Environmental micro-niche filtering shapes bacterial pioneer communities during primary colonization of a Himalayas' glacier forefield.

The pedogenesis from the mineral substrate released upon glacier melting has been explained with the succession of consortia of pioneer microorganisms, whose structure and functionality are determined by the environmental conditions developing in the moraine. However, the microbiome variability that can be expected in the environmentally heterogeneous niches occurring in a moraine at a given successional stage is poorly investigated. In a 50 m2 area in the forefield of the Lobuche glacier (Himalayas, 5050 m above sea level), we studied six sites of primary colonization presenting different topographical features (orientation, elevation and slope) and harbouring greyish/dark biological soil crusts (BSCs). The spatial vicinity of the sites opposed to their topographical differences, allowed us to examine the effect of environmental conditions independently from the time of deglaciation. The bacterial microbiome diversity and their co-occurrence network, the bacterial metabolisms predicted from 16S rRNA gene high-throughput sequencing, and the microbiome intact polar lipids were investigated in the BSCs and the underlying sediment deep layers (DLs). Different bacterial microbiomes inhabited the BSCs and the DLs, and their composition varied among sites, indicating a niche-specific role of the micro-environmental conditions in the bacterial communities' assembly. In the heterogeneous sediments of glacier moraines, physico-chemical and micro-climatic variations at the site-spatial scale are crucial in shaping the microbiome microvariability and structuring the pioneer bacterial communities during pedogenesis.

Growth Performance, Biochemical Composition and Nutrient Recovery Ability of Twelve Microalgae Consortia Isolated from Various Local Organic Wastes Grown on Nano-Filtered Pig Slurry.

This paper demonstrated the growth ability of twelve algae-microbial consortia (AC) isolated from organic wastes when a pig slurry-derived wastewater (NFP) was used as growth substrate in autotrophic cultivation. Nutrient recovery, biochemical composition, fatty acid and amino acid profiles of algae consortia were evaluated and compared. Three algae-microbial consortia, i.e., a Chlorella-dominated consortium (AC_1), a Tetradesmus and Synechocystis co-dominated consortium (AC_10), and a Chlorella and Tetradesmus co-dominated consortium (AC_12) were found to have the best growth rates (µ of 0.55 ± 0.04, 0.52 ± 0.06, and 0.58 ± 0.03 d-1, respectively), which made them good candidates for further applications. The ACs showed high carbohydrates and lipid contents but low contents of both proteins and essential amino acids, probably because of the low N concentration of NFP. AC_1 and AC_12 showed optimal ω6:ω3 ratios of 3.1 and 3.6, which make them interesting from a nutritional point of view.

Local circular economy: BSF insect rearing in the Italian Agri-Food Industry.

With a growing population, both food and waste production will increase. There is an urgent need for innovative ways of valorizing waste. The black soldier fly (Hermetia illucens L.) efficiently converts agri-food by-products (BPs) into high-quality materials; its rearing process yields larvae (BSFL) rich in fat and protein for feed purposes, with "frass" acting as organic fertilizer. While the insect rearing sector is expanding, few producers use BPs. Therefore, a case study approach was adopted to evaluate the potential for establishing an Italian BSFL production plant on BPs available on the territory. After contacting more than 115 agri-food companies (maximum 100 km from the BSFL plant), they were classified based on sector, distance, size, and BPs (quantity, seasonality, management). BPs with a low value (fruit and vegetable residues) were treated as waste, associated with costs and low valorization. By merging the available BPs on the territory and following the literature on BSFL nutritional needs' two diets (Scenario BSFL) were created, assessing their suitability comparing them to the current full-scale plant diet (Scenario 0). The exploitation of BPs for BSFL rearing reduced local waste production by 52 % compared to conventional composting (Scenario 0). In addition, integrating BPs into the larval feed formulation increased BSFL production value (+47 times). These results highlight the potential of locally-based insect rearing to valorize BPs and create a network of sustainable actors within the agri-food industry. Further investigations are needed to improve the connection between agri-food and insect industrial activities, expanding this framework to other regions.

Antibacterial Potential of Essential Oils and Silver Nanoparticles against Multidrug-Resistant Staphylococcus pseudintermedius Isolates.

Staphylococcus pseudintermedius is an emergent zoonotic agent associated with multidrug resistance (MDR). This work aimed to describe the antibacterial activity of four essential oils (EOs) and silver nanoparticles (AgNPs) against 15 S. pseudintermedius strains isolated from pyoderma. The four EOs, namely Rosmarinus officinalis (RO), Juniperus communis (GI), Citrus sinensis (AR), and Abies alba (AB), and AgNPs were used alone and in combination to determine the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). All strains were MDR and methicillin-resistant. Among the antibiotic cohort, only rifampicin, doxycycline, and amikacin were effective. EOs' chemical analysis revealed 124 compounds belonging to various chemical classes. Of them, 35 were found in AR, 75 in AB, 77 in GI, and 57 in RO. The monoterpenic fraction prevailed over the sesquiterpenic in all EOs. When EOs were tested alone, AB showed the lowest MIC followed by GI, AR, and RO (with values ranging from 1:128 to 1:2048). MBC increased in the following order: AB, AR, GI, and RO (with values ranging from 1:512 to 1:2048). MIC and MBC values for AgNPs were 10.74 mg/L ± 4.23 and 261.05 mg/L ± 172.74. In conclusion, EOs and AgNPs could limit the use of antibiotics or improve the efficacy of conventional therapies.

Cr(VI) reduction capability of humic acid extracted from the organic component of municipal solid waste.

The capacity of humic acid extracted from organic waste (HAw) to reduce Cr(VI) was tested at pH 2.5, 4 and 6 and compared with coal-derived humic acid (HAc). HAw was more effective than HAc in reducing Cr(VI). The kinetics of Cr(VI) reductions depended strongly on pH. The calculation of the apparent rate coefficients indicated that HAw was more efficient at reducing Cr(VI) than HAc, but was also more efficient than HAs from soil and peat. The reduction capability of HAs depends on the type of functional groups (i.e., thiols and phenols) present, rather than the free radicals. HAw was more efficient at reducing Cr(VI) than HAc because more reactive phenols were present, i.e., methoxy- and methyl-phenols.

Two-stage vs single-stage thermophilic anaerobic digestion: comparison of energy production and biodegradation efficiencies.

Two-stage anaerobic digestion (AD) for integrated biohydrogen and biomethane production from organic materials has been reported to promise higher process efficiency and energy recoveries as compared to traditional one-stage AD. This work presents a comparison between two-stage (reactors R1 and R2) and one-stage (reactor R3) AD systems, fed with identical organic substrates and loading rates, focusing the attention on chemical and microbiological aspects. Contrary to previous experiences, no significant differences in overall energy recovery were found for the two-stage and one-stage AD systems. However, an accumulation in R2 of undegraded intermediate metabolites (volatile fatty acids, ketones, amines, amino acids, and phenols) was observed by GC-MS. These compounds were thought to be both cause and effect of this partial inefficiency of the two-stage system, as confirmed also by the less diverse, and thereby less efficient, population of fermentative bacteria observed (by PCR-DGGE) in R2. The extreme environment of R1 (low pH and high metabolites concentrations) probably acted as selector of metabolic pathways, favoring H(2)-producing bacteria able to degrade such a wide variability of intermediate metabolites while limiting other strains. Therefore, if two-stage AD may potentially lead to higher energy recoveries, further efforts should be directed to ensure process efficiency and stability.

Diversifying the products from the organic fraction of municipal solid waste (OFMSW) by producing polyhydroxyalkanoates from the liquid fraction and biomethane from the residual solid fraction.

This study describes the diversification of products obtainable from the organic fraction of municipal solid waste (OFMSW) by producing polyhydroxyalkanoates (PHA) from the liquid fraction and biomethane from the residual solid fraction. OFMSW samples were taken during the 2021 season from two full field scale plants treating wastes. After solid/liquid (S/L) separation, 80% of initial organic acids (OAs) were released in the liquid stream. OAs were then used as feed for PHA production and residual solid cakes were tested for biomethane production. Complete mass balance and energy balance were calculated. PHAs production was of 115 ± 23 (n = 6) g kg- 1 OFMSW (TS) and residual biomethane of 219 ± 3 g kg- 1 OFMSW TS, (n = 6). Energy balance indicated that nearly 40% of OFMSW energy was recovered as products. This value was lower than that obtained previously when AD was performed before OAs separation (i.e. 64%).

Polyphenol bioactivity evolution during the spontaneous fermentation of vegetal by-products.

Food industry by-products such as grape pomace (GP), tomato pomace (TP), and spent coffee grounds (SCG) are rich in polyphenols (PP) but are easily biodegradable. The aim of this study is to test Spontaneous Fermentation (SF) as treatment to modify PP profile and bioactivity. The results highlighted that the by-products' organic matter and the microbial populations drove the SF evolution; heterolactic, alcoholic, and their mixtures were the predominant metabolisms of TP, GP, and SCG + GP co-fermentation. Increases in the extractable amounts and antiradical activity occurred for all the biomasses. Regarding the aglycate-PPs (APP), i.e. the most bioreactive PPs, significant changes occurred for TP and GP but did not influence the anti-inflammatory bioactivity. The co-fermentation increased significantly chlorogenic acid and consumed most of the APPs, acting as a purification system to obtain a highly concentrated APP fraction, so that the extract might be employed for a specific purpose.

Rock weathering creates oases of life in a high Arctic desert.

During primary colonization of rock substrates by plants, mineral weathering is strongly accelerated under plant roots, but little is known on how it affects soil ecosystem development before plant establishment. Here we show that rock mineral weathering mediated by chemolithoautotrophic bacteria is associated to plant community formation in sites recently released by permanent glacier ice cover in the Midtre Lovénbreen glacier moraine (78 degrees 53'N), Svalbard. Increased soil fertility fosters growth of prokaryotes and plants at the boundary between sites of intense bacterial mediated chemolithotrophic iron-sulfur oxidation and pH decrease, and the common moraine substrate where carbon and nitrogen are fixed by cyanobacteria. Microbial iron oxidizing activity determines acidity and corresponding fertility gradients, where water retention, cation exchange capacity and nutrient availability are increased. This fertilization is enabled by abundant mineral nutrients and reduced forms of iron and sulfur in pyrite minerals within a conglomerate type of moraine rock. Such an interaction between microorganisms and moraine minerals determines a peculiar, not yet described model for soil genesis and plant ecosystem formation with potential past and present analogues in other harsh environments with similar geochemical settings.

δ13C data of the total water-soluble fraction and triacylglycerols as related indexes for differentiating the geographical origin of saffron (Crocus sativus L.).

Using isotopic ratio mass spectrometry (IRMS) measurements, this study analyzed samples of saffron originating from two distinct geographical regions. We then used the results to distinguish saffron of the two considered origins. δ13C data related to the crocin fractions in 48 saffron samples from Western Macedonia (Greece) and 48 samples from Khorasan Province (Iran) were correlated to an index derived from triacylglycerols. Isotopic data could clearly differentiate between samples from the two areas. The isotopic measurements were -28.3 to -26.9 for Greek samples, and -26.1 to -24.5 for Iranian samples. Another index, derived from a gas-chromatographic analysis of the triacylglycerols, successfully determined that the range of isotopic values that characterized Greek samples was 52% larger than the range that characterized Iranian samples. The application of statistical evaluations permitted us to identify the two groups of saffron with confidence and to accurately identify the site of origin of a saffron sample.

Supercritical CO2 extraction of tomato pomace: Evaluation of the solubility of lycopene in tomato oil as limiting factor of the process performance.

This work considered lycopene (lyc) amount and (all-E)-lyc:Z-lyc (E:Z) ratio as driving parameters of the tomato pomace (TP) supercritical CO2 extraction (SFE_CO2) performance. By testing lyc concentrations solubilization in tomato seed oil and E:Z ratios of 75:25, 59:39 and 25:75, full and partial equations (SE) were calculated. The application of mass balances to experimental TP_SFE_CO2 highlighted an extraction yield of 84.6% TP lyc, although the recovery into the extract was 48.4% of the extracted lyc (lyc = 1339 µg g-1 oil). The SE application to TP_SFE_CO2 data confirmed that partial solubilization mainly depended on oil availability vs. lyc amount. Thus an improved TP_SFE_CO2 was designed in which 703 g of exogenous tomato oil will be fluxed from the co-solvent tank: the new process will produce 884 g kg-1 d.m. of extract with an expected recovery of 99.3% of the extractable lyc (lyc = 502 µg g-1 oil).

Implementing polyhydroxyalkanoates production to anaerobic digestion of organic fraction of municipal solid waste to diversify products and increase total energy recovery.

A simple biorefinery aimed at producing both biomethane (CH4) and polyhydroxyalkanoates (PHAs), was proposed to valorize the organic fraction of municipal solid waste (OFMSW). Anaerobic digestion (AD) was tested at different organic loading rates (OLR-I-II-III) (i.e. 3, 4 and 6 g L-1 d-1, respectively), producing biomethane and volatile fatty acids (VFAs)-rich digestate, the VFAs were then used to produce PHAs. Specific biogas and CH4 production remained similar when adopting different OLRs (biogas of 522-600 NL kg-1 VS and CH4 of 64-67% v/v). VFAs concentrated with OLR increases and their patterns were modified. PHA production was in the range of 117-199 g kg-1 OFMSWTS with the lowest production being associated to different polymer composition. The net energy recovery of this simple biorefinery accounted for 64% of OFMSW energy content, and the PHAs produced represented over 30% of the total energy.

The distribution of functional N-cycle related genes and ammonia and nitrate nitrogen in soil profiles fertilized with mineral and organic N fertilizer.

Nitrogen transformation in soil is a complex process and the soil microbial population can regulate the potential for N mineralization, nitrification and denitrification. Here we show that agricultural soils under standard agricultural N-management are consistently characterized by a high presence of gene copies for some of the key biological activities related to the N-cycle. This led to a strong NO3- reduction (75%) passing from the soil surface (15.38 ± 11.36 g N-NO3 kg-1 on average) to the 1 m deep layer (3.92 ± 4.42 g N-NO3 kg-1 on average), and ensured low nitrate presence in the deepest layer. Under these circumstances the other soil properties play a minor role in reducing soil nitrate presence in soil. However, with excessive N fertilization, the abundance of bacterial gene copies is not sufficient to explain N leaching in soil and other factors, i.e. soil texture and rainfall, become more important in controlling these aspects.

Antioxidant and Anti-Inflammatory Activities of the Crude Extracts of Raw and Fermented Tomato Pomace and Their Correlations with Aglycate-Polyphenols.

Two tomato pomace (TP) were studied as feedstocks to obtain extracts that are rich in polyphenols. TPs prompt degradation impairs biomass safety, thus naturally present microflora were tested to perform conservation, and own lactic bacteria became predominant after 60 days of treatment. The extracts of TPs and TPs fermented (TPF) were chemically characterized and tested for antioxidant and anti-inflammatory activities. Flavonoids and phenolic acids were classed as aglycone-polyphenols (A-PP), the most bioactive polyphenol fraction. Fermentation led to a reduction of the A-PP amount, but no significant change in composition. Antioxidant power increased, despite the A-PP reduction, for the presence of fermentation metabolites having aromatic-substituent. TP and TPF both have anti-inflammatory properties that were strictly dependent upon the A-PP content. Fermentation preserved the anti-inflammatory activity and the Partial Least Square (PLS) identified as the most active molecules naringenin chalcone, kaempferol, gallic acid, and cinnamic acid, together with the definition of the active dose.

Biodegradability of soil water soluble organic carbon extracted from seven different soils.

Water soluble organic carbon (WSOC) is considered the most mobile and reactive soil carbon source and its characterization is an important issue for soil ecology study. A biodegradability test was set up to study WSOC extracted from 7 soils differently managed. WSOC was extracted from soil with water (soil/water ratio of 1:2, W/V) for 30 min, and then tested for biodegradability by a liquid state respirometric test. Result obtained confirmed the finding that WSOC biodegradability depended on the both land use and management practice. These results suggested the biodegradability test as suitable method to characterize WSOC, and provided useful information to soil fertility.

Biohydrogen and polyhydroxyalkanoates (PHA) as products of a two-steps bioprocess from deproteinized dairy wastes.

In this study a two-steps bioprocess approach aimed at biohydrogen production via dark-fermentation, and polyhydroxyalkanoates-PHA production by mixed microbial cultures, was proposed to valorise two dairy-waste streams coming from cheese whey deproteinization (i.e. Ricotta cheese production and ultrafiltration). During the first step, the increase of OLR was tested, resulting in higher daily H2 volume (3.47 and 5.07 NL H2 d-1 for second cheese whey-SCW and concentrated cheese whey permeate-CCWP) and organic acids production (14.6 and 12.6 g L-1 d-1 for SCW and CCWP) for both the substrates, keeping good conversion of sugars into H2 (1.37 and 1.93 mol H2 mol-1 sugars for SCW and CCWP). During the second step, the organic acids were used for PHA production reaching high conversion yields for both the fermented streams (as average 0.74 ±â€¯0.14 mg CODPHA mg-1 CODOA-in), with a maximum polymer content of 62 ±â€¯4.5 and 55.1 ±â€¯1.3% (g PHA g-1 VSS) for fermented SCW and fermented CCWP respectively. For the results reported, this study could be taken into consideration for larger scale application.

An index for quantifying the aerobic reactivity of municipal solid wastes and derived waste products.

The organic matter contained in municipal solid waste (MSW) and in the MSW fractions obtained by mechanical separation has strong environmental impact when the waste is used as landfill. This is partly due to the biological activity that occurs under anaerobic conditions. Negative effects on the environment include unpleasant odors, biogas, leachate and biomass self-heating. Measuring the biological reactivity of waste with the help of indicators is an important tool to prevent waste impact. The aim of this study was to develop an index capable of describing the aerobic reactivity of waste, using both biological and chemical indicators. To develop this index, 71 MSW and MSW-product samples, including biologically treated MSW and mechanically separated MSW fractions, were analyzed. Fifty of the 71 samples analyzed represented MSWs and their derived products collected from a number of Italian waste plants and sites. The remaining 21 were MSW samples collected at different times during 8 different full-scale aerobic biological processes in four treatment plants used to reduce the biological reactivity of wastes. Five of these processes used the entire (unsorted) MSW, while the remaining three used the organic fraction of the MSW obtained by mechanical pre-treatment (waste sieving). Respirometric activity (Dynamic Respiration Index, DRI) and eluates characterization (chemical oxygen demand--COD, and 5 days biological oxygen demand--BOD5) were used as indicators of waste strength, as they had previously been reported to be indirect measures of waste impact on landfill. Summarizing all studied indicators, Principal Component Analysis (PCA) was used to develop the Putrescibility Index (Ip). The results revealed Ip index of 204+/-33 (mean+/-standard deviation) and 159+/-14 for the organic fraction of MSW and MSW untreated waste respectively, and of 106+/-16 and 101+/-22 for the corresponding biologically treated waste.

Potential agronomic and environmental properties of thermophilic anaerobically digested municipal sewage sludge measured by an unsupervised and a supervised chemometric approach.

Anaerobic digestion (AD) is the most widely used method of sewage sludge treatment (SS) before its agricultural use. AD achieves the required "sterilisation" of pathogens and is able to cover the energy required by the process, reducing pre-treatment costs, thanks to the production of biogas. The SS agronomic (fertilizer properties), environmental (pollutants contents) characteristics and nuisance to people (odours and pathogens) need to be evaluated together for the safe and useful deployment of SS in agriculture. To evaluate SS properties an unsupervised (Principal Component Analysis) and a supervised (K nearest neighbours) chemometric approach was applied to rank digested SS for agronomic and environmental properties in comparison with other organic matrices for which the agronomic and/or environmental properties are well known or expected. To do so, complete chemical, biological and "impact on people" characterization was carried out on SS ingestate (SS-ing.) and SS digestate (SS-dig.) and another 10 biomasses. The SS-AD process enhanced the agronomic properties of sewage sludge and did not lead to a substantial concentration of pollutants because of the low degradation of organic matter. The best PCA performances were reached for amendment and fertilizer modules but the results found for the environment and nuisance to inhabitants were not satisfactory. The KNN approach proposed to evaluate the suitability of a biomass for agricultural purposes, represents a win-win approach as it allows one to avoid time-consuming and costly full field studies.

The stage of soil development modulates rhizosphere effect along a High Arctic desert chronosequence.

In mature soils, plant species and soil type determine the selection of root microbiota. Which of these two factors drives rhizosphere selection in barren substrates of developing desert soils has, however, not yet been established. Chronosequences of glacier forelands provide ideal natural environments to identify primary rhizosphere selection factors along the changing edaphic conditions of a developing soil. Here, we analyze changes in bacterial diversity in bulk soils and rhizospheres of a pioneer plant across a High Arctic glacier chronosequence. We show that the developmental stage of soil strongly modulates rhizosphere community assembly, even though plant-induced selection buffers the effect of changing edaphic factors. Bulk and rhizosphere soils host distinct bacterial communities that differentially vary along the chronosequence. Cation exchange capacity, exchangeable potassium, and metabolite concentration in the soil account for the rhizosphere bacterial diversity. Although the soil fraction (bulk soil and rhizosphere) explains up to 17.2% of the variation in bacterial microbiota, the soil developmental stage explains up to 47.7% of this variation. In addition, the operational taxonomic unit (OTU) co-occurrence network of the rhizosphere, whose complexity increases along the chronosequence, is loosely structured in barren compared with mature soils, corroborating our hypothesis that soil development tunes the rhizosphere effect.

The anaerobic digestion process capability to produce biostimulant: the case study of the dissolved organic matter (DOM) vs. auxin-like property.

Biostimulants improve plant growth by stimulating nutrient uptake and efficiency, improving tolerance to abiotic stress and raising crop quality. Biostimulants are currently only recognised in five categories. However, the recent interest in this sector has led to the identification of some new ones. The aim of this work was to study the auxin-like activity of digestate dissolved organic matter (DOM) obtained from full scale anaerobic digester plants. All DOMs had biostimulant capacity comparable with humic acid and amino acids. The auxin-like activities depended mainly on the hydrophobic DOM fractions for the presence of auxin-active and other auxin-like molecules. Significant correlations were found for the auxin-effect in relation to auxin-active molecules and fatty acids responsible for most of the auxin-like effects (67% of the total importance in giving auxin-like activity) while a minor or null contribution was attributable to the carboxylic acids and aminoacid categories. Therefore, the anaerobic digestion process seems to be a useful biotechnology to produce biostimulants. Basing on these first results, the expanding anaerobic digestion sector could become important for the production of new biostimulant classes to meet the agricultural sector's new requirements and saving on raw materials.