Dataset Information

Independent iron and light limitation in a low-light-adapted Prochlorococcus from the deep chlorophyll maximum.

ABSTRACT: Throughout the open ocean, a minimum in dissolved iron concentration (dFe) overlaps with the deep chlorophyll maximum (DCM), which marks the lower limit of the euphotic zone. Maximizing light capture in these dim waters is expected to require upregulation of Fe-bearing photosystems, further depleting dFe and possibly leading to co-limitation by both iron and light. However, this effect has not been quantified for important phytoplankton groups like Prochlorococcus, which contributes most of the productivity in the oligotrophic DCM. Here, we present culture experiments with Prochlorococcus strain MIT1214, a member of the Low Light 1 ecotype isolated from the DCM in the North Pacific subtropical gyre. Under a matrix of iron and irradiance matching those found at the DCM, the ratio of Fe to carbon in Prochlorococcus MIT1214 cells ranged from 10-40?×?10^-6?mol Fe:mol C and increased with light intensity and growth rate. These results challenge theoretical models predicting highest Fe:C at lowest light intensity, and are best explained by a large photosynthetic Fe demand that is not downregulated at higher light. To sustain primary production in the DCM with the rigid Fe requirements of low-light-adapted Prochlorococcus, dFe must be recycled rapidly and at high efficiency.

SUBMITTER: Hawco NJ

PROVIDER: S-EPMC7852507 | biostudies-literature | 2021 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Independent iron and light limitation in a low-light-adapted Prochlorococcus from the deep chlorophyll maximum.

Hawco Nicholas J NJ Fu Feixue F Yang Nina N Hutchins David A DA John Seth G SG

The ISME journal 20200923 1

Throughout the open ocean, a minimum in dissolved iron concentration (dFe) overlaps with the deep chlorophyll maximum (DCM), which marks the lower limit of the euphotic zone. Maximizing light capture in these dim waters is expected to require upregulation of Fe-bearing photosystems, further depleting dFe and possibly leading to co-limitation by both iron and light. However, this effect has not been quantified for important phytoplankton groups like Prochlorococcus, which contributes most of the ...[more]

PMID: 32968212

Similar Datasets

Project description:Marine viral concentrates (VCs) contains a substantial amount of non-cellular biological particles, e.g. viruses, gene transfer agents (GTAs) and membrane vesicles that are ecological significant. Metagenomic sequencing of VCs has been extensively applied to study the diversity and function potential of natural virions whereas information of nonn-viral components are often excluded for investigation. Here we apply a shotgun proteomic approach to characterize the origin and function of proteins in the VCs collected from the deep chlorophyll maximum (DCM) of the South China Sea. Using a custom database, we identified 636 non-redundant proteins represented by a total of 7220 spectra from the two VC samples. Cyanophages, pelagiphages, Phycodnaviridae and a group of uncultured viruses (previouly collected from DCM of Mediterranean Sea) contributed the most in the viral proteome. Seldom proteins related to RNA viruses and known GTAs were found despites of the presence of their sequences in the protein-searching database, suggested that these particles might be low abundant in the samples. Over 60% of identified spectra could not be assigned to viruses. The non-viral spectra were dominated by microbial groups of SAR324, SAR11, Actinobacteria and picoeukaryotic algae such as prasinophytes.Interestingly, we found that periplasmic proteins such as diverse ABC and TRAP transporters, and 56 kDa selenium-binding proteins, were enriched in this fraction.Together with other detected non-viral proteins,we could identify significant microbial functions, such as the utilization of glycine betaine, 3-dimethylsulphoniopropionate,and taurine by SAR11,and urea by prochlorococcus, nitrous oxide production by ammonia-oxidizing archaea and peroxide detoxification by unkonwn gammaproteobacteria. Our study of marine VCs demonstrates the potential application of metaproteomics to link the nano-size materials to the diversity of virions and interesting microbial functions in the ocean.

Project description:Prochlorococcus is the key primary producer in marine ecosystems, and the high-light-adapted clade II (HLII) is the most abundant ecotype. However, the genomic and ecological basis of Prochlorococcus HLII in the marine environment has remained elusive. Here, we show that the ecologically coherent subclade differentiation of HLII corresponds to genomic and ecological characteristics on the basis of analyses of 31 different strains of HLII, including 12 novel isolates. Different subclades of HLII with different core and accessory genes were identified, and their distribution in the marine environment was explored using the TARA Oceans metagenome database. Three major subclade groups were identified, viz., the surface group (HLII-SG), the transition group (HLII-TG), and the deep group (HLII-DG). These subclade groups showed different temperature ranges and optima for distribution. In regression analyses, temperature and nutrient availability were identified as key factors affecting the distribution of HLII subclades. A 35% increase in the relative abundance of HLII-SG by the end of the 21st century was predicted under the Representative Concentration Pathway 8.5 scenario. Our results show that the ubiquity and distribution of Prochlorococcus HLII in the marine environment are associated with the differentiation of diverse subclades. These findings provide insights into the large-scale shifts in the Prochlorococcus community in response to future climate change. IMPORTANCE Prochlorococcus is the most abundant oxygenic photosynthetic microorganism on Earth, and high-light-adapted clade II (HLII) is the dominant ecotype. However, the factors behind the dominance of HLII in the vast oligotrophic oceans are still unknown. Here, we identified three distinct groups of HLII subclades, viz., the surface group (HLII-SG), the transition group (HLII-TG), and the deep group (HLII-DG). We further demonstrated that the ecologically coherent subclade differentiation of HLII corresponds to genomic and ecological characteristics. Our study suggests that the differentiation of diverse subclades underlies the ubiquity and distribution of Prochlorococcus HLII in the marine environment and provides insights into the shifts in the Prochlorococcus community in response to future climate change.

Dataset Information

Independent iron and light limitation in a low-light-adapted Prochlorococcus from the deep chlorophyll maximum.

Publications

Independent iron and light limitation in a low-light-adapted Prochlorococcus from the deep chlorophyll maximum.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets