Disentangling the Possible Drivers of Indri indri Microbiome: A Threatened Lemur Species of Madagascar.

Research on the gut microbiome may help with increasing our understanding of primate health with species' ecology, evolution, and behavior. In particular, microbiome-related information has the potential to clarify ecology issues, providing knowledge in support of wild primates conservation and their associated habitats. Indri (Indri indri) is the largest extant living lemur of Madagascar. This species is classified as "critically endangered" by the IUCN Red List of Threatened Species, representing one of the world's 25 most endangered primates. Indris diet is mainly folivorous, but these primates frequently and voluntarily engage in geophagy. Indris have never been successfully bred under human care, suggesting that some behavioral and/or ecological factors are still not considered from the ex situ conservation protocols. Here, we explored gut microbiome composition of 18 indris belonging to 5 different family groups. The most represented phyla were Proteobacteria 40.1 ± 9.5%, Bacteroidetes 28.7 ± 2.8%, Synergistetes 16.7 ± 4.5%, and Firmicutes 11.1 ± 1.9%. Further, our results revealed that bacterial alpha and beta diversity were influenced by indri family group and sex. In addition, we investigated the chemical composition of geophagic soil to explore the possible ecological value of soil as a nutrient supply. The quite acidic pH and high levels of secondary oxide-hydroxides of the soils could play a role in the folivorous diet's gut detoxification activity. In addition, the high contents of iron and manganese found the soils could act as micronutrients in the indris' diet. Nevertheless, the concentration of a few elements (i.e., calcium, sulfur, boron, nickel, sodium, and chromium) was higher in non-geophagic than in geophagic soils. In conclusion, the data presented herein provide a baseline for outlining some possible drivers responsible for the gut microbiome diversity in indris, thus laying the foundations for developing further strategies involved in indris' conservation.

I Like the Way You Eat It: Lemur (Indri indri) Gut Mycobiome and Geophagy.

Here, we investigated the possible linkages among geophagy, soil characteristics, and gut mycobiome of indri (Indri indri), an endangered lemur species able to survive only in wild conditions. The soil eaten by indri resulted in enriched secondary oxide-hydroxides and clays, together with a high concentration of specific essential micronutrients. This could partially explain the role of the soil in detoxification and as a nutrient supply. Besides, we found that soil subject to geophagy and indris' faeces shared about 8.9% of the fungal OTUs. Also, several genera (e.g. Fusarium, Aspergillus and Penicillium) commonly associated with soil and plant material were found in both geophagic soil and indri samples. On the contrary, some taxa with pathogenic potentials, such as Cryptococcus, were only found in indri samples. Further, many saprotrophs and plant-associated fungal taxa were detected in the indri faeces. These fungal species may be involved in the digestion processes of leaves and could have a beneficial role in their health. In conclusion, we found an intimate connection between gut mycobiome and soil, highlighting, once again, the potential consequent impacts on the wider habitat.

Fourteen years of compost application in a commercial nectarine orchard: effect on microelements and potential harmful elements in soil and plants.

The objective of this experiment was to valuate, after 14 years, the impact of annual compost applications on micronutrient and potentially toxic trace elements on nectarine tree uptake and soil fertility. The study was performed in the Po valley, Italy, on the variety Stark RedGold (grafted on GF677). Since orchard planting, the following treatments were applied, in a randomized complete block design, with four replicates: 1. unfertilized control; 2. mineral fertilization (N was supplied as NO3NH4 at 70-130 kg ha-1 year-1); 3. compost at 5 t DW ha-1 year-1; 4. compost at 10 t DW ha-1 year-1. The actual rate of application was 12.5 (LOW) and 25 (HIGH) t ha-1, since compost was concentrated in the tree row. Compost was made from domestic organic wastes mixed with pruning material from urban ornamental trees and garden management and stabilized for 3 months. The supply of compost HIGH induced an enrichment of soil total Cu, Zn and Cd, and a decrease of Fe and Co concentration; with values always below the European threshold limits for heavy metals in the soil. In addition, compost (at both rates) increased availability (DTPA-extractable) of Fe, Mn and Zn, Cd, Ni, and Pb in the top soil (0-0.15 m). Total micronutrient and trace element tree content was not affected by fertilization treatments; however, the recycled fraction returned to the soil at the end of the season through abscised leaves and pruned wood of Cu, Fe, Mn and Zn was increased by mineral fertilization; Fe and Zn also by compost HIGH. Our data show that the introduction of compost at both 12.5 and 25 t ha-1 year-1 in the row did not increase the risk of pollution related to potentially toxic trace elements and at the same time increased the bioavailability of Fe, Mn and Zn.

The fertilising potential of manure-based biogas fermentation residues: pelleted vs. liquid digestate.

Spreading of manure on agricultural soils is a main source of ammonia emissions and/or nitrate leaching. It has been addressed by the European Union with the Directives 2001/81/EC and 91/676/EEC to protect the environment and the human health. The disposal of manure has therefore become an economic and environmental challenge for farmers. Thus, the conversion of manure via anaerobic digestion in a biogas plant could be a sustainable solution, having the byproducts (solid and liquid digestates) the potential to be used as fertilizers for crops. This work aimed at characterizing and assessing the effect of digestates obtained from a local biogas plant (Biogas Wipptal, Gmbh), either in the form of liquid fraction or as a solid pellet on: (i) the fertility of the soils during an incubation experiment; (ii) the plant growth and nutritional status of different species (maize and cucumber). Moreover, an extensive characterization of the pellet was performed via X-ray microanalytical techniques. The data obtained showed that both digestates exhibit a fertilizing potential for crops, depending on the plant species and the fertilizer dose: the liquid fraction increases the shoot fresh weight at low dose in cucumber, conversely, the solid pellet increases the shoot fresh weight at high dose in maize. The liquid digestate may have the advantage to release nutrients (i.e. nitrogen) more rapidly to plants, but its storage represents the main constraint (i.e. ammonia volatilization). Indeed, pelleting the digestates could improve the storability of the fertilizer besides enhancing plant nutrient availability (i.e. phosphate and potassium), plant biomass and soil biochemical quality (i.e. microbial biomass and activity). The physical structure and chemical composition of pellet digestates allow nutrients to be easily mobilized over time, representing a possible source of mineral nutrients also in long-term applications.

Current and residual phosphorous availability from compost in a ryegrass pot test.

Compost can provide nitrogen (N) and especially phosphorous (P) available for plant growth, thus representing a potential alternative to chemical P-fertilizers a non-renewable resource. However, little is known about their residual capacity to provide plant-available P. In this study four compost: a green waste compost (GWC), one from anaerobically-digested bio-waste (DC), one from sewage sludge (SSC), and one from bio-waste (BWC), were compared (10 and 20 Mg VS ha-1) in a ryegrass pot test (112 days), for their N- and P-relative mineral fertilizer equivalence (MFE; %) vs. a chemical fertilizer (NPK). After the test period, the exploited treatments were tested for their MFE during an additional ryegrass growth cycle (112 days) in an N-rich environment (N+). After 112 days, the pot test showed that DC and SSC produced dry biomass in the same range as did NPK, attaining the best N-MFE (80-100%) and P-MFE (100-125%), whereas GWC and BWC performed poorly (60-80 and 80-90%; N-MFE and P-MFE). At the end of the first growth cycle, DC and SSC still showed relevant Olsen-P (20-30 mg kg-1). This was reflected in the best ryegrass P-MFE in DC and SSC at the end of the second growth cycle (N+), after 224 days (100-110%), whereas BWC and GWC poorly performed (90-95%). DC and SSC may therefore represent valuable sources of N available for plant nutrition in the short term, and also represent medium-term valuable P sources, alternative to rock phosphate P fertilizers. This promising approach need further field-scale investigation to confirm the medium-long term capacity of composts to be alternative to rock phosphate P fertilizers.

Soil-plant nitrogen pools in nectarine orchard in response to long-term compost application.

The search for sustainable source of N, the need of soil organic matter restoration, along with the call for recycling of organic wastes has led to a rise of the use of organic fertilizers. The aim of the present experiment was to evaluate: the effectiveness of compost application as a N fertilizer, the impact on N distribution in soil and plant and on tree performances, in a long-term experiment (14 years). The study was carried out in the Po valley, Italy and, since orchard planting (2001), the following treatments were applied: 1. unfertilized control; 2. mineral fertilization; 3. compost at a rate of 5 t DW ha-1 yr-1; 4. compost at a rate of 10 t DW ha-1 yr-1. Soil total N, potentially mineralizable, microbial and extractable N were higher in compost in comparison to mineral (fertilizer). The effect was found both in the row and in the inter-row and the rise of N fractions was evident in the shallowest soil layer of the row. Soil mineral, potentially mineralizable N was increased by mineral (11.1 mg kg-1) and compost 10 (12.4 mg kg-1) fertilization compared with control (6.7 mg kg-1). Vegetative growth and yield were increased in trees treated with mineral and compost 10; moreover, these plants were able to recycle (66.1 and 70.5 kg ha-1 yr-1, respectively) and remobilize (41.5 and 48.7 kg ha-1 yr-1, respectively) a higher amount of N than those of control and compost 5. In conclusion, organic fertilization strategy promoted the buildup of soil N reserve, meaning a capacity of the ecosystem to sequestrate N. The application of compost 10 showed a similar effect on plant growth and production as mineral fertilization, but introduced the advantage of the use of a cheap, renewable waste material, providing a new insight on N fertilization management.

Ecological restoration of a copper polluted vineyard: Long-term impact of farmland abandonment on soil bio-chemical properties and microbial communities.

This study aimed at investigating the degree of interference of high soil copper (Cu) contamination when an old vineyard is converted into a protected area. This study was performed within an intensive agricultural system; it was organized into a two-factorial nested design to analyze the impact of management (conventional vs re-naturalized orchard) and position within each orchard (tree-rows and strips). Chemical and biochemical properties along with bacterial and fungal communities, evaluated with PCR-DGGE starting from total soil DNA, were analyzed. Total Cu was localized in tree rows in the old vineyard at 1000 mg kg(-1) of soil, whereas it did not exceed 80 mg kg(-1) soil in the other treatments. Total organic carbon and all biochemical properties significantly improved in re-naturalized compared to conventionally cultivated site, while no significant differences were observed between tree row and strip. Moreover, a higher extractable carbon-extractable nitrogen (Cext-to-Next) ratio in the re-naturalized (19.3) site than in the conventionally managed site (10.2) indicated a shift of soil system from C-limited to N-limited, confirming a successful ecological restoration. Deep improvement of soil biochemical properties exceeded the negative impact of Cu contamination. A shift of bacterial community composition as well as increased bacterial diversity in Cu contaminated treatment indicated a bacterial response to Cu stress; to the contrary, soil fungi were less susceptible than bacteria, though an overall reduction of fungal DNA was detected. Findings suggest that ecological restoration of highly polluted agricultural soils leads to overcoming the reduction of soil functionalities linked to Cu contamination and opens interesting perspectives for mitigating Cu stress in agricultural soils with strategies based on conservative agriculture.

Relationships between stability, maturity, water-extractable organic matter of municipal sewage sludge composts and soil functionality.

Compost capability of restoring or enhancing soil quality depends on several parameters, such as soil characteristics, compost carbon, nitrogen and other nutrient content, heavy metal occurrence, stability and maturity. This study investigated the possibility of relating compost stability and maturity to water-extractable organic matter (WEOM) properties and amendment effect on soil quality. Three composts from municipal sewage sludge and rice husk (AN, from anaerobic wastewater treatment plants; AE, from aerobic ones; MIX, from both anaerobic and aerobic ones) have been analysed and compared to a traditional green waste compost (GM, from green manure, solid waste and urban sewage sludge). To this aim, WEOMs were characterized through chemical analysis; furthermore, compost stability was evaluated through oxygen uptake rate calculation and maturity was estimated through germination index determination, whereas compost impact on soil fertility was studied, in a lab-scale experiment, through indicators as inorganic nitrogen release, soil microbial biomass carbon, basal respiration rate and fluorescein di-acetate hydrolysis. The obtained results indicated that WEOM characterization could be useful to investigate compost stability (which is related to protein and phenol concentrations) and maturity (related to nitrate/ammonium ratio and degree of aromaticity) and then compost impact on soil functionality. Indeed, compost stability resulted inversely related to soil microbial biomass, basal respiration rate and fluorescein di-acetate hydrolysis when the products were applied to the soil.

Rates of production of hydroxyl radicals and singlet oxygen from irradiated compost.

The use of organic matter from compost to promote the catalytic photodegradation of micropollutants by solar light appears to be environmentally promising. However, quantitative evaluation of the photodegradation potential of the compost is needed. Our goal was to measure the formation rate of hydroxyl radicals and singlet oxygen, two strongly oxidant species, from irradiated compost organic matter. These two reactive species were photogenerated in all of our extracts regardless of the origin of the compost or the extraction procedure; however, their formation rates increased with composting time. Two herbicides and a fungicide were successfully photodegraded when irradiated with simulated or natural solar light in the presence of the compost organic matter or compost suspensions. For reasons of simplification and ease, the use of the latter is recommended in practice.

The evaluation of stability during the composting of different starting materials: comparison of chemical and biological parameters.

Three blends formed by: (i) food processing waste (CP(FP)), (ii) waste water sewage sludge (CP(WW)), and (iii) their mixture (CP(FP+WW)), blended with tree pruning as bulking agent, were composted over 3 months. During composting the blends were monitored for the main physical-chemical characteristics: temperature, oxygen saturation level (O(2)%), pH, total and volatile solids, total organic carbon, and organic nitrogen (N(org)). In addition to the main parameters, the dissolved organic carbon (DOC), the inorganic nitrogen and the Oxygen Uptake Rate (OUR) were monitored. All the mixtures easily reached a peak temperature around 70°C, related to the lowest O(2)%. After 90 d, CP(FP), CP(FP+WW), and CP(WW) showed an organic matter mineralization of 43%, 35% and 33%, respectively; CP(FP) fitted an exponential model while both CP(FP+WW), and CP(WW) fitted a logistic model. During composting an OUR reduction of 79%, 78% and 73% was registered in CP(FP), CP(FP+WW), and CP(WW), respectively; the OUR successfully fitted the adopted exponential model and well reflected the stabilization process in time. The N(org) recovery at the end of the process was positive only in CP(WW) (11.6%). The DOC significantly decreased during the composting process but did not successfully fit any model. The mineral nitrogen did not follow the typical pattern with NH(4)(+) disappearance and NO(3)(-) accumulation. Strong NO(3)(-) losses were evident in all blends, while NH(4)(+) accumulations were detectable only in CP(FP), and CP(FP+WW). The NH(4)(+)/NO(3)(-) ratio did not satisfactorily reflect the composting process over time. The comparison of the first order (exponential) and logistic (sigmoidal) models applied to the OUR and OM course highlights the role of mineral nitrogen as limiting factor during composting of the more stabilized sludge.

Relationship between photosensitizing and emission properties of peat humic acid fractions obtained by tangential ultrafiltration.

Peat humic acid was fractionated by tangential ultrafiltration into six nominal molecular weight (NMW) fractions, HA5-10, HA10-20, HA20-50, HA50-100, HA100-300 and HA > 300, which were purified by dialysis using a 0.5 kDa membrane. The absorbing and emission properties of the separated fractions were compared and their ability to generate singlet oxygen under light excitation was evaluated, using furfuryl alcohol (FFA) as a singlet oxygen scavenger. The absorbance, the emission intensity, and the apparent first order rate constants of FFA loss were normalized per mole of organic carbon (a*, IF*, and k*, respectively). The fraction absorbance decreased with NMW, except for HA > 300 which was less absorbing than HA100-300. The low NMW fractions and the HA > 300 fraction generally showed lower k* and IF* values compared to the HA50-100 and HA100-300 fractions. A plot of k* versus IF* indicates that the first order rate constant of FFA photo-oxygenation increased with the intensity of fluorescence at 380, 430, and 500 nm (R2 = 0.77-0.84). This shows that the distribution of fluorescent centers among fractions paralleled that of photosensitizing centers. Plotting k* or IF* versus a* at365 nm reveals the apparent relative quantum efficiency of the different fractions. Higher values for low NMW fractions and HA50-100 are either due higher percentages of absorbing centers able to produce singlet oxygen or exhibit fluorescence or to lower quenching processes.

Electrofocusing the compost organic matter obtained by coupling SEC-PAGE.

Humic acids (HA)-like extracted from compost at the beginning (t(0)) and after 130 days of composting (t(130)) were fractionated by coupling size exclusion chromatography to polyacrylamide gel electrophoresis (SEC-PAGE). HA-like fractions with the same molecular size (MS) and electrophoretic mobility were pooled and further characterised by analytical polyacrylamide gel electrofocusing (EF) and compared with HA separated from a Typic Chernozem soil. During the composting process all fractions were subjected to quantitative and qualitative modifications: the high MS fraction was degraded, the mid MS fractions were qualitatively changed, the content of low MS fractions increased and changed qualitatively. The main changes in EF pattern of the non fractionated HA-like t(130) were associated to low MS fractions. Such data seem to be reliable for explanation what mechanisms and monitoring of the evolution of the compost organic matter for their agricultural uses.

A multivariate approach to the study of the composting process by means of analytical electrofocusing.

Three blends formed by: agro-industrial waste, wastewater sewage sludge, and their mixture, blended with tree pruning as bulking agent, were composted over a 3-month period. During the composting process the blends were monitored for the main physical and chemical characteristics. Electrofocusing (EF) was carried out on the extracted organic matter. The EF profiles were analyzed by principal component analysis (PCA) in order to assess the suitability of EF to evaluate the stabilisation level during the composting process. Throughout the process, the blends showed a general shifting of focused bands, from low to high pH, even though the compost origin affected the EF profiles. If the EF profile is analyzed by dividing it into pH regions, the interpretation of the results can be affected by the origin of compost. A good clustering of compost samples depending on the process time was obtained by analyzing the whole profile by PCA. Analysis of EF results with PCA represents a useful analytical technique to study the evolution and the stabilisation of composted organic matter.

Photosensitizing properties of protein hydrolysate-based fertilizers.

The use of protein hydrolysate-based fertilizers (PHF) as adjuvant for pesticides or herbicides has been proposed; however, the behaviors of mixtures of PHFs and pesticides under solar light are not known, and various photochemical reactions may occur. The photosensitizing properties of PHFs were investigated in water solutions (0.8 g of total organic carbon L(-1)) within the wavelength range of 300-450 nm, using furfuryl alcohol (FA) as a probe to test the involvement of singlet oxygen and Irgarol 1051 as an example of organic pollutant. Two commercial PHFs and one standard PHF were studied, all of the products being of animal origin. PHFs photosensitize the transformation of FA (10(-4) M), and the kinetics of FA disappearance follows an apparent first-order rate law. Through the use of sodium azide (1 x 10(-3) M) as singlet oxygen scavenger and deuterium oxide (D2O) for increasing the singlet oxygen lifetime it was shown that singlet oxygen contributes largely to the phototransformation of FA. The replacement of water by D2O increases the apparent first-order rate constant 6 times, whereas the addition of sodium azide reduces it by approximately 90%. These results are confirmed using Irgarol 1051 (10(-5) M). The photosensitizing properties of PHFs might be due to pigments naturally present in tissues from which they are extracted or to compounds generated during the production processes.

Humic-like substances extracted from composts can promote the photodegradation of Irgarol 1051 in solar light.

Humic-like substances (HLS) were extracted from a mixture of sewage sludges and trimmings (70-30%, w/w) after different times of composting (0, 70 days and 130 days). HLS were analyzed by elemental analysis, UV-visible and fluorescence spectroscopy and also tested for their ability to photosensitize the degradation of Irgarol. The rate of Irgarol photodegradation in artificial solar light was found to be 2.5- to 4.3-fold higher in the presence of HLS than in buffered Milli-Q water. These results were confirmed by experiments in solar light that evidenced the photodegrading properties of HLS in a more striking way. Using 2-propanol as hydroxyl radical scavenger, we could show that hydroxyl radicals contributed to the photosensitized Irgarol degradation for about 25%. The photodegrading activity of HLS, their absorbance and their emissive properties were all found to increase between 0 and 70 days of composting and to remain quite constant between 70 and 130 days. The degree of humification varied in the same way, linking all these properties to the humification process.

Determination of free L- and D-alanine in hydrolysed protein fertilisers by capillary electrophoresis.

of racemisation of hydrolysed protein fertilisers (HPFs) using an The objective of this study was to determine the degree inexpensive and easy to handle analytical method for qualitative control of the products. Using a polyacrylamide coated capillary and a run buffer containing 0.1 M Tris-borate+2.5 mM EDTA-Na2+0.1% sodium dodecylsulfate+10 mM beta-cyclodextrin a quantitative separation of D- and L-alanine (Ala) was made from an not treated HPF sample derivatised with dansyl chlorine by capillary electrophoresis. The D-Ala:[D-Ala+L-Ala] ratio, called degree of racemisation (RD), was calculated. The analysis of ten commercial HPFs has shown that more than 60% of HPFs have an RD > or = 40%. while only one product has shown an RD <5%. These results showed that most of the HPFs on the market are obtained with strong hydrolytic processes and high contents of D-amino acids are probably less effective as plant nutrients or even potentially dangerous to plants.

Capillary zone electrophoresis of soil humic acid fractions obtained by coupling size-exclusion chromatography and polyacrylamide gel electrophoresis.

Capillary zone electrophoresis (CZE) was used for characterisation of soil humic acid (HA) fractions obtained by coupling size-exclusion chromatography with polyacrylamide gel electrophoresis, on the basis of their molecular size and electrophoretic mobility. CZE was conducted using several low alkaline buffers as background electrolyte (BGE): 50 mM carbonate, pH 9.0; 50 mM phosphate, pH 8.5; 50 mM borate, pH 8.3; 50 mM Tris-borate+1 mM EDTA+7 M urea+0.1% sodium dodecyl sulphate (SDS), pH 8.3. Independently of BGE conditions, the effective electrophoretic mobility of HA fractions were in good agreement with their molecular size. The better resolution of HA were obtained in Tris-borate-EDTA buffer with urea and SDS. This results indicated that CZE, mostly with BGE-contained disaggregating agents, is useful for separating HAs in fractions with different molecular sizes.