Composting has been traditionally considered a process in which a succession of mesophilic and thermophilic microbial populations occurs due to temperature changes. In order to deepen in this model, ...1380 bacterial and fungal strains (the entire culturable microbiota isolated from a composting process) were investigated for their ability to grow across a wide range of temperatures (20 to 60 °C). First, qualitative tests were performed to establish a thermal profile for each strain. Then, quantitative tests allowed ascertaining the extent of growth for each strain at each of the tested temperatures. The identity of the isolates enabled to position them taxonomically and permitted tracking the strains throughout the process. Results showed that 90% of the isolates were classified as thermotolerant (they grew at all tested temperatures). Only 9% and 1% of the studied strains showed to be strictly mesophilic or thermophilic, respectively. Firmicutes exhibited the greatest thermal plasticity, followed by Actinobacteria and Ascomycota. Most of the Proteobacteria and all Basidiomycota strains were also able to grow at all the assayed temperatures. Thermotolerance was clearly demonstrated among the composting microbiota, suggesting that the idea of the succession of mesophilic and thermophilic populations throughout the process might need a reassessment.
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•The temperature-driven succession of the composting microbial populations was revisited.•Thermotolerance was demonstrated for a vast majority of the composting microbiota.•Thermotolerant strains were repeatedly identified in most of the composting stages.•Firmicutes and Ascomycota accounted for the best represented thermotolerant phyla.•Thermal plasticity is a microbial reply to the ever changing composting conditions.
Abstract
The use of rhizobacteria provide great benefits in terms of nitrogen supply, suppression of plant diseases, or production of vitamins and phytohormones that stimulate the plant growth. At ...the same time, cyanobacteria can photosynthesize, fix nitrogen, synthesize substances that stimulate rhizogenesis, plant aerial growth, or even suppose an extra supply of carbon usable by heterotrophic bacteria, as well as act as biological control agents, give them an enormous value as plant growth promoters. The present study focused on the in vitro establishment of consortia using heterotrophic bacteria and cyanobacteria and the determination of their effectiveness in the development of tomato seedlings. Microbial collection was composed of 3 cyanobacteria (SAB-M612 and SAB-B866 belonging to
Nostocaceae
Family) and GS (unidentified cyanobacterium) and two phosphate and potassium solubilizing heterotrophic bacteria (
Pseudomonas putida
-BIO175 and
Pantoea cypripedii
-BIO175). The results revealed the influence of the culture medium, incubation time and the microbial components of each consortium in determining their success as biofertilizers. In this work, the most compatible consortia were obtained by combining the SAB-B866 and GS cyanobacteria with either of the two heterotrophic bacteria. Cyanobacteria GS promoted the growth of both rhizobacteria in vitro (increasing logarithmic units when they grew together). While Cyanobacteria SAB-B866 together with both rhizobacteria stimulated the growth of tomato seedlings
in planta
, leading to greater aerial development of the treated seedlings. Parameters such as fresh weight and stem diameter stood out in the plants treated with the consortia (SAB-B866 and both bacteria) compared to the untreated plants, where the values doubled. However, the increase was more discrete for the parameters stem length and number of leaves. These results suggest that the artificial formulation of microbial consortia can have positive synergistic effects on plant growth, which is of enormous agro-biotechnological interest.
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•Intense turnover of organic matter was induced by inoculation of composting piles.•More simple compounds were released from polymeric fractions in inoculated piles.•Humification was ...more intense and earlier achieved in inoculated piles.•Inoculation clearly stimulated growth and activity of the composting microbiota.•Inoculation affected microbiota structure but its functionality remained unaltered.
Enhanced organic matter turnover was detected in lignocellulosic composting piles inoculated with microorganisms specifically capable of decomposing polymeric compounds. In comparison to uninoculated piles, the following results were obtained in the inoculated piles: degradation of hemicellulose, cellulose and lignin were 28%, 21% and 25% respectively higher. Total organic matter, total sugars and phenolic compounds also decreased more intensely. Greater amounts of soluble organic carbon, reducing sugars and soluble proteins were available to the composting microbiota. Recycling of organic to inorganic nitrogen was improved and humification was more intense and earlier attained. Microbial community structure was also affected by inoculation. It was initially thought that these effects were due to enzymatic capabilities of inoculants, however, microbial counts, especially those corresponding to functional groups, revealed that inoculation induced a true stimulation of microbial growth and activity in the entire composting microbiota which was actually responsible for all the beneficial effects reported here.
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•Heterogeneity of composting process hinds the establishment of bioindicators.•Biodiversity and respirometric index affect phytostimulant power of compost.•Phenolic content and ...nitrification index could impact compost biodiversity.•Compost biodiversity is greater the lower the activity of xylanase.•Different raw materials evolve similar products by different bioestrategies.
Currently, the metagenomic study of the composting process has gained great importance since it has allowed the identification of the existence of microorganisms that, until now, had not been isolated during the process by traditional techniques. However, it is still complex to determine which bioindicators could reveal the degree of maturity and stability of a particular compost. Thereby, the main objective of this work was to demonstrate the possible correlation between traditional parameters of maturity and stability of compost, with other indicators of biodiversity in products highly heterogeneous from composting processes on an industrial scale.
The results demonstrated the enormous influence of the raw materials in characterizing the products obtained. Even so, important relationships were established between the Chao1 and Shannon indexes, and certain parameters related to the maturity, stability and toxicity of the samples, such as nitrification index, humification rate, phenolic content, germination index or oxygen consumption.
Cyanogen (NCCN) is the simplest member of the series of dicyanopolyynes. It has been hypothesized that this family of molecules can be important constituents of interstellar and circumstellar media, ...although the lack of a permanent electric dipole moment prevents its detection through radioastronomical techniques. Here we present the first solid evidence of the presence of cyanogen in interstellar clouds by detection of its protonated form toward the cold dark clouds TMC-1 and L483. Protonated cyanogen (NCCNH+) has been identified through the J = 5−4 and J = 10−9 rotational transitions using the 40 m radiotelescope of Yebes and the IRAM 30 m telescope. We derive beam-averaged column densities for NCCNH+ of (8.6 ± 4.4) × 1010 cm-2 in TMC-1 and (3.9 ± 1.8) × 1010 cm-2 in L483, which translate into fairly low fractional abundances relative to H2, in the range (1–10) × 10-12. The chemistry of protonated molecules in dark clouds is discussed, and it is found that, in general terms, the abundance ratio between the protonated and non-protonated forms of a molecule increases with increasing proton affinity. Our chemical model predicts an abundance ratio NCCNH+/NCCN of ~10-4, which implies that the abundance of cyanogen in dark clouds could be as high as (1–10) × 10-8 relative to H2, i.e., comparable to that of other abundant nitriles such as HCN, HNC, and HC3N.
Many alternatives for the proper disposal of horticultural plant wastes have been studied, and composting is one of the most attractive due to its insignificant environmental impact and low cost. The ...quality of compost for agronomical use is related to the degree of organic matter maturation and stabilization. Traditional parameters as well as temperature, ratio C/N, cationic exchange capacity, extractable carbon, or evolution of humificated substances have been successfully used to assess compost maturity and stability. However, microorganisms frequently isolated during composting release a wide range of hydrolytic enzymes, whose activity could apparently give interesting information on the rate of decomposition of organic matter and, therefore, on the product stability. The aim of this work was to study the evolution of some important enzymatic activities during composting of agricultural wastes and their comparison with other chemical parameters commonly employed as quality and maturity indexes, to establish a relationship between the degradation intensity of specific organic carbon fractions throughout the process. In this work, the chemical and biochemical parameters of plant wastes were studied along a composting process of 189 days to evaluate their importance as tools for compost characterization. Results showed an intense enzymatic activity during the first 2–3 weeks of composting (bio-oxidative phase), because of the availability of easily decomposable organic compounds. From a biological point of view, a less intense phase was observed between second and third month of composting (mesophilic or cooling phase). Finally, chemical humification parameters were more closely associated with the period between 119 and 189 days (maturation phase). Significant correlations between the enzymatic activities as well as between enzyme activities and other more traditional parameters were also highlighted, indicating that both kind of indexes can be a reliable tool to determine the degree of stability and maturation of horticultural plant wastes based-compost.
•Enzymatic and temperature patterns registered inside the pile are directly related.•Enzymatic activity reaches its peak during the first days of the composting process.•When piles begin to cool, the enzymatic activity decreases noticeably.•The intensity of the enzymatic activity indirectly affects the humification process.
Microorganisms drive the degradation of organic matter thanks to their enzymatic versatility. However, the structure of lignocellulose poses a great challenge for the microbiota inhabiting a compost ...pile. Our purpose was to increase the biodegradability of vegetable waste in the early stages of the composting process by applying a microbial consortium with lignocelllulolytic capacity. For this, a previous screening was performed among the culturable microbiota from different composting processes to find inoculants with ligninocellulolytic activity. Selected strains were applied as a pure culture and as a microbial consortium. The starting material was composed of tomato plant and pruning remains mixed in a ratio (50:50 v/v), whose humidity was adjusted to around 65%. To determine the ability of both treatments to activate the biodegradation of the mixtures, moisture, organic matter, ash, C/N ratio, 4-day cumulative respirometric index (AT4) and degradation rates of cellulose, hemicellulose and lignin were evaluated. Subsequently, a real composting process was developed in which the performance of the microbial consortium was compared with the composting process without inoculum (control). According to our tests, three microbial strains (Bacillus safensis, Bacillus licheniformis and Fusarium oxysporum) were selected. The results showed that the application of the bacteria strains at low doses (104 CFU g−1 on the complete residual material of the pile) resulted in higher rates of lignocelullose degradation after 10 days of treatment compared to that observed after application of the fungus in pure culture or untreated controls. The implementation of the strategy described in this work resulted in obtaining compost with better agronomic quality than the uninoculated controls. Therefore, the application of this consortium could be considered as an interesting tool for bioactivation of lignocellulosic waste prior to the composting process.
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•Resident lignocellulolytic microbiota is useful to improve the composting process.•A simple protocol for the pretreatment of plant wastes was developed.•Bacillus spp. represent an excellent biotechnological tool in composting processes.•10 days of pretreatment at low inoculum doses improves the final product quality.
Nowadays, atom-based quantum sensors are leaving the laboratory towards field applications requiring compact and robust laser systems. Here we describe the realization of a compact laser system for ...atomic gravimetry. Starting with a single diode laser operating at 780 nm and adding only one fiber electro-optical modulator, one acousto-optical modulator and one laser amplifier we produce laser beams at all the frequencies required for a Rb-87 atomic gravimeter. Furthermore, we demonstrate that an atomic fountain configuration can also be implemented with our laser system. The modulated system reported here represents a substantial advance in the simplification of the laser source for transportable atom-based quantum sensors that can be adapted to other sensors such as atomic clocks, accelerometers, gyroscopes or magnetometers with minor modifications.
The abuse of chemical fertilizers in recent decades has led the promotion of less harmful alternatives, such as compost or aqueous extracts obtained from it. Therefore, it is essential to develop ...liquid biofertilizers, which in addition of being stable and useful for fertigation and foliar application in intensive agriculture had a remarkable phytostimulant extracts. For this purpose, a collection of aqueous extracts was obtained by applying four different Compost Extraction Protocols (CEP1, CEP2, CEP3, CEP4) in terms of incubation time, temperature and agitation of compost samples from agri-food waste, olive mill waste, sewage sludge and vegetable waste. Subsequently, a physicochemical characterization of the obtained set was performed in which pH, electrical conductivity and Total Organic Carbon (TOC) were measured. In addition, a biological characterization was also carried out by calculating the Germination Index (GI) and determining the Biological Oxygen Demand (BOD5). Furthermore, functional diversity was studied using the Biolog EcoPlates technique. The results obtained confirmed the great heterogeneity of the selected raw materials. However, it was observed that the less aggressive treatments in terms of temperature and incubation time, such as CEP1 (48 h, room temperature (RT)) or CEP4 (14 days, RT), provided aqueous compost extracts with better phytostimulant characteristics than the starting composts. It was even possible to find a compost extraction protocol that maximize the beneficial effects of compost. This was the case of CEP1, which improved the GI and reduced the phytotoxicity in most of the raw materials analyzed. Therefore, the use of this type of liquid organic amendment could mitigate the phytotoxic effect of several composts being a good alternative to the use of chemical fertilizers.
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•Compost extracts improve the biofertilizing characteristics of the compost.•Temperature and incubation periods mainly determine the quality of the extracts.•The phytotoxic effect of composts is reduced by the use of compost extracts.•Moderate temperatures guarantee the preservation of microbial functionality.
Yebes 40m radio telescope is the main and largest observing instrument at Yebes Observatory and it is devoted to Very Long Baseline Interferometry (VLBI) and single dish observations since 2010. It ...has been covering frequency bands between 2 GHz and 90 GHz in discontinuous and narrow windows in most of the cases, to match the current needs of the European VLBI Network (EVN) and the Global Millimeter VLBI Array (GMVA).
Nanocosmos project, a European Union funded synergy grant, opened the possibility to increase the instantaneous frequency coverage to observe many molecular transitions with single tunnings in single dish mode. This reduces the observing time and maximises the output from the telescope.
We present the technical specifications of the recently installed 31.5 - 50GHz (Q band) and 72 - 90.5 GHz (W band) receivers along with the main characteristics of the telescope at these frequency ranges. We have observed IRC+10216, CRL 2688 and CRL 618, which harbour a rich molecular chemistry, to demonstrate the capabilities of the new instrumentation for spectral observations in single dish mode.
The results show the high sensitivity of the telescope in the Q band. The spectrum of IRC+10126 offers a signal to noise ratio never seen before for this source in this band. On the other hand, the spectrum normalised by the continuum flux towards CRL 618 in the W band demonstrates that the 40 m radio telescope produces comparable results to those from the IRAM 30 m radio telescope, although with a smaller sensitivity. The new receivers fulfil one of the main goals of Nanocosmos and open the possibility to study the spectrum of different astrophysical media with unprecedented sensitivity.
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