Reconstructing genomes of carbon monoxide oxidisers in volcanic deposits including members of the class Ktedonobacteria

Microorganisms can potentially colonise volcanic rocks using the chemical energy in reduced gases such as methane, hydrogen (H2) and carbon monoxide (CO). In this study, we analysed soil metagenomes from Chilean volcanic soils, representing three different successional stages with ages of 380, 269 and 63 years, respectively. A total of 19 metagenome-assembled genomes (MAGs) were retrieved from all stages with a higher number observed in the youngest soil (1640: 2 MAGs, 1751: 1 MAG, 1957: 16 MAGs). Genomic similarity indices showed that several MAGs had amino-acid identity (AAI) values >50% to the phyla Actinobacteria, Acidobacteria, Gemmatimonadetes, Proteobacteria and Chloroflexi. Three MAGs from the youngest site (1957) belonged to the class Ktedonobacteria (Chloroflexi). Complete cellular functions of all the MAGs were characterised, including carbon fixation, terpenoid backbone biosynthesis, formate oxidation and CO oxidation. All 19 environmental genomes contained at least one gene encoding a putative carbon monoxide dehydrogenase (CODH). Three MAGs had form I coxL operon (encoding the large subunit CO-dehydrogenase). One of these MAGs (MAG-1957-2.1, Ktedonobacterales) was highly abundant in the youngest soil. MAG-1957-2.1 also contained genes encoding a [NiFe]-hydrogenase and hyp genes encoding accessory enzymes and proteins. Little is known about the Ktedonobacterales through cultivated isolates, but some species can utilise H2 and CO for growth. Our results strongly suggest that the remote volcanic sites in Chile represent a natural habitat for Ktedonobacteria and they may use reduced gases for growth

Smart fertilizers as a strategy for sustainable agriculture

In the coming decades there will be increasing pressure on global food systems, and agriculture will have the challenge to provide food security for a growing world population without impacting environmental security. Accordingly, it will be necessary to use modern technologies in agroecosystems in order to supply sufficient food and decrease the negative impacts on the environment induced by chemical fertilization and by inadequate disposal or reuse of agricultural wastes. A combination of biotechnology and nanotechnology has the potential to revolutionize agricultural systems and provide solutions for current and future problems. These include the development and use of smart fertilizers with controlled nutrient release, together with bioformulations based on bacteria or enzymes. This study was designed to provide a critical review of information related to current food security issues and the role of smart fertilizer development in future food production. We concentrate on advances in the development of controlled-release biofertilizers and the use of harvesting residues as coating and carrier materials

Closing Biogeochemical Cycles and Meeting Plant Requirements by Smart Fertilizers and Innovative Organic Amendments

Expansion of farmland with food production as a major service has been largely associated with conversion of natural ecosystems like the Amazon and Savanna into new agricultural land [...

Nanominerals and biochar as additives in the composting of agricultural waste: effects on GHG emissions, composition and biodegradability of end-products on grassland soils.

Presentación y abstract EGU2020-21430The utilization of additives is a strategy commonly used in composting operations to enhance the physicochemical properties and optimize the process. However, little is known about the impact of nanominerals, biochar and their combination during composting. The objective of this research was to evaluate the effects of iron oxide/halloysite nanominerals and oat hull-biochar as additives in the physicochemical properties of an aerobic composting process, the emission of greenhouse gases (GHG) and the composition of end-products. In order to analyze the biodegradability of composting end-products in grassland soils, an incubation experiment was also carried out. Wheat straw, lupine and beef manure were mixed (C/N: ~25) with iron oxide (Fe) or halloysite (Ha) nanoparticles (2% w/w), oat hull-biochar (B) (7% w/w) and their combination (BFe, BHa). pH, EC, C/N ratio, NH4-NO3 contents and the emission of CO2 and CH4 were analyzed. After 128 days of aerobic composting process, the end-products and their NaOH soluble fraction were characterized by using spectroscopic analysis that included E4/E6 ratio and solid state nuclear magnetic resonance (13CNMR). To analyze the biodegradability of produced compost in grassland soils, a respiration experiment (60 days) using Respicond Apparatus IV, combined with ¿13C isotopic analysis was conducted. A decrease of final C/N ratio was observed in all treatments that was lower in B treated compost. Nitrate concentration increased as composting progressed, and compost supplied with Ha showed the higher final content of NO3 (5800 mg kg-1) and NH4 (220 mg kg-1). The addition of B significantly decreased the mean emission of both CO2 (~400 g CO2 m2 d-1) and CH4 (~4.5 g CH4 m2 d-1). Nanominerals significantly decreased the final E4/E6 ratio (<6) and the addition of B increased the aromaticity (twice), the alkyl-C/O alkyl-C ratio and the hydrophobicity which are parameters associated to stabilized end-products. In soil, the incorporation of additives reduced the loss of C (<5% after 60 days of incubation). Treatments supplied with B and Ha showed a higher mean residence time (8 and 5 years respectively) than compost without additives. These results suggest that the addition of halloysite and biochar to composting operations have significant effects on C stabilization and biodegradability of compost in grassland soils, that is relevant in the production of C sequestrant amendments

Addition of nanoparticles and biochar to agricultural waste composting: effects on composting process and CO2-CH4 emissions

Comunicación oral presentada en el ISMOM 2019 - 8th International Symposium on Interactions of Soil Minerals with Organic Components and Microorganisms: (Abstract number: A 5.21), 23-28 june, Sevilla (Spain)Little is known about the impact of inorganic nanoparticles as additives in composting systems. The objective of this research was to evaluate the effects of iron oxide/halloysite nanoparticles and biochar as additives in the main physical and chemical properties and greenhouse gas (GHG) emissions of agricultural waste composting. Wheat straw and beef manure were mixed (2:1 w/w; C/N: 25) and co-composted with iron oxide (CFe) and halloysite (CHa) nanoparticles (2% w/w) oat-biochar (CB) (7% w/w) and their combination (CBFe CBHa). Changes in pH and EC organic matter (OM) losses NH4-NO3 concentration C/N and E4/E6 ratio and the emissions of CO2 and CH4 were analyzed. Additionally the initial mixtures and end-products were characterized by nuclear magnetic resonance (13C NMR). Additives slightly affected pH (final pH about 8.0) and increased the electroconductivity of mixtures. Nanoparticles biochar and their combination reduced the OM and C losses (about 15%) compared to control without additives. A decrease of C/N ratio between initial and end-products were also observed in all treatments and lower differences were observed in treatments with additives. Nitrate concentration increased as composting progressed. CHa showed the higher mean concentration of NO3 (2500 mg kg-1) and NH4 (120 mg kg-1). Conversely CBFe and CBHa showed the lower mean concentration of NH4 (60 mg kg-1). Nanoparticles significantly decreased the final E4/E6 ratio (<6) and the addition of biochar and its combination with nanoparticles increased the aromaticity (twice) the alkyl-C/O alkyl-C ratio and the hydrophobicity which are parameters associated to stabilized end-products. Clear relative diminution of O alkyl-C region (50%) associated to carbohydrates was observed in treatments with additives suggesting an active composting process. Furthermore the addition of biochar (CB) significantly decreased the mean emission of both CO2 (~400 g CO2 m2 d-1) and CH4 (4.5 g CH4 m2 d-1) during the process. These results suggest that the addition of iron oxide/halloysite nanoparticles biochar and their combination as co-composting additives had important effects on composting process GHG emissions and chemical composition of the end-products.FONDECYT/CONICYT Project N° 3170677

Optimization of wheat straw co-composting for carrier material development

International audienceIn modern agriculture large amounts of harvesting residues are produced each year due to the increase of agricultural activities in order to maintain food production for the growing population. The development of innovative fertilizers, able to satisfy nutrient needs without adverse effects on the environment. In order to allow for effective production of a carrier material for smart fertilizers, the objective of this study is to propose a statistical method to optimize the water holding capacity (WHC) and organic matter stability properties of co-composted wheat straw (WS) by using a multi response method. We varied WS size (2 cm), charge of Trichoderma harzianum (0, 7 and 14 discs), and nitrogen addition (0, 0.95 and 1.95 g kg(-1)). Optimized carrier material was characterized by a higher porosity (WHC 91.7%) than raw WS, associated to structural changes and slightly increased stability as indicated by C:N ratio of the 59.5, slightly alkaline (pH similar to 8.0), with high OM structural complexity (E-4:E-6 similar to 7,9) and enhanced sorption properties (total acidity similar to 11.6). We conclude that the optimal treatment included co-composting of WS with fine particle size (<1 cm), with a charge of T. harzianum (14 discs), and 0.98 g kg(-1) of NH4NO3 to obtain a suitable WS carrier material with high possibility to improve nutrient and water holding capacity in soil

Influence of saprophytic fungi and inorganic additives on enzyme activities and chemical properties of the biodegradation process of wheat straw for the production of organo-mineral amendments

Cellulose and lignin as main components of crop residues have a significant influence on composting operations and composition of the final products. Both are strongly associated, and lignin can be considered an important barrier during the biodegradation process of lignocellulosic materials. Saprophytic fungi are efficient lignin degraders due to their complex enzymatic system. Therefore, the influence of the inoculation of saprophytic fungi (Coriolopsis rigida, Pleurotus ostreams, Trichoderma harzianum and Trametes versicolor) and the supply of inorganic additives (Al2O3, Fe2O3 and allophanic soil) that promote the stabilization of carbon (C), were analyzed in the biodegradation of wheat straw (WS). The activity of Laccase (LAC), manganese peroxidase (MnP) and beta-glucosidase and changes in temperature, pH and E-4/E-6 ratio were analyzed in a biodegradation process of 126 days. The activity of LAC, MnP and the E-4/E-6 ratio were significantly influenced and increased (enzymes) by fungi species, inorganic additives, and time of inorganic material addition, as well as their interactions (p < 0.05). The WS inoculated with T. versicolor showed the highest average activities for LAC, MnP and beta-glucosidase (2000, 220 UL-1 and 400 mu mol pNP g(-1) h(-1) respectively). Furthermore, the addition of Al2O3 and Fe2O3 increased all the activities regarded to the decomposition of WS and influenced the changes associated with the stabilization of OM in composted WS. In conclusion, the inoculation of WS with T. versicolor in combination with metal oxides improved the enzyme related to the biodegradation process of WS favorizing its stabilization in the medium time, which is of importance in the composting of residues with high C/N ratio

Chemical nature of residual phosphorus in Andisols

International audienceSequential fractionation has been widely used to study the nature and dynamics of soil P. Residual P - the recalcitrant P fraction remaining after sequential extraction with alkali and acid reagents - often constitutes the majority of the soil P, yet its nature and bioavailability is poorly understood. The objective of this study was to isolate, quantify, and characterize residual P following Hedley fractionation in a range of Andisols under grazed pasture by 31P nuclear magnetic resonance (NMR) spectroscopy. Residual P accounted for 45-63% of the total soil P, of which 53-77% was inorganic orthophosphate. Organic P accounted for 21-42% of the residual P, the majority of which occurred as phosphomonoesters including myo- (16% of the residual P) and scyllo-inositol hexaldsphosphate (10% of the residual P). No phosphodiesters were detected in the residual fraction. We conclude that residual P in Andisols consists of a mixture of inorganic P and organic P. Our findings provide the basis for the development of new approaches to improve P use efficiency in agriculture

Utilization of inorganic nanoparticles and biochar as additives of agricultural waste composting : Effects of end-products on plant growth, c and nutrient stock in soils from a mediterranean region

This study was conducted to evaluate the effect of compost produced with agricultural residues and oat-based biochar, iron oxide and halloysite nanoparticles as additives of the process of composting on soil chemical properties, nutrient status and growth of ryegrass Lolium perenne L. For this, a 90-day mesocosm experiment was carried out under greenhouse conditions. Bare soil and a basal fertilization treatment were compared to soils amended with nonadditive compost (NA compost), compost supplied with oat-based biochar (Bioch compost), iron oxide nanoparticles (Fe compost), and halloysite nanoparticles (Ha compost). Compost supplied with nanoparticles and biochar combined were also considered. The incorporation of compost with or without additives increased the content of total C and N in soil, with N diminishing (total and mineral forms) and C/N modifications after 90 days. The addition of compost and co-composted treatments also increased the total contents of main nutrients such as Ca, K, P and S. Furthermore, the supply of additives into composting did not increase the concentration of trace toxic elements. At the end of the experiment, plant biomass increased by the addition of the different organic amendments, with the highest shoot biomass in soils amended with compost supplied with nanoparticles. These results suggest that the addition of compost based on agricultural residues with additives such as halloysite or biochar improves chemical properties and nutritional status of soil that favor and increase plant growth of Lollium perenne stablished in soils from the Mediterranean Region

Influence of inorganic additives on wheat straw composting: Characterization and structural composition of organic matter derived from the process

10 páginas.- 3 figuras.- 6 tablas.- referencias.-Metallic oxides and clay minerals have gained increasing interest as additives of composting due to their influence in greenhouse gas emissions reduction and their effectivity in the stabilization of carbon both in compost and soils, leading to a cleaner compost production and potentially C sequestrant amendments. In this study, wheat straw (WS) was co-composted with iron oxide and allophanic soil and their influence on WS composting and composition of the end-products was evaluated. WS compost and their humic like-substances (HS) fraction were characterized by chemical and spectroscopic analyzes. After 126 days of process, the elemental composition showed slight differences of the N content for compost and HS, where the C/N atomic ratio tended to decrease relative to the initial material (WS; ~130). This trend was more pronounced in the HS from co-composted treatments (<30). The addition of inorganic materials increased the total acidity and phenolic-OH group contents (~15 and 14 mEq g−1 respectively, iron oxide treatment) relative to the treatment without inorganic additives. Nevertheless, the FTIR and solid-state 13CNMR spectroscopy barely support the wet chemical analysis and revealed a similar final composition between all the studied compost treatments. These results suggest that the incorporation of these materials as compost additives had no major effect on the spectroscopic features of the end-products, however, critical changes of the properties such as the extractability, functionality and composition of HS were revealed by traditional methods. In conclusion, the supply of metal oxides and clays could impact the aerobic composting of WS favorizing the stabilization of certain C pools and adsorptive properties of the end-products, that is of importance in production of amendments suitable for being used in degraded and contaminated soils. Nevertheless, under the experimental conditions of our research C stabilization apparently depends of other mechanisms that still need to be elucidate.The authors thank the Comisión Nacional de Investigación Científica y Tecnológica (CONICYT-Chile), for the economic support through the program CONICYT/FONDECYT/1170264 and CONICYT/FONDAP/15130015 (P. Cornejo). H. Knicker thanks the Ministerio de Ciencia, Innovacion y Universidades of Spain and the European Regional Development Fund for financial support through the project CGL2015-64811-P. J. Medina and M. Calabi-Floody thanks CONICYT for the financial support through the CONICYT/FONDECYT/3170677 grant and CONICYT/FONDECYT/11150555 grant, respectively. M. Antilén and P. Cornejo also thank CONICYT for the economic support through the project CONICYT-PIA Rings in Mining Topics ACM170002.Peer reviewe