Accumulation and utilization of polysaccharide by hot-spring phototrophs during a light-dark transition

Konopka, Allan

doi:10.1111/j.1574-6968.1992.tb05792.x

Cited by 14 publications

(7 citation statements)

References 18 publications

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“…The ratio of cyanobacterial to FAP biovolume in a Mushroom Spring mat sample was experimentally measured to be 1.6:1 [ 16 ]. It is assumed here that biomass and biovolume are related in the same manner for both species.…”

Section: Resultsmentioning

confidence: 99%

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In silico approaches to study mass and energy flows in microbial consortia: a syntrophic case study

et al. 2009

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BackgroundThree methods were developed for the application of stoichiometry-based network analysis approaches including elementary mode analysis to the study of mass and energy flows in microbial communities. Each has distinct advantages and disadvantages suitable for analyzing systems with different degrees of complexity and a priori knowledge. These approaches were tested and compared using data from the thermophilic, phototrophic mat communities from Octopus and Mushroom Springs in Yellowstone National Park (USA). The models were based on three distinct microbial guilds: oxygenic phototrophs, filamentous anoxygenic phototrophs, and sulfate-reducing bacteria. Two phases, day and night, were modeled to account for differences in the sources of mass and energy and the routes available for their exchange.ResultsThe in silico models were used to explore fundamental questions in ecology including the prediction of and explanation for measured relative abundances of primary producers in the mat, theoretical tradeoffs between overall productivity and the generation of toxic by-products, and the relative robustness of various guild interactions.ConclusionThe three modeling approaches represent a flexible toolbox for creating cellular metabolic networks to study microbial communities on scales ranging from cells to ecosystems. A comparison of the three methods highlights considerations for selecting the one most appropriate for a given microbial system. For instance, communities represented only by metagenomic data can be modeled using the pooled method which analyzes a community's total metabolic potential without attempting to partition enzymes to different organisms. Systems with extensive a priori information on microbial guilds can be represented using the compartmentalized technique, employing distinct control volumes to separate guild-appropriate enzymes and metabolites. If the complexity of a compartmentalized network creates an unacceptable computational burden, the nested analysis approach permits greater scalability at the cost of more user intervention through multiple rounds of pathway analysis.

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Section: Resultsmentioning

confidence: 99%

“…Other community members, including the photoheterotrophic FAP, can use glycolate as a carbon and energy source [ 15 ]. The cyanobacteria can also store excess photosynthate as polyglucose [ 16 ]. This carbon and energy storage material is fermented at night to organic acids (Figure 1B ) [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

In silico approaches to study mass and energy flows in microbial consortia: a syntrophic case study

et al. 2009

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“…4C), the green fraction descended to the bottom of the gradient through the afternoon, then migrated upwards throughout the evening and reached a maximum by early morning (08:50) before descending again to the bottom throughout the next afternoon. This was probably due to changes in Synechococcus cell density upon the synthesis during the day and fermentation during the night of polyglucose (Konopka, 1992; Nold and Ward, 1996). A diel cycle was less obvious for the glucose concentration in the brown fraction containing GNSLB.…”

Section: Resultsmentioning

confidence: 99%

“…Indeed, the dominant mat sugar, glucose, was shown to be strongly enriched in 13 C (van der Meer et al ., 2003). However, as both cyanobacteria and GNSLB are known to produce polyglucose storage materials (Holo and Grace, 1987; Konopka, 1992) it is unclear whether cyanobacteria within the mat produce 13 C‐enriched polyglucose and how this pool varies over time.…”

Section: Introductionmentioning

confidence: 99%

Impact of carbon metabolism on ¹³C signatures of cyanobacteria and green non‐sulfur‐like bacteria inhabiting a microbial mat from an alkaline siliceous hot spring in Yellowstone National Park (USA)

Meer

Schouten

Damsté

et al. 2006

Environmental Microbiology

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Alkaline siliceous hot spring microbial mats in Yellowstone National Park are composed of two dominant phototropic groups, cyanobacteria and green non-sulfur-like bacteria (GNSLB). While cyanobacteria are thought to cross-feed low-molecular-weight organic compounds to support photoheterotrophic metabolism in GNSLB, it is unclear how this could lead to the heavier stable carbon isotopic signatures in GNSLB lipids compared with cyanobacterial lipids found in previous studies. The two groups of phototrophs were separated using percoll density gradient centrifugation and subsequent lipid and stable carbon isotopic analysis revealed that we obtained fractions with a approximately 60-fold enrichment in cyanobacterial and an approximately twofold enrichment in GNSLB biomass, respectively, compared with the mat itself. This technique was used to study the diel cycling and 13C content of the glucose pools in and the uptake of 13C-bicarbonate by the cyanobacteria and GNSLB, as well as the transfer of incorporated 13C from cyanobacteria to GNSLB. The results show that cyanobacteria have the highest bicarbonate uptake rates and accumulate glucose during the afternoon in full light conditions. In contrast, GNSLB have relatively higher bicarbonate uptake rates compared with cyanobacteria in the morning at low light levels. During the night GNSLB take up carbon that is likely derived through fermentation of cyanobacterial glucose enriched in 13C. The assimilation of 13C-enriched cyanobacterial carbon may thus lead to enriched 13C-contents of GNSLB cell components.

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“…The cyanobacterial TCA cycle, in contrast, functions in an environment in which light provides the energy for growth and maintenance during half of the diel cycle, and the breakdown of saccharides provides energy during the other half of the diel cycle. 6 Photosynthesis itself provides a significant amount of NADPH and ATP necessary for growth, yet despite high ATP and NADPH concentrations the TCA cycle in cyanobacteria must be able to produce three carbon precursors for anapleuritic reactions necessary for synthesis of biopolymers. The reductive TCA cycle of C. tepidum functions in a low oxygen environment and uses sulfide and thiosulfate as electron donors and CO 2 as a carbon source.…”

Section: ■ Introductionmentioning

confidence: 99%

Comparison of Optimal Thermodynamic Models of the Tricarboxylic Acid Cycle from Heterotrophs, Cyanobacteria, and Green Sulfur Bacteria

et al. 2014

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We have applied a new stochastic simulation approach to predict the metabolite levels, material flux, and thermodynamic profiles of the oxidative TCA cycles found in E. coli and Synechococcus sp. PCC 7002, and in the reductive TCA cycle typical of chemolithoautotrophs and phototrophic green sulfur bacteria such as Chlorobaculum tepidum. The simulation approach is based on modeling states using statistical thermodynamics and employs an assumption similar to that used in transition state theory. The ability to evaluate the thermodynamics of metabolic pathways allows one to understand the relationship between coupling of energy and material gradients in the environment and the self-organization of stable biological systems, and it is shown that each cycle operates in the direction expected due to its environmental niche. The simulations predict changes in metabolite levels and flux in response to changes in cofactor concentrations that would be hard to predict without an elaborate model based on the law of mass action. In fact, we show that a thermodynamically unfavorable reaction can still have flux in the forward direction when it is part of a reaction network. The ability to predict metabolite levels, energy flow, and material flux should be significant for understanding the dynamics of natural systems and for understanding principles for engineering organisms for production of specialty chemicals.

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Accumulation and utilization of polysaccharide by hot-spring phototrophs during a light-dark transition

Cited by 14 publications

References 18 publications

In silico approaches to study mass and energy flows in microbial consortia: a syntrophic case study

In silico approaches to study mass and energy flows in microbial consortia: a syntrophic case study

Impact of carbon metabolism on ¹³C signatures of cyanobacteria and green non‐sulfur‐like bacteria inhabiting a microbial mat from an alkaline siliceous hot spring in Yellowstone National Park (USA)

Comparison of Optimal Thermodynamic Models of the Tricarboxylic Acid Cycle from Heterotrophs, Cyanobacteria, and Green Sulfur Bacteria

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Accumulation and utilization of polysaccharide by hot-spring phototrophs during a light-dark transition

Cited by 14 publications

References 18 publications

In silico approaches to study mass and energy flows in microbial consortia: a syntrophic case study

In silico approaches to study mass and energy flows in microbial consortia: a syntrophic case study

Impact of carbon metabolism on 13C signatures of cyanobacteria and green non‐sulfur‐like bacteria inhabiting a microbial mat from an alkaline siliceous hot spring in Yellowstone National Park (USA)

Comparison of Optimal Thermodynamic Models of the Tricarboxylic Acid Cycle from Heterotrophs, Cyanobacteria, and Green Sulfur Bacteria

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Impact of carbon metabolism on ¹³C signatures of cyanobacteria and green non‐sulfur‐like bacteria inhabiting a microbial mat from an alkaline siliceous hot spring in Yellowstone National Park (USA)