Using microorganisms to improve and repair soil and assist plant growth is an effective ecological restoration method. The compound microbial inoculant prepared by mixing several microorganisms with different functions is one of the hot spots in the current research of agricultural green development and food security. In this study, four treatments were set up: no microbial agent (CK), Trichoderma harzianum agent (H), Bacillus subtilis agent (K), and compound microbial agent (K + H). The effects of single and compound microbial agents on tomato growth, rhizosphere soil physical and chemical properties, enzyme activity and microbial community structure and function were investigated, and the correlation between soil nutrients and microbial community was analyzed. The results showed that the application of microbial agents significantly promoted the growth of tomato, and the effect of K + H treatment was the best. The fresh weight, dry weight, plant height and stem diameter of tomato were 25.06%, 17.61%, 3.05% and 16.62% higher than CK, respectively. Microbial agents changed the physical and chemical properties and enzyme activities of rhizosphere soil, significantly increased the content of alkali-hydrolyzable nitrogen and significantly decreased the activity of catalase, and the activity of alkaline phosphatase increased the most under K treatment. High-throughput sequencing showed that microbial agents had a significant effect on the diversity and structure of microbial community in rhizosphere soil. In terms of microbial community diversity, K + H treatment significantly increased the Simpson index of bacteria, and significantly reduced the Chao1, ACE richness index and Shannon, Simpson diversity index of fungi. In the microbial community structure, the dominant phylum of the bacterial community is Proteobacteria, Gemmatimonadota, Actinobacteriota and Acidobacteriota, and the fungi are Ascomycota and Basidiomycota. After microbial inoculant treatment, the relative abundance of Gemmatimonadota, Acidobacteriota, Chloroflexi and Ascomycota increased significantly, while the relative abundance of Actinobacteriota, Olpidiomycota and Chytridiomycota decreased. At the genus level, the abundance of KD4-96, SC-I-84, Penicillium and Trichoderma spp. changed significantly. Microbial agents also regulated microbial functions, and bacterial amino acid transport and metabolic functions were the most active. K + H treatment increased the relative abundance of fungal saprophytic nutrients to 52.37%, which was the highest in each treatment. Redundancy analysis showed that soil alkaline phosphatase, catalase and alkali-hydrolyzable nitrogen were the key environmental factors affecting microbial community structure, which were significantly correlated with the dominant genera of bacteria and fungi. This study confirmed that Bacillus subtilis and Trichoderma harzianum compound inoculants had a good synergistic effect in promoting tomato growth and improving soil microecology, which provided theoretical and practical basis for the development and application of microbial inoculants in tomato production.
Microplastic pollution threatens agricultural soil multifunctionality (SMF) by disturbing microbial communities and nutrient cycling. Straw return is widely used to improve soil quality, but whether it can offset the decline in SMF caused by microplastics (MPs) and which microbial pathways are involved remain unclear. We conducted a soybean pot experiment for 90 days with four treatments: control (CK), 2% polyethylene microplastics (PE), 1% corn straw (CS), and PE combined with corn straw (PC). Soil physicochemical properties, enzyme activities, microbial biomass, soybean growth and SMF were measured at the seedling, flowering, filling and harvesting stages, while microbial diversity, keystone taxa and predicted functions were analyzed at the flowering stage. PE significantly reduced enzyme activities, microbial biomass, soybean growth and SMF, and intensified microbial phosphorus limitation. Across the four stages, PE decreased SMF by 30.65% to 51.35% compared with CK (P < 0.05), whereas CS and PC increased SMF by 65.91% to 97.22% and 36.36% to 75.00%, respectively (P < 0.05). MPs constrained SMF by altering fungal diversity, keystone taxa and functions, and decreasing microbial biomass and extracellular enzyme production. These changes aggravated microbial phosphorus limitation, thereby impairing nutrient transformation and plant growth. In contrast, straw return supplied labile carbon and nutrients, stimulated microbial proliferation and enzyme synthesis, restored bacterial and fungal functional complementarity and relieved microbial resource limitation. Overall, straw return mitigated the reduction in SMF caused by MPs by rebuilding microbial diversity, function and resource acquisition efficiency, providing practical guidance and theoretical support for managing microplastic pollution in agricultural soils.
This study investigated the effects of a fermented compound Chinese herbal medicine (FCHM) on growth performance, antioxidant capacity, immune function, and gastrointestinal microbiota in suckling lambs. FCHM consisted of 10 herbs fermented with Candida utilis and Bacillus subtilis. Sixty twin Hu lambs (15 days) were randomly fed a basal diet (CON) or the diet supplemented with 0.6% FCHM (Treat) for 45 days. The results indicated that the Treat group exhibited a significant increase in average daily gain (ADG) (P < 0.05). Serum analyses revealed elevated levels of growth hormone (GH), insulin-like growth factor-1 (IGF-1), total antioxidant capacity (T-AOC), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and glucose (GLU), whereas malondialdehyde (MDA) and pro-inflammatory cytokines (IL-6 and TNF-α) were reduced (P < 0.05). In the duodenal mucosa, SOD and GSH-Px activities and T-AOC levels were significantly elevated, while MDA content was notably decreased (P < 0.05). Ruminal fermentation profiles showed increased concentrations of propionate and total volatile fatty acids (TVFA) in the Treat group (P < 0.05). Microbiome analysis revealed that FCHM supplementation selectively modulated the ruminal microbial community, enriching beneficial genera such as Prevotellaceae_UCG-003 and Butyrivibrio, while reducing the abundance of potentially harmful genera like Streptococcus, despite no significant changes in the overall community diversity. Metagenomic sequencing further demonstrated the enrichment of KEGG enzymes and carbohydrate-active enzyme genes involved in carbohydrate metabolism and propionate biosynthesis. Correlation network analyses revealed significant associations among specific microbial taxa, serum antioxidant, immune biomarkers, and growth performance. In conclusion, dietary FCHM supplementation improves growth performance in suckling lambs by optimizing ruminal fermentation patterns, selectively regulating gastrointestinal microbiota, and enhancing systemic antioxidant capacity. These findings support the potential of FCHM as a functional feed additive in lamb production systems. Enhancing growth performance and ensuring gastrointestinal health during the suckling period are critical for lamb productivity and welfare. In the context of the antibiotic-free mandate in animal feed, we evaluated the effects of a fermented compound Chinese herbal medicine (FCHM) on growth, antioxidant status, immune parameters, and gastrointestinal microbiota in lambs. Our findings demonstrate that FCHM improves average daily gain, enhances systemic and mucosal antioxidant capacity, and modulates ruminal and hindgut microbiota by enriching beneficial taxa and suppressing potentially harmful bacteria. These effects are linked to upregulated microbial functions in carbohydrate metabolism and propionate biosynthesis. This study provides a microbial-based mechanism for FCHM as a natural feed additive to promote lamb growth and gastrointestinal resilience, offering a sustainable strategy to support early-life development in ruminant production systems.
Although chicken meat is a major source of dietary protein globally, it is highly prone to microbial spoilage, especially under refrigeration, posing economic and public health risks. Psychrotrophic Pseudomonas spp., particularly Pseudomonas fluorescens and Pseudomonas aeruginosa, are key spoilage organisms due to their enzyme production, biofilm formation, and cold tolerance. This study determined the prevalence, virulence gene profiles, enzymatic activity, and antibiotic resistance profiles of P. fluorescens and P. aeruginosa isolated from raw chicken meat sold in supermarkets. Detection and isolation of Pseudomonas spp. in raw chicken samples were carried out using selective Pseudomonas agar. PCR assay used species-specific primers targeting adnA and toxA genes to confirm the presence of P. fluorescens and P. aeruginosa, respectively.The isolated P. fluorescens and P. aeruginosa were molecularly characterized using a polymerase chain reaction (PCR) assay for the presence of genes responsible for biofilm formation, proteolytic enzymes, and virulence. The proteolytic and lipolytic activities of the isolates at 30 °C and 4°C using skim milk agar and tributyrin agar. Antibiotic susceptibility was determined using the Kirby-Bauer disk diffusion method. Of 180 samples, 61 (33.9%) were positive for P. fluorescens and 34 (18.9%) were contaminated with P. aeruginosa, as confirmed by PCR assay. Molecular characterization of the P. fluorescens isolates revealed that 41.0% were positive for aprX and 8.2% had fliC, whereas the P. aeruginosa isolates showed the presence of oprL (58.8%), lasB (11.4%), and exoS (20.6%). Gene distribution varied across retail outlets, possibly reflecting differences in hygiene and storage conditions. At 4 °C, most P. fluorescens isolates (82%) displayed proteolytic activity, and all isolates showed lipolytic activity. P. aeruginosa showed low proteolytic (29.4%) but high lipolytic (88.2%) activity. These findings show their ability to degrade meat even under refrigeration conditions. Antibiotic susceptibility testing revealed high resistance to penicillin G, ampicillin, and piperacillin among all isolates. P. fluorescens showed notable resistance to ceftazidime (100%) but remained largely susceptible to gentamicin (80.3%) and levofloxacin (82.0%). P. aeruginosa exhibited similar trends, with high susceptibility to gentamicin (85.3%) and levofloxacin (91.2%). Moderate susceptibility to amikacin was observed in both of the aforementioned species. All isolates had MAR index scores above 0.2, and 19 P. fluorescens and 5 P. aeruginosa isolates were identified as extensively drug-resistant (XDR), resistant to at least five antibiotic classes. These findings highlight the contamination of retail chicken meat by virulent, spoilage-causing, and antibiotic-resistant Pseudomonas spp., which requires improved control measures to minimize spoilage and safeguard public health.
Propolis is recognized for its biological activities; however, its chemical composition varies according to environmental conditions, which presents challenges for quality standardization and biological evaluation. Although propolis has been widely investigated, information regarding variation among samples collected from geographically close locations within the same region is limited. Therefore, this study investigated whether propolis samples obtained from different locations within Erzincan Province exhibit differences in chemical composition and biological activities and evaluated the relationship between environmental conditions and propolis characteristics. Eleven propolis samples collected from Erzincan, Türkiye, were analyzed for phenolic composition, antioxidant capacity, antimicrobial activity, acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and α-glucosidase inhibitory activities. Twenty-eight compounds were identified, with gallic acid, protocatechuic acid, chlorogenic acid, hydroxybenzaldehyde, caffeic acid, and vanillin detected as major constituents. AChE inhibitory activity varied between 1.28 and 6.44 µg/mL, while BChE inhibitory activity varied between 1.85 and 9.66 µg/mL. All samples exhibited antibacterial activity. Total phenolic and flavonoid contents were 141.70-255.04 mg GAE/g extract and 30.48-93.81 mg QE/g extract, respectively. The KMH sample showed the antioxidant activity. The results demonstrated variation in phytochemical composition and biological activities among propolis samples collected within the same province, indicating associations between flora, environmental conditions, propolis quality, and bioactivity.
Growing evidence links air pollution to cognitive dysfunction in older adults. The gut microbiome and circulating metabolites present an important yet unexplored pathway given their crucial role in the gut-brain axis. We aimed to explore the potential roles of gut bacteria, fungi, microbial functional potentials, and circulating metabolites in the association of residential PM2.5 and O3 exposure with cognitive dysfunction. We analyzed gut microbiome data from 1,027 older adults using metagenome and internal transcribed spacer sequencing to profile bacterial and fungal taxa, functional pathways, and enzyme abundances. Targeted metabolomics quantified 195 circulating metabolites, such as amino acids and organic acids. Annual average ambient PM2.5 and O3 exposures were estimated by using satellite-based models. Cognitive outcomes, including mild cognitive impairment and cognitive decline, were assessed using the Mini-Mental State Examination and Hasegawa Dementia Scale. Statistical analyses included Microbiome Multivariable Association with Linear Models (with a false discovery rate threshold of 0.25) for microbial associations and multivariate regression for metabolites and cognitive outcomes. Higher PM2.5 and O3 exposures were associated with disturbances in microbial composition, altered taxonomic profiles (e.g., decreased abundances of Blautia obeum and Gordonibacter pamelaeae), and disrupted functional pathways, particularly those regulating 2-oxoglutarate. These findings were partially replicated in an independent population. Higher air pollution levels were associated with increased circulating levels of 2-oxoglutarate and l-glutamine (key metabolites in neurodegenerative progression), which were further linked to higher odds of concurrent mild cognitive impairment (OR: 1.39-1.56) and an increased 2-year risk of cognitive decline (OR: 1.26-1.37). These associations were partially mediated by air pollution-related changes in microbial anaerobic energy metabolism pathways, especially involving 2-oxoglutarate metabolism and the enzyme aspartate transaminase. Our findings highlight the role of the gut microbiome and microbial metabolites in mediating the detrimental impact of air pollution on cognitive health in older adults, providing new insights into the underlying etiology for future hypothesis generation.
Soil pollution associated with heavy metals and organic contaminants is a significant barrier to sustainable agriculture, soil fertility, and global food security. Conventional fertilizers serve mainly as nutrient carriers, often exhibit low nutrient-use efficiency, and have limited potential to mitigate soil contamination. At the same time, Fe3O4-based nanofertilizers are considered a multifunctional approach to balance nutrient delivery and soil remediation. Magnetite (Fe3O4) nanoparticles have unique physicochemical features, with high surface area, redox properties, and magnetic response, that regulate essential intermediate reactions like ion exchange, surface complexation, and redox transformations. Under environmental conditions, these mechanisms account for controlled nutrient release, improved nutrient bioavailability, and enhanced plant uptake. Aside from nutrient delivery, Fe3O4 nanoparticles can modulate soil microbial processes, e.g., enzyme-dependent nutrient mineralization, iron cycling, and redox-active microbial interactions; however, these effects are highly condition-dependent and depend on soil chemistry, nanoparticle properties, and microbial community composition. Concurrently, Fe3O4 nanoparticles may adsorb, immobilize, or transform pollutants via electrostatic interactions, surface complexation, and redox reactions, thereby reducing their mobility and bioavailability. Their magnetic abilities also have the potential to help recovery or redistribution after pollutant binding. Notwithstanding these benefits, the evidence is still limited and, in some instances, inconclusive, and is based on laboratory or greenhouse investigations. There remain important uncertainties regarding mechanistic pathways at the field site, long-term environmental fate, and repercussions for soil biota. However, inadequate field-scale validation and unresolved ecotoxicological hazards are among the major hurdles to practical deployment, whereas cost, large-scale synthesis, and regulatory frameworks remain impeding barriers to applications. Filling these gaps requires holistic, global strategies, including long-term field studies, established risk-assessment methodologies, and life-cycle analyses. The development of Fe3O4-based nanofertilizers will also rely on a trade-off between agronomic benefits and environmental safety, through context-specific, evidence-supported design approaches.
In this study, we used lactic acid bacteria to ferment the byproduct of Arundo donax papermaking, Arundo donax juice (ADJ), to obtain fermented Arundo donax juice (FADJ). We aimed to investigate the effects of FADJ on the growth performance, immunocompetence, antioxidant capacity, and intestinal digestive enzyme activity of broilers. For the experiment, 288 one-day-old Arbor Acres broilers were selected and randomly divided into four groups (A+, A, B, and CK), with six replicates per group and 72 chickens per group. The control group (CK) was fed a basal diet, while groups A and A+ were supplemented with 3% and 6% FADJ A fermented with ADJ as the substrate, respectively, and group B was supplemented with 3% FADJ B fermented with ADJ supplemented with a small amount of lysine as the substrate. The trial period lasted 42 days. Compared with the control diet, supplementation with 6% FADJ A significantly increased the final body weight, average daily feed intake (ADFI), and average daily gain (ADG) of broilers, with no significant difference in the feed conversion ratio (FCR). The serum levels of T-AOC, GSH-Px, and SOD in broilers on days 21 and 42 were significantly elevated (P < 0.05) in all experimental groups, with the highest levels observed in group B. The concentrations of IgM, IgA, and IgG in broilers increased significantly (P < 0.05) across all experimental groups, with the highest concentrations found in group B. The addition of FADJ significantly increased the activities of intestinal lipase and trypsin in broilers (P < 0.05). These findings indicate that FADJ feed can improve the growth performance of broilers and increase their immunocompetence, antioxidant capacity, and intestinal digestive enzyme activity.
Root rot is a major threat to red kidney beans (Phaseolus vulgaris), caused mainly by Fusarium oxysporum. This study tested single/combined inoculation of Bacillus mojavensis BA23 and Rhizobium indicum RH64 on disease control, plant growth, and systemic defense in greenhouse pots. Both single strains reduced disease index and improved growth, but coinoculation was better: vs single BA23/RH64, it increased plant biomass by 11.05%/23.81% and reduced disease index by 18.87%/40.27%. BA23 inhibited F. oxysporum (80.54% in vitro) and activated plant defense (e.g., boosted antioxidant enzyme activity), while RH64 had nitrogen-fixing activity (253.22 U·L-1) and recruited beneficial rhizobacteria. Coinoculation enriched taxa like Sphingomonadaceae and Vicinamibacteraceae (key for disease suppression and growth promotion) and enhanced rhizosphere microbial network stability (e.g., higher modularity and average degree). Partial least squares path modeling (PLS-PM) showed that bacterial community structure was significantly correlated with reduced disease index and increased plant biomass. In conclusion, coinoculating BA23 and RH64 effectively controls red kidney bean root rot and promotes plant growth by inducing systemic defense-related responses and beneficially reshaping the rhizosphere microbiome.
Aleuritopteris bicolor, a fern species known locally as "Raani Sinkaa" in Nepal, has traditionally been used to treat wounds, diarrhea, dysentery, and gastritis. Despite its widespread use, scientific data on its bioactive compounds and bioactivities remain limited. To address this gap, this study aimed to isolate bioactive compounds from A. bicolor and evaluate their antioxidant, antibacterial, and antidiabetic properties using both in vitro and in silico methods. The 70% methanol extract of A. bicolor afforded three compounds: 20-hydroxyecdysone (1), and a mixture of quercetin 3-O-β-D-glucopyranoside (2) and quercetin 3-O-β-D-galactopyranoside (3), isolated via column chromatography. The structures of the isolated compounds were elucidated based on spectroscopic (NMR) and spectrometric (LC-MS) analyses. Compound 1 exhibited weak antioxidant activity, with an IC50 of 38.38 ± 3.41 µg/mL in the DPPH free radical scavenging assay. In contrast, the mixture of compounds 2 and 3 demonstrated significant antioxidant activity, with an IC50 of 1.56 ± 0.3 µg/mL, surpassing the standard ascorbic acid (IC50: 4.15 ± 0.3 µg/mL). Compounds 2 and 3 also showed moderate antibacterial activity against Staphylococcus aureus and Klebsiella pneumoniae. Furthermore, these compounds exhibited notable inhibition of α-amylase and α-glucosidase enzymes in in vitro assays, with EC50 values of 99.48 ± 3.2 µg/mL and 68.53 ± 1.7 µg/mL, respectively. In silico molecular docking analyses supported these enzyme inhibitions by revealing favorable interactions between compound 2 and key catalytic residues of the target enzymes, with binding energies of -7.2 kcal/mol for α-amylase and -7.1 kcal/mol for α-glucosidase. Additionally, ADMET analysis suggests further lead optimization of compounds 2 and 3. This study successfully isolated three bioactive compounds from A. bicolor and recommends further medicinal chemistry and in vivo investigations to establish their therapeutic potential as antidiabetic phytomedicine.
Alternaria blight, caused by Alternaria brassicae, is a major constraint in Indian rapeseed-mustard cultivation, causing substantial yield losses. Diplotaxis erucoides, an oligotrophic wild crucifer exhibiting natural tolerance to Alternaria blight was explored as a source of beneficial endophytic bacteria. In this study, endophytic bacteria isolated from various tissues of D. erucoides were screened for plant growth-promoting and antagonistic traits against A. brassicae. Functionally efficient isolates showing growth promotion, phytohormone production, siderophore production and pathogen inhibition were selected using a Bonitur-based trait-guided approach to synthesize root-derived, leaf-derived and combined synthetic microbial communities (SynComs) comprising 12, 14 and 26 isolates, respectively. In pot trials, the Combined SynCom (CSC) significantly improved plant growth and yield-related parameters in Brassica juncea and provided the greatest disease suppression, reducing disease severity by 30.75% and conferring 47.08% disease protection at 21 days post-inoculation. Histochemical and biochemical analysis revealed reduced Hydrogen peroxide (H2O2) accumulation and necrotic symptoms, along with enhanced antioxidative enzyme activity in CSC-treated Alternaria-challenged plants. These responses were accompanied by increased activities of phenylalanine ammonia lyase, peroxidase, and polyphenol oxidase, together with greater accumulation of callose and phenolics compounds. These findings indicate that a SynCom assembled from functionally complementary endophytes associated with a wild Brassica relative can enhance plant growth and promote disease resistance through both microbial antagonism and activation of host defense responses. The results demonstrate the utility of trait-guided SynCom assembly for developing microbial inoculants and highlights CSC as a promising SynCom-based biocontrol and biofertilizer candidate for sustainable mustard production.
Both biochar and nano-zero-valent iron (nZVI) are increasingly used to remediate soils polluted with heavy metals, such as the toxic Cr(VI). However, how soil microbiomes respond to biochar and nZVI applied in Cr(VI)-contaminated soil has not yet been clarified. The current study compared the effects of bare nZVI (B-nZVI) and starch-stabilized nZVI (S-nZVI) at 100 and 1000 mg/kg on soil enzyme activity and microbial communities in Cr(VI)-contaminated soil growing mung bean amended with or without 1% biochar. High-throughput metagenomic sequencing was conducted to determine the evenness (Simpson index), diversity (Shannon index), and richness (Chao-1 index) of soil bacteria, fungi, archaea, and viruses. Soil catalase activity was inhibited by S-nZVI but stimulated by biochar. Soil phosphatase activity was stimulated by both types of nZVI, but not influenced by biochar. The combination of 1000 mg/kg nZVI and biochar decreased bacterial and fungal evenness and diversity, but did not significantly alter their richness. Archaeal communities remained relatively stable across most treatments. The evenness and diversity of viral communities increased significantly at 1000 mg/kg S-nZVI, whereas the richness decreased conversely. PCoA showed that soil microbial community structure was significantly changed by 1000 mg/kg S-nZVI, which diminished Actinobacteria but enriched Cellvibrio. Furthermore, 1000 mg/kg S-nZVI increased the abundances of some genes involved in antioxidant enzymes and the metabolism of Fe and Cr, and decreased the abundance of C-cycling genes significantly. Overall, S-nZVI caused significant perturbations in soil microbial activity and community structure, but these adverse effects were alleviated by the incorporation of biochar.
In this study feather hydrolysate served as the sole nitrogen source for the cultivation of Spirulina (Limnospira platensis) replacing nitrate used in the standard medium. Although Spirulina is well known for its excellent nutritional content ideal for food and animal feed application and it allows a climate smart production system, its wide use remains limited because of high production cost. The growth medium used for cultivation where nitrate serves as the nitrogen source has significant contribution to the high production cost. Therefore, the use of cheaper growth substrates could help lower production cost and make Spirulina biomass accessible to most users. The feather hydrolysate used in this study was prepared through microbial solubilization which also resulted in the production of a protease that has properties suitable for different industrial applications. The whole feather hydrolysate and the enzyme-free feather hydrolysate obtained after recovery of the enzyme supported good growth of Spirulina equivalent to nitrate in the standard medium. Currently the poultry industry releases huge quantities of feather as waste posing serious risks of environmental pollution. The results of this study, therefore, indicate that feather could serve as a cheap substrate to produce an industrially important enzyme while the enzyme free hydrolysate serve as a substrate for the cultivation of Spirulina. This process, in addition to lowering production costs, could help to reduce environmental pollution. Therefore, integration of feather hydrolysis, enzyme production, and Spirulina cultivation could lead to a circular bioeconomy offering huge environmental and economic benefits.
To clarify the microbial contamination and wood degradation risk of the Nanhai No. 1 shipwreck hull and verify on-site antibacterial agent effectiveness, microbial samples were collected and analyzed via SEM, metagenomic sequencing, bacterial isolation, enzyme activity detection, and antibacterial experiments. The results showed that Actinomycetota was the dominant phylum, and Brachybacterium, Microbacterium, and Brevibacterium were the dominant genera. Seven bacterial strains were isolated and purified, among which Brevibacterium sp. (NH.SH-B6) had the strongest wood degradation ability, possessing cellulase, LiP, MnP, and Lac activities. When cultured with hull wood as the sole carbon source, LiP was the dominant degrading enzyme of NH.SH-B6, and its maximum enzyme activity was achieved under the optimal conditions of pH = 7, 10% NaCl, 1000 mg/L FeSO4, and no PEG400 added. 50 mg/mL cinnamaldehyde and 0.5% isothiazolinone K100 had good inhibitory effects on the isolated bacteria, and bacterial proliferation was due to incomplete antibacterial agent spraying. This study clarifies the microbial degradation risk of the Nanhai No. 1 shipwreck hull and provides a scientific basis for optimizing the on-site protection strategy of the shipwreck.
Stenotrophomonas sepilia SMBL8 is a motile, hemolytic, Gram-negative environmental bacterium isolated from a polluted lake. S. sepilia, a recently identified member of the Stenotrophomonas maltophilia complex, has been reported in both clinical and environmental settings; however, it remains understudied. In this study, we comprehensively investigated the phenotypic and genomic characteristics, emphasising metabolic versatility, antibiotic resistance profile, and pathogenic potential. Antibiotic susceptibility testing revealed sensitivity to trimethoprim/sulphamethoxazole, levofloxacin, and minocycline; resistance and intermediate resistance to β-lactams, aminoglycosides, and chloramphenicol. Whole-genome sequencing revealed a genome length of 4,510,692 bp and a G + C content of 66.56%. Functional annotation revealed enrichment and abundant gene distribution in carbohydrate metabolism and binding activity essential for carbohydrate-active metabolism. Subsequent analysis identified a diverse carbohydrate-active enzyme repertoire with potential biotechnological applications as a biocatalyst for substrates such as xylan and chitin. Conversely, further genomic analysis revealed siderophore-encoding genes, multiple putative resistance genes, and mobile genetic elements, including prophages and genomic islands, that encode cascades of putative virulence-associated genes with G + C content distinct from the core genome, suggesting acquisition through horizontal gene transfer. In conclusion, our findings address an existing knowledge gap and highlight the potential dualistic nature of S. sepilia SMBL8, both as a beneficial industrial bacterium and an opportunistic pathogen, facilitated by metabolic versatility and genomic plasticity. Our study also emphasises the critical need for environmental surveillance in anthropogenically disturbed habitats to monitor and mitigate the potential emergence of resistant opportunistic pathogens.
Enzymes are indispensable biocatalysts; however, their industrial and environmental applications are often constrained due to their narrow pH ranges. This review provides a comprehensive overview of computational-guided strategies for rationally engineering enzyme pH profiles, shifting optima, broadening functional windows, and enhancing acid- or alkaline-tolerance. The mechanistic approaches to engineering pH enzymes, including electrostatic optimization (active-site pKa tuning, surface charge engineering), stability reinforcement (salt-bridge and hydrogen-bond network design), and dynamics-driven analysis using constant-pH molecular dynamics (CpHMD) and free-energy calculations, have also been discussed herein. Beyond physics-based methods, we highlight the transformative role of data-driven and artificial intelligence approaches, such as machine learning, evolutionary-guided consensus design, and generative protein language models for de novo sequence exploration. By integrating mechanistic biophysical models with AI-driven discovery, hybrid computational workflows are enabling a paradigm shift from retrospective explanation to predictive design. Computational-guided rational design of enzyme engineering provides a synergistic framework that accelerates the development of robust, pH-adapted biocatalysts, paving the way for more sustainable industrial processes and effective environmental technologies.
The application of steam-exploded green coconut fiber (GCF) (an agro-industrial waste) was studied as a support for the immobilization of lipases, using lipase B from Candida antarctica (CALB), lipase from Pseudomonas fluorescens (PFL) or the engineered lipase Eversa (EL) as model enzymes. The achieved immobilization yield was 82.01 ± 2.02%, 87.62 ± 4.34%, and 77.47 ± 1.88% for GCF-PFL and GCF-CALB in 24 h, and GCF-EL in 48 h, respectively. The biocatalysts' activities (U/mg) and recovered activities in relation to the soluble enzymes (%) were 10.22 ± 0.96 U/mg and 26.37 ± 2.25%, 9.22 ± 0.17 U/mg and 49.84 ± 2.30%, 27.23 ± 0.21 U/mg and 9.48 ± 0.11% for GCF-CALB, GCF-PFL, and GCF-EL, respectively. After the immobilization, the enzymes were subjected to modification with glutaraldehyde (GA) or/and polyethylenimine (PEI). The modification with both GA and PEI was the best achievement as it reduced the desorption of lipases from the support and substantially increased their thermostability (for GCF-CALB-GA-PEI: stabilization factor (SF) > 154.8 at 60 ºC; for GCF-PFL-GA-PEI: SF > 58.6 at 75 ºC and GCF-EL-GA-PEI: SF > 172.6 at 80 ºC). The maximum enzyme load was determined to be 5 mg/g for CALB biocatalysts, 10 mg/g for PFL and EL. This study shows an alternative use of this agroindustrial, with the environmental relevance that it presents.
Mutations in the pncA gene of Mycobacterium tuberculosis, which encodes the PZase enzyme, are closely linked to pyrazinamide (PZA) resistance. Two clinical isolates, R1 and R2, which are resistant to pyrazinamide at concentrations of 100 μg/mL and 150 μg/mL, respectively, harbor multiple pncA mutations. The pncA R1 gene carries T41C, G419A, and A535G, causing Cys14Arg, Arg140His, and Ser179Gly substitutions in PZase; the pncA R2 gene has G76T, G112C, A403C, and G419A, resulting in Ala26Ser, Ala38Pro, Thr135Pro, and Arg140His changes. The relationship between the biochemical characteristics of the enzymes with pyrazinamide resistance in isolates R1 and R2 remains unclear. This paper presents the catalytic kinetics of mutant enzymes and explores their association with PZA resistance. The impact of these mutations on enzyme function was evaluated by expressing recombinant PZase in Escherichia coli, resulting in the production of proteins approximately 21 kDa in size, as confirmed by SDS-PAGE analysis. Kinetic analysis revealed reduced catalytic efficiency (kcat/KM) for the PZase-R1 and PZase-R2 variants, measured at 1.759 mM¯¹·min¯¹ and 1.500 mM¯¹·min¯¹, respectively, in comparison to the wild-type enzyme, which exhibited a value of 2.443 mM¯¹·min¯¹. These reductions correspond to decreases of 28.0% for PZase-R1 and 38.6% for PZase-R2. The observed declines in catalytic efficiency are likely to contribute to the development of resistance to pyrazinamide (PZA). Further studies, including site-directed mutagenesis and structural modelling, are needed to clarify the impact of each mutation on PZase function and drug interaction.
To synthesize novel 1,2,4-triazole-5-thione-quinoline Schiff base hybrids and evaluate their urease inhibitory, antimicrobial, antioxidant, and computational properties. Two series of compounds, 7(a-d) and 8(a-d), were synthesized and structurally characterized by Fourier Transform-Infrared (FT-IR), 1 H/13C Nuclear Magnetic Resonance (NMR), mass spectrometry, and elemental analysis. Urease inhibition was determined spectrophotometrically. Antimicrobial activity was assessed by disc diffusion and broth microdilution methods. Antioxidant activity was evaluated using ferric-reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays. Density functional theory (DFT) and molecular docking studies were also performed. Compounds 7c and 8c showed the strongest urease inhibitory activity, each with an IC50 value of 1.37 mM. 8c displayed the best docking score (-7.6 kcal/mol), while 7c showed favorable binding affinity (-6.9 kcal/mol). Antimicrobial screening revealed selective activity mainly against Gram-positive bacteria and fungi, while Gram-negative bacteria were generally resistant. Compound 7d displayed the broadest antimicrobial profile, with minimum inhibition concentration (MIC) values of 39.06 µg/mL against Staphylococcus aureus and 19.53 µg/mL against Streptococcus pyogenes. In antioxidant assays, 7d and 8d showed the highest FRAP values, whereas 8c and 8a showed the strongest DPPH radical-scavenging activity. DFT results supported the observed structure-activity relationships.
Different AMF species regulate soil nitrogen transformation by guiding divergent cotton carbon investment strategies. Moderate inoculation with Acaulospora scrobiculata achieves optimal nitrogen benefits at minimal carbon cost. Arbuscular mycorrhizal fungi (AMF) form symbioses with most terrestrial plants, enhancing phosphorus and nitrogen uptake. However, the mechanisms by which different AMF species and inoculation dosages synergistically regulate host nitrogen uptake efficiency remain insufficiently elucidated. This study investigated three AMF species-Glomus heterosporum (Gh), Acaulospora scrobiculata (As), and Paraglomus occultum (Po)-at different inoculation dosages (440, 880, and 1320 spores g-1) on cotton growth, nitrogen uptake, plant carbon-to-nitrogen ratio, soil organic carbon input via hyphae, and soil enzyme activities. AMF significantly reduced soil organic carbon content and plant carbon-to-nitrogen ratio, altered soil enzyme activities, alleviated soil microbial nitrogen limitation, and promoted cotton growth and nitrogen uptake. At the moderate inoculation dosage (880 spores g-1), As exhibited the strongest promoting effect, increasing soil nitrogen acquisition-related enzyme activities by 103.7%, and enhancing shoot and root nitrogen accumulation by 3.46-fold and 2.40-fold, respectively. It effectively drives soil nitrogen transformation processes by guiding a moderate allocation of plant carbon. Gh exhibited the highest mycorrhizal nitrogen response at the high inoculation dosage (1320 spores g-1), but its carbon flow had limited stimulatory effects on nitrogen transformation. In contrast, the growth-promoting effect of Po and its ability to regulate soil nitrogen transformation were weaker. Furthermore, the AMF colonization rate was positively correlated with the mycorrhizal nitrogen and growth response, but negatively correlated with the input of soil organic carbon via the hyphal pathway. This study elucidates how carbon investment strategies directed by different AMF species regulate soil nitrogen transformation, supporting sustainable, AMF-based fertilization strategies in cotton cultivation.