Community composition and functional genes as well as ecological role of bacteria attached to different bloom-forming cyanobacteria

2020 ◽  
Author(s):  
Chunlei Song ◽  
Liu Yang ◽  
Xiuyun Cao ◽  
Xiaoyan Chen ◽  
Qinghui Deng ◽  
...  

Abstract Background Eutrophication leads to frequent outbreaks of cyanobacterial blooms, especially those of the genera Dolichospermum and Microcystis. The contribution of bacteria attached to algal cells to cyanobacterial blooms is still not clear and specific. To gain a deeper understanding of functional genes and their role in bacteria attached to different bloom-forming cyanobacteria, we carried out microbial experiments associated with Dolichospermum and Microcystis in four fish ponds. Results The significantly positive relationships between Dolichospermum density and total nitrogen (TN) and between Microcystis density and particle nitrogen (PN) indicated the strong nitrogen (N) demand of these two species. The lack of functional genes mediating the nitrification process in bacteria attached to both Microcystis and Dolichospermum indicated that these two species preferred ammonium (NH 4 + -N). Dolichospermum could overcome N limitation through N 2 fixation expressed by high nitrogenase genes abundance. Compared to bacteria attached to Dolichospermum cells, bacteria attached to Microcystis cells showed a higher activity of leucine aminopeptidase (LAP) and a significantly higher abundance of functional genes (such as nrfA , nirB and aminopeptidase genes) mediating the dissimilatory nitrate reduction to ammonium (DNRA). The significantly higher abundance of functional genes (carbon degradation) and β-glucosidase (GLU) activity of bacteria attached to Microcystis than those of bacteria attached to Dolichospermum suggested the abundant organic carbon bound Microcystis cells, which was prerequisite for DNRA. Also, Microcystis had a great advantage in solving phosphorus (P) stress, including high levels of organic phosphorus hydrolysis associated with high levels of phosphatase genes of attached bacteria. The difference of functional community compositions of bacteria attached to Microcystis and Dolichospermum resulted in the functional differentiation. Conclusions Dolichospermum and Microcystis growth was susceptible to P and N (especially NH 4 + -N) limitation, respectively, the latter of which could be effectively solved by attached bacteria through DNRA and ammonification. The P acquisition disadvantage of Dolichospermum resulted in its frequent replacement by Microcystis , especially in conditions of P deficiency. Hence, the evaluation of nutrient limitation (N or P) type of algal growth should combine the nutrient concentration and ratio as well as the ability to solve nutrient deficiency.

1990 ◽  
Vol 47 (12) ◽  
pp. 2328-2338 ◽  
Author(s):  
Walter K. Dodds ◽  
John C. Priscu

Short-term (h) and Song-term (d) changes in phytoplankton community physiology and bsomass in response to nutrient enrichment were used concomitantly as bioassays of phytoplankton nutrient deficiency in oligotrophic Flathead Lake, Montana, six times over the course of a year. Long-term bioassays consisted of nutrient amendments to epilimnetic water in 20 L containers which were subsequently monitored for algal growth. Short-term bioassays included measurement of NH4+ stimulation of dark carbon fixation, measurement of PO43− and NH4+ uptake over time to assess depletion of internal pools and stimulation effects of PO43− on NH4+ uptake and NH4+ on PO43− uptake. During thermal stratification, simultaneous additions of NH4+ and PO43− in long-term bioassays caused significant increases in chlorophyll a concentration, photosynthetic 14CO2 uptake, and particulate N concentration within 4.5 d; single additions of NH4+ or PO43− had little or no effect. During winter mixing there was little evidence for N or P deficiency in either short- or long-term bioassays. In general, short-term bioassays did not consistently agree with each other or with long-term bioassays. Our results suggest that it may be necessary to elicit growth of phytoplankton with nutrient addition to make definitive statements regarding nutrient deficiency.


1995 ◽  
Vol 32 (4) ◽  
pp. 187-196 ◽  
Author(s):  
L. Pechar

The study presents data on the species composition of cyanobacterial water blooms in Czech fish ponds from the 1950s to the 1990s. Since the 1950s, a shift from large-colonial Aphanizomenon flos-aquae var. flos-aquae through Microcystis aeruginosa and small-colonial species of Anabaena to single-filament species (Planktohrix agardhii, Limnothrix redekei, Aphanizomenon gracile) or single-cell forms (Microcystis ichtyoblabe), has been observed. The changes in the species composition of the water blooms are closely related to changes in fishery management (increase in fish stock, increase in application of organic fertilizers). At present the high predation of fish upon zooplankton results in elimination of large colonial blooms of A. flos-aquae associated with large filtering zooplankton (Daphnia). Low grazing pressure of zooplankton, low light conditions and low N:P ratios are suitable conditions for mass development of the small species of cyanobacteria. High pH is not necessary to achieve cyanobacteria dominance.


Author(s):  
Vanessa Minden ◽  
Jörg Schaller ◽  
Harry Olde Venterink

Abstract Aims Silicon (Si) has been shown to beneficially affect plant performance under stressful environmental conditions, such as water or nutrient deficiency. Here we tested the effects of two important plant nutrients, nitrogen (N) and phosphorus (P), on Si content in different plant organs in the grass species Holcus lanatus. Methods We studied trait responses to N limitation, balanced nutrient availability and P limitation. Single plant individuals were grown in sand-filled pots in a greenhouse for 2 months. Nitrogen, phosphorus, carbon and silicon contents were determined in leaves, stems and roots, as were leaf and roots traits, biomass production and root enzyme activity. Results Si content was lowest under balanced nutrient supply in all plant organs. Under P limitation Si content was highest in leaves and stems, in roots it was highest under N limitation. Si:C ratios were lowest under balanced conditions, and highest under nutrient limitation. Root phosphatase activity was highest under P limitation and chlorophyll content was lowest under N limitation. Conclusions Our model species assimilated less ‘high cost C’ and took up more ‘low cost Si’ under nutrient limitation, especially under P deficiency. Si potentially plays an important role in different environments, such as nutrient or light limitation, which in turn may be related to different plant strategies, for example higher stem rigidity in high Si plants versus higher stem flexibility in low Si plants. More research is needed to further elucidate the role of silicon in different concepts of trait-environment relationships.


2001 ◽  
Vol 52 (1) ◽  
pp. 139 ◽  
Author(s):  
Graham P. Harris

This paper reviews the factors influencing the nitrogen (N) and phosphorus (P) exports from Australian catchments. Pristine, forested catchments export little N and P and the predominant form of N is dissolved organic nitrogen (DON). As catchments are cleared, exports increase and the predominant form of N changes from DON to dissolved inorganic N (DIN). Soluble reactive P (SRP) represents a roughly constant fraction of total P in these systems. As catchments are cleared, DIN:SRP export ratios increase sharply and DIN comes to represent a larger and larger fraction of the total N. The ratios of total N:P and DIN:SRP in rivers reflect land use and the residence times of the water. In Australian lakes and reservoirs, DON and total Kjeldahl N (TKN)are consumed and DIN is exported downstream. Australian freshwater systems with long residence times show stoichiometric evidence of N limitation, and the frequent occurrence of N-fixing cyanobacterial blooms. Despite TN:TP loading ratios equalling or exceeding Redfield stoichiometry, many Australian estuaries and coastal lagoons also show extensive evidence of rapid denitrification and N limitation. Coastal lagoons also have long water residence times (up to 1 year) and a high proportion of the N load is denitrified.


Bragantia ◽  
2016 ◽  
Vol 75 (2) ◽  
pp. 152-163 ◽  
Author(s):  
Daiana Alves da Silva ◽  
Jose Antonio de Fatima Esteves ◽  
João Guilherme Ribeiro Gonçalves ◽  
Cleber Vinícius Giaretta Azevedo ◽  
Tamires Ribeiro ◽  
...  

ABSTRACT Common bean is one of the most important legumes in Latin America, mostly grown in soils with low phosphorus (P) availability. Thus, this study aimed to evaluate the responses of 20 bean genotypes to P deficiency. The experiment was a completely randomized design in a 2 × 20 factorial arrangement; the first factor consisted of P levels and the second factor, of 20 bean genotypes, with six replications. The substrate was a Red Eutrophic Oxisol with low P content. For application of the P treatments, it was applied simple superphosphate, consisting of two levels: restrictive and control, with the application of 45 and 90 kg∙ha–1 of P2O5, respectively. At 28 days, we observed the first symptoms of nutrient deficiency, with the decrease in the relative chlorophyll index in the restrictive level treatment. In addition, the treatments were effective in differentiating effects of both factors levels of P and genotypes for most traits evaluated relative to shoot, root and grain yield. It was possible to classify the genotypes in relation to use efficiency and responsiveness to P application, according to their average yield performances. Seven genotypes presented better performances for both P levels, being classified as Efficient and Responsive: G 2333, IAC Carioca Tybatã, IAPAR 81, IAC Imperador, IAC Formoso, BRS Esplendor and IPR Tangará; the first four genotypes were also classified as Efficient and Responsive under hydroponic conditions.


2021 ◽  
Vol 12 ◽  
Author(s):  
María José García ◽  
Macarena Angulo ◽  
Carlos García ◽  
Carlos Lucena ◽  
Esteban Alcántara ◽  
...  

To cope with P, S, or Fe deficiency, dicot plants, like Arabidopsis, develop several responses (mainly in their roots) aimed to facilitate the mobilization and uptake of the deficient nutrient. Within these responses are the modification of root morphology, an increased number of transporters, augmented synthesis-release of nutrient solubilizing compounds and the enhancement of some enzymatic activities, like ferric reductase activity (FRA) or phosphatase activity (PA). Once a nutrient has been acquired in enough quantity, these responses should be switched off to minimize energy costs and toxicity. This implies that they are tightly regulated. Although the responses to each deficiency are induced in a rather specific manner, crosstalk between them is frequent and in such a way that P, S, or Fe deficiency can induce responses related to the other two nutrients. The regulation of the responses is not totally known but some hormones and signaling substances have been involved, either as activators [ethylene (ET), auxin, nitric oxide (NO)], or repressors [cytokinins (CKs)]. The plant hormone ET is involved in the regulation of responses to P, S, or Fe deficiency, and this could partly explain the crosstalk between them. In spite of these crosslinks, it can be hypothesized that, to confer the maximum specificity to the responses of each deficiency, ET should act in conjunction with other signals and/or through different transduction pathways. To study this latter possibility, several responses to P, S, or Fe deficiency have been studied in the Arabidopis wild-type cultivar (WT) Columbia and in some of its ethylene signaling mutants (ctr1, ein2-1, ein3eil1) subjected to the three deficiencies. Results show that key elements of the ET transduction pathway, like CTR1, EIN2, and EIN3/EIL1, can play a role in the crosstalk among nutrient deficiency responses.


2016 ◽  
Vol 75 (s1) ◽  
Author(s):  
Fernando W. Bernal-Brooks ◽  
José J. Sánchez Chávez ◽  
Luis Bravo Inclán ◽  
Rubén Hernández Morales ◽  
Ana K. Martínez Cano ◽  
...  

<p>This paper reports on the algal growth-limiting nutrients of five lakes located on Mexico’s Mesa Central - a topic poorly known in the regional limnology of Mexico. The five case studies involved three contiguous watersheds of Michoacán State and provided a trophic state variation from mesotrophic to hypereutrophic; the case studies included Lakes Zirahuén, Pátzcuaro, Teremendo, Cuitzeo and the Cointzio Reservoir. The fieldwork involved the collection of physical and chemical data (including nutrients) from each case study during the dry and rainy seasons of 2010. Additionally, water samples (1 L) were obtained and filtered (0.45 µm) in the laboratory to keep the nutrient content available for bioassays. The chemical analyses suggested a phosphorus (P) limitation in the Cointzio Reservoir, Lake Teremendo and Lake Zirahuén relative to an N:P&gt;16:1. There was a nitrogen (N) limitation at three sampling stations of Lake Pátzcuaro, with an N:P&lt;16:1. As result of the bioassays conducted in July 2012, the Cointzio Reservoir and Lake Teremendo appeared to be P-limited and Lake Pátzcuaro appeared to be N-limited at three sampling stations. Lake Zirahuén showed seasonal variation, with an N limitation during the dry season and a P limitation during the wet season. Those cases with similar results from both methods confirmed the limiting nutrient identification. Lake Cuitzeo, Lake Zirahuén (dry season), and the shallowest sampling station in Lake Pátzcuaro produced unclear results because of divergent outcomes. In terms of the algal growth potential, the Cointzio Reservoir remained unaltered from one season to the next. However, for most of the lakes (with the exception of Lake Pátzcuaro sites 2 and 4), the rainy season provided a dilution effect. Effective lake management depends on a clear recognition of such elements that are in control of the aquatic productivity. In the area of Michoacán, both N and P may act as limiting nutrients.</p>


2020 ◽  
Vol 57 (1) ◽  
pp. 47-64
Author(s):  
Alberto Andrino ◽  
Georg Guggenberger ◽  
Leopold Sauheitl ◽  
Stefan Burkart ◽  
Jens Boy

AbstractTo overcome phosphorus (P) deficiency, about 80% of plant species establish symbiosis with arbuscular mycorrhizal fungi (AMF), which in return constitute a major sink of photosynthates. Information on whether plant carbon (C) allocation towards AMF increases with declining availability of the P source is limited. We offered orthophosphate (OP), apatite (AP), or phytic acid (PA) as the only P source available to arbuscular mycorrhiza (AM) (Solanum lycopersicum x Rhizophagus irregularis) in a mesocosm experiment, where the fungi had exclusive access to each P source. After exposure, we determined P contents in the plant, related these to the overall C budget of the system, including the organic C (OC) contents, the respired CO2, the phospholipid fatty acid (PLFA) 16:1ω5c (extraradical mycelium), and the neutral fatty acid (NLFA) 16:1ω5c (energy storage) at the fungal compartment. Arbuscular mycorrhizal (AM) plants incorporated P derived from the three P sources through the mycorrhizal pathway, but did this with differing C-P trading costs. The mobilization of PA and AP by the AM plant entailed larger mycelium infrastructure and significantly larger respiratory losses of CO2, in comparison with the utilization of the readily soluble OP. Our study thus suggests that AM plants invest larger C amounts into their fungal partners at lower P availability. This larger C flux to the AM fungi might also lead to larger soil organic C contents, in the course of forming larger AM biomass under P-limiting conditions.


2019 ◽  
Vol 255 ◽  
pp. 113235 ◽  
Author(s):  
Zhaokui Ni ◽  
Shengrui Wang ◽  
Jingjing Cai ◽  
Hong Li ◽  
Alan Jenkins ◽  
...  

2020 ◽  
Author(s):  
Congmin Zhu ◽  
Junyi Zhang ◽  
Xin Wang ◽  
Yuqing Yang ◽  
Ning Chen ◽  
...  

Abstract BackgroundFreshwater lakes are threatened by harmful cyanobacterial blooms; whose basic unit is Cyanobacterial Aggregate (CA). Community variations of CA-attached bacteria are substantial during different blooming stages. However, little is known about their transcriptional and metabolic variations. Most bacterial genomes in CA were not constructed in existing database, which limits our understanding of the bacterial variations as responses to cyanobacterial blooms. ResultsIn this longitudinal study, 16 CA samples were collected from Lake Taihu, one of the largest freshwater lakes in China, from April of 2015 to February of 2016. By sequencing the V4 region of 16S rRNA genes, full metagenomes (MG) and metatranscriptomes (MT), we generated 424 Mb of 16S rRNA gene data, 122 Gb of high-quality MG data and 160 Gb of high-quality MT data. We analyzed the taxonomic, functional and transcriptional variations of microbes in CAs along three blooming stages, and constructed metagenome-assembled genomes (MAGs) by binning analysis. First, 55 OTUs, 456 genes and 37 transcripts mainly associated with pathways of transporters, photosystem and energy metabolism showed significantly different abundance among the three stages. Second, 161 high-quality MAGs in CAs were achieved, with 19 of which significantly shifted in relative abundance among three stages. The most abundant MAGs have gene capacities to synthesize flagella and divers of transporters, and participate in metabolic pathways of nitrogen, phosphorus and sulfur. Finally, 22 high-quality cyanobacterial MAGs were constructed and can be divided into four functional clusters, which showed significant differences on the energy pathways, transporters and prokaryotic defense system.ConclusionOverall, these results demonstrated the taxonomic, functional and transcriptional variations of microbes in CAs among three different blooming stages. Genome construction and metabolic analysis of cyanobacteria and their attached bacteria suggested that the material exchange and signal transmission do, indeed, exist among them. Our understanding of the underlying molecular pathways for cyanobacterial blooms could potentially lead to the control of blooms by interventional strategies to disrupt the expression of critical microbes.


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