Impacts of AlaAT3 transgenic poplar on rhizosphere soil chemical properties, enzyme activity, bacterial community, and metabolites under two nitrogen conditions

Poplar stands as one of the primary afforestation trees globally. We successfully generated transgenic poplar trees characterized by enhanced biomass under identical nutrient conditions, through the overexpression of the pivotal nitrogen assimilation gene, pxAlaAT3. An environmental risk assessment was conducted for investigate the potential changes in rhizosphere soil associated with these overexpressing lines (OL). The results show that acid phosphatase activity was significantly altered under ammonium in OL compared to the wild-type control (WT), and a similar difference was observed for protease under nitrate. 16SrDNA sequencing indicated no significant divergence in rhizosphere soil microbial community diversity between WT and OL. Metabolomics analysis revealed that the OL caused minimal alterations in the metabolites of the rhizosphere soil, posing no potential harm to the environment. With these findings in mind, we anticipate that overexpressed plants will not adversely impact the surrounding soil environment.

Metabolic engineering of Caldicellulosiruptor bescii for hydrogen production

Hydrogen is an alternative fuel for transportation vehicles because it is clean, sustainable, and highly flammable. However, the production of hydrogen from lignocellulosic biomass by microorganisms presents challenges. This microbial process involves multiple complex steps, including thermal, chemical, and mechanical treatment of biomass to remove hemicellulose and lignin, as well as enzymatic hydrolysis to solubilize the plant cell walls. These steps not only incur costs but also result in the production of toxic hydrolysates, which inhibit microbial growth. A hyper-thermophilic bacterium of Caldicellulosiruptor bescii can produce hydrogen by decomposing and fermenting plant biomass without the need for conventional pretreatment. It is considered as a consolidated bioprocessing (CBP) microorganism. This review summarizes the basic scientific knowledge and hydrogen-producing capacity of C. bescii. Its genetic system and metabolic engineering strategies to improve hydrogen production are also discussed. KEY POINTS: • Hydrogen is an alternative and eco-friendly fuel. • Caldicellulosiruptor bescii produces hydrogen with a high yield in nature. • Metabolic engineering can make C. bescii to improve hydrogen production.

Enhanced growth and metabolite production from a novel strain of Porphyridium sp

Microalgae are capable of generating numerous metabolites that possess notable biological activities and hold substantial promise for various industrial applications. Nevertheless, the taxonomic diversity of these photosynthetic microorganisms has not received thorough investigation. Using the 18S rRNA encoding gene, a recently discovered strain originating from the Tunisian coast (the governorate of Mahdia) was identified as a member of the Porphyridium genus. The growth response as well as the metabolite accumulation of Porphyridium sp. to different culture media (Pm, F/2, and Hemerick) was investigated over a period of 52 days. The highest biomass production was recorded with Pm medium (2 × 107 cell/mL). The apparent growth rates (µ) and the doubling time (Dt) were about 0.081 day-1 and 12.34 days, respectively. The highest chlorophyll a (0.678 ± 0.005 pg/cell), total carotenoids (0.18 ± 0.003 pg/cell), phycoerythrin (3.88 ± 0.003 pg/cell), and proteins (14.58 ± 0.35 pg/cell) contents were observed with F/2 medium. Cultivating Porphyridium sp. in both F/2 and Hemerick media yielded similar levels of starch accumulation. The Hemerick medium has proven to be the most suitable for the production of lipids (2.23% DW) and exopolysaccharides (5.41 ± 0.56 pg/cell).

Current models in bacterial hemicellulase-encoding gene regulation

The discovery and characterization of bacterial carbohydrate-active enzymes is a fundamental component of biotechnology innovation, particularly for renewable fuels and chemicals; however, these studies have increasingly transitioned to exploring the complex regulation required for recalcitrant polysaccharide utilization. This pivot is largely due to the current need to engineer and optimize enzymes for maximal degradation in industrial or biomedical applications. Given the structural simplicity of a single cellulose polymer, and the relatively few enzyme classes required for complete bioconversion, the regulation of cellulases in bacteria has been thoroughly discussed in the literature. However, the diversity of hemicelluloses found in plant biomass and the multitude of carbohydrate-active enzymes required for their deconstruction has resulted in a less comprehensive understanding of bacterial hemicellulase-encoding gene regulation. Here we review the mechanisms of this process and common themes found in the transcriptomic response during plant biomass utilization. By comparing regulatory systems from both Gram-negative and Gram-positive bacteria, as well as drawing parallels to cellulase regulation, our goals are to highlight the shared and distinct features of bacterial hemicellulase-encoding gene regulation and provide a set of guiding questions to improve our understanding of bacterial lignocellulose utilization. KEY POINTS: • Canonical regulatory mechanisms for bacterial hemicellulase-encoding gene expression include hybrid two-component systems (HTCS), extracytoplasmic function (ECF)-σ/anti-σ systems, and carbon catabolite repression (CCR). • Current transcriptomic approaches are increasingly being used to identify hemicellulase-encoding gene regulatory patterns coupled with computational predictions for transcriptional regulators. • Future work should emphasize genetic approaches to improve systems biology tools available for model bacterial systems and emerging microbes with biotechnology potential. Specifically, optimization of Gram-positive systems will require integration of degradative and fermentative capabilities, while optimization of Gram-negative systems will require bolstering the potency of lignocellulolytic capabilities.

Selecting a preculture strategy for improving biomass and astaxanthin productivity of Chromochloris zofingiensis

Chromochloris zofingiensis is a potential source of natural astaxanthin; however, its rapid growth and astaxanthin enrichment cannot be achieved simultaneously. This study established autotrophic, mixotrophic, and heterotrophic preculture patterns to assess their ameliorative effect on the C. zofingiensis heterotrophic growth state. In comparison, mixotrophic preculture (MP) exhibited the best improving effect on heterotrophic biomass concentration of C. zofingiensis (up to 121.5 g L-1) in a 20 L fermenter, reaching the global leading level. The astaxanthin productivity achieved 111 mg L-1 day-1, 7.4-fold higher than the best record. The transcriptome and 13C tracer-based metabolic flux analysis were used for mechanism inquiry. The results revealed that MP promoted carotenoid and lipid synthesis, and supported synthesis preference of low unsaturated fatty acids represented by C18:1 and C16:0. The MP group maintained the best astaxanthin productivity via mastering the balance between increasing glucose metabolism and inhibition of carotenoid synthesis. The MP strategy optimized the physiological state of C. zofingiensis and realized its heterotrophic high-density growth for an excellent astaxanthin yield on a pilot scale. This strategy exhibits great application potential in the microalgae-related industry. KEY POINTS: • Preculture strategies changed carbon flux and gene expression in C. zofingiensis • C. zofingiensis realized a high-density culture with MP and fed-batch culture (FBC) • Astaxanthin productivity achieved 0.111 g L-1 day-1 with MP and FBC.

DNA methylation variation and growth in the clonal Duchesnea indica is regulated by both past and present lead environments

Studies suggest that clonal plants' ability to select habitats and forage in a heterogeneous environment is influenced by their past environment, with stress legacy potentially playing a crucial role. In this study, we examined parental ramets of Duchesnea indica Focke that were subject to either a control or lead-contaminated environment (past environment), and their newborn offspring were then transplanted into control, homogeneous lead or heterogeneous lead environment (present environment). We analysed how past and present environments affect plant growth and DNA methylation in offspring. The result shown that the DNA methylation loci composition of offspring was affected by the interaction of parental environment and offspring environment, and DNA methylation levels were higher in heterogeneous environments. Moreover, our findings indicate that offspring would thrive in the heterogeneous lead environment if they did not experience lead pollution in the past, their progeny will avoid lead toxicity by reducing underground biomass allocation. However, when the parents experienced lead stress environment, their biomass allocation strategies disappeared, and they prefer to grow in favourable patches to avoid lead-contaminated patches. We concluded that the integration of historical parental exposure to lead-contaminated and current information about their offspring's environment are impacting plant phenotypes. It is possible that the stress legacy from the parents has been transmitted to their offspring ramets, and the stress legacy is at least partly based on heritable epigenetic variation. The phenotypic variation regulated by the stress legacy affects the growth performance, biomass allocation strategy, and even the behaviour of D. indica.

Influence of biomass burning on ozone levels in the Megalopolis of Central Mexico during the COVID-19 lockdown

The massive reductions in anthropogenic emissions resulting from the COVID-19 lockdown provided a unique opportunity to evaluate the effect of mitigation measures aiming to abate air pollution. In Mexico, the total lockdown period took place during the dry-hot season when biomass burning activity is enhanced. Here, we investigate the role of biomass burning emissions on regional ozone levels in the Megalopolis of Central Mexico. The studied period covers the lockdown phases 2 and 3, and the first month of the New Normal. We applied a factor separation technique and process analysis to estimate the pure and synergistic contributions of emission reductions under lockdown and that from biomass burning to daily ozone maximum concentrations in 7 metropolitan areas of different states in the Megalopolis. The results revealed that biomass burning plumes likely masked the effect of massive reductions from mobile emissions, impacted the PBL development during phase 3 and favored transition and mixed NOx-limited and VOC-limited regional regimes. This contributed to increased ozone production in the middle to lower PBL by changing the regional background levels which potentially could bias high ozone production efficiency estimations. Given the Megalopolis contribution to economic and societal development at national scale, our study suggests that ozone mitigation measures during the dry-hot season targeting mainly mobile emissions will likely be offset by biomass burning plumes. A regional and synergic policy aiming to control biomass burning would help to reduce the occurrence of high ozone levels in Central Mexico with the co-benefit of tackling short-lived climate pollutants.

Ionic-physical-chemical triple cross-linked all-biomass-based aerogel for thermal insulation applications

Aerogels, as a unique porous material, are expected to be used as insulation materials to solve the global environmental and energy crisis. Using chitosan, citric acid, pectin and phytic acid as raw materials, an all-biomass-based aerogel with high modulus was prepared by the triple strategy of ionic, physical and chemical cross-linking through directional freezing technique. Based on this three-dimensional network, the aerogel exhibited excellent compressive modulus (24.89 ± 1.76 MPa) over a wide temperature range and thermal insulation properties. In the presence of chitosan, citric acid and phytic acid, the aerogel obtained excellent fire safety (LOI value up to 31.2%) and antibacterial properties (antibacterial activity against Staphylococcus aureus and Escherichia coli reached 81.98% and 67.43%). In addition, the modified aerogel exhibited excellent hydrophobicity (hydrophobic angle of 146°) and oil-water separation properties. More importantly, the aerogel exhibited a biodegradation rate of up to 40.31% for 35 days due to its all-biomass nature. This work provides a green and sustainable strategy for the production of highly environmentally friendly thermal insulation materials with high strength, flame retardant, antibacterial and hydrophobic properties.

Green and efficient method to acquire high-value phycobiliprotein from microalgal biomass involving deep eutectic solvent-based ultrasound-assisted extraction

Phycoerythrin (PE) is a phycobiliprotein holding great potential as a high-value food colorant and medicine. Deep eutectic solvent (DES)-based ultrasound-assisted extraction (UAE) was applied to extract B-PE by disrupting the resistant polysaccharide cell wall of Porphyridium purpureum. The solubility of cell wall monomers in 31 DESs was predicted using COSMO-RS. Five glycerol-based DESs were tested for extraction, all of which showed significantly higher B-PE yields by up to 13.5 folds than water. The DES-dependent B-PE extraction efficiencies were proposedly associated with different cell disrupting capabilities and protein stabilizing effects of DESs. The DES-based UAE method could be considered green according to a metric assessment tool, AGREEprep. The crude extract containing DES was further subjected to aqueous two-phase system, two-step ammonium sulfate precipitation, and ultrafiltration processes. The final purified B-PE had a PE purity ratio of 3.60 and a PC purity ratio of 0.08, comparable to the purity of commercial products.

Casein-based hydrogels: Advances and prospects

Casein-based hydrogels (Casein Gels) possess advantageous properties, including mechanical strength, stability, biocompatibility, and even adhesion, conductivity, sensing capabilities, as well as controlled-releasing behavior of drugs. These features are attributed to their gelation methods and functionalization with various polymers. Casein Gels is an important protein-based material in the food industry, in terms of dairy and functional foods, biological and medicine, in terms of carrier for bioactive and sensitive drugs, wound healing, and flexible sensors and wearable devices. Herein, this review aims to highlight the importance of the features mentioned above via a comprehensive investigation of Casein Gels through multiple directions and dimensional applications. Firstly, the composition, structure, and properties of casein, along with the gelation methods employed to create Casein Gels are elaborated, which serves as a foundation for further exploration. Then, the application progresses of Casein Gels in dairy products, functional foods, medicine, flexible sensors and wearable devices, are thoroughly discussed to provide insights into the diverse fields where Casein Gels have shown promise and utility. Lastly, the existing challenges and future research trends are highlighted from an interdisciplinary perspective. We present the latest research advances of Casein Gels and provide references for the development of multifunctional biomass-based hydrogels.

Matrix-free laser desorption/ionization mass spectrometry imaging for rapid evaluation of wood biomass conversion

RATIONALE

This study overcomes traditional biomass analysis limitations by introducing a pioneering matrix-free laser desorption/ionization (LDI) approach in mass spectrometry imaging (MSI) for efficient lignin evaluation in wood. The innovative acetic acid-peracetic acid (APA) treatment significantly enhances lignin detection, enabling high-throughput, on-site analysis.

METHODS

Wood slices, softwood from a conifer tree (Japanese cypress) and hardwood from a broadleaf tree (Japanese beech), were analyzed using MSI with a Fourier transform ion cyclotron resonance mass spectrometer. The developed APA treatment demonstrated effectiveness for MSI analysis of biomass.

RESULTS

Our imaging technique successfully distinguishes between earlywood and latewood and enables the distinct visualization of lignin in these and other wood tissues, such as the radial parenchyma. This approach reveals significant contrasts in MSI. It has identified intense ions from β-O-4-type lignin, specifically in the radial parenchyma of hardwood, highlighting the method's precision and utility in wood tissue analysis.

CONCLUSIONS

The benefits of matrix-free LDI include reduced peak overlap, consistent sample quality, preservation of natural sample properties, enhanced analytical accuracy, and reduced operational costs. This innovative approach is poised to become a standard method for rapid and precise biomass evaluation and has important applications in environmental research and sustainable resource management and is crucial for the effective management of diverse biomass, paving the way towards a sustainable, circular society.

Benefit of aerosol reduction to winter wheat during China's clean air action: A case study of Henan Province

A strongly declining aerosol radiative effect has been observed in China since 2013 after implementing the clean air action, yet its impact on wheat (Triticum aestivum L.) production remains unclear. We use satellite measures and a biophysical crop model to assess the impact of aerosol-induced radiative perturbations on winter wheat production in the agricultural belt of Henan province from 2013 to 2018. After calibrating parameters with the extended Fourier Amplitude Sensitivity Test (EFAST) and the generalized likelihood uncertainty estimation (GLUE) method, the DSSAT CERES-Wheat model was able to simulate crop biomass and yield more accurately. We found that the aerosol negatively impacted wheat biomass by 21.87% and yield by 22.48% from 2006 to 2018, and the biomass effects from planting to anthesis were more significant compared to anthesis to maturity. Due to the strict clean air action, under all-sky conditions, the surface solar shortwave radiation (SSR) in 2018 increased by about 7.08% over 2006-2013 during the wheat growing seasons. As a result of the improvement of crop photosynthesis, winter wheat biomass and yield increased by an average of 5.46% and 2.9%, respectively. Our findings show that crop carbon uptake and yield will benefit from the clean air action in China, helping to ensure national food and health security.

Microalgae production in olive mill wastewater fractions and cattle digestate slurry: Bioremediation effects and suitability for energy and feed uses

The possibility of obtaining energy or nutritive streams and bioremediation as an add-on opens new perspectives for the massive culturing of microalgal biomass on waste waters generated by the agro-food sector. Ordinary revenue streams are fully preserved, or even boosted, if they are used in microalgal cultivation; however, the suitability of wastewaters depends on multiple nutritional and toxic factors. Here, the effect of modulating the Olive Mill Wastewater (OMW) and cattle digestate (CD) fraction in the formulation of a growth medium on biomass accumulation and productivity of selected biomass fractions and their relevance for biofuel and/or feed production were tested for the microalga Scenedesmus dimorphus and for the cyanobacterium Arthrospira platensis (Spirulina). Tests highlighted the strong S. dimorphus adaptability to digestate, as on OMW, compared to A. platensis, with the maximum lipid storage (48 %) when culture medium was composed by 50 % of cattle digestate.

Effects of seasonal precipitation regimes on microbial biomass and extracellular enzyme activity during shrub foliar litter decomposition in a subtropical forest

Elucidating the mechanisms underlying microbial biomass and extracellular enzyme activity responses to the seasonal precipitation regime during foliar litter decomposition is highly important for understanding the material cycle of forest ecosystems in the context of global climate change; however, the specific underlying mechanisms remain unclear. Hence, a precipitation manipulation experiment involving a control (CK) and treatments with decreased precipitation in the dry season and extremely increased precipitation in the wet season (IE) and decreased precipitation in the dry season and proportionally increased precipitation in the wet season (IP) was conducted in a subtropical evergreen broad-leaved forest in China from October 2020 to October 2021. The moisture, microbial biomass, and extracellular enzyme activities of foliar litter from two dominant shrub species, Phyllostachys violascens and Alangium chinense, were measured at six stages during the dry and wet seasons. The results showed that (1) both IE and IP significantly decreased the microbial biomass carbon and microbial biomass nitrogen content and the activities of β-1,4-glucosidase, β-1,4-N-acetylglucosaminidase, acid phosphatase and cellulase in the dry season, while the opposite effects were observed in the wet season. (2) Compared with those of IE, the effects of IP on foliar litter microbial biomass and extracellular enzyme activity were more significant. (3) The results from the partial least squares model indicated that extracellular enzyme activity during foliar litter decomposition was strongly controlled by the foliar litter water content, microbial biomass nitrogen, the ratio of total carbon to total phosphorus, foliar litter total carbon, and foliar litter total nitrogen. These results provide an important theoretical basis for elucidating the microbial mechanisms driving litter decomposition in a subtropical forest under global climate change scenarios.

Monitoring insect numbers and biodiversity with a vertical-beam entomological radar

Concerns about perceived widespread declines in insect numbers have led to recognition of a requirement for long-term monitoring of insect biodiversity. Here we examine whether an existing, radar-based, insect monitoring system developed for research on insect migration could be adapted to this role. The radar detects individual larger (greater than 10 mg) insects flying at heights of 150-2550 m and estimates their size and mass. It operates automatically and almost continuously through both day and night. Accumulation of data over a 'half-month' (approx. 15 days) averages out weather effects and broadens the source area of the wind-borne observation sample. Insect counts are scaled or interpolated to compensate for missed observations; adjustment for variation of detectability with range and insect size is also possible. Size distributions for individual days and nights exhibit distinct peaks, representing different insect types, and Simpson and Shannon-Wiener indices of biodiversity are calculated from these. Half-month count, biomass and index statistics exhibit variations associated with the annual cycle and year to year changes that can be attributed to drought and periods of high rainfall. While species-based biodiversity measures cannot be provided, the radar's capacity to estimate insect biomass over a wide area indicates utility for tracking insect population sizes. This article is part of the theme issue 'Towards a toolkit for global insect biodiversity monitoring'.

Mixing of pine and arbuscular mycorrhizal tree species changed soil organic carbon storage by affecting soil microbial characteristics

Pure and mixed pine forests are found all over the world. The mycorrhizal type affects soil microbial activity and carbon sequestration capacity in pure forests. However, the effects of mycorrhizal type on microbial characteristics and carbon sequestration capacity in pine mixed forests remain untested. Further, making it difficult to predict carbon storage of the conversion from pure pine forests to mixed forests at larger scales. Herein, a meta-analysis showed that the contents of soil microbial biomass, mineral-associated organic carbon, and soil organic carbon in pine mixed forests with introduced arbuscular mycorrhizal tree species (PMAM) increased by 26.41 %, 58.55 %, and 27.41 %, respectively, compared to pure pine forests, whereas those of pine mixed forests without arbuscular mycorrhizal tree species (PMEcM) remained unchanged. Furthermore, the effect size of microbial biomass, mineral-associated organic carbon and organic carbon contents in subsoil of PMAM are 56.48 %, 78.49 % and 43.05 %, respectively, which are higher than those in topsoil. The improvement of carbon sinks throughout the PMAM soil profile is positively correlated with increases in microbial biomass and mineral-associated organic carbon in subsoil, according to regression analysis and structural equation modelling. In summary, these results highlight that the positive effects of introducing arbuscular mycorrhizal tree species rather than ectomycorrhizal tree species into pure pine forests on soil microbial biomass and carbon sequestration. The positive link between microbial biomass, mineral-associated organic carbon, and soil organic carbon suggests an underlying mechanism for how soil microorganisms store carbon in pine mixed forests. Nevertheless, our findings also imply that the soil carbon pool of PMAM may be vulnerable under climate change. Based on the above findings, we propose that incorporating mycorrhizal type of tree species and soil thickness into mixed forests management and biodiversity conservation.

Exclusion of livestock decouples the relationship between plant production and diversity, species richness on complex topography in typical steppe in the Loess Plateau, China

Grazing is widely used in more than one-forth of global terrestrial ecosystems, with three quarters are distributed on complex topography. Grazing and topography have both resulted in degradation of approximately 49 % of natural grasslands. However, research on the interaction between topography and livestock exclusion on grassland characteristics is scarce. This study was carried out on a typical steppe to explore the effect of topography and enclosure year on vegetation characteristics. Aboveground biomass, and species richness were examined for three different enclosure years (0, 3, and 6 years), on four slopes (0°, 15°, 30°, and 45° slope), and three aspects (flat, shady and sunny). The results indicated that: The aboveground biomass on the 0° slope had a greater value after 6 years of the enclosure. Aboveground biomass increased with the increasing enclosure year, while it decreased with increasing slope except enclosure for 0 year on shady slope. Aboveground biomass on the shady slopes was greater than on the sunny slopes. Species richness of community and perennial plants increased with increasing slope and enclosure year. The annual plants richness inversely correlated with slope and enclosure year. All plant diversity indexes increased with increasing enclosure year. Margalef and Shannon-wiener indexes decreased with increasing slope, while Simpson and Pielou indexes increased. This paper demonstrates that aspect, slope and enclosure affect aboveground biomass by affecting other vegetation characteristics. In conclusion, grassland production can be improved with moderate livestock exclusion under different topography.

Salinity decreases the contribution of microbial necromass to soil organic carbon pool in arid regions

Saline soils are widely distributed in arid areas but there is a lack of mechanistic understanding on the effect of salinity on the formation and biochemical composition of soil organic carbon (SOC). We investigated the effects of salinity on the accumulation of microbial necromass under natural vegetation and in cropland in salt-affected arid areas stretching over a 1200-km transect in northwest China. Under both natural vegetation and cropland, microbial physiological activity (indicated by microbial biomass carbon normalized enzymatic activity) decreased sharply where the electrical conductivity approached 4 ds m-1 (a threshold to distinguish between saline and non-saline soils), but microbial biomass was only slightly affected by salinity. These indicated that a larger proportion of microbes could be inactive or dormant in saline soils. The contribution of fungal necromass C to SOC decreased but the contribution of bacterial necromass C to the SOC increased with increasing soil salinity. Adding fungal and bacterial necromass C together, the contribution of microbial necromass C to SOC in saline soils was 32-39 % smaller compared with non-saline soils. Fungal necromass C took up 85-86 % of microbial necromass C in non-saline soils but this proportion dropped to 60-66 % in saline soils. We suggested that the activity, growth, and turnover rate of microbes slowed by salinity was responsible for the decreased accumulation of fungal necromass in saline compared with non-saline soils, while the increased accumulation of bacterial residue in saline soils could be induced mainly by its slower decomposition. Soil microbial biomass was a poor predictor for the accumulation of microbial necromass in saline soils. We demonstrated a reduced contribution of microbial necromass to SOC and a shift in its composition towards the increase in bacterial origin in saline relative to non-saline soils. We concluded that salinity profoundly changes the biochemistry of SOC in arid regions.

Enhanced humification of full-scale apple wood and cow manure by promoting lignocellulose degradation via biomass pretreatments

Agroforestry waste and cow manure pollute the environment, of which, agroforestry waste is difficult to degrade. Compost is an effective way to dispose agroforestry waste; however, the low degradation efficiency of lignocellulose in agroforestry waste affects the process of composting humification. This study investigated lignocellulose degradation and composting humification in full-size apple wood and cow manure composting processes by applying different pretreatments (acidic, alkaline, and high-temperature) to apple wood. Simultaneously, physicochemical characterization and metagenome sequencing were combined to analyze the function of carbohydrate-active enzymes database (CAZy). Therefore, microbial communities and functions were linked during the composting process and the lignocellulose degradation mechanism was elaborated. The results showed that the addition of apple wood increased the compost humus (HS) yield, and pretreatment of apple wood enhanced the lignocellulose degradation during composting processes. In addition, pretreatment improved the physicochemical properties, such as temperature, pH, electric conductivity (EC), ammonium nitrogen (NH4+), and nitrate nitrogen (NO3-) in the compost, of which, acid treated apple wood compost (AcAWC) achieved the highest temperature of 58.4 °C, effectively promoting nitrification with NO3- ultimately reaching 0.127 g/kg. In all composts, microbial networks constructed a high proportion of positively correlated connections, and microorganisms promoted the composting process through cooperation. The proportions of glycosyltransferase (GT) and glycoside hydrolase (GH) promoted the separation and degradation of lignocellulose during composting to form HS. Notably, the adverse effects of the alkali-treated apple wood compost on bacteria were greater. AcAWC showed significant correlations between bacterial and fungal communities and both lignin and hemicellulose, and had more biomarkers associated with lignocellulose degradation and humification. The lignin degradation rate was 24.57 % and the HS yield increased by 27.49 %. Therefore, AcAWC has been confirmed to enhance lignocellulose degradation and promote compost humification by altering the properties of the apple wood and establishing a richer microbial community.

Understanding the dependence of biochar properties on different types of biomass

Owing to the diversity of biomasses and many variables in pyrolysis process, the property of biochar from varied biomass feedstock or even same biomass could differ significantly. Since the property of biochar governs the further application of biochar, this review paid particular attention to the correlation between the nature of biomass feedstock and the specifications of biochar in terms of yield, elemental composition, pH, functionalities, heating value, pore structures, morphologies, etc. The property of the biochar from the pyrolysis of cellulose, hemicellulose, lignin, woody biomass (pine, mallee, poplar, acacia, oak, eucalyptus and beech), bark of woody biomass, leaves of woody biomass, straw, algae, fruit peels, tea waste was compared and summarized. In addition, the differences of the biochar of these varied origins were also analyzed. The remaining questions, about the correlation of biomass nature with biochar characteristics, to be further investigated are analyzed in detail. The deduced information about the relationship of the nature of biochar and biomass feedstock as well as key pyrolysis parameters is of importance for further development of the methods for tailoring or production of the biochar of desirable properties. The results from this study could be interesting technically and commercially for the technology developer using biochar as the source of carbon in different applications.

Unraveling interplay between lignocellulosic structures caused by chemical pretreatments in enhancing enzymatic hydrolysis

To investigate the interplay between substrate structure and enzymatic hydrolysis (EH) efficiency, poplar was pretreated with acidic sodium-chlorite (ASC), 3 % sodium-hydroxide (3-SH), and 3 % sulfuric acid (3-SA), resulting in different glucose yields of 94.10 %, 74.35 %, and 24.51 %, respectively, of pretreated residues. Residues were fractionated into cellulose, lignin and unhydrolyzed residue after EH (for lignin-carbohydrate complex (LCC) analysis) and analyzed using HPLC, FTIR, XPS, CP MAS 13C NMR and 2D-NMR (Lignin and LCC analysis). After delignification, holocellulose exhibited a dramatic increase in glucose yield (74.35 % to 90.82 % for 3-SH and 24.51 % to 80.0 % for 3-SA). Structural analysis of holocellulose suggested the synergistic interplay among cellulose allomorphs to limit glucose yield. Residual lignin analysis from un/pretreated residues indicated that higher β-β' contents and S/G ratios were favorable to the inhibitory effect but unfavourable to the holocellulose digestibility and followed the trend in the following order: 3-SA (L3) > 3-SH (L2) > native-lignin (L1). Analysis of enzymatically unhydrolyzed pretreated residues revealed the presence of benzyl ether (BE1,2) LCC and phenyl glycoside (PG) bond linking to xylose (X) and mannose (M), which yielded a xylan-lignin-glucomannan network. The stability, steric hindrance and hydrophobicity of this network may play a central role in defining poplar recalcitrance.

Long-term species-level observations indicate the critical role of soil moisture in regulating China's grassland productivity relative to phenological and climatic factors

As a sensitive indicator of climate change and a key variable in ecosystem surface-atmosphere interaction, vegetation phenology, and the growing season length, as well as climatic factors (i.e., temperature, precipitation, and sunshine duration) are widely recognized as key factors influencing vegetation productivity. Recent studies have highlighted the importance of soil moisture in regulating grassland productivity. However, the relative importance of phenology, climatic factors, and soil moisture to plant species-level productivity across China's grasslands remains poorly understood. Here, we use nearly four decades (1981 to 2018) of in situ species-level observations from 17 stations distributed across grasslands in China to examine the key mechanisms that control grassland productivity. The results reveal that soil moisture is the strongest determinant of the interannual variability in grassland productivity. In contrast, the spring/autumn phenology, the length of vegetation growing season, and climate factors have relatively minor impacts. Generally, annual aboveground biomass increases by 3.9 to 25.3 g∙m2 (dry weight) with a 1 % increase in growing season mean soil moisture across the stations. Specifically, the sensitivity of productivity to moisture in wetter and colder environments (e.g., alpine meadows) is significantly higher than that in drier and warmer environments (e.g., temperate desert steppes). In contrast, the sensitivity to the precipitation of the latter is greater than the former. The effect of soil moisture is the most pronounced during summer. Dominant herb productivity is more sensitive to soil moisture than the others. Moreover, multivariate regression analyses show that the primary climatic factors and their attributions to variations in soil moisture differ among the stations, indicating the interaction between climate and soil moisture is very complex. Our study highlights the interspecific difference in the soil moisture dependence of grassland productivity and provides guidance to climate change impact assessments in grassland ecosystems.

Techno-economic assessment of biopolymer production from methane and volatile fatty acids: effect of the reactor size and biomass concentration on the poly(3-hydroxybutyrate-co-3-hydroxyvalerate) selling price

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) is a biobased and biodegradable polymer that could efficiently replace fossil-based plastics. However, its widespread deployment is slowed down by the high production cost. In this work, the techno-economic assessment of the process for producing poly(3-hydroxybutyrate-co-3-hydroxyvalerate) from low-cost substrates, such as methane and valeric acid derived from the anaerobic digestion of organic wastes, is proposed. Several strategies for cost abatement, such as the use of a mixed consortium and a line for reagent recycling during downstream, were adopted. Different scenarios in terms of production, from 100 to 100,000 t/y, were analysed, and, for each case, the effect of the reactor volume (small, medium and large size) on the selling price was assessed. In addition, the effect of biomass concentration was also considered. Results show that the selling price of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) is minimum for a production plant with 100,000 t/y capacity, accounting for 18.4 €/kg, and highly influenced by the biomass concentration since it can be reduced up to 8.6 €/kg by increasing the total suspended solids from 5 to 30 g/L, This adjustment aligns the breakeven point of PHBV with the reported average commercial price.

Regime shift in microalgal dynamics: Impact of water level changes on planktonic and benthic algal biomass

Whole-lake microalgal biomass surveys were carried out in Lake Balaton to investigate the seasonal, spatial, and temporal changes of benthic algae, as well as to identify the drivers of the phytobenthos. Phytobenthos was controlled mainly by light: the highest benthic algal biomass was in the shallow littoral region characterized by large grain size (sand) with good light availability but lower nutrient content in the sediment. During the investigated period, phytoplankton biomass showed a significant decrease in almost the entire lake. At the same time, the biomass of benthic algae increased significantly in the eastern areas, increasing the contribution of total lake microalgae biomass (from 20 % to 27 %). Benthic algal biomass increase can be explained by the better light supply, owing to the artificially maintained high water level which greatly mitigates water mixing. The decrease in planktonic algal biomass could be attributed to increased zooplankton grazing, which is otherwise negatively affected by mixing. As a result of the high water level, the trophic structure of the lake has been rearranged in recent decades with a shift from the planktonic life form to the benthic one while the nutrient supply has largely remained unchanged.

Soil microbes deal with the nitrogen deposition enhanced phosphorus limitation by shifting community structure in an old-growth subtropical forest

Elevated atmospheric nitrogen (N) deposition potentially enhances the degree of phosphorus (P) limitation in tropical and subtropical forests. However, it remains elusive that how soil microorganisms deal with the N deposition-enhanced P limitation. We collected soils experienced 9 years of manipulative N input at various rates (0, 40, and 80 kg N ha-1 y-1) in an old-growth subtropical natural forest. We measured soil total and available carbon (C), N and P, microbial biomass C, N and P, enzyme activities involved in C, N and P acquisition, microbial community structure, as well as net N and P mineralization. Additionally, we calculated element use efficiency and evaluated microbial homeostasis index. Our findings revealed that N input increased microbial biomass C:P (MBC:P) and N:P (MBN:P) ratios. The homeostasis indexes of MBC:P and MBN:P were 0.68 and 0.75, respectively, indicating stoichiometric flexibility. Interestingly, MBC:P and MBN:P correlated significantly with the fungi:bacteria ratio (F:B), not with N and P use efficiencies, net N and P mineralization, and enzyme C:P (EEAC:P) and N:P (EEAN:P) ratios. Furthermore, EEAC:P and EEAN:P correlated positively with F:B but did not negatively correlate with the C:P and N:P ratios of available resources and microbial biomass. The effects of N deposition on MBC:P, MBN:P and EEAN:P became insignificant when including F:B as a covariate. These findings suggest that microbes flexibly adapted to the N deposition enhanced P limitation by changing microbial community structure, which not only alter microbial biomass C:N:P stoichiometry, but also the enzyme production strategy. In summary, our research advances our understanding of how soil microorganisms deal with the N deposition-enhanced soil P limitation in subtropical forests.

A meta-analysis on crop growth and heavy metals accumulation with PGPB inoculation in contaminated soils

Plant growth-promoting bacteria (PGPB) offer a promising solution for mitigating heavy metals (HMs) stress in crops, yet the mechanisms underlying the way they operate in the soil-plant system are not fully understood. We therefore conducted a meta-analysis with 2037 observations to quantitatively evaluate the effects and determinants of PGPB inoculation on crop growth and HMs accumulation in contaminated soils. We found that inoculation increased shoot and root biomass of all five crops (rice, maize, wheat, soybean, and sorghum) and decreased metal accumulation in rice and wheat shoots together with wheat roots. Key factors driving inoculation efficiency included soil organic matter (SOM) and the addition of exogenous fertilizers (N, P, and K). The phylum Proteobacteria was identified as the keystone taxa in effectively alleviating HMs stress in crops. More antioxidant enzyme activity, photosynthetic pigment, and nutrient absorption were induced by it. Overall, using PGPB inoculation improved the growth performance of all five crops, significantly increasing crop biomass in shoots, roots, and grains by 33 %, 35 %, and 20 %, respectively, while concurrently significantly decreasing heavy metal accumulation by 16 %, 9 %, and 37 %, respectively. These results are vital to grasping the benefits of PGPB and its future application in enhancing crop resistance to HMs.

UHPM dominance in driving the formation of petroleum-contaminated soil aggregate, the bacterial communities succession, and phytoremediation

This study focused on the effects of urea humate-based porous materials (UHPM) on soil aggregates, plant physiological characteristics, and microbial diversity to explore the effects of UHPM on the phytoremediation of petroleum-contaminated soil. The compositions of soil aggregates, ryegrass (Lolium perenne) biomass, plant petroleum enrichment capacity, and bacterial communities in soils with and without UHPM were investigated. The results showed that UHPM significantly increased soil aggregate content by 0.25 mm-5 mm, resulting in higher fertilizer holding capacity, erosion resistance capacity, and plant biomass and microbial number than the soil without UHPM mixed. In addition, UHPM decreased the absorption of petroleum by plants in the soil while increasing the abundance of degrading bacteria and petroleum-degrading-related genes in the soil, thereby promoting the removal of hard-to-degrade petroleum components. RDA showed that, compared with the unimproved soil, each soil indicator was positively correlated with a high abundance of degrading bacteria in the improved soil and was significant. UHPM can be regarded as a petroleum-contaminated soil remediation agent that combines slow nutrient release with soil improvement effects.

Removal of RNA viruses from swine wastewater using anaerobic membrane bioreactor: Performance and mechanisms

The effective removal of viruses from swine wastewater using anaerobic membrane bioreactor (AnMBR) is vital to ecological safety. However, most studies have focused only on disinfectants, whereas the capabilities of the treatment process have not been investigated. In this study, the performance and mechanism of an AnMBR in the removal of porcine hepatitis E virus (HEV), porcine kobuvirus (PKoV), porcine epidemic diarrhea virus (PEDV), and transmissible gastroenteritis coronavirus (TGEV) are systematically investigated. The results show that the AnMBR effectively removes the four viruses, with average removal efficiencies of 1.62, 3.05, 2.41, and 1.34 log for HEV, PKoV, PEDV and TGEV, respectively. Biomass adsorption contributes primarily to the total virus removal in the initial stage of reactor operation, with contributions to HEV and PKoV removal exceeding 71.7 % and 68.2 %, respectively. When the membrane is fouled, membrane rejection dominated virus removal. The membrane rejection contribution test shows the significant contribution of membrane pore foulants (23-76 %). Correlation analysis shows that the surface characteristics and size differences of the four viruses contribute primarily to their different effects on biomass adsorption and membrane rejection. This study provides technical guidance for viral removal during the treatment of high-concentration swine wastewater using an AnMBR.

Nitrogen addition changed soil fungal community structure and increased the biomass of functional fungi in Korean pine plantations in temperate northeast China

Nitrogen (N) deposition is a global environmental issue that can have significant impacts on the community structure and function in ecosystems. Fungi play a key role in soil biogeochemical cycles and their community structures are tightly linked to the health and productivity of forest ecosystems. Based on high-throughput sequencing and ergosterol extraction, we examined the changes in community structure, composition, and biomass of soil ectomycorrhizal (ECM) and saprophytic (SAP) fungi in 0-10 cm soil layer after 8 years of continuous N addition and their driving factors in a temperate Korean pine plantation in northeast China. Our results showed that N addition increased fungal community richness, with the highest richness and Chao1 index under the low N treatment (LN: 20 kg N ha-1 yr-1). Based on the FUN Guild database, we found that the relative abundance of ECM and SAP fungi increased first and then decreased with increasing N deposition concentration. The molecular ecological network analysis showed that the interaction between ECM and SAP fungi was enhanced by N addition, and the interaction was mainly positive in the ECM fungal network. N addition increased fungal biomass, and the total fungal biomass (TFB) was the highest under the MN treatment (6.05 ± 0.3 mg g-1). Overall, we concluded that N addition changed soil biochemical parameters, increased fungal activity, and enhanced functional fungal interactions in the Korean pine plantation over an 8-year simulated N addition. We need to consider the effects of complex soil conditions on soil fungi and emphasize the importance of regulating soil fungal community structure and biomass for managing forest ecosystems. These findings could deepen our understanding of the effects of increased N deposition on soil fungi in temperate forests in northern China, which can provide the theoretical basis for reducing the effects of increased N deposition on forest soil.

Enhancing biomass conversion to bioenergy with machine learning: Gains and problems

The growing concerns about environmental sustainability and energy security, such as exhaustion of traditional fossil fuels and global carbon footprint growth have led to an increasing interest in alternative energy sources, especially bioenergy. Recently, numerous scenarios have been proposed regarding the use of bioenergy from different sources in the future energy systems. In this regard, one of the biggest challenges for scientists is managing, modeling, decision-making, and future forecasting of bioenergy systems. The development of machine learning (ML) techniques can provide new opportunities for modeling, optimizing and managing the production, consumption and environmental effects of bioenergy. However, researchers in bioenergy fields have not widely utilized the ML concepts and practices. Therefore, a comparative review of the current ML techniques used for bioenergy productions is presented in this paper. This review summarizes the common issues and difficulties existing in integrating ML with bioenergy studies, and discusses and proposes the possible solutions. Additionally, a detailed discussion of the appropriate ML application scenarios is also conducted in every sector of the entire bioenergy chain. This indicates the modernized conversion processes supported by ML techniques are imperative to accurately capture process-level subtleties, and thus improving techno-economic resilience and socio-ecological integrity of bioenergy production. All the efforts are believed to help in sustainable bioenergy production with ML technologies for the future.

Towards consolidated bioprocessing of biomass and plastic substrates for semi-synthetic production of bio-poly(ethylene furanoate) (PEF) polymer using omics-guided construction of artificial microbial consortia

Poly(ethylene furanoate) (PEF) plastic is a 100% renewable polyester that is currently being pursued for commercialization as the next-generation bio-based plastic. This is in line with growing demand for circular bioeconomy and new plastics economy that is aimed at minimizing plastic waste mismanagement and lowering carbon footprint of plastics. However, the current catalytic route for the synthesis of PEF is impeded with technical challenges including high cost of pretreatment and catalyst refurbishment. On the other hand, the semi-biosynthetic route of PEF plastic production is of increased biotechnological interest. In particular, the PEF monomers (Furan dicarboxylic acid and ethylene glycol) can be synthesized via microbial-based biorefinery and purified for subsequent catalyst-mediated polycondensation into PEF. Several bioengineering and bioprocessing issues such as efficient substrate utilization and pathway optimization need to be addressed prior to establishing industrial-scale production of the monomers. This review highlights current advances in semi-biosynthetic production of PEF monomers using consolidated waste biorefinery strategies, with an emphasis on the employment of omics-driven systems biology approaches in enzyme discovery and pathway construction. The roles of microbial protein transporters will be discussed, especially in terms of improving substrate uptake and utilization from lignocellulosic biomass, as well as from depolymerized plastic waste as potential bio-feedstock. The employment of artificial bioengineered microbial consortia will also be highlighted to provide streamlined systems and synthetic biology strategies for bio-based PEF monomer production using both plant biomass and plastic-derived substrates, which are important for circular and new plastics economy advances.

Pilot composite tubular bioreactor for outdoor photo-fermentation hydrogen production: From batch to continuous operation

A novel 70 L composite tubular photo-bioreactor was constructed, and its photo-fermentation hydrogen production characteristics of batch and continuous modes were investigated with glucose as the substrate in an outdoor environment. In the batch fermentation stage, the hydrogen production rate peaked at 37.6 mL H2/(L·h) accompanied by a high hydrogen yield of 7 mol H2/mol glucose. The daytime light conversion efficiency is 4 %, with 37 % of light energy from the sun. An optimal hydraulic retention time of 5 d was identified during continuous photo-fermentation. Under this condition, the stability of the cell concentration is maintained and more electrons can be driven to the hydrogen generation pathway while attaining a hydrogen production rate of 20.7 ± 0.9 mL H2/(L·h). The changes of biomass, volatile fatty acids concentration and ion concentration during fermentation were analyzed. Continuous hydrogen production by composite tubular photo-bioreactor offers new ideas for the large-scale deployment of photobiological hydrogen production.

Integration of lactic acid biorefinery with treatment of red mud from alumina refinery: win-win paradigm for waste valorization

The cost of detoxification and neutralization poses certain challenges to the development of an economically viable lactic acid biorefinery with lignocellulosic biomass as feedstock. Herein, red mud, an alkaline waste, was explored as both a detoxifying agent and a neutralizer. Red mud treatment of lignocellulosic hydrolysate effectively removed the inhibitors generated in dilute acid pretreatment, improving the lactic acid productivity from 1.0 g/L·h-1 to 1.9 g/L·h-1 in later fermentation. In addition, red mud could replace CaCO3 as a neutralizer in lactic acid fermentation, which in turn enabled simultaneous bioleaching of valuable metals (Sc, Y, Nd, and Al) from red mud. The neutralization of alkali in red mud by acids retained in lignocellulosic hydrolysate and lactic acid produced from fermentation led to effective dealkalization, rendering a maximum alkali removal efficiency of 92.2 %. Overall, this study offered a win-win strategy for the valorization of both lignocellulosic biomass and red mud.

A strong and tough supramolecular assembled β-cyclodextrin and chitin nanocrystals protein adhesive: Synthesis, characterization, bonding performance on three-layer plywood

The development of a biomass adhesive as a substitute for petroleum-derived adhesives has been considered a viable option. However, achieving both superior bonding strength and toughness in biomass adhesives remains a significant challenge. Inspired by the human skeletal muscles structure, this study reveals a promising supramolecular structure using tannin acid (TA) functionalized poly-β-cyclodextrin (PCD) (TA@PCD) as elastic tissues and chitin nanocrystals (ChNCs) as green reinforcements to strengthen the soybean meal (SM) adhesive crosslinking network. TA@PCD acts as a dynamic crosslinker that facilitates reversible host-guest interactions, hydrogen bonds, and electrostatic interactions between adjacent stiff ChNCs and SM matrix, resulting in satisfactory strength and toughness. The resulting SM/TA@PCD/ChNCs-2 adhesive has demonstrated satisfactory wet and dry shear strength (1.25 MPa and 2.57 MPa, respectively), toughness (0.69 J), and long-term solvents resistance (80 d). Furthermore, the adhesive can exhibit desirable antimildew characteristics owing to the phenol hydroxyl groups of TA and amino groups of ChNCs. This work showcases an effective supramolecular chemistry strategy for fabricating high-performance biomass adhesives with great potential for practical applications.

Pilot-scale production of Bacillus subtilis MSCL 897 spore biomass and antifungal secondary metabolites in a low-cost medium

OBJECTIVES

Bacillus subtilis is a plant growth promoting bacterium (PGPB) that acts as a microbial fertilizer and biocontrol agent, providing benefits such as boosting crop productivity and improving nutrient content. It is able to produce secondary metabolites and endospores simultaneously, enhancing its ability to survive in unfavorable conditions and eliminate competing microorganisms. Optimizing cultivation methods to produce B. subtilis MSCL 897 spores on an industrial scale, requires a suitable medium, typically made from food industry by-products, and optimal temperature and pH levels to achieve high vegetative cell and spore densities with maximum productivity.

RESULTS

This research demonstrates successful pilot-scale (100 L bioreactor) production of a biocontrol agent B. subtilis with good spore yields (1.5 × 109 spores mL-1) and a high degree of sporulation (>80%) using a low-cost cultivation medium. Culture samples showed excellent antifungal activity (1.6-2.3 cm) against several phytopathogenic fungi. An improved methodology for inoculum preparation was investigated to ensure an optimal seed culture state prior to inoculation, promoting process batch-to-batch repeatability. Increasing the molasses concentration in the medium and operating the process in fed-batch mode with additional molasses feed, did not improve the overall spore yield, hence, process operation in batch mode with 10 g molasses L-1 is preferred. Results also showed that the product quality was not significantly impacted for up to 12 months of storage at room temperature.

CONCLUSION

An economically-feasible process for B. subtilis-based biocontrol agent production was successfully developed at the pilot scale.

Catalytic co-combustion of biomass and brown coal in a fluidized bed: Economic and environmental benefits

The work is devoted to the study of combustion of brown coal, pine sawdust, and their mixtures in a fluidized bed of catalyst at 600-750°С. It is shown that an increase in the content of sawdust in a mixture with brown coal leads to an increase in the burnout degree of solid fuel from 94.4% to 99.9%, while the emission of greenhouse gases in the form of CO2 CO and NOx is reduced (CO2 from the biomass is not included in the balance). The high content of alkaline earth metal oxides (CaO and MgO) in the mineral part of brown coal, sawdust, and their mixtures eliminates the emission of sulfur oxides and the slagging of heat-exchange surfaces during the combustion in a fluidized bed of catalyst. The optimal temperature, when the highest burnout degree of the above fuels is achieved in the combustion is 750°С. It is also shown that the increase in temperature and the content of sawdust in the composition of the fuel mixtures has a positive effect on the economic and environmental process indicators.

Forest carbon storage and sink estimates under different management scenarios in China from 2020 to 2100

Forests play a crucial role in mitigating climate change through carbon storage and sequestration, though environmental change drivers and management scenarios are likely to influence these contributions across multiple spatial and temporal scales. In this study, we employed three tree growth models-the Richard, Hossfeld, and Korf models-that account for the biological characteristics of trees, alongside national forest inventory (NFI) datasets from 1994 to 2018, to evaluate the carbon sink potential of existing forests and afforested regions in China from 2020 to 2100, assuming multiple afforestation and forest management scenarios. Our results indicate that the Richard, Hossfeld, and Korf models provided a good fit for 26 types of vegetation biomass in both natural and planted Chinese forests. These models estimate that in 2020, carbon stocks in existing Chinese forests are 7.62 ± 0.05 Pg C, equivalent to an average of 44.32 ± 0.32 Mg C/ ha. Our predictions then indicate this total forest carbon stock is expected to increase to 15.51 ± 0.99 Pg C (or 72.26 ± 4.6 Mg C/ha) in 2060, and further to 19.59 ± 1.36 Pg C (or 91.31 ± 6.33 Mg C/ha) in 2100. We also show that plantation management measures, namely tree species replacement, would increase carbon sinks to 0.09 Pg C/ year (contributing 38.9 %) in 2030 and 0.06 Pg C/ year (contributing 32.4 %) in 2060. Afforestation using tree species with strong carbon sink capacity in existing plantations would further significantly increase carbon sinks from 0.02 Pg C/year (contributing 10.3 %) in 2030 to 0.06 Pg C/year (contributing 28.2 %) in 2060. Our results quantify the role plantation management plays in providing a strong increase in forest carbon sequestration at national scales, pointing to afforestation with native tree species with high carbon sequestration as key in achieving China's 2060 carbon neutrality target.

Toxicity of particulate emissions from residential biomass combustion: An overview of in vitro studies using cell models

This article aims to critically review the current state of knowledge on in vitro toxicological assessments of particulate emissions from residential biomass heating systems. The review covers various aspects of particulate matter (PM) toxicity, including oxidative stress, inflammation, genotoxicity, and cytotoxicity, all of which have important implications for understanding the development of diseases. Studies in this field have highlighted the different mechanisms that biomass combustion particles activate, which vary depending on the combustion appliances and fuels. In general, particles from conventional combustion appliances are more potent in inducing cytotoxicity, DNA damage, inflammatory responses, and oxidative stress than those from modern appliances. The sensitivity of different cell lines to the toxic effects of biomass combustion particles is also influenced by cell type and culture conditions. One of the main challenges in this field is the considerable variation in sampling strategies, sample processing, experimental conditions, assays, and extraction techniques used in biomass burning PM studies. Advanced culture systems, such as co-cultures and air-liquid interface exposures, can provide more accurate insights into the effects of biomass combustion particles compared to simpler submerged monocultures. This review provides critical insights into the complex field of toxicity from residential biomass combustion emissions, underscoring the importance of continued research and standardisation of methodologies to better understand the associated health hazards and to inform targeted interventions.

Biomass to green surfactants: Microwave-assisted transglycosylation of wheat bran for alkyl glycosides production

Depolymerization of carbohydrate biomass using a long-chain alcohol (transglycosylation) to produce alkyl glycoside-based bio-surfactants has been gaining industrial interest. This study introduces microwave-assisted transglycosylation in transforming wheat bran, a substantial agricultural side stream, into these valuable compounds. Compared to traditional heating, microwave-assisted processing significantly enhances the product yield by 53 % while reducing the reaction time by 72 %, achieving a yield of 29 % within 5 h. This enhancement results from the microwave's capacity to activate intermolecular hydrogen and glycosidic bonds, thereby facilitating transglycosylation. Life-cycle assessment and techno-economic analysis demonstrate the benefits of microwave heating in reducing energy consumption by 42 %, CO2 emissions by 56 %, and equipment, operational and production costs by 44 %, 35 % and 30 %, respectively. The study suggests that microwave heating is a promising approach for efficiently producing bio-surfactants from agricultural wastes, with potential cost reductions and environmental benefits that could enhance industrial biomass conversion processes.

Advancements in Nano-Enhanced microalgae bioprocessing

Microalgae are promising sources of valuable compounds: carotenoids, polyunsaturated fatty acids, lipids, etc. To overcome the feasibility challenge due to low yield and attain commercial potential, researchers merge technologies to enhance algal bioprocess. In this context, nanomaterials are attractive for enhancing microalgal bioprocessing, from cultivation to downstream extraction. Nanomaterials enhance biomass and product yields (mainly lipid and carotenoids) through improved nutrient uptake and stress tolerance during cultivation. They also provide mechanistic insights from recent studies. They also revolutionize harvesting via nano-induced sedimentation, flocculation, and flotation. Downstream processing benefits from nanomaterials, improving extraction and purification. Special attention is given to cost-effective extraction, showcasing nanomaterial integration, and providing a comparative account. The review also profiles nanomaterial types, including metallic nanoparticles, magnetic nanomaterials, carbon-based nanomaterials, silica nanoparticles, polymers, and functionalized nanomaterials. Challenges and future trends are discussed, emphasizing nanomaterials' role in advancing sustainable and efficient microalgal bioprocessing, unlocking their potential for bio-based industries.

Physiological evaluation of yeast strains under anaerobic conditions using glucose, fructose, or sucrose as the carbon source

The aim of this study was to evaluate the physiology of 13 yeast strains by assessing their kinetic parameters under anaerobic conditions. They included Saccharomyces cerevisiae CAT-1 and 12 isolated yeasts from different regions in Brazil. The study aimed to enhance understanding of the metabolism of these strains for more effective applications. Measurements included quantification of sugars, ethanol, glycerol, and organic acids. Various kinetic parameters were analyzed, such as specific substrate utilization rate (qS), maximum specific growth rate (μmax), doubling time, biomass yield, product yield, maximum cell concentration, ethanol productivity (PEth), biomass productivity, and CO2 concentration. S. cerevisiae CAT-1 exhibited the highest values in glucose for μmax (0.35 h-1), qS (3.06 h-1), and PEth (0.69 gEth L-1 h-1). Candida parapsilosis Recol 37 did not fully consume the substrate. In fructose, S. cerevisiae CAT-1 stood out with higher values for μmax (0.25 h-1), qS (2.24 h-1), and PEth (0.60 gEth L-1 h-1). Meyerozyma guilliermondii Recol 09 and C. parapsilosis Recol 37 had prolonged fermentation times and residual substrate. In sucrose, only S. cerevisiae CAT-1, S. cerevisiae BB9, and Pichia kudriavzevii Recol 39 consumed all the substrate, displaying higher PEth (0.72, 0.51, and 0.44 gEth L-1 h-1, respectively) compared to other carbon sources.

Application of Thermomyces lanuginosus polygalacturonase produced in Komagataella phaffii in biomass hydrolysis and textile bioscouring

In this work, the polygalacturonase (TL-PG1) from the thermophilic fungus Thermomyces lanuginosus was heterologously produced for the first time in the yeast Komagataella phaffii. The TL-PG1 was successfully expressed under the control of the AOX1 promoter and sequentially purified by His-tag affinity. The purified recombinant pectinase exhibited an activity of 462.6 U/mL toward polygalacturonic acid under optimal conditions (pH 6 and 55 ˚C) with a 2.83 mg/mL and 0.063 μmol/minute for Km and Vmax, respectively. When used as supplementation for biomass hydrolysis, TL-PG1 demonstrated synergy with the enzymatic cocktail Ctec3 to depolymerize orange citrus pulp, releasing 1.43 mg/mL of reducing sugar. In addition, TL-PG1 exhibited efficiency in fabric bioscouring, showing potential usage in the textile industry. Applying a protein dosage of 7 mg/mL, the time for the fabric to absorb water was 19.77 seconds (ten times faster than the control). Adding the surfactant Triton to the treatment allowed the reduction of the enzyme dosage by 50% and the water absorption time to 6.38 seconds. Altogether, this work describes a new versatile polygalacturonase from T. lanuginosus with the potential to be employed in the hydrolysis of lignocellulosic biomass and bioscouring.

Rodent disturbance reduces ecosystem stability through regulating plant and soil functions in Hulun Buir steppe

Brandt's vole (Lasiopodomys brandtii), a typical rodent in the eastern Eurasian Steppe, has unclear impacts on ecosystem stability. In our field study in the Hulun Buir steppe, a multifunctional grazing ecosystem in this region, we used burrow entrance area and burrow density as alternative disturbance indices to derive a Disturbance Index (DI) for quantifying disturbance levels from rodents, and employed generalized linear mixed-effects model and the N-dimensional hypervolume framework to assess the influence of Brandt's vole disturbance on plant and soil functions, and then on the ecosystem functional stability. Our findings unequivocally illustrate that various plant functions including vegetation cover (Cover), aboveground biomass (ABG) and shoot carbon (ShootC) significantly declined with increasing disturbance, while shoot nitrogen (ShootN) and root nitrogen (RootN) show significantly positive responses. Soil functions such as soil nitrogen (SoilN), soil phosphorus (SoilP) and soil organic carbon (SoilC) showed significantly negative responses. Notably, the burrow entrance area exerts a more pronounced impact on both plant and soil functions in comparison to burrow density. Additionally, both disturbance indicators have a more significant influence on plant functions than on soil functions. Overall, the ecosystem functional stability progressively decreases with intensified disturbance, with varying response patterns for plant and soil functions, the former exhibited heightened stability as disturbance intensified, while the latter proved more stable at moderate disturbance levels. Our findings suggest that plant functions were more susceptible to disturbance by Brandt's vole compared to soils. Additionally, an ecosystem destabilization was synchronized with increasing Brandt's vole disturbance, although alterations in the functional stability of plants and soil show a different pattern.

Harmony in detoxification: Microalgae unleashing the potential of lignocellulosic pretreatment wastewater for resource utilization

Lignocellulosic biomass is a pivotal renewable resource in biorefinery process, requiring pretreatment, primarily chemical pretreatment, for effective depolymerization and subsequent transformation. This process yields solid residue for saccharification and lignocellulosic pretreatment wastewater (LPW), which comprises sugars and inhibitors such as phenols and furans. This study explored the microalgal capacity to treat LPW, focusing on two key hydrolysate inhibitors: furfural and vanillin, which impact the growth of six green microalgae. Chlorella sorokiniana exhibited higher tolerance to furfural and vanillin. However, both inhibitors hindered the growth of C. sorokiniana and disrupted algal photosynthetic system, with vanillin displaying superior inhibition. A synergistic inhibitory effect (Q < 0.85) was observed with furfural and vanillin on algal growth. Furfural transformation to low-toxic furfuryl alcohol was rapid, yet the addition of vanillin hindered this process. Vanillin stimulated carbohydrate accumulation, with 50.48 % observed in the 0.1 g/L furfural + 0.1 g/L vanillin group. Additionally, vanillin enhanced the accumulation of C16: 0 and C18: 2, reaching 21.71 % and 40.36 %, respectively, with 0.1 g/L vanillin. This study proposed a microalgae-based detoxification and resource utilization approach for LPW, enhancing the comprehensive utilization of lignocellulosic components. The observed biomass modifications also suggested potential applications for biofuel production, contributing to the evolving landscape of sustainable biorefinery processes.

Impact of climate change and oligotrophication on quality and quantity of lake primary production: A case study in Lake Biwa

Global climate change and anthropogenic oligotrophication are expected to reshape the dynamics of primary production (PP) in aquatic ecosystems; however, few studies have explored their long-term effects. In theory, the PP of phytoplankton in Lake Biwa may decline over decades due to warming, heightened stratification, and anthropogenic oligotrophication. Furthermore, the PP of large phytoplankton, which are inedible to zooplankton, along with biomass-specific productivity (PBc), could decrease. In this study, data from 1976 to 2021 and active fluorometry measurements taken in 2020 and 2021 were evaluated. Quantitatively, the temporal dynamics of mean seasonal PP during 1971-2021 were assessed according to the carbon fixation rate to investigate relationships among environmental factors. Qualitatively, phytoplankton biomass, PP, and PBc were measured in two size fractions [edible (S) or inedible (L) for zooplankton] in 2020 and 2021, and the L:S balance for these three measures was compared between 1992 (low-temperature/high-nutrient conditions) and 2020-2021 (high-temperature/low-nutrient conditions) to assess seasonal dynamics. The results indicated that climate change and anthropogenic oligotrophication over the past 30 years have diminished Lake Biwa's PP since the 1990s, impacting the phenology of PP dynamics. However, the L:S balance in PP and PBc has exhibited minimal change between the data from 1992 and the 2020-2021 period. These findings suggest that, although climate change and oligotrophication may reduce overall PP, they may not markedly alter the inedible/edible phytoplankton balance in terms of PP and PBc. Instead, as total PP declines, the production of small edible phytoplankton may decrease proportionally, potentially affecting trophic transfer efficiency and material cycling in Lake Biwa.

Biomass hydrothermal carbonization solution-assisted synthesis of intercalation-expanded core-shell structured molybdenum disulfide for efficient adsorption of Cr (VI) in electroplating wastewater treatment

Cr (VI) is a common heavy metal pollutant in electroplating wastewater. This study introduces the liquid-phase product from the hydrothermal reaction of coffee grounds (CGHCL) into the synthesis process of molybdenum disulfide, assisting in the fabrication of an intercalated, expanded core-shell structured molybdenum disulfide adsorbent (C-MoS2), designed for the adsorption and reduction of Cr (VI) from electroplating wastewater. The addition of CGHCL significantly enhances the adsorption performance of MoS2. Furthermore, C-MoS2 exhibits exceedingly high removal efficiency and excellent regenerative capability for Cr (VI)-containing electroplating wastewater. The core-shell structure effectively minimizes molybdenum leaching to the greatest extent, while the oleophobic interface is unaffected by oily substances in water, and the expanded interlayer structure ensures the long-term stability of C-MoS2 in air (90 days). This study provides a viable pathway for the resource utilization of biomass and the application of molybdenum disulfide-based materials in wastewater treatment.

Australian Black summer smoke signal on Antarctic aerosol collected between New Zealand and the Ross sea

Open biomass burning (BB) events are a well-known primary aerosol source, resulting in the emission of significant amount of gaseous and particulate matter and affecting Earth's radiation budget. The 2019-2020 summer, known as "Australian Black Summer", showed exceptional duration and intensity of seasonal wildfires, triggered by high temperatures and severe droughts. Since increasing megafires are predicted due to expected climate changes, it is critical to study the impact of BB aerosol on a large scale and evaluate related transport processes. In this study, five aerosol samples (total suspended particles with a diameter >1 μm) were collected during the XXXV Italian Expedition in Antarctica on board of the R/V Laura Bassi from 6th of January to February 16, 2020, along the sailing route from Lyttelton harbor (New Zealand) to Terra Nova Bay (Antarctica). Levoglucosan and its isomers have been analyzed as markers of BB, together with polycyclic aromatic hydrocarbons (PAHs), sucrose and alcohol sugars. Ionic species and carboxylic acids have been analyzed to support the identification of aerosol sources and its aging. Results showed high levoglucosan concentrations (325-1266 pg m-3) during the campaign, suggesting the widespread presence of smoke in the region, because of huge wildfire releases. Backward trajectories indicated the presence of long-range atmospheric transport from South America, probably carrying wildfires plume, in agreement with literature. Regional sources have been suggested for PAHs, particularly for 3-4 rings' compounds; monosaccharides, sucrose, arabitol, and mannitol were related to marine and biogenic contributions. In a warming climate scenario, more frequent and extensive wildfire episodes are expected in Australia, potentially altering albedo, aerosol radiative properties, and cloud interactions. Therefore, it is crucial to strengthens the investigations on the regional climatic effects of these events in Antarctica.

Chlamydomonas reinhardtii chloroplast factory construction for formate bioconversion

The photosynthetic autotrophic production of microalgae is limited by the effective supply of carbon and light energy, and the production efficiency is lower than the theoretical value. Represented by methanol, C1 compounds have been industrially produced by artificial photosynthesis with a solar energy efficiency over 10%, but the complexity of artificial products is weak. Here, based on a construction of chloroplast factory, green microalgae Chlamydomonas reinhardtii CC137c was modified for the bioconversion of formate for biomass production. By screening the optimal combination of chloroplast transport peptides, the cabII-1 cTP1 fusion formate dehydrogenase showed significant enhancement on the conversion of formate with a better performance in the maintenance of light reaction activity. This work provided a new way to obtain bioproducts from solar energy and CO2 with potentially higher-than-nature efficiency by the artificial-natural hybrid photosynthesis.

Biomass gasification, catalytic technologies and energy integration for production of circular methanol: New horizons for industry decarbonisation

The Intergovernmental Panel on Climate Change (IPCC) recognises the pivotal role of renewable energies in the future energy system and the achievement of the zero-emission target. The implementation of renewables should provide major opportunities and enable a more secure and decentralised energy supply system. Renewable fuels provide long-term solutions for the transport sector, particularly for applications where fuels with high energy density are required. In addition, it helps reducing the carbon footprint of these sectors in the long-term. Information on biomass characteristics feedstock is essential for scaling-up gasification from the laboratory to industrial-scale. This review deals with the transformation biogenic residues into a valuable bioenergy carrier like biomethanol as the liquid sunshine based on the combination of modified mature technologies such as gasification with other innovative solutions such as membranes and microchannel reactors. Tar abatement is a critical process in product gas upgrading since tars compromise downstream processes and equipment, for this, membrane technology for upgrading syngas quality is discussed in this paper. Microchannel reactor technology with the design of state-of-the-art multifunctional catalysts provides a path to develop decentralised biomethanol synthesis from biogenic residues. Finally, the development of a process chain for the production of (i) methanol as an intermediate energy carrier, (ii) electricity and (iii) heat for decentralised applications based on biomass feedstock flexible gasification, gas upgrading and methanol synthesis is analysed.

One pot synthesis of furan-modified lignin from agricultural waste via lignin-first approach

This study investigated a lignin-first approach to produce furan-modified lignin from sugarcane bagasse (SB), rice hull (RH), and sunn hemp biomass (SHB) using 5 methylfurfural (MF) and 5 methul-2-furanmethanol (MFM). The reaction time (5 h) was selected based on the delignification of SB using methanol and Ru/C catalyst which yielded the highest hydroxyl content. Delignification of SB with various MF weight ratios (1:1, 1:2, 1:3, 2:1, and 3:1) revealed that 1:1 and 2:1 ratios produced the highest hydroxyl content (7.7 mmol/g) and bio-oil yield (23.2 % wt% total weight). Further exploration identified that RH and MF at 1:1 ratio and SHB and MF at a 2:1 ratio produced the highest hydroxyl content (13.0 mmol/g) and bio-oil yield (31.6 % wt% tot. weight). This study developed a one-step method to extract and modify lignin with furan compounds simultaneously while opening new avenues for developing value-added products.