Non-Redfield, nutrient synergy and flexible internal elemental stoichiometry in a marine bacterium

Abstract

The stoichiometric constraints of algal growth are well understood, whereas there is less knowledge for heterotrophic bacterioplankton. Growth of the marine bacterium Phaeobacter inhibens DSM 17395, belonging to the globally distributed Roseobacter group, was studied across a wide concentration range of NH4+ and PO43−. The unique dataset covers 415 different concentration pairs, corresponding to 207 different molar N:P ratios (from 10−2 to 105). Maximal growth (by growth rate and biomass yield) was observed within a restricted concentration range at N:P ratios (∼50−120) markedly above Redfield. Experimentally determined growth parameters deviated to a large part from model predictions based on Liebig's law of the minimum, thus implicating synergistic co-limitation due to biochemical dependence of resources. Internal elemental ratios of P. inhibens varied with external nutrient supply within physiological constraints, thus adding to the growing evidence that aquatic bacteria can be flexible in their internal elemental composition. Taken together, the findings reported here revealed that P. inhibens is well adapted to fluctuating availability of inorganic N and P, expected to occur in its natural habitat (e.g. colonized algae, coastal areas). Moreover, this study suggests that elemental variability in bacterioplankton needs to be considered in the ecological stoichiometry of the oceans.

The marine bacterium Phaeobacter inhibens secures external ammonium by rapid buildup of intracellular nitrogen stocks

“…The capacity to rapidly store nitrogen internally possibly reflects the strong influence of NH 4 + availability on the growth of P. inhibens DSM 17395 (Trautwein et al. 2017 ) and in more general terms an adaptation to fluctuating NH 4 + supply. The latter is expected to occur frequently in the natural habitat of the studied roseobacters: on a larger scale in coastal regions and on a microcosm-scale on marine snow particles representing nutrient-rich hotspots in otherwise oligotrophic water columns (Azam and Long 2001 ; Gram et al.…”

“…2017). Considering the important role of NH 4 + for growth of P. inhibens DSM 17395 in particular and the general relevance of this macronutrient for the productivity of marine heterotrophic bacteria, the present study aims at investigating the NH 4 + acquisition and processing strategies of P. inhibens DSM 17395 as a well-studied representative of the Roseobacter group.…”

“…A recent growth physiological study covering a wide concentration range of NH 4 + and PO 4 3− revealed P. inhibens DSM 17395 to be well adapted to fluctuating availability of inorganic N and P, and to grow optimally at N:P supply ratios (<50–120) markedly above Redfield (Trautwein et al. 2017 ). Considering the important role of NH 4 + for growth of P. inhibens DSM 17395 in particular and the general relevance of this macronutrient for the productivity of marine heterotrophic bacteria, the present study aims at investigating the NH 4 + acquisition and processing strategies of P. inhibens DSM 17395 as a well-studied representative of the Roseobacter group.…”

Oil Hydrocarbon Degradation by Caspian Sea Microbial Communities

“…Two Rhodobacterales genera responded to oil amendment, which is consistent with previous reports (Chakraborty et al, 2012). Rhodobacterales ( Phaeobacter ) are commonly reported to be marine heterotrophs capable of growing on a wide range of nitrogen and phosphorous concentrations and in a wide range of temperatures (Lee et al, 2016; Trautwein et al, 2017; Wienhausen et al, 2017). Unclassified Kiloniellales ( Kiloniellaceae ) also responded to oil amendment, and, although many are host associated (Soffer et al, 2015; Cleary et al, 2016; Lawler et al, 2016), one member of this order was isolated and reported as a chemoheterotrophic aerobe that may be involved in denitrification (Wiese et al, 2009).…”

Eutrophication disrupts summer trophic links in an estuarine microbial food web

“…Moreover, nutrient loading is often linked with the limitation of diatom growth due to silicate deficiency and the proliferation of non-siliceous, unpalatable algae (Officer and Ryther 1980, Breton et al 2006, Panizzo et al 2018. Alternatively, primary producers and heterotrophic bacteria may utilize inorganic nutrients outside the Redfield ratio thus altering their intracellular C:N:P ratio (Mills and Arrigo 2010, Meunier et al 2014, Trautwein et al 2017).…”