An efficient screening method for the isolation of heterotrophic bacteria influencing growth of diatoms under photoautotrophic conditions

Zecher, Karsten; Jagmann, Nina; Seemann, Philipp; Philipp, Bodo

doi:10.1016/j.mimet.2015.10.016

Cited by 17 publications

(20 citation statements)

References 47 publications

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“…The diatom Phaeodactylum tricornutum (strain UTEX 646) was kindly provided by Peter Kroth (Constance, Germany) and verified as an axenic culture as described previously (28). All bacterial strains used for cocultivation with P. tricornutum were isolated in this study.…”

Section: Methodsmentioning

confidence: 99%

“…Bacteria able to degrade MMA were enriched by cocultivation with axenic diatom cultures of P. tricornutum as described previously (28). Samples from the North Sea (seawater samples from Baltrum and from Bremerhaven, Germany) were used for inoculation of SW-f/2 medium with 0.88 mM NaNO 3 or 2 mM MMAcontaining axenic diatom cultures at a chlorophyll concentration of 0.2 g ml Ϫ1 .…”

Section: Methodsmentioning

confidence: 99%

“…Samples from the North Sea (seawater samples from Baltrum and from Bremerhaven, Germany) were used for inoculation of SW-f/2 medium with 0.88 mM NaNO 3 or 2 mM MMAcontaining axenic diatom cultures at a chlorophyll concentration of 0.2 g ml Ϫ1 . Photoautotrophic growth in enrichment cultures was measured with a ChemiDoc MP imaging device (Bio-Rad) as described previously (28). After 14 days of incubation, 50 l of enrichment cultures showing photoautotrophic growth was plated on SW-f/2 solid medium containing 10 mM MMA and incubated at 30°C in the dark.…”

Section: Methodsmentioning

confidence: 99%

“…Growth of P. tricornutum in cocultures was measured by chlorophyll fluorescence and by microscopic cell counts using aliquots taken at regular intervals from the growing cultures. To measure chlorophyll fluorescence, 200-l aliquots were transferred to a microtiter plate, which was placed into an imaging device as described previously (28). For counting of cell numbers, aliquots were transferred to a microscopic Thoma cell counting chamber; each sample was evaluated three times in six-count quadrats.…”

Section: Methodsmentioning

confidence: 99%

“…Amplification of 16S rRNA genes was performed as described previously (28). Sequence alignment was performed using the default setting of SeqMan Pro (DNAStar, Inc., Madison, WI).…”

Section: Methodsmentioning

confidence: 99%

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Interkingdom Cross-Feeding of Ammonium from Marine Methylamine-Degrading Bacteria to the Diatom Phaeodactylum tricornutum

Suleiman

Zecher

Yücel

et al. 2016

Appl Environ Microbiol

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Methylamines occur ubiquitously in the oceans and can serve as carbon, nitrogen, and energy sources for heterotrophic bacteria from different phylogenetic groups within the marine bacterioplankton. Diatoms, which constitute a large part of the marine phytoplankton, are believed to be incapable of using methylamines as a nitrogen source. As diatoms are typically associated with heterotrophic bacteria, the hypothesis came up that methylotrophic bacteria may provide ammonium to diatoms by degradation of methylamines. This hypothesis was investigated with the diatom Phaeodactylum tricornutum and monomethylamine (MMA) as the substrate. Bacteria supporting photoautotrophic growth of P. tricornutum with MMA as the sole nitrogen source could readily be isolated from seawater. Two strains, Donghicola sp. strain KarMa, which harbored genes for both monomethylamine dehydrogenase and the N methylglutamate pathway, and Methylophaga sp. strain M1, which catalyzed MMA oxidation by MMA dehydrogenase, were selected for further characterization. While strain M1 grew with MMA as the sole substrate, strain KarMa could utilize MMA as a nitrogen source only when, e.g., glucose was provided as a carbon source. With both strains, release of ammonium was detected during MMA utilization. In coculture with P. tricornutum, strain KarMa supported photoautotrophic growth with 2 mM MMA to the same extent as with the equimolar amount of NH 4 Cl. In coculture with strain M1, photoautotrophic growth of P. tricornutum was also supported, but to a much lower degree than by strain KarMa. This proof-of-principle study with a synthetic microbial community suggests that interkingdom cross-feeding of ammonium from methylaminedegrading bacteria is a contribution to phytoplankton growth which has been overlooked so far. IMPORTANCEInteractions between diatoms and heterotrophic bacteria are important for marine carbon cycling. In this study, a novel interaction is described. Bacteria able to degrade monomethylamine, which is a ubiquitous organic nitrogen compound in marine environments, can provide ammonium to diatoms. This interkingdom metabolite transfer enables growth under photoautotrophic conditions in coculture, which would not be possible in the respective monocultures. This proof-of-principle study calls attention to a so far overlooked contribution to phytoplankton growth. W ithin the marine phytoplankton, diatoms (Bacillariophyceae) contribute significantly to the phototrophic primary production in the oceans (1). Typically, pelagic as well as benthic diatoms are associated with heterotrophic bacteria, leading to organismic interactions that range from commensal to antagonistic relationships (2). As the concentration of dissolved organic carbon is usually low in the water column of the oceans, heterotrophic bacteria can obviously profit from these interactions by using organic substrates released by the photoautotrophic diatoms. This mainly commensal relationship has been known for a long time and led to the definition of the phycosphere ...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…Amplification of 16S rRNA genes was performed as described previously (28). Sequence alignment was performed using the default setting of SeqMan Pro (DNAStar, Inc., Madison, WI).…”

Section: Methodsmentioning

confidence: 99%

See 3 more Smart Citations