Seasonal nitrogen removal in an outdoor microalgal polyculture at Nordic conditions.

Microalgal solutions to clean waste streams and produce biomass were evaluated in Nordic conditions during winter, spring, and autumn in Southeast Sweden. The study investigated nitrogen (N) removal, biomass quality, and safety by treating industrial leachate water with a polyculture of local microalgae and bacteria in open raceway ponds, supplied with industrial CO effluent. Total N (TN) removal was higher in spring (1.

Ploidy levels in diverse picocyanobacteria from the Baltic Sea.

In nature, the number of genome or chromosome copies within cells (ploidy) can vary between species and environmental conditions, potentially influencing how organisms adapt to changing environments. Although ploidy levels cannot be easily determined by standard genome sequencing, understanding ploidy is crucial for the quantitative interpretation of molecular data. Cyanobacteria are known to contain haploid, oligoploid, and polyploid species.

Ecophysiological analysis reveals distinct environmental preferences in closely related Baltic Sea picocyanobacteria.

Cluster 5 picocyanobacteria significantly contribute to primary productivity in aquatic ecosystems. Estuarine populations are highly diverse and consist of many co-occurring strains, but their physiology remains largely understudied. In this study, we characterized 17 novel estuarine picocyanobacterial strains.

Multiyear analysis uncovers coordinated seasonality in stocks and composition of the planktonic food web in the Baltic Sea proper.

The planktonic realm from bacteria to zooplankton provides the baseline for pelagic aquatic food webs. However, multiple trophic levels are seldomly included in time series studies, hampering a holistic understanding of the influence of seasonal dynamics and species interactions on food web structure and biogeochemical cycles. Here, we investigated plankton community composition, focusing on bacterio-, phyto- and large mesozooplankton, and how biotic and abiotic factors correlate at the Linnaeus Microbial Observatory (LMO) station in the Baltic Sea from 2011 to 2018.

Biogenic silica accumulation in picoeukaryotes: Novel players in the marine silica cycle.

It is well known that the biological control of oceanic silica cycling is dominated by diatoms, with sponges and radiolarians playing additional roles. Recent studies have revealed that some smaller marine organisms (e.g.

Functional responses of key marine bacteria to environmental change - toward genetic counselling for coastal waters.

Coastal ecosystems deteriorate globally due to human-induced stress factors, like nutrient loading and pollution. Bacteria are critical to marine ecosystems, e.g.

Seasonal dynamics in picocyanobacterial abundance and clade composition at coastal and offshore stations in the Baltic Sea.

Picocyanobacteria (< 2 µm in diameter) are significant contributors to total phytoplankton biomass. Due to the high diversity within this group, their seasonal dynamics and relationship with environmental parameters, especially in brackish waters, are largely unknown. In this study, the abundance and community composition of phycoerythrin rich picocyanobacteria (PE-SYN) and phycocyanin rich picocyanobacteria (PC-SYN) were monitored at a coastal (K-station) and at an offshore station (LMO; ~ 10 km from land) in the Baltic Sea over three years (2018-2020).

Seasonal and Spatial Variations in Abundance and Diversity Throughout the Gullmar Fjord, Swedish Skagerrak.

The picophytoplankton is a globally abundant autotroph that contributes significantly to primary production in the oceans and coastal areas. These cyanobacteria constitute a diverse genus of organisms that have developed independent niche spaces throughout aquatic environments. Here, we use the 16S V3-V4 rRNA gene region and flow cytometry to explore the diversity of within the picophytoplankton community in the Gullmar Fjord, on the west coast of Sweden.

Seasonality of Coastal Picophytoplankton Growth, Nutrient Limitation, and Biomass Contribution.

Picophytoplankton in the Baltic Sea includes the simplest unicellular cyanoprokaryotes (/) and photosynthetic picoeukaryotes (PPE). Picophytoplankton are thought to be a key component of the phytoplankton community, but their seasonal dynamics and relationships with nutrients and temperature are largely unknown. We monitored pico- and larger phytoplankton at a coastal site in Kalmar Sound (K-Station) weekly during 2018.

Quality of phytoplankton deposition structures bacterial communities at the water-sediment interface.

Phytoplankton comprises a large fraction of the vertical carbon flux to deep water via the sinking of particulate organic matter (POM). However, despite the importance of phytoplankton in the coupling of benthic-pelagic productivity, the extent to which its deposition in the sediment affects bacterial dynamics at the water-sediment interface is poorly understood. Here, we conducted a microcosm experiment in which varying mixtures of diatom and cyanobacteria, representing phytoplankton-derived POM of differing quality, served as inputs to sediment cores.

Temperature Stress Induces Shift From Co-Existence to Competition for Organic Carbon in Microalgae-Bacterial Photobioreactor Community - Enabling Continuous Production of Microalgal Biomass.

To better predict the consequences of environmental change on aquatic microbial ecosystems it is important to understand what enables community resilience. The mechanisms by which a microbial community maintain its overall function, for example, the cycling of carbon, when exposed to a stressor, can be explored by considering three concepts: biotic interactions, functional adaptations, and community structure. Interactions between species are traditionally considered as, e.

Cell sorting reveals few novel prokaryote and photosynthetic picoeukaryote associations in the oligotrophic ocean.

Close associations between single-celled marine organisms can have a central role in biogeochemical processes and are of great interest for understanding the evolution of organisms. The global significance of such associations raises the question of whether unidentified associations are yet to be discovered. In this study, fluorescence-activated cell sorted photosynthetic picoeukayote (PPE) populations and single cells were analysed by sequencing of 16S rRNA genes in the oligotrophic North Pacific Subtropical Gyre.

Consistency in microbiomes in cultures of Alexandrium species isolated from brackish and marine waters.

Phytoplankton and bacteria interactions have a significant role in aquatic ecosystem functioning. Associations can range from mutualistic to parasitic, shaping biogeochemical cycles and having a direct influence on phytoplankton growth. How variations in phenotype and sampling location, affect the phytoplankton microbiome is largely unknown.

The Transcriptional Cycle Is Suited to Daytime N Fixation in the Unicellular Cyanobacterium " Atelocyanobacterium thalassa" (UCYN-A).

Symbiosis between a marine alga and a N-fixing cyanobacterium ( UCYN-A) is geographically widespread in the oceans and is important in the marine N cycle. UCYN-A is uncultivated and is an unusual unicellular cyanobacterium because it lacks many metabolic functions, including oxygenic photosynthesis and carbon fixation, which are typical in cyanobacteria. It is now presumed to be an obligate symbiont of haptophytes closely related to N-fixing cyanobacteria use different strategies to avoid inhibition of N fixation by the oxygen evolved in photosynthesis.

UCYN-A3, a newly characterized open ocean sublineage of the symbiotic N -fixing cyanobacterium Candidatus Atelocyanobacterium thalassa.

The symbiotic unicellular cyanobacterium Candidatus Atelocyanobacterium thalassa (UCYN-A) is one of the most abundant and widespread nitrogen (N )-fixing cyanobacteria in the ocean. Although it remains uncultivated, multiple sublineages have been detected based on partial nitrogenase (nifH) gene sequences, including the four most commonly detected sublineages UCYN-A1, UCYN-A2, UCYN-A3 and UCYN-A4. However, very little is known about UCYN-A3 beyond the nifH sequences from nifH gene diversity surveys.

Diverse diazotrophs are present on sinking particles in the North Pacific Subtropical Gyre.

Sinking particles transport carbon and nutrients from the surface ocean into the deep sea and are considered hot spots for bacterial diversity and activity. In the oligotrophic oceans, nitrogen (N)-fixing organisms (diazotrophs) are an important source of new N but the extent to which these organisms are present and exported on sinking particles is not well known. Sinking particles were collected every 6 h over a 2-day period using net traps deployed at 150 m in the North Pacific Subtropical Gyre.

Diazotroph Population Dynamics Under Different Resource Ratios in the North Pacific Subtropical Gyre.

Major advances in understanding the diversity, distribution, and activity of marine N-fixing microorganisms (diazotrophs) have been made in the past decades, however, large gaps in knowledge remain about the environmental controls on growth and mortality rates. In order to measure diazotroph net growth rates and microzooplankton grazing rates on diazotrophs, nutrient perturbation experiments and dilution grazing experiments were conducted using free-floating incubation arrays in the vicinity of Station ALOHA in March 2016. Net growth rates for targeted diazotroph taxa as well as and photosynthetic picoeukaryotes were determined under high (H) and low (L) nitrate:phosphate (NP) ratio conditions at four depths in the photic zone (25, 45, 75, and 100 m) using quantitative PCR and flow cytometry.

Distinct ecological niches of marine symbiotic N -fixing cyanobacterium Candidatus Atelocyanobacterium thalassa sublineages.

A recently described symbiosis between the metabolically streamlined nitrogen-fixing cyanobacterium UCYN-A and a single-celled eukaryote prymnesiophyte alga is widely distributed throughout tropical and subtropical marine waters, and is thought to contribute significantly to nitrogen fixation in these regions. Several UCYN-A sublineages have been defined based on UCYN-A nitrogenase (nifH) sequences. Due to the low abundances of UCYN-A in the global oceans, currently existing molecular techniques are limited for detecting and quantifying these organisms.

Unscrambling Cyanobacteria Community Dynamics Related to Environmental Factors.

Future climate scenarios in the Baltic Sea project an increase of cyanobacterial bloom frequency and duration, attributed to eutrophication and climate change. Some cyanobacteria can be toxic and their impact on ecosystem services is relevant for a sustainable sea. Yet, there is limited understanding of the mechanisms regulating cyanobacterial diversity and biogeography.

Identification of Associations between Bacterioplankton and Photosynthetic Picoeukaryotes in Coastal Waters.

Photosynthetic picoeukaryotes are significant contributors to marine primary productivity. Associations between marine bacterioplankton and picoeukaryotes frequently occur and can have large biogeochemical impacts. We used flow cytometry to sort cells from seawater to identify non-eukaryotic phylotypes that are associated with photosynthetic picoeukaryotes.

Cultivation and isolation of N2-fixing bacteria from suboxic waters in the Baltic Sea.

Nitrogenase genes (nifH) from heterotrophic dinitrogen (N2)-fixing bacteria appear ubiquitous in marine bacterioplankton, but the significance of these bacteria for N cycling is unknown. Quantitative data on the N2-fixation potential of marine and estuarine heterotrophs are scarce, and the shortage of cultivated specimens currently precludes ecophysiological characterization of these bacteria. Through the cultivation of diazotrophs from suboxic (1.