Seed microbiota is becoming an emergent area of research. Host plant microbial diversity is increasingly well described, yet relatively little is known about the stressors driving plant ...endomicrobiota at the metaorganism level. The present work examines the role of horizontal and vertical transmission of bacterial microbiota in response to abiotic stress generated by arsenic. Horizontal transmission is achieved by bioaugmentation with the endophyte
Rhodococcus rhodochrous
, while vertical transmission comes
via
maternal inheritance from seeds. To achieve this goal, all experiments were conducted with two
Jasione
species.
J. montana
is tolerant to arsenic (As), whereas
J. sessiliflora
, being phylogenetically close to
J. montana
, was not previously described as As tolerant. The
Jasione
core bacterial endophytes are composed of genera
Pseudomonas
,
Ralstonia
,
Undibacterium
,
Cutibacterium
, and
Kocuria
and family
Comamanadaceae
across different environmental conditions. All these operational taxonomic units (OTUs) coexisted from seeds to the development of the seedling, independently of As stress, or bioaugmentation treatment and
Jasione
species.
R. rhodochrous
colonized efficiently both species, driving the endomicrobiota structure of
Jasione
with a stronger effect than As stress. Despite the fact that most of the OTUs identified inside
Jasione
seeds and seedlings belonged to rare microbiota, they represent a large bacterial reservoir offering important physiological and ecological traits to the host.
Jasione
traits co-regulated with
R. rhodochrous
, and the associated microbiota improved the host response to As stress. NGS-Illumina tools provided further knowledge about the ecological and functional roles of plant endophytes.
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•RGO biosynthesis independent of bacterial respiration.•Efficient of new graphene oxide reduction process provided by microbial biomass.•Microbial biomass (extremophile consortium and ...single strains) as biological reducing agents in the RGO biosynthesis.
Graphene synthesis has created great interest because of the potential applications in various fields. Many works of graphene synthesis from chemical reduction of graphene oxide involving harmful reactants have been published. A battery of both aerobic and anaerobic gram-negative and gram-positive strains as well as an extremophile microbial consortium from natural environment (Rio Tinto, Spain) were tested in graphene oxide reduction at simplest operating conditions. Results showed biological reduction of GO by all microorganisms, under aerobic conditions without any nutrient and carbon source addition and at room temperature (20–25 °C). UV–vis spectra of RGO showed the adsorption maximum gradually shifted from 230 nm to 270 nm, indicating an increase in the electronic conjugation. Moreover, G band in Raman spectra of RGO shifted from the original value of 1589 ± 1 cm−1 in GO. TGA analyses indicated that only weak weight losses of 2.5% both at 200 °C and above 300 °C, were achieved for Shewanella baltica strain and extremophile microbial consortium related to the presence of oxygen functional groups, indicating the GO reduction. The main novelty of the present work suggests that RGO biosynthesis was mediated by chemical oxidation independently of the bacterial respiration. The method described in the present work is comparable to other biological as well as physicochemical processes and environmentally friendly taking advantage of natural resources for graphene synthesis.
The carbon fluxes between phytoplankton and heterotrophic bacterioplankton were studied in two coastal oligotrophic sites in the NW Mediterranean. Phytoplankton and bacterial production rates were ...measured under natural conditions using different methods. In the Bay of Villefranche, the temporal variability revealed net heterotrophy in July-October and net autotrophy in December-March. The spatial variability was studied in the Bay of Palma, showing net autotrophic areas in the west and heterotrophic areas in the east. On average bacterial respiration, represented 62% of the total community respiration. Bacterial growth efficiency (BGE) values were significantly higher in autotrophic conditions than in heterotrophic ones. During autotrophic periods, dissolved primary production (DPP) was enough to sustained bacterial metabolism, although it showed a positive correlation with organic carbon stock (DOC). Under heterotrophic conditions, DPP did not sustain bacterial metabolism but bacterial respiration correlated with DPP and bacterial production with DOC. Temperature affected positively, DOC, BGE, bacterial respiration and production when the trophic status was autotrophic. To summarize, the response of bacterial metabolism to temperature and carbon sources depends on the trophic status within these oligotrophic coastal systems.
The presence of a wide variety of emerging pollutants in natural water resources is an important global water quality challenge. Pharmaceuticals and personal care products (PPCPs) are known as ...emerging contaminants, widely used by modern society. This objective ensures availability and sustainable management of water and sanitation for all, according to the 2030 Agenda. Wastewater treatment plants (WWTP) do not always mitigate the presence of these emerging contaminants in effluents discharged into the environment, although the removal efficiency of WWTP varies based on the techniques used. This main subject is framed within a broader environmental paradigm, such as the transition to a circular economy. The research and innovation within the WWTP will play a key role in improving the water resource management and its surrounding industrial and natural ecosystems. Even though bioremediation is a green technology, its integration into the bio-economy strategy, which improves the quality of the environment, is surprisingly rare if we compare to other corrective techniques (physical and chemical). This work carries out a bibliographic review, since the beginning of the 21st century, on the biological remediation of some PPCPs, focusing on organisms (or their by-products) used at the scale of laboratory or scale-up. PPCPs have been selected on the basics of their occurrence in water resources. The data reveal that, despite the advantages that are associated with bioremediation, it is not the first option in the case of the recovery of systems contaminated with PPCPs. The results also show that fungi and bacteria are the most frequently studied microorganisms, with the latter being more easily implanted in complex biotechnological systems (78% of bacterial manuscripts vs. 40% fungi). A total of 52 works has been published while using microalgae and only in 7% of them, these organisms were used on a large scale. Special emphasis is made on the advantages that are provided by biotechnological systems in series, as well as on the need for eco-toxicological control that is associated with any process of recovery of contaminated systems.
The Ecuadorian Amazon rainforest stands out as one of the world's most biodiverse regions, yet faces significant threats due to oil extraction activities dating back to the 1970s in the northeastern ...provinces. This research investigates the environmental and societal consequences of prolonged petroleum exploitation and oil spills in Ecuador's Amazon. Conducted in June 2015, the study involved a comprehensive analysis of freshwater sediment samples from 24 locations in the Rio Aguarico and Napo basins. Parameters such as water and air temperature, conductivity, soil pH, and hydrocarbon concentrations were examined. Total petroleum hydrocarbon (TPH) concentrations ranged from 9.4 to 847.4 mg kg
, with polycyclic aromatic hydrocarbon (PAH) levels varying from 10.15 to 711.1 mg kg
. The pristane/phytane ratio indicated historic hydrocarbon pollution in 8 of the 15 chemically analyzed sediments. Using non-culturable techniques (Illumina), bacterial analyses identified over 350 ASV, with prominent families including
,
,
,
, and
. Bacterial diversity, assessed in eight samples, exhibited a positive correlation with PAH concentrations. The study provides insights into how microbial communities respond to varying levels of hydrocarbon pollution, shedding light on the enduring impact of oil exploitation in the Amazonian region. Its objective is to deepen our understanding of the environmental and human well-being in the affected area, underscoring the pressing need for remedial actions in the face of ongoing ecological challenges.
Diesel fuel storage tanks are not hostile environments for microorganisms and tend to form sludges in the water deposited at the bottom of the tanks. The lack of nutrient, carbon and energy ...limitations within these habitats boost the abundance and the metabolic activity of microorganisms providing microbial hotspots with high growing rates of diesel degradation (0.10 ± 0.021 d
−1
). Five different Phyla (Thermotogae, Spirochaetes, Firmicutes, Bacteroidetes Proteobacteria) were identified within the aqueous/sludge phase from in situ diesel storage tanks, by cultured independent molecular surveys using the 16S rDNA gene fragment. The identified dominant strains were
Geotoga aestuarianus
,
Flavobacterium ceti
,
Spirochaeta thermophila
,
Propionispira arboris
,
Sporobacterium olearium
and
Dysgonomonas
genera. The altitude where the storage tanks are located and the organic carbon concentration within the aqueous/sludge phases affected the bacterial diversity. Therefore, the more diverse the microbial communities are, the more probability of the presence of bacteria with capacity to metabolized diesel and eliminate organic matter. Despite, only phosphate showed an effect on the bacterial distribution within the storage tanks, there was an apparent lack of deterministic process in structuring microbial communities. Consequently, preventative protocols are a priority to avoid the microbial growth within diesel fuel storage tanks. A new focus of this worldwide problem within the oil industry would be to explore deeply the wide range of metabolic and adaptive capacities of these microorganisms. These microbial consortia are potential tools with new specific services to apply in bioremediation among others.
Graphical Abstract
Microbes are key players in oceanic carbon fluxes. Temperate ecosystems are seasonally variable and thus suitable for testing the effect of warming on microbial carbon fluxes at contrasting ...oceanographic conditions. In four experiments conducted in February, April, August and October 2013 in coastal NE Atlantic waters, we monitored microbial plankton stocks and daily rates of primary production, bacterial heterotrophic production and respiration at in situ temperature and at 2 and 4°C over ambient values during 4-day incubations. Ambient total primary production (TPP) exceeded total community respiration (< 200 μm, TR) in winter and fall but not in spring and summer. The bacterial contribution to ecosystem carbon fluxes was low, with bacterial production representing on average 6.9 ± 3.2% of TPP and bacterial respiration (between 0.8 and 0.2 μm) contributing on average 35 ± 7% to TR. Warming did not result in a uniform increase in the variables considered, and most significant effects were found only for the 4°C increase. In the summer and fall experiments, under warm and nutrient-deficient conditions, the net TPP/TR ratio decreased by 39 and 34% in the 4°C treatment, mainly due to the increase in respiration of large organisms rather than bacteria. Our results indicate that the interaction of temperature and substrate availability in determining microbial carbon fluxes has a strong seasonal component in temperate planktonic ecosystems, with temperature having a more pronounced effect and generating a shift toward net heterotrophy under more oligotrophic conditions as found in summer and early fall.
So far, the relative importance of the plant and its microbiome in the development of early stages of plant seedling growth under arsenic stress has not been studied. To test the role of endophytic ...bacteria in increasing plant success under arsenic stress, gnotobiotic seeds of
were inoculated with two endophytic bacteria:
MC-K1 (PGPB and As resistant bacteria) and
sp. MC-D3A (non-helper and non-As resistant bacteria) and an endobacteria mixture. In holobiotic seedlings (with seed-vectored microbes intact), neither the capacity of germination nor development of roots and lateral hairs was affected at 125 μM As(V). However, in gnotobiotic seedlings, the plants are negatively impacted by absence of a microbiome and presence of arsenic, resulting in reduced growth of roots and root hairs. The inoculation of a single PGPB (
-MCK1) shows a tendency to the recovery of the plant, both in arsenic enriched and arsenic-free media, while the inoculation with
sp. does not help in the recovery of the plants. Inoculation with a bacterial mixture allows recovery of plants in arsenic free media; however, plants did not recover under arsenic stress, probably because of a bacterial interaction in the mixture.
Domestic wastewater treatment by purple phototrophic bacteria (PPB) is based on the assimilative uptake of organics and nutrients into the bacterial biomass. Thereby, it strongly depends on the ...carbon/nutrients ratio of the wastewater. The physiological COD/N/P ratio for PPB growth in domestic wastewater makes the addition of an external organic carbon source necessary in order to allow for an efficient process. However, PPB need a source of alkalinity (as CO2) to grow on reduced organics that serves as an electron acceptor since biohydrogen production (an alternative electron sink) is inhibited by ammonium. A preliminary experiment showed that high nutrients-loading wastewater was limited by CO2 imbalance, leading to poor removal efficiencies. Subsequently, the effect of the oxidation state of the organics added as external organic carbon sources to PPB reactors treating low nutrients-loading domestic wastewater has been analyzed. Three organics were used as additives to PPB development in four consecutive batches: acetate (more oxidized), ethanol and butyrate (more reduced). The PPB population was settled and the general performance under the three situations, in terms of organics, N and P assimilation, and growth kinetics was not significantly different irrespective of the external organic carbon source. The reactors were dominated by PPB, though reduced organics allowed for dominance of Rhodopseudomonas palustris, whereas oxidized organics caused co-dominance of R. palustris and Rhodobacter capsulatus. Thereby, alkalinity (as bicarbonate), and not the oxidation state of the organics, is the key parameter for the efficient treatment of domestic wastewater by PPB.
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