uu.seUppsala University Publications
Change search
ReferencesLink to record
Permanent link

Direct link
Are freshwater bacterioplankton indifferent to variable types of amino acid substrates?
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
2016 (English)In: FEMS Microbiology Ecology, ISSN 0168-6496, E-ISSN 1574-6941, Vol. 92, no 2, UNSP fiw005Article in journal (Refereed) Published
Abstract [en]

A wide range of carbon compounds sustain bacterial activity and growth in freshwater ecosystems and the amount and quality of these substrates influence bacterial diversity and metabolic function. Biologically labile low-molecular-weight compounds, such as dissolved free amino acids, are particularly important substrates and can fuel as much as 20% of the total heterotrophic production. In this study, we show that extensive laboratory incubations with variable amino acids as substrates caused only minimal differences in bacterial growth rate, growth yield, quantitative amino acid usage, community composition and diversity. This was in marked contrast to incubations under dark or light regimes, where significant responses were observed in bacterial community composition and with higher diversity in the dark incubations. While a few individual taxa still responded to amendment with specific amino acids, our results suggest that compositional shifts in the specific supply of amino acids and possibly also other labile organic substrates have a minor impact on heterotrophic bacterioplankton communities, at least in nutrient rich lakes and compared to other prevailing environmental factors.

Place, publisher, year, edition, pages
2016. Vol. 92, no 2, UNSP fiw005
Keyword [en]
freshwater bacteria; amino acid substrates; light regime; community composition; substrate specialization
National Category
URN: urn:nbn:se:uu:diva-275179DOI: 10.1093/femsec/fiw005ISI: 000371249600019OAI: oai:DiVA.org:uu-275179DiVA: diva2:899143
Swedish Research CouncilSwedish Research Council Formas
Available from: 2016-02-01 Created: 2016-02-01 Last updated: 2016-04-14Bibliographically approved
In thesis
1. Life strategies for substrate assimilation by freshwater bacterioplankton
Open this publication in new window or tab >>Life strategies for substrate assimilation by freshwater bacterioplankton
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The availability of substrates is one of the most important environmental constraints on the diversity and functioning of microorganisms. Substrate quantity and quality as well as the metabolic features of heterotrophic microorganisms determine the efficiency, speed and type of transformation that can occur in nature. As such their interplay with the environment regulates how much carbon and energy is incorporated by bacteria and subsequently reaches higher trophic levels. In lakes the bulk substrate that is available for bacteria is composed of a complex mixture of compounds, varying in lability and distribution in the environment. This thesis addresses the coupling of organic substrates, their metabolic use and the composition and ecology of the microbial community. Controlled laboratory experiments with mixed bacterial communities in either batch cultures or chemostats were designed to shed further light on bacterial use of labile and quantitatively significant carbon compounds.

I show that different amino acid substrates only exert a minor influence on bacterioplankton community composition and growth. Hence the ability to use a wide range of such abundantly produced protein monomers seems to be widespread among freshwater bacteria. In contrast, when acetate was provided as the only carbon substrate, in either pulsed or continuous amendments, this very different substrate input mode had a strong effect on bacterial community composition. Biomass yield, for example, was twice as high when acetate was given in the form of pulses rather than provided continuously.

In another set of experiments, I show that the oxidation of the globally significant greenhouse gas methane is a process that can potentially take place at the water-ice interface of seasonally ice-covered lakes and was not constrained by temperature as suggested in previous studies. This work also suggests that methane oxidation in ice-covered lakes can be constrained by competition for nutrients between specialized methanotrophs and heterotrophic bacteria.

Combined these studies suggest that some labile substrates cause minor selection on bacterial community structure and functioning. This probably reflects the competitive advantage of using a broad range of low molecular weight substrates. However, as in the case of methanotrophs there is specialization for a specific low molecular weight substrate such as methane. In which case, competition with other community members i.e. for nutrients can constrain methane oxidation. In both cases it might however not depend just on the availability of substrate, but also on how substrates are distributed in time and space.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2016. 39 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1342
lake, methane, bacteria, substrate, methanotrophs, pulse, chemostat
National Category
Natural Sciences
urn:nbn:se:uu:diva-275181 (URN)978-91-554-9470-4 (ISBN)
Public defence
2016-03-18, Friessalen, EBC, Norbyvägen 14, Uppsala, 09:00 (English)
Available from: 2016-02-26 Created: 2016-02-01 Last updated: 2016-03-09

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Ricão Canelhas, MonicaEiler, AlexanderBertilsson, Stefan
By organisation
In the same journal
FEMS Microbiology Ecology

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 98 hits
ReferencesLink to record
Permanent link

Direct link