, remains unclear. Thus, we investigated the seasonal patterns of the free-living and marine snow-associated microbial community composition and their functional potential in the northern Adriatic Sea. Our data revealed seasonal patterns in both, the free-living and marine snow-associated prokaryotes. The two assemblages were more similar to each other in spring and fall than in winter and summer. The taxonomic distinctness resulted in a contrasting functional potential. Motility and adaptations to low temperature in winter and partly anaerobic metabolism in summer characterized the marine snow-associated prokaryotes. Free-living prokaryotes were enriched in genes indicative for functions related to phosphorus limitation in winter and in genes tentatively supplementing heterotrophic growth with proteorhodopsins and CO-oxidation in summer. Taken together, the results suggest a strong influence of environmental parameters on both free-living and marine snow-associated prokaryotic communities in spring and fall leading to higher similarity between the communities, while the marine snow habitat in winter and summer leads to a specific prokaryotic community in marine snow in these two seasons.

Subsurface Bacterioplankton Structure and Diversity in the Strongly-Stratified Water Columns within the Equatorial Eastern Indian Ocean

“…Interestingly, the low contribution of SAR11 clade in equatorial EIO was previously reported in a metagenomic study conducted in equatorial EIO [ 40 ], indicating that the low proportion of SAR11 in this region was not random. Members of these clades are typically enriched in free-living communities [ 72 ]. Their relatively low proportions in our study may indicate limited carbon and sulfate cycling in the surface layer.…”

Reaching unreachables: Obstacles and successes of microbial cultivation and their reasons

“…Periodically varying conditions exist in nature, from the feast and famine cycles ( Koch, 1971 ) to alternating oxic and anoxic periods ( Dorofeev et al, 2019 ) and seasonality ( Steiner et al, 2020 ), all of which can affect microbial communities. Besides culturing in continuous cultures (open systems) or batch cultures (closed systems), cyclic cultivation can be useful for microorganisms with a cyclic type of metabolism.…”

Pathway-Centric Analysis of Microbial Metabolic Potential and Expression Along Nutrient and Energy Gradients in the Western Atlantic Ocean

“…Thermoplasmatales, as a member of the phylum Euryarchaeota are likely capable of methylotrophic methanogenesis, and members of the phylum Chloroflexi, such as Anaerolineaceae, have been previously shown to contain genes involved in methanogenesis (Paul et al, 2012;Liang et al, 2015). Given the higher oxygen concentrations found in the bathypelagic layers of the ocean (Figure 2A), methanogenesis may be occurring within the lower oxygen micro-environments of marine snow particles (Steiner et al, 2020). Branching of Thermoplasmatales and Chloroflexi away from other indicator taxa in Supplementary Figure 3C indicates that they may occupy a different metabolic niche compared to other indicator taxa for the bottom waters and may reflect different metabolisms required for particle-associated vs planktonic lifestyles Milici et al, 2017).…”