This study investigates the waste cardboard (WCB) fungal pretreatment (Oligoporus placenta and Tremetes hirsuta) under monoculture and mixed culture and then composting for 35 d after mixing with cow dung in different ratios. Fungal pretreatment caused significant reduction in cellulose (28.3-35.8%), hemicellulose (61.4-68.4%), lignin (67.5-69.3%) content in WCB. Pretreated WCB showed better rates of decrement in total organic carbon (26.02-47.92%), carbon-to-nitrogen ratio (19.4-23.5), and lignocellulose contents, as well as incensement in total nitrogen (40.48-63.31%), total potassium (51.92-73.91%), germination index (88.5-102.0%), and elemental (Cu, Fe, Zn, Cr, and Mn) levels. Dehydrogenases (142-210 µg g-1h-1), and β-galactosidase (210-256 µg g-1h-1) activities indicates high microbial-mediated mineralization in setups. Results suggested that WCB could be used as a valuable substrate for valuable-added compost preparation after pretreating with a consortium of white-rot fungi.

The extreme halophilic archaeon, Haloferax mediterranei can accumulate polyhydroxyalkanoate (PHA) from different renewable resources. To enhance the biosynthesis and quality of PHA, H. mediterranei cultivation media was optimized at different C/N ratios using glucose as the main carbon source. Three sets of media (yeast extract [YE], NH4 Cl and combination of YE and NH4 Cl) were prepared at different nitrogen concentrations to achieve C/N ratios of 9, 20, and 35, respectively. The media containing YE (organic nitrogen source) produced a higher growth rate of H. mediterranei than NH4 Cl (inorganic source) at all tested C/N ratios. The highest PHA accumulation (18.4% PHA/cell dry mass) was achieved in a media that combined YE with NH4 Cl at a C/N ratio of 20. Analysis of the produced polymers revealed the production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) with different 3-hydroxyvalerate (3HV) content. The polymers produced from YE and the combined media have greater 3HV content (10 mol%) than those polymers recovered from NH4 Cl (1.5 mol%). Resultingly, PHBHV from YE and the combined media displayed reduced melting points at 144°C. The nitrogen type/concentration was found to also have an impact on the molecular weights and polydispersity indices of the produced biopolymers. Furthermore, the tensile strengths were found to vary with the best tensile strength (14.4 MPa) being recorded for the polymer recovered from YE at C/N = 9. Interestingly, the tensile strength of PHBHV was significantly higher than petroleum-based polyethylene (13.5 MPa), making it a much more suitable bioplastic for industrial application.

Quantifying changes in soil organic carbon (SOC) stocks and other soil properties is essential for understanding how soils will respond to land management practices and global change. Although they are widely used, comparisons of SOC stocks at fixed depth (FD) intervals are subject to errors when changes in bulk density or soil organic matter occur. The equivalent soil mass (ESM) method has been recommended in lieu of FD for assessing changes in SOC stocks in mineral soils, but ESM remains underutilized for SOC stocks and has rarely been used for other soil properties. In this paper, we draw attention to the limitations of the FD method and demonstrate the advantages of the ESM approach. We provide illustrations to show that the FD approach is susceptible to errors not only for quantifying SOC stocks but also for soil mass-based properties such as SOC mass percent, C:N mass ratio, and δ13 C. We describe the ESM approach and show how it mitigates the FD method limitations. Using bulk density change simulations applied to an empirical dataset from bioenergy cropping systems, we show that the ESM method provides consistently lower errors than FD when quantifying changes in SOC stocks and other soil properties. To simplify the use of ESM, we detail how the method can be integrated into sampling schemes, and we provide an example R computer script that can perform ESM calculations on large datasets. We encourage future studies, whether temporal or comparative, to utilize sampling methods that are amenable to the ESM approach. Overall, we agree with previous recommendations that ESM should be the standard method for evaluating SOC stock changes in mineral soils, but we further suggest that ESM may also be preferred for comparisons of other soil properties including mass percentages, elemental mass ratios, and stable isotope composition.

Bioretention cell (BRC), bioretention cell with microbial fuel cell (BRC-MFC), and an enhanced combined BRC-MFC system with bimetallic zero-valent iron (BRC-MFC-BZVI) were implemented in current study to treat the domestic wastewater. Nitrogen removal characteristics of three systems were investigated by adjusting influent carbon/nitrogen ratio (C/N ratio of 2.54-19.36). Results revealed that the nitrification and denitrification performances were mainly influenced by organic matter and system combination, which further affected nitrogen removal. When the influent C/N ratio was between 2 to 3, compared with BRC system, in BRC-MFC and BRC-MFC-BZVI system, chemical oxygen demand (COD), total nitrogen (TN), and ammonical nitrogen (NH4+-N) removal efficiencies were still reached to 83.04%, 61.06%, and 42.26% and 86.53%, 43.61%, and 50.99% respectively, which simultaneously achieved high-efficiency of organic matter and nitrogen removal. The efficient supply of electrons in the BRC-MFC and BRC-MFC-BZVI processes was the main reason to achieve profound denitrification removal under the condition of low C/N. Removal rates of nitrate (NO3--N) and nitrite (NO2--N) were relatively higher due to microbial-driven redox reactions caused by driving electrons to flow in the closed circuit of metal wire connection. Moreover, phylogenetic diversity of bacterial communities mainly induced the catalytic iron, which further enhanced biological nitrogen reduction. The maximum efficient removal of organic matter (OM), TN, and NH4 + -N were obtained in the BRC-MFC-BZVI system, which were 98.42% (C/N = 10.42), 55.61% (C/N = 4.16), and 61.13% (C/N = 4.16), respectively.

Seaweed (T1), sugarcane trash (T2), coir pith (T3) and vegetable waste (T4) with cowdung (1:1, w/w) were vermicomposted using Eudrilus eugeniae (50 days). The pH in vermicomposts showed a decrease while electrical conductivity showed increment. The organic matter content, organic carbon, lignin, cellulose, C/N and C/P ratios in vermicompost was significantly lower than compost. Total NPK contents of vermicompost were significantly elevated (P < 0.05) with 12.04-63.75%, 19.05-31.58% and 22.47-42.55%, respectively. The significantly higher growth rate of 1.41 and 7.74 mg/worm/day was observed in T1 on 10th and 50th day respectively, with 23.91 initial C/N ratio; while it was 0.85 and 4.81 mg/worm/day in T4 with 69.81 initial C/N ratio. A similar pattern was reflected in cocoon production, hatchling success and hatchling number/cocoon. Results revealed that vermicompost quality, worm growth, and reproduction depend on C/N ratio. The study suggests that amendment materials like cowdung are necessary to reduce C/N ratio for effective vermicomposting.

Temperature, primary productivity, plant functional traits, and herbivore abundances are considered key predictors of leaf herbivory but their direct and indirect contributions to community-level herbivory are not well understood along broad climatic gradients. Here, we determined elevational herbivory patterns and used a path analytical approach to disentangle the direct and indirect effects of climate, land use, net primary productivity (NPP), herbivore abundance, and plant functional traits on community-level invertebrate herbivory along the extensive elevational and land use gradients at Mt. Kilimanjaro, Tanzania. We recorded standing leaf herbivory caused by leaf chewers, leaf miners and leaf gallers on 55 study sites distributed in natural and anthropogenic habitats along a 3,060 m elevation gradient. We related the total community-level herbivory to climate (temperature and precipitation), NPP, plant functional traits (specific leaf area, leaf carbon-to-nitrogen [CN] ratio and leaf nitrogen-to-phosphorus [NP] ratio) and herbivore abundances. Leaf herbivory ranged from 5% to 11% along the elevation gradient. Total leaf herbivory showed unimodal pattern in natural habitats but a strongly contrasting bimodal pattern in anthropogenic habitats. We also detected some variation in the patterns of leaf herbivory along environmental gradients across feeding guilds with leaf chewers being responsible for a disproportionally large part of herbivory. Path analyses indicated that the variation in leaf herbivory was mainly driven by changes in leaf CN and NP ratios which were closely linked to changes in NPP in natural habitats. Similarly, patterns of leaf herbivory in anthropogenic habitats were best explained by variation in leaf CN ratios and a negative effect of land use. Our study elucidates the strong role of leaf nutrient stoichiometry and its linkages to climate and NPP for explaining the variation in leaf herbivory along broad climatic gradients. Furthermore, the study suggests that climatic changes and nutrient inputs in the course of land use change may alter leaf herbivory and consequently energy and nutrient fluxes in terrestrial habitats.

The elemental composition of organisms belongs to a suite of functional traits that may adaptively respond to fluctuating selection pressures. Life history theory predicts that predation risk and resource limitations impose selection pressures on organisms\' developmental time and are further associated with variability in energetic and behavioral traits. Individual differences in developmental speed, behaviors and physiology have been explained using the pace-of-life syndrome (POLS) hypothesis. However, how an organism\'s developmental speed is linked with elemental body composition, metabolism and behavior is not well understood. We compared elemental body composition, latency to resume activity and resting metabolic rate (RMR) of western stutter-trilling crickets (Gryllus integer) in three selection lines that differ in developmental speed. We found that slowly developing crickets had significantly higher body carbon, lower body nitrogen and higher carbon-to-nitrogen ratio than rapidly developing crickets. Slowly developing crickets had significantly higher RMR than rapidly developing crickets. Male crickets had higher RMR than females. Slowly developing crickets resumed activity faster in an unfamiliar relative to a familiar environment. The rapidly developing crickets did the opposite. The results highlight the tight association between life history, physiology and behavior. This study indicates that traditional methods used in POLS research should be complemented by those used in ecological stoichiometry, resulting in a synthetic approach that potentially advances the whole field of behavioral and physiological ecology.

Micropollutants such as pharmaceutical active compounds, present at high concentration in hospital wastewater (HWW), pose both environmental and human health challenges. Fungal reactors can effectively remove such contaminants and produce non-toxic effluents, but their ability to operate for a long period of time is yet to be demonstrated in real hospital wastewater. Several process variables need to be studied beforehand. Here, variables: pellet size, aeration and carbon-to-nitrogen ratio are studied in continuous operations with real HWW. Moreover, a novel strategy for inoculum production that could reduce economical and operational costs is proposed and tested. Optimum pellet size was found to be 2 mm and an aeration of 0.8 L min-1 was needed to maintain fungal viability. The carbon-to-nitrogen ratio of 7.5 was selected and the pellet production time was reduced from 6 to 3 days. The novel low-cost inoculum preparation produced pellets with the same characteristics as the traditionally prepared ones.

The main characteristic of discarded flue-cured tobacco leaves is their high nicotine content. Aerobic composting is an effective method to decrease the nicotine level in tobacco leaves and stabilize tobacco wastes. However, high levels of nicotine in discarded flue-cured tobacco leaves complicate tobacco waste composting. This work proposes a drying pretreatment process to reduce the nicotine content in discarded flue-cured tobacco leaves and thus enhance its carbon-to-nitrogen ratio to a suitable level for composting. The effect of another pretreatment method, particle size adjustment, on composting efficiency was also tested in this work. The results indicated that the air-dried (nicotine content: 1.35%) and relatively long discarded flue-cured tobacco leaves (25 mm) had a higher composting efficiency than damp (nicotine content: 1.57%) and short discarded flue-cured tobacco leaves (15 mm). When dry/25 mm discarded flue-cured tobacco leaves mixed with tobacco stems in an 8:2 ratio was composted at a temperature above 55 °C for 9 days, the nicotine content dropped from 1.29% to 0.28%. Since the discarded flue-cured tobacco leaves was successfully composted to a fertile and harmless material, the germination index values increased to 85.2%. The drying pretreatment and particle size adjustment offered ideal physical and chemical conditions to support microbial growth and bioactivity during the composting process, resulting in efficient conversion of discarded flue-cured tobacco leaves into a high quality and mature compost.

Carbon-to-nitrogen ratio (CNR) has shown to be a relevant factor in microorganisms growth and metabolites production. It is usual that this factor compromises the productivity yield of different microorganisms. However, CNR has been rarely modeled and therefore the nature of its specific influence on metabolites production has not been understood clearly. This paper describes a parametric characterization of the CNR effect on the Escherichia coli metabolism. A set of parameters was proposed to introduce a mathematical model that considers the biomass, substrate and several byproducts dynamical behavior under batch regimen and CNR influence. Identification algorithm used to calculate the parameters considers a novel least mean square strategy that formalizes the CNR influence in E. coli metabolism. This scheme produced a step-by-step method that was suitable for obtaining the set of parameters that describes the model. This method was evaluated under two scenarios: (a) using the data from a set of numerical simulations where the model was tested under the presence of artificial noises and (b) the information obtained from a set of experiments under different CNR. In both cases, a leave-one-experiment-out cross-validation study was considered to evaluate the model prediction capabilities. Feasibility of the parametric identification method was proven in both considered scenarios.