Response of a summertime Antarctic marine ­bacterial community to glucose and ammonium enrichment

Abstract

Along the western Antarctic Peninsula, marine bacterioplankton respond to the spring phytoplankton bloom with increases in abundance, production and growth rates, and a seasonal succession in bacterial community composition (BCC). We investigated the response of the bacterial community to experimental additions of glucose and ammonium, alone or in combination, 1°W). Changes in bulk propertiesand BCC in ammonium-amended carboys were small relative to controls, compared to the glucoseamended treatments. The BCC in Day 0 and Day 10 controls and ammonium treatments were > 72% similar when assessed by denaturing-gradient gel electrophoresis (DGGE), length heterogeneity polymerase chain reaction (LH-PCR) and capillary electrophoresis single-strand conformation polymorphism (CE-SSCP) fingerprinting techniques. Bacterial abundance increased 2-to 10-fold and leucine incorporation rates increased 2-to 30-fold in the glucose treatments over 6 d. The BCC in carboys receiving glucose (with or without ammonium) remained > 60% similar to that in Day 0 controls at 6 d and evolved to < 20% similar to that in Day 0 controls after 10 d incubation. The increases in bacterial production rates, and the changes in BCC, suggest that selection for glucose-utilizing bacteria was slow under the ambient environmental conditions. The results suggest that organic carbon enrichment is a major factor influencing the observed winter-to-summer increase in bacterial abundance and activity. In contrast, the BCC was relatively robust, changing little until after repeated additions of glucose and prolonged (~10 d) incubation.

Bacterioplankton communities in the Southern Ocean: composition and growth response to various substrate regimes

“…The composition of the heterotrophic picoplankton community, including Bacteria and Archaea, has also been studied in the Southern Ocean and most intensely in the last decade. These studies have revealed that Alpha-and Gammaproteobacteria, Sphingobacteria and Flavo bacteria of the Bacteroidetes phylum and in particular distinct subclusters of these groups are the major phylogenetic lineages , Abell & Bowman 2005a, West et al 2008, Manganelli et al 2009, Straza et al 2010, Ducklow et al 2011. These findings corroborate observations in other oceanic regions, but relevant subclusters of these major phylogenetic lineages in the Southern Ocean differ from other regions with higher water temperatures and other hydrographic regimes (Selje et al 2004, Abell & Bowman 2005a, Giebel et al 2009, Straza et al 2010, Ghiglione & Murray 2012.…”

“…Lebaron et al 1999, Riemann et al 2000, Murray et al 2007 or selected simple inorganic nutrients and/or organic substrates, such as glucose and/or DFAA, were applied (e.g. Church et al 2000, Massana et al 2001, Ducklow et al 2011, Gómez-Consarnau et al 2012). More than 2 treatments with different organic compounds were rarely applied, such as dissolved protein and starch (Pinhassi et al 1999) The scale bar indicates the percentage of the sequence divergence organic acids and amino acids (Gómez-Consarnau et al 2012).…”

“…In a study around the western Antarctic Peninsula using microautoradiography and fluorescence in situ hybridization (MAR-FISH), Straza et al (2010) found that specific subgroups of Gammaproteobacteria, SAR11 and of Sphingobacteria/Flavobacteria were the major bacterioplankton groups in organic matter consumption. Specific phylotypes of Gammaproteobacteria and Sphingobacteria/Flavobacteria were reported to be particularly responsive to glucose plus ammonium additions in a mesocosm experiment in the same region (Ducklow et al 2011). To better understand organic matter cycling by bacterioplankton phylogenetic lineages in the Southern Ocean, more studies with various potentially important substrates are needed.…”

Hydrocarbon biodegradation by Arctic sea-ice and sub-ice microbial communities during microcosm experiments, Northwest Passage (Nunavut, Canada)

“…2). This lag period was similar to the 5 to 8 day lag observed during other carbon enrichment experiments on polar bacterial communities (Dyda et al 2009;Ducklow et al 2011). Bacterial communities usually need time to activate the pathway of enzymes required for hydrocarbon degradation (Rojo 2009).…”

Effects of temperature and fertilization on the structure of total versus active bacterial communities from sub-Antarctic seawater exposed to crude oil and diesel fuel

“…The use of a high-throughput fingerprinting technique, such as the CE-SSCP, permits the comparison of a large number of samples (Ghiglione et al 2005), providing an accurate inter-sample analysis (Hong et al 2007). Recently, CE-SSCP has been shown to provide similar results compared to other fingerprinting techniques (Ducklow et al 2011) and to next generation sequencing techniques (Ghiglione & Murray 2012).…”