Algal Exudates and Stream Organic Matter Influence the Structure and Function of Denitrifying Bacterial Communities

Kalscheur, Kathryn N.; Rojas, M. Guadalupe; Peterson, Christopher G.; Kelly, John J.; Gray, Kimberly A.

doi:10.1007/s00248-012-0091-1

Cited by 43 publications

(19 citation statements)

References 49 publications

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“…This data suggest that in this dam we can observe organisms generalists and specialists such as has been recently proposed for denitrifiers by Bowen et al (2013) where the generalists can inhabit in a wide range of habitats unlike specialists. We observe the presence of many OTUs with low number of sequences (36 of 45 OTUs) which also has been reported in other studies as "rare biosphere" (Bowen et al 2013, Huse et al 2010, Kalscheur et al 2012. This information suggest that several factor prevalent in the reservoir could favor the differentiation of ecological niches for different types of microorganisms, such as a wide range of substrates available, an intricate functional and ecological network between denitrifying bacteria, greater biological effectiveness (present only in specialists) and a great adaptive and evolutionary capacity, as has been proposed by others authors (Koeppel and Wu 2012, Logares et al 2013, Matulich 2013).…”

Section: Discussionsupporting

confidence: 90%

Spatial Variation of -communities in the Low Oxygen Waters of Prado Hydroelectric (South-West of Colombia)

Montealegre¹,

González²

2016

Open Ecol. J.

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Denitrification is a process of reduction of nitrate to dinitrogen by facultative anaerobic microorganisms, which have functional genes encoding denitrification enzymes (reductases). The nosZ gene encoding the enzyme that reduces nitrous oxide to dinitrogen was utilized in this research, as molecular marker for denitrifying communities into low oxygen waters of Prado reservoir. Our objective was to analyze and compare the composition (richness and abundance) of nosZ-type denitrifiers in relationship with physicochemical variables (oxygen, pH, temperature, nitrate, nitrite and ammonium) in three areas of this dam: Isla del Sol, Lozanía and Tomogó which are distant and have different anthropogenic influences. For this, we performed DNA extraction, amplification, 454 pyrosequencing and phylogenetic analysis of nosZ gene. The Chao1 estimator and Shannon index were used for compare richness and diversity of nosZ gene; and the relationship between compositions of operational taxonomic units (OTU) with physicochemical variables was established by canonical correspondence analysis (CCA). In the reservoir 45 nosZ-OTUs to species level (80% similarity) were detected. Lozanía had the highest number of OTUs (25) and greatest diversity (S CHAO1 : 35; H: 2.0), compared to the other areas sampling. The phylogenetic analysis showed the presence of many OTUs (28 of 45) with low similarity to Proteobacteria group and high similarity with sequences of environmental clones reported previously. The CCA showed that the nosZ-community composition of Prado dam was related with low pH (6.2), oxygen (0.01mg / L) and nitrate (<0.25 mg / L) recorded in the water column.

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Section: Discussionsupporting

confidence: 90%

Spatial Variation of -communities in the Low Oxygen Waters of Prado Hydroelectric (South-West of Colombia)

Montealegre¹,

González²

2016

Open Ecol. J.

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“…These primary producers could form the base of food chains and interact with heterotrophs that feed on algal exudates, senescent algae, and algal detritus (Cole, 1982). In fact, studies in other systems show that the chemical constituents of algal exudates differ by species (Aluwihare and Repeta, 1999) and this affects the composition of bacterial heterotrophs (Kalscheur et al, 2012). Interactions between heterotrophic organisms and algae and cyanobacteria would result in high network complexity in early succession that would decline in later succession as increasing plant cover shades out photosynthetic microbes.…”

Section: Discussionmentioning

confidence: 99%

Soil Microbial Networks Shift Across a High-Elevation Successional Gradient

et al. 2019

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While it is well established that microbial composition and diversity shift along environmental gradients, how interactions among microbes change is poorly understood. Here, we tested how community structure and species interactions among diverse groups of soil microbes (bacteria, fungi, non-fungal eukaryotes) change across a fundamental ecological gradient, succession. Our study system is a high-elevation alpine ecosystem that exhibits variability in successional stage due to topography and harsh environmental conditions. We used hierarchical Bayesian joint distribution modeling to remove the influence of environmental covariates on species distributions and generated interaction networks using the residual species-to-species variance-covariance matrix. We hypothesized that as ecological succession proceeds, diversity will increase, species composition will change, and soil microbial networks will become more complex. As expected, we found that diversity of most taxonomic groups increased over succession, and species composition changed considerably. Interestingly, and contrary to our hypothesis, interaction networks became less complex over succession (fewer interactions per taxon). Interactions between photosynthetic microbes and any other organism became less frequent over the gradient, whereas interactions between plants or soil microfauna and any other organism were more abundant in late succession. Results demonstrate that patterns in diversity and composition do not necessarily relate to patterns in network complexity and suggest that network analyses provide new insight into the ecology of highly diverse, microscopic communities.

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“…This is particularly true for lakes, where research on producer–decomposer interactions has focused overwhelmingly on planktonic assemblages and benthic environments have been considered mainly in regard to their exchange of nutrients with the pelagic zone (Vadeboncoeur, Vander Zanden, & Lodge, ). Relatively few studies have evaluated the effect of nutrient supply on heterotrophic activity in lake biofilms, despite the established role of decomposers in biofilm function in other aquatic environments (e.g., Battin, Kaplan, Newbold, & Hansen, ; Kalscheur, Rojas, Peterson, Kelly, & Gray, ). Furthermore, research aimed to simultaneously test for nutrient limitation of both autotrophs and heterotrophs in biofilms may have inadvertently favoured autotrophic production by limiting sampling to inorganic substrates (i.e., rocks), which selects for a largely autotrophic community (Johnson, Tank, & Dodds, ).…”

Section: Introductionmentioning

confidence: 99%

Resource constraints highlight complex microbial interactions during lake biofilm development

et al. 2019

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1. This study evaluated how the availability of nutrients and organic carbon interact to influence the associations between autotrophic and heterotrophic micro-organisms during lake biofilm development. Considering that decomposers are often better competitors for nutrients than producers in aquatic environments, we hypothesized that heterotrophs would outcompete autotrophs for available nutrients unless heterotrophs were limited by organic carbon provided by autotrophs.2. To test our hypothesis, we evaluated autotrophic (algae) and heterotrophic (fungi, bacteria) biomass in response to a factorial enrichment of nutrients (nitrogen and phosphorus in combination) and glucose using nutrient-diffusing substrates with either inorganic or organic discs in a subalpine lake. In the field, nutrient-diffusing substrates were exposed to either natural sunlight or placed under a darkened experimental canopy to evaluate the response of heterotrophs to nutrients and carbon subsidies in the presence or absence of algae. We expected that heterotrophs would be limited by organic carbon on inorganic substrates in the absence of autotrophic production (i.e., dark treatments), and that organic substrates would provide a carbon subsidy for heterotrophic metabolism.3. Fungi were stimulated by nutrient enrichment on inorganic substrates in the presence of algae (light treatment), but not in the dark (without algae). The response of fungi to algal presence on inorganic substrates was similar in magnitude to the response of fungi to nutrients and glucose substrates incubated in the dark. In contrast to our expectations, elevated algal biomass did not stimulate heterotrophic bacteria in the presence of elevated nutrient levels on inorganic substrates, possibly owing to antagonistic interactions between bacteria and fungi. 4. The positive effect of nutrients on algal biomass was significantly reduced in favour of heterotrophs when nutrients were combined with glucose, suggesting that heterotrophs were able to outcompete algae for available nutrients in the absence of carbon limitation. 5.Synthesis. These results expand our understanding of how the availability of limiting resources governs the outcomes of complex interactions among micro-organisms in aquatic biofilms, and suggests that background levels of organic carbon | 2739Journal of Ecology WYATT eT Al.

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Algal Exudates and Stream Organic Matter Influence the Structure and Function of Denitrifying Bacterial Communities

Cited by 43 publications

References 49 publications

Spatial Variation of -communities in the Low Oxygen Waters of Prado Hydroelectric (South-West of Colombia)

Spatial Variation of -communities in the Low Oxygen Waters of Prado Hydroelectric (South-West of Colombia)

Soil Microbial Networks Shift Across a High-Elevation Successional Gradient

Resource constraints highlight complex microbial interactions during lake biofilm development

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