Uncoupling of chitinase activity and uptake of hydrolysis products in freshwater bacterioplankton

Beier, Sara; Bertilsson, Stefan

doi:10.4319/lo.2011.56.4.1179

Cited by 63 publications

(81 citation statements)

References 36 publications

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“…Salcher et al (2013) also found that acI was active in leucine uptake. Some MAR-FISH studies have suggested that another nitrogen-rich compound, NAG may be an important acI substrate (Beier and Bertilsson, 2011;Eckert et al, 2012Eckert et al, , 2013. However, we could not identify machinery to support the ability to take up and incorporate this substance.…”

Section: Ecogenomics Of the Aci Lineagecontrasting

confidence: 39%

“…These studies have shown that acI members can take up glucose (Buck et al, 2009), leucine (Buck et al, 2009;Perez et al, 2010;Salcher et al, 2010;Eckert et al, 2012), acetate (Buck et al, 2009), thymidine (Perez et al, 2010), N-acetylglucosamine (NAG) (Beier and Bertilsson, 2011;Eckert et al, 2012) and di-NAG (Beier and Bertilsson, 2011;Eckert et al, 2012;Tada and Grossart, 2014). A recent MAR-FISH study performed on fall samples from Lake Zü rich in Switzerland showed that acI bacteria consumed an amino acid mixture as well (Salcher et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

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Comparative single-cell genomics reveals potential ecological niches for the freshwater acI Actinobacteria lineage

et al. 2014

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Members of the acI lineage of Actinobacteria are the most abundant microorganisms in most freshwater lakes; however, our understanding of the keys to their success and their role in carbon and nutrient cycling in freshwater systems has been hampered by the lack of pure cultures and genomes. We obtained draft genome assemblies from 11 single cells representing three acI tribes (acI-A1, acI-A7, acI-B1) from four temperate lakes in the United States and Europe. Comparative analysis of acI SAGs and other available freshwater bacterial genomes showed that acI has more gene content directed toward carbohydrate acquisition as compared to Polynucleobacter and LD12 Alphaproteobacteria, which seem to specialize more on carboxylic acids. The acI genomes contain actinorhodopsin as well as some genes involved in anaplerotic carbon fixation indicating the capacity to supplement their known heterotrophic lifestyle. Genome-level differences between the acI-A and acI-B clades suggest specialization at the clade level for carbon substrate acquisition. Overall, the acI genomes appear to be highly streamlined versions of Actinobacteria that include some genes allowing it to take advantage of sunlight and N-rich organic compounds such as polyamines, di-and oligopeptides, branched-chain amino acids and cyanophycin. This work significantly expands the known metabolic potential of the cosmopolitan freshwater acI lineage and its ecological and genetic traits.

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Section: Ecogenomics Of the Aci Lineagecontrasting

confidence: 39%

Section: Introductionmentioning

confidence: 99%

Comparative single-cell genomics reveals potential ecological niches for the freshwater acI Actinobacteria lineage

et al. 2014

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“…Particle-associated microbes have the advantage of benefiting directly from the soluble oligomers produced by chitin hydrolysis. However, planktonic bacteria can also profit from chitin hydrolysis products, which has been shown recently for members of planktonic freshwater Actinobacteria (5).…”

Section: Discussionmentioning

confidence: 99%

Bacterial Chitin Hydrolysis in Two Lakes with Contrasting Trophic Statuses

Köllner

Carstens

Keller

et al. 2012

Appl Environ Microbiol

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Chitin, which is a biopolymer of the amino sugar glucosamine (GlcN), is highly abundant in aquatic ecosystems, and its degradation is assigned a key role in the recycling of carbon and nitrogen. In order to study the significance of chitin decomposition in two temperate freshwater lakes with contrasting trophic and redox conditions, we measured the turnover rate of the chitin analog methylumbelliferyl-N,N=-diacetylchitobioside (MUF-DC) and the presence of chitinase (chiA) genes in zooplankton, water, and sediment samples. In contrast to the eutrophic and partially anoxic lake, chiA gene fragments were detectable throughout the oligotrophic water column and chiA copy numbers per ml of water were up to 15 times higher than in the eutrophic waters. For both lakes, the highest chiA abundance was found in the euphotic zone-the main habitat of zooplankton, but also the site of production of easily degradable algal chitin. The bulk of chitinase activity was measured in zooplankton samples and the sediments, where recalcitrant chitin is deposited. Both, chiA abundance and chitinase activity correlated well with organic carbon, nitrogen, and concentrations of particulate GlcN. Our findings show that chitin, although its overall contribution to the total organic carbon is small (ϳ0.01 to 0.1%), constitutes an important microbial growth substrate in these temperate freshwater lakes, particularly where other easily degradable carbon sources are scarce.

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“…Marine and brackish Flavobacteriales preferably incorporated high-molecular-weight DOM such as proteins or chitin (Cottrell and Kirchman, 2000). Freshwater Flavobacteriales were repeatedly reported to be only marginally involved in AA turnover (Pérez and Sommaruga, 2006;Salcher et al, 2010), but could be experimentally enriched with chitin (Beier and Bertilsson, 2011) and incorporated the mono-and dimeric chitin units N-acetyl-glucosamine and di-N-acetyl-glucosamine (Beier and Bertilsson, 2011;Eckert et al, 2012). The freshwater bacterium Flavobacterium johnsoniae strain A3 preferentially utilized oligopeptides and proteins over individual AAs and had a higher specific affinity for di-and polysaccharides than for Fru (Sack et al, 2011).…”

Section: Differences Within Bacteroidetesmentioning

confidence: 99%

In situ substrate preferences of abundant bacterioplankton populations in a prealpine freshwater lake

2012

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The substrate partitioning of sympatric populations of freshwater bacterioplankton was studied via microautoradiography and fluorescence in situ hybridization. Fourteen radiolabeled tracers were used to assess microbial acquisition spectra of low-molecular-weight (LMW) organic compounds. The most abundant group, ac1 Actinobacteria, were highly active in leucine, thymidine and glucose assimilation, whereas Alphaproteobacteria from the LD12 lineage (the freshwater sister clade of SAR11) only weakly incorporated these tracers, but exhibited a distinct preference for glutamine and glutamate. Different Bacteroidetes showed contrasting uptake patterns: Flavobacteriales did not incorporate significant amounts of any LMW compound, and Cyclobacteriaceae were clearly specialized on leucine, glucose and arginine. Betaproteobacteria represented the most active and versatile bacterioplankton fraction and 490% of them could be assigned to eight species-to genuslike populations with contrasting substrate specialization. Limnohabitans sp. were the most abundant and active Betaproteobacteria, incorporating almost all tracers. While three closely related betaproteobacterial populations substantially differed in their uptake spectra, two more distantly related lineages had very similar preferences, and one population did not incorporate any tracer. The dominant phototrophic microorganism, the filamentous cyanobacterium Planktothrix rubescens, assimilated several substrates, whereas other (pico)cyanobacteria had no heterotrophic activity. The variable extent of specialization by the studied bacterial taxa on subsets of LMW compounds contrasts theoretical considerations about non-selective microbial substrate assimilation at oligotrophic conditions. This physiological niche separation might be one explanation for the coexistence of freshwater bacterioplankton species in a seemingly uniform environment.

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Uncoupling of chitinase activity and uptake of hydrolysis products in freshwater bacterioplankton

Cited by 63 publications

References 36 publications

Comparative single-cell genomics reveals potential ecological niches for the freshwater acI Actinobacteria lineage

Comparative single-cell genomics reveals potential ecological niches for the freshwater acI Actinobacteria lineage

Bacterial Chitin Hydrolysis in Two Lakes with Contrasting Trophic Statuses

In situ substrate preferences of abundant bacterioplankton populations in a prealpine freshwater lake

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