Search Results (292)

High culture medium costs economically constrain bacterial cellulose (BC) production. In parallel, agro-industrial wastes are plentiful but often underutilised sources of carbon and nitrogen substrates that could support microbial growth and metabolite production. This study aimed to bioconvert agro-industrial waste sustainably into BC using response surface methodology. A novel lactic acid bacterium, Levilactobacillus brevis DSS.01, isolated from nata de coco wastewater, was evaluated alongside Acetobacter tropicalis KBC and Komagataeibacter xylinus TISTR 086 for BC production using Australian agro-industrial wastes. Preliminary screening identified pear pomace and rice bran as optimal low-cost carbon and nitrogen sources, respectively. The response surface methodology employing Box–Behnken Design determined the optimal agro-industrial waste medium composition for L. brevis DSS.01 to produce BC at 1.56 ± 0.15 g/L. The optimised agro-industrial waste medium substituted 85% of standard Hestrin-Schramm medium components, suggesting a significant reduction in culture medium and production costs. Scanning electron microscopy revealed BC fibres from L. brevis DSS.01 maintained a uniform diameter. Fourier transform infrared spectroscopy and X-ray diffraction analyses indicated minimal structural deviation in BC produced from optimised agro-industrial waste medium versus standard medium. These findings demonstrate economic and sustainable BC production through valorisation of agro-industrial residues, establishing lactic acid bacteria as alternative BC producers with potential food-grade applications in circular economy frameworks. Full article

Polyhydroxyalkanoates (PHAs), a family of biodegradable polyesters produced through microbial fermentation of carbon-rich residues, are emerging as attractive alternatives to petroleum-based plastics. Their appeal lies in their exceptional biocompatibility, inherent biodegradability, and tunable physicochemical properties across diverse applications. These materials are environmentally friendly not just at the end of their life, but throughout their entire production–use–disposal cycle. This mini-review presents an update on the expanding biomedical relevance of PHAs, with emphasis on their utility in tissue engineering and drug delivery platforms. In addition, current clinical evaluations and regulatory frameworks are briefly discussed, underscoring the translational potential of PHAs in meeting unmet medical needs. As the healthcare sector advances toward environmentally responsible and patient-focused innovations, PHAs exemplify the convergence of waste valorization and biomedical progress, transforming discarded resources into functional materials for repair, regeneration, and healing. Full article

Agricultural biomass has potential as a renewable and versatile carbon feedstock for developing eco-friendly and biodegradable polymers capable of replacing conventional petrochemical plastics. To address the growing environmental concerns associated with plastic waste and carbon emissions, lignocellulosic residues, edible crop by-products, and algal biomass were utilized as sustainable raw materials. These biomasses provided carbohydrate-, lipid-, and lignin-rich fractions that were deconstructed through optimised physical, chemical, and enzymatic pretreatments to yield fermentable intermediates, such as reducing sugars, organic acids, and fatty acids. The intermediates were subsequently converted through tailored microbial fermentation processes into biopolymer precursors, primarily polyhydroxyalkanoates (PHAs) and lactate-based monomers. The resulting monomers underwent polymerization via polycondensation and ring-opening reactions to produce high-performance biodegradable plastics with tunable structural and mechanical properties. Additionally, the direct extraction and modification of naturally occurring polymers, such as starch, cellulose, and lignin, were explored to develop blended and functionalized bioplastic formulations. Comparative evaluation revealed that these biomass-derived polymers possess favourable physical strength, thermal stability, and biodegradability under composting conditions. Life-cycle evaluation further indicated a significant reduction in greenhouse gas emissions and improved carbon recycling compared to fossil-derived counterparts. The study demonstrates that integrating agricultural residues into bioplastic production not only enhances waste valorization and rural bioeconomy but also supports sustainable material innovation for packaging, farming, and consumer goods industries. These findings position agriculture-based biodegradable polymers as a critical component of circular bioeconomy strategies, contributing to reduced plastic pollution and improved environmental sustainability. Full article

Chronic wounds remain locked in persistent inflammation with high microbial burden, demanding dressings that suppress infection without sacrificing biocompatibility. Bacterial nanocellulose (BNC) is an attractive matrix due to its biocompatibility, nanofibrillar architecture, and moisture retention, but it lacks antimicrobial activity. Here, we engineer BNC membranes post-functionalized with functionalized graphite (f-Gr; predominantly graphitic with residual surface groups) and/or niobium pentoxide (Nb₂O₅), and evaluate four groups: BNC (matrix control), BNC/Nb₂O₅, BNC/f-Gr, and BNC/f-Gr/Nb₂O₅. Physicochemical analyses (Raman and Voigt fitting, FTIR-ATR, XRD, and SEM) confirm a graphitic carbon phase and physical incorporation of the modifiers into the BNC network, with a noticeable shift in the hydration/polarity profile—more evident in the presence of f-Gr. In standardized microbiological assays, BNC/f-Gr promoted a moderate, contact-dependent reduction in bacterial proliferation, particularly against Staphylococcus aureus, whereas BNC/Nb₂O₅ behaved similarly to pristine BNC under the tested conditions. The combined f-Gr/Nb₂O₅ formulation showed an intermediate antimicrobial response, with no clear synergy beyond f-Gr alone. Cytotoxicity assays indicated cytocompatibility for BNC, BNC/f-Gr, and BNC/Nb₂O₅; the combined group displayed a slight reduction that remained within acceptable limits. Overall, BNC/f-Gr emerges as the most promising antimicrobial dressing, while Nb₂O₅ did not significantly enhance antimicrobial performance under the tested conditions and warrants further optimization regarding loading and distribution. Full article

Soil organic carbon (SOC) sequestration plays a vital role in sustaining soil productivity and mitigating climate change. Although biochar and charcoal-based fertilizers are known to enhance SOC sequestration, current understanding is predominantly derived from studies applying high doses. With the goal of elucidating the mechanisms through which long-term, low-dose biochar application influences SOC composition and stability, this study evaluated the long-term impacts of biochar and carbon-based fertilizers on SOC content, chemical structure, and microbial residual carbon assessed via amino sugar biomarkers. The following features are demonstrated by this study: (1) The application of biochar and carbon-based fertilizers significantly increased the contents of active organic carbon components (DOC, MBC, POC) and stable carbon components (MAOC, humic carbon) in the plow layer soil. Notably, the C50 treatment reduced the easily oxidizable organic carbon (EOC) content by 19.25% compared to the control. (2) Long-term application increased the relative abundance of aromatic functional groups in SOC, enhanced SOC decomposition resistance (as reflected by the F-index). Compared with NPK, the BBF treatment increased the F-index by 21.28% and 25.00% in the 0–20 cm and 20–40 cm soil layers. (3) The BBF treatment significantly increased both soil amino sugar content and the contribution of microbial residual carbon to SOC. Specifically, it elevated the levels of GluN, GalN, and MurN by 9.24% to 33.31% across soil layers. Fungal residual carbon constituted the dominant fraction across all treatments. In summary, the content and stability of SOC are enhanced by biochar and biochar-based fertilizers through synergistic mechanisms that involve altering its chemical composition and stimulating the accumulation of fungal residual carbon. Full article

To optimize and model the fermentation process of Beauveria bassiana, adsorbed carrier solid-state fermentation (ACSSF) was used with rice husk as the inert support. The sample pretreating method was improved by combining homogenization and ultrasonic treatment after dry crushing; the large particles (100–1000 μm in size) were broken and the content of small particles (2–100 μm in size) increased, and the relative standard deviation of the biomass detection method was as low as 3.32% (intra-day) and 3.75% (inter-day). The most suitable carbon source—cassava starch—and the most suitable nitrogen source—corn steep liquor powder (CSLP)—were screened from multiple carbon and nitrogen sources. Through single-factor optimization and an artificial neural network combining genetic algorithm optimization, the optimal recipe including cassava starch 0.0314 g·cm⁻³, CSLP 0.004885 g·cm⁻³ and water 0.2630 g·cm⁻³ was obtained, and the highest biomass yield was verified as 0.1379 g·cm⁻³, which was 45.0% higher than the original recipe before the optimization (0.0951 g·cm⁻³). The modeling of microbial growth was based on the Logistic model and executed by nonlinear regression with the R² value as high as 0.9525 and absolute value of the residues completely under 0.003 g·cm⁻³, which validated not only the feasibility of modeling the growth kinetics of B. bassiana using total biomass content, but also the reliability of the improved biomass pretreating and determination method. Full article

Co-incorporating rice straw and Chinese milk vetch (CMV) residues can enhance soil organic carbon (SOC) sequestration and productivity. However, limited information exists regarding its effects on SOC and nitrogen (N) pools as well as the sustainability of rice production in the middle and lower reaches of the Yangtze River Basin. A 3-year field experiment was conducted to assess the effects of co-incorporating rice and CMV residues into paddy soils with chemical-N reduction on SOC and total N (TN) sequestration, SOC and N fractions, grain yields and the sustainable yield index (SYI) in Ma’anshan City, Anhui Province. The treatments included winter fallow–rice rotation without or with both rice straw incorporation and fertilization, as the control (CK and WF-IF, respectively), and rice-CMV rotation with the co-incorporation of rice and CMV residues under 100%, 80%, and 70% recommended N fertilization (CMV-IF, CMV-MIF and CMV-LIF, respectively). Compared with the CK, the CMV-IF significantly increased the rice grain yield and the SYI by 82.1% and 90.4%, respectively. The SOC and TN stocks under CMV-IF were significantly enhanced by 6.3% and 26.4%, respectively, relative to the CK. The CMV-IF exhibited the highest soil active organic C (AOC) and active total N (ATN) contents, followed by CMV-MIF, CMV-LIF, WF-IF, and CK. Microbial biomass C and microbial biomass N were the primary components of soil AOC and ATN, respectively, and linked more explicitly to the SYI than other soil C and N parameters. Therefore, the co-incorporation of rice and CMV residues, coupled with 70~80% recommended N fertilization, might represent an environmentally friendly field management practice for rice production in the middle and lower reaches of the Yangtze River Basin. Full article

Microbial degradation of pectin is a fundamental process for the carbon cycle and a strategic approach for treating industrial residues. This study characterizes a novel marine bacterium, Paenarthrobacter sp. FR1, isolated from East China Sea intertidal sediment, which exhibits the ability to utilize pectin. Its draft genome (4.83 Mb, 62.92% GC content) is predicted to encode 4498 protein-coding genes. Genomic analysis revealed a rich repertoire of Carbohydrate-Active Enzymes (CAZymes) crucial for this process, including 108 glycoside hydrolases (GHs), 7 polysaccharide lyases (PLs), 35 carbohydrate esterases (CEs), and 11 auxiliary activities (AAs). Genomic analysis provides supportive evidence that FR1 may target both homogalacturonan (HG) and rhamnogalacturonan (RG) pectin domains, potentially through complementary hydrolytic and oxidative pathways. Phylogenomic analysis based on Average Nucleotide Identity (ANI, 83.56%) and digital DNA-DNA Hybridization (dDDH, 27.8%) confirmed its status as a potential novel species. Notably, FR1 is a rare Paenarthrobacter isolate with innate pectinolytic capability, a characteristic not previously documented in this genus. This strain’s unique enzymatic machinery highlights its importance in marine carbon cycling and provides a valuable biotechnological resource for degrading pectin-rich wastes. Full article

Karstic regions are globally distributed, and the soil-forming parent rocks and their weathering process primarily cause elevated geochemical heavy metal (HM) accumulation in karst soils. However, the patterns of HMs, the genes related to resistance, and their interactions in karstic soils developed from different parent materials remain unexplored. In this study, 36 field karst soil samples originating from two parent materials were collected, including 19 samples from the residues of the weathering and leaching of carbonate rocks (Car) and 17 samples from Quaternary sediments (Qua). In the Car soils, the levels of As, Cd, Cr, Zn, Cu, Ni, and Pb exceeded the risk screening values for soil contamination of agricultural land set by the Chinese standard GB15618-2018 by 100%, 100%, 94.11%, 64.71%, 64.71%, 47.06%, and 41.18%, respectively, while only 11.76% of As in Qua soils exceeded the risk screening values. The proportion of metal resistance genes (MRGs) and antibiotic resistance genes (ARGs) in Car soils was significantly higher than that in Qua soils. However, HM content had a significantly positive correlation with Nemerow integrated pollution index (NIPI), individual HM-related genes, MRGs, ARGs, and mobile genetic elements (MGEs) in Qua soils, respectively. Although the corresponding correlation was positive in the Car soils, it was not statistically significant. Results demonstrated that microbial activity was more crucial for the accumulation of HMs in Qua soils compared with Car soils. Meanwhile, our in-depth research also provides new perspectives to establish a more rational ecological assessment for the elevated HMs by identifying applicable and valid biomarkers from functional genes, which is vital in contamination monitoring, prevention, and standard establishment in agricultural soils of karst regions. Full article

Soil organic carbon (SOC) plays a crucial role in climate change mitigation by regulating atmospheric CO₂ and maintaining ecosystem balance; however, its stability is influenced by land use in anthropized areas such as the tropical Andes. This study developed a dynamic compartmental model based on ordinary differential equations to simulate carbon fluxes among litter, humus, and microbial biomass under four land uses in the Las-Piedras River basin (Popayán, Colombia): riparian forest (RF), ecological restoration (ER), natural-regeneration (NR), and livestock (LS). The model includes two decomposition rate constants: k₁, for the transformation of fresh organic matter, and k₂, for the turnover of humified organic matter. It was calibrated using field data on soil physicochemical and biological properties, as well as carbon inputs and outputs. The results showed clear differences in SOC dynamics among land uses: RF had the highest SOC stocks (148.7 Mg ha⁻¹) and microbial biomass, while LS showed the lowest values and the greatest deviation due to compaction and low residue input. The humus fraction remained the most stable pool (k₂ ≈ 10⁻⁴ month⁻¹), confirming its recalcitrant nature. Overall, the model reproduced SOC behavior accurately (MAE = 0.01–0.30 Mg ha⁻¹) and provides a framework for improving soil carbon management in mountain ecosystems. Full article

Soil conservation technologies are widely studied for their effects on soil organic carbon (SOC) preservation, yet their impact on the composition of soil organic matter (SOM) remains underinvestigated. This study evaluated the effects of two non-inversion tillage systems, MP and NT, on agro-physical and chemical properties and SOM composition (including water-extractable matter) in Haplic Chernozem Pachic. After 12 years, non-inversion tillage showed no significant differences in SOC, WEOC, and soil structure condition compared to MP. Only NT treatment distinctly enhanced the coefficient of soil structuring (K_str) and mean diameter of water-stable aggregates (MWD_WSA), by 1.5 and 2 times, respectively. Differences in SOM composition were clearly pronounced between treatments in the 0–10 cm layer. Non-inversion tillage favored microbial-derived stable SOM, whereas NT enriched SOM with fresh plant material. Our findings revealed that non-inversion tillage shifts the composition of SOM toward recalcitrant components even more than MP due to limited fresh OM input and enhanced mineralization of unprotected SOM during tillage. This poses carbon loss risks. Periodic moldboard plowing may be a way to improve carbon retention in non-inversion tillage, as it allows plant residues to be incorporated into the soil profile and replenish organic matter. Full article

Caproate is a valuable medium-chain fatty acid (MCFA) that is found to be extensively used in biofuel production, food preservation, and the pharmaceutical industries. Short-chain fatty acids (SCFAs) from waste streams can be upgraded sustainably through their biological synthesis via anaerobic chain elongation. However, caproate production is frequently limited in real-world systems due to low carbon conversion efficiency and a lack of electron donors. In this study, we developed a two-stage fermentation strategy employing yellow water—a high-strength organic wastewater from liquor manufacturing—as a novel substrate. During primary fermentation, Lactobacillus provided endogenous electron donors by converting the residual carbohydrates in the yellow water into lactic acid. Nano zero-valent iron (NZVI) was introduced to the secondary fermentation to enhance power reduction and electron flow, further promoting caproate biosynthesis. The caproate production increased significantly due to the synergistic action of lactic acid and NZVI, reaching a maximum concentration of 20.41 g·L⁻¹ and a conversion efficiency of 69.50%. This strategy enhances carbon recovery and electron transport kinetics while lowering dependency on expensive external donors like hydrogen or ethanol. Microbial community analysis using 16S rRNA sequencing revealed enrichment of chain-elongating bacteria such as Clostridium kluyveri. These findings demonstrate the feasibility of employing an integrated fermentation–electron management technique to valorize industrial yellow water into compounds with added value. This study offers a scalable and environmentally sound pathway for MCFA production from waste-derived resources. Full article

Understanding how soil organic matter (SOM) responds to agricultural management at the molecular scale remains a central challenge, particularly in semi-arid Mediterranean systems where long-term monitoring is limited, and soils face marked seasonal fluctuations, salinity constraints, and sustained cultivation pressure. In this study, lignin and lipid biomarkers were combined to provide complementary views of SOM dynamics in the agricultural soils of Oued Rhiou (Algeria), enabling the simultaneous assessment of plant-derived inputs, microbial processing, and stabilization pathways under cultivation and subsequent rest periods. Depth-dependent patterns showed that lignin indicators responded strongly to shifts between crop residue inputs and root-derived material, while lipid proxies captured changes in microbial activity, biosynthesis, and OM stabilization. Surface soils exhibited enhanced microbial turnover during cultivation, whereas deeper layers were characterized by selective preservation of recalcitrant compounds. Principal Component Analysis (PCA) further highlighted these processes by distinguishing vegetation-driven variability from microbial reworking patterns, with subset analyses (lignin-only and lipid-only) providing clearer explanatory power than the combined dataset. Collectively, the findings underscore the importance of integrating rest periods into agricultural cycles to promote SOM stabilization, highlight the complementarity of lignin and lipid proxies for deciphering SOM transformation pathways, and offer molecular-level insights that can guide sustainable soil management strategies aimed at balancing productivity, soil resilience, and long-term carbon sequestration. Full article

Corncob residues, an abundant but underutilized organic resource in Northeast Asia, offer substantial potential for improving soil health and plant productivity. This study investigates the effects of corncob returning on soil physicochemical properties, microbial processes, and the performance of Eleutherococcus sessiliflorus in a cold–temperate region (Jilin Province, China). The treatments included no-amendment control (CK), corncob incorporation (CI), and corncob mulching (CM). Corncob returning significantly increased soil organic carbon, moisture content, and the availability of N–P–K, while reducing soil bulk density, thus improving soil structure and nutrient availability. Both CI and CM treatments enhanced microbial biomass C, N, and P, as well as nutrient-cycling enzyme activities (β-glucosidase, urease, and alkaline phosphatase), accelerating C–N–P turnover in the rhizosphere. These improvements resulted in enhanced plant nutrient status and significant gains in biomass, with plant height and fruit number increasing by up to 44% and 136%, respectively. Multivariate analysis and PLS-SEM revealed that soil improvements strongly stimulated enzyme activity (path coefficient = 0.956), and enhances the microbial niche, thereby promoting plant traits through nutrient release (enzyme → plant path coefficient = 0.694). Microbial functional activity, rather than microbial richness, plays a more crucial role in plant growth promotion. Collectively, these findings underscore that corncob returning improves E. sessiliflorus performance through a soil biochemical activation pathway mediated by microbial metabolism and enzymatic nutrient release. This study provides strong evidence supporting corncob recycling as a cost-effective, environmentally sustainable approach for improving medicinal plant production and advancing circular agriculture in cold-region ecosystems. Full article

To investigate the combined impacts of temperature and plant residues on the mineralization capacity of soil organic matter, in addition to the impact on the taxonomic composition and activity of the soil microbiome, a 364-day experiment involving gray forest soil (Greyzemic Phaeozem Albic) was conducted under controlled laboratory conditions. Three substrate treatments were applied, control (C), amendment with aspen leaves (L), and amendment with aspen branches (B), combined with three temperature regimes (2, 12, and 22 °C). The results showed that long-term experimental warming reduced microbial alpha diversity (number of species and richness), increased microbial respiration and decomposition rates, and altered community composition. Over the year, the percentage of mineralization of added carbon was higher for leaves (29.9%–57.8%) than for branches (20.1%–47.6%). The efficiency of organic matter decomposition increased by 1.5- to 2-fold between 2 and 12 °C. Across all treatments, Proteobacteria were found to be the dominant phylum. According to α-diversity analysis, leaves served as the most preferred substrate for enhancing species representation. β-diversity analysis results indicated that temperature was the most significant factor shaping the microbial community’s structure. Our research findings provide new insights into soil organic matter formation and highlight the need for further research on microbial functional genes. Full article