Search Results (2,477)

This review comprehensively examines the structural architecture, catalytic mechanisms, and targeted molecular engineering of α-amylase (primarily the GH13 family), a pivotal biocatalyst in the food industry. We highlight diverse microbial sources of α-amylases and their cost-effective heterologous expression in well-characterized hosts like Bacillus subtilis and Escherichia coli. To overcome extreme operational bottlenecks—such as elevated temperatures and acidic environments—recent advances in protein engineering are critically evaluated. These strategies, including directed evolution, semi-rational design, and advanced immobilization on nanomaterials, synergistically enhance the enzyme’s thermostability, catalytic efficiency, and reusability. Furthermore, this paper synthesizes the state-of-the-art applications of engineered α-amylases across key food processing sectors, including baking, sugar refining, and brewing. By integrating structural biology with advanced material science, this review provides a targeted roadmap for developing next-generation, high-performance α-amylases to address current and future challenges in sustainable food processing. Full article

This work presents an energy-efficient and simple method for producing luminescent, antibacterial sulfur quantum dots (SQDs). For the first time, polyethyleneimine (PEI)-coated SQDs were synthesized via a mechanochemical technique, utilizing either elemental sulfur or sodium thiosulfate as the sulfur source. The roles of hydrogen peroxide (H₂O₂) as an etching agent and of sodium hydroxide (NaOH) in the PEI-mediated SQD formation were investigated. The as-synthesized SQDs were characterized by UV-visible, Raman, infrared (IR), and photoluminescence (PL) spectroscopy, as well as by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Both TEM and AFM analyses revealed similarly small SQD sizes (average diameter ~3 nm), independent of the sulfur source used. The influence of synthesis conditions on the optical properties, including the photoluminescence quantum yield (QY), was evaluated. SQDs derived from elemental sulfur, PEI, and NaOH exhibited the best water solubility and the strongest photoemission in the 400–550 nm range. Antibacterial activity was assessed against representative Gram-positive and Gram-negative strains, and minimum inhibitory concentration (MIC) values were determined. The PEI-coated SQDs demonstrated antibacterial activity against the Gram-positive bacteria Bacillus subtilis, Staphylococcus aureus, and Staphylococcus epidermidis, which is attributed primarily to the sulfur component. Full article

Grapevine (Vitis vinifera L.) is an economically important fruit crop cultivated worldwide. However, its production and fruit quality are severely constrained by powdery mildew (Erysiphe necator) and Botrytis bunch rot (Botrytis cinerea) diseases. Increasing concerns regarding chemical fungicide resistance and environmental sustainability highlight the urgent need to develop alternative and more sustainable disease management strategies. This study assessed the field efficacy of Pseudomonas protegens-based formulations (TANIRI^® WP at 1 g·L⁻¹ and MaxGrowth at 1 mL·L⁻¹) within an integrated disease management program in cv. Chardonnay. Defense-related gene expression analysis revealed that biological treatments predominantly up-regulated pr1, pr2, and pr10 in both leaves and berries. In contrast, the chemical inducer acibenzolar-S-methyl (ASM) triggered earlier but less consistent induction of pr1 and pr2, alongside transient activation of pal and lox9. Repeated field applications of P. protegens formulations moderately reduced the severity of Botrytis bunch rot (20.89%) and powdery mildew (6.14%), though control levels remained below conventional sulfur/Bacillus subtilis-based treatments (30.04% and 13.56%, respectively). Overall, these findings suggest that biological inducers could complement conventional management practices for grapevine health. In particular, P. protegens may act mainly by systemically inducing host defense responses and partially suppressing pathogen development under field conditions. Full article

Eye cosmetic products are widely used and applied in close proximity to the ocular surface, making their microbiological safety particularly important. The aim of this study was to assess bacterial contamination in used eye cosmetic products, characterize the antimicrobial resistance profiles of the isolated bacteria, and perform molecular genotypic analysis. A total of 71 samples, including mascara, eyeliner, and eyeshadow, were analyzed. Microbiological analysis revealed that Bacillus spp. and coagulase-negative staphylococci (CoNS) were the predominant microorganisms, while no major pathogens such as Staphylococcus aureus, Escherichia coli, or Pseudomonas aeruginosa were detected. Antimicrobial susceptibility testing demonstrated high susceptibility of isolates to gentamicin, vancomycin, and linezolid, whereas resistance to benzylpenicillin and clindamycin was observed among Staphylococcus spp. Molecular identification based on 16S rRNA gene sequencing confirmed the presence of Bacillus licheniformis, Bacillus subtilis, Staphylococcus epidermidis, and Staphylococcus warneri, with sequences showing high similarity to globally distributed strains. Although the detected microorganisms were predominantly opportunistic, their presence in products applied near the eyes suggests a potential risk of microbial transfer to the ocular surface. These findings highlight the importance of proper hygiene practices, regular product replacement, and effective quality control measures to minimize microbial contamination and associated health risks. Full article

Peanut (Arachis hypogaea L.) forms root nodules that host microbial communities influencing plant nutrition and stress tolerance, and herbicide use may act as an environmental filter altering the cultivable nodule microbiota. This study isolated and characterized bacteria from peanut nodules collected in fields with and without imazapic application in Jaboticabal, São Paulo, Brazil. Eight isolates were obtained, and one hemolytic strain was excluded after pathogenicity screening. Based on 16S rRNA gene sequencing and phylogenetic analysis, the isolates were identified as Bacillus aerophilus, Bacillus inaquosorum, Bacillus subtilis, Bradyrhizobium yuanmingense, Burkholderia lata, and Rhizobium tropici. Nodules from herbicide-treated plants yielded exclusively Bacillus spp., whereas those from non-treated plants showed greater taxonomic diversity. Molecular screening detected genes associated with biological nitrogen fixation (nifH) and nodulation (nodA, nodB, nodC, nodD), indicating potential functional capacity. In greenhouse assays, the isolates showed strain-dependent effects on early plant development, with pronounced responses in root growth and nodulation. Burkholderia lata and bacterial consortia enhanced root development and nodulation, with performance comparable to the commercial inoculant SEMIA 6144. Herbicide management shapes the cultivable nodule microbiota, and selected isolates show potential as bioinoculants for peanut production systems. Full article

L-theanine is a characteristic non-proteinogenic amino acid found in tea leaves and has attracted considerable attention because of its diverse physiological activity and broad application prospects. γ-glutamyl transpeptidase (GGT) can catalyze the synthesis of L-theanine from L-glutamine and ethylamine without ATP consumption, highlighting its advantages for enzymatic production. In this study, a complete process was established for L-theanine production. Through screening of single and dual promoters, the optimal expression combination, PyxiE-PspoVG, was identified. Furthermore, by integrating the dal selection marker, an antibiotic-free engineered strain was developed. After flask-level optimization, the GGT activity reached 27.32 U/mL and further increased to 127.37 U/mL in 3 L fed-batch fermentation. Using the fermentation broth as the biocatalyst, fed-batch conversion of 0.6 M L-glutamine and 2 M ethylamine yielded 0.52 M (91.44 g/L) L-theanine within 24 h. Further integration of ceramic membrane filtration, ultrafiltration, nanofiltration, electrodialysis, activated-carbon decolorization and ethanol crystallization afforded a final product purity of 95.6%. This study offers a useful reference for large-scale L-theanine production. Full article

Abundant non-medicinal byproducts of Polygonatum sibiricum and Gentiana scabra are severely underutilized, resulting in resource waste and environmental burden. A previous study confirmed that triple-microbial co-fermentation enhances their antibacterial activity, yet the temporal metabolic mechanism and optimal process parameters remain unclear due to endpoint-only metabolomics limitations. This study aimed to optimize the staged solid-state fermentation (SSF) system for maximum antibacterial activity, verify the triple-microbial consortium’s synergistic enhancement effect, and elucidate the dynamic metabolic mechanism via time-series metabolomics. A staged SSF strategy was established: Aspergillus niger monoculture (0–48 h) followed by Bacillus subtilis and Saccharomyces cerevisiae co-culture (48–72 h). Key parameters were optimized via single-factor experiments and a Box–Behnken design. Under optimal conditions, inhibition zones against Staphylococcus aureus and Escherichia coli reached 20.8 ± 0.3 mm and 17.6 ± 0.2 mm, respectively, with a 17.5% increase in S. aureus inhibition and markedly improved E. coli inter-batch consistency. Time-series untargeted LC-MS/MS metabolomics (2681 identified metabolites) revealed a three-stage metabolic relay model driving antibacterial enhancement: 0–48 h shikimate pathway activation for phenolic precursor accumulation; 48–60 h dipeptide conversion and ABC transporter enrichment initiating antibacterial synthesis; 60–72 h metabolic flux redirected to indole alkaloid biosynthesis for complex antibacterial compound accumulation. This work provides a mechanistic paradigm for the high-value valorization of herbal byproducts, with applications in natural antibacterial agents and functional feed additives. Full article

Cellulose-derived gel films are promising matrices for the immobilization and delivery of beneficial microorganisms in sustainable plant protection. This study evaluated the effects of polymer molecular weight and chemical structure on the physicochemical properties and biocontrol performance of hydroxyethyl cellulose (HEC) films of low, medium, and high molecular weight, as well as sodium carboxymethyl cellulose (CMC-Na), loaded with Bacillus subtilis. The films were characterized in terms of morphology, swelling behavior, mechanical properties, microbial viability, and antifungal activity against Fusarium avenaceum and Alternaria solani. Increasing HEC molecular weight produced progressively denser and more homogeneous gel networks, resulting in improved structural integrity, whereas CMC-Na formed dense but less stable networks. Swelling studies at pH 4, 7, and 9 showed high water uptake for all HEC systems, with enhanced structural stability observed in high-molecular-weight films, whereas CMC-Na dissolved rapidly under all conditions. Mechanical testing further confirmed that increasing molecular weight enhanced stiffness and tensile strength but reduced flexibility. Immobilized in gel matrices, B. subtilis remained viable after 12 months of storage and rapidly reactivated after rehydration. All biohybrid films inhibited fungal growth, with stronger formulation-dependent responses against F. avenaceum than against A. solani. In general, polymer molecular weight and structure were identified as key parameters controlling network organization, hydration behavior, mechanical performance, and biological functionality. These findings highlight the potential of cellulose-derived gel matrices as tunable carriers for microbial biocontrol applications. Full article

Prophylactic antibiotic use in intensive aquaculture promotes antimicrobial resistance, necessitating the development of microbial-based interventions. This study evaluated the individual, complementary, and synergistic effects of Bacillus subtilis natto (BSN) and Lactobacillus plantarum (LP) on the physiological performance and intestinal microecology of juvenile Japanese flounder (Paralichthys olivaceus). Over a 60-day trial, juveniles (initial weight: 5.81 ± 0.03 g) received a basal diet (CON) or a diet supplemented with 10⁷ CFU/g of BSN, LP, or both (BSN+LP). The BSN+LP consortium elicited complementary improvements in final body weight (21.39 ± 0.75 g vs. 18.66 ± 0.44 g in CON) and feed conversion efficiency (p < 0.05). Transcriptomic analysis revealed synergistic upregulation of digestive proteases (trypsin, chymotrypsin). Notably, an in pro-inflammatory markers (IL-1β, TNF-α) was counterbalanced by substantial upregulation of anti-inflammatory cytokines (IL-10, 5.65-fold; TGF-β1, 4.48-fold), suggesting the induction of mucosal tolerance rather than pathological enteritis. High-throughput 16S rRNA sequencing showed that the control cohort had a potential baseline microbial, characterized by a high relative abundance of Proteobacteria. BSN+LP administration significantly altered this microbial community into a fermentative eubiosis enriched in Firmicutes and Bacteroidota. Correlation network analyses confirmed negative interaction dynamics: increased abundance of Lactobacillus, Bacteroides, and Muribaculaceae was negatively correlated with baseline pathobiont abundance. These findings indicate that co-administration of BSN and LP hypothetically enhances metabolic energy harvest via short-chain fatty acid-producing taxa, strengthens the gut–immune axis, and competitively mitigates opportunistic pathogens. Full article

The olive tree (Olea europaea L.) is one of the oldest known cultivated trees worldwide and an iconic species within the Mediterranean Basin. This study evaluated the impact of three bacterial strains, Bacillus subtilis D3, Paenibacillus tundrae M4, and Streptomyces tricolor HM10, on the mortality of the following four mite pests: Oxycenus niloticus, Tegolophus hassani, Aceria olivi, and Tetranychus urticae. B. subtilis D3 confirmed the highest efficacy, causing 91.84–85.36% mortality in laboratory tests and 88.90–84.12% in field trials after five days. In addition, P. tundrae M4 ranked second, achieving 90.49–84.26% mortality in the lab and 87.87–83.81% in the field after one week. S. tricolor HM10 produced 80.06–74.09% mortality in laboratory assays and 76.73–73.36% under the field conditions. Effects on the predatory mites Agistemus exsertus and Amblyseius swirskii were minimal, with mortality ranging from 13.28 to 18.55% in the lab work and 12.46–16.74% in the field experiment. Genome analysis of strain HM10 revealed a biosynthetic gene cluster with predicted terpenes production. Terpenes can cause chemo-osmotic stress and broad membrane-disrupting capabilities. These results highlight the promise of microbial agents for sustainable mite management and provide a foundation for further optimization of bacterial biocontrol strategies. Full article

The Activators Regenerated by Electron Transfer Atom Transfer Radical Polymerization (ARGET-ATRP) of vanillin methacrylate (VMA), a bio-based methacrylic monomer derived from vanillin, was systematically studied for the first time. The reaction conditions were optimized aiming at achieving good monomer conversions while preserving the antimicrobial aldehyde functionality. Bipyridine-based catalysts showed limited effectiveness, whereas polydentate aliphatic amines displayed higher activity. Kinetic studies showed linear profiles during the early stages of the polymerization before reaching a conversion plateau accountable to the depletion of the reducing agent, as confirmed by reactivation experiments. The resulting polymer (PVMA) exhibited a glass transition temperature comparable to that of poly(styrene), emerging as a potential bio-derived alternative to fossil-based thermoplastic materials. Furthermore, preliminary in vitro tests demonstrated that PVMA has potential antimicrobial activity against both Escherichia coli (Gram-negative) and Bacillus subtilis (Gram-positive). Full article

The increasing demand for sustainable plant protection products has intensified interest in microbial biocontrol agents (BCAs). This study aimed to evaluate the antifungal activity of selected Streptomyces, Bacillus, and Trichoderma asperellum strains against phytopathogenic fungi and to assess their potential as BCAs under in vitro conditions. The antifungal activity of ten Streptomyces strains was first evaluated against Botrytis cinerea, Colletotrichum salicis, Fusarium oxysporum, and F. graminearum using a dual-culture assay. All isolates exhibited antifungal activity, with Streptomyces venezuelae MSCL 350 showing the strongest inhibition. In addition, the antifungal activity of T. asperellum MSCL 309 and three Bacillus strains was assessed against twelve Fusarium spp. isolates obtained from oats. T. asperellum demonstrated broad-spectrum inhibition, with growth inhibition ranging from 44.6% to 78.4%, primarily due to soluble metabolites, while volatile compounds showed no significant effect. Among the other tested Bacillus strains, only Bacillus subtilis MSCL 1441 exhibited antifungal activity, inhibiting all tested isolates. These results demonstrate strong strain-dependent antifungal activity and highlight T. asperellum MSCL 309, S. venezuelae MSCL 350, and B. subtilis MSCL 1441 as promising candidates for the development of environmentally friendly biocontrol agents. Full article

Naturally abundant endophytes colonize plants internally without causing harm to their host plants. Endophytes are likely to occupy the same ecological niches as phytopathogens and thus have a high potential to be effective biological control agents. Their demonstrated ability to suppress more than one plant pathogen suggests that they can offer a viable alternative to chemical fungicides and a strategy for decreasing the inoculum potential of soil-borne pathogens. Some biocontrol endophytes are also known to improve soil health and the overall health of plants. However, the results in greenhouse studies do not always translate to consistent field efficacy. In this study, the efficacy of three endophytic bacterial isolates (PRT (Bacillus subtilis), PSL (Bacillus amyloliquefaciens), and IMC8 (Bacillus thuringiesis) were evaluated against Phytophthora capsici in a field environment and compared with two commercial biological fungicides, Serenade^® (Bayer Crop Science, St Louis MO, USA) and Double Nickel^® (Certis Biologicals, Columbia, MO, USA), and water control. Plants were inoculated with the bacteria strains using seed treatment for early plant colonization before transplanting to a field infested with P. capsici. Treatments with commercial bio-fungicides followed label recommendations. Data on plant growth vigor, disease severity, number of fruits, fruit size, total yield per plant, and percent of diseased fruits displayed significant differences between the bacteria treatments. While PRT was the best treatment for most traits, followed by PSL on pepper, PSL and Double Nickel were the best treatments on tomatoes. IMC8 was best for plant vigor and larger fruit size, but with fewer fruits per plant on both crops. This study suggests bacterial isolates PRT, PSL, and IMC8 can provide additional products for growth promotion and P. capsici disease management in pepper and tomatoes. Full article

Aflatoxin B₁ (AFB₁) is a highly stable mycotoxin that can persist during conventional food processing and therefore poses a serious risk to food and feed safety. In this study, two enzymes (CotA and Prx) were heterologously expressed in Bacillus subtilis, purified by Ni–NTA affinity chromatography, and evaluated for their ability to degrade AFB₁. Both enzymes exhibited remarkable thermostability and distinct catalytic optima. CotA exhibited its highest activity at 80 °C with an AFB₁ removal of 38.4%, whereas Prx showed its highest activity at 90 °C with a removal of 82.6%. The optimal pH values were near neutral, with CotA performing best at pH 7.0 and Prx at pH 7.5, and both reactions approached maximal conversion within approximately 10 h. When the two enzymes were combined, a clear cooperative effect was observed. The mixed system achieved 91.0% AFB₁ removal at 80 °C after 10 h, with the best degradation activity occurring at a CotA to Prx ratio of 1:3. At 50 °C, neither enzyme alone caused appreciable AFB₁ degradation, but the addition of hydrogen peroxide markedly enhanced catalytic activity. Both enzymes also retained substantial activity after boiling and autoclaving. In a maize flour model, the mixed-enzyme system showed strong AFB₁ degradation capacity, and peroxide-assisted treatment further improved activity. These results establish a thermostable and peroxide-responsive enzymatic platform for AFB₁ degradation and support future development of enzyme-based detoxification strategies for food and feed applications. Product identification and toxicological validation will be needed to confirm the safety of the treated products. Full article

Mungbean (Vigna radiata) is an important cash crop, yet the production is significantly compromised by continuous cropping. Beneficial microbial inoculation offers a promising strategy to alleviate the stresses through rhizosphere modulation and host physiological reprogramming. This study evaluated the efficacy of two biological control agents, Bacillus subtilis (B. subtilis) and Trichoderma harzianum (T. harzianum), in promoting mungbean growth under continuous-cropping conditions. Both individual applications of B. subtilis and T. harzianum significantly improved plant biomass, root system architecture, and yield. Combined metagenomic and transcriptomic analyses were conducted to unravel the underlying mechanisms. According to metagenomic analysis, both B. subtilis and T. harzianum were responsible for significant changes in beta diversity without significantly affecting the alpha diversity of the rhizosphere microbial community. T. harzianum recruited Chitinophagaceae unclassified, Abditibacterium, Hydrogenophilaceae unclassified, Methylophilaceae unclassified, and Chimaeribacter, while Bs recruited Candidatus Saccharibacteria unclassified. Transcriptomic analysis indicated that T. harzianum induced more extensive transcriptional reprogramming than B. subtilis. The enrichment analysis revealed both shared and distinct responses triggered by the two treatments. These findings suggest that B. subtilis and T. harzianum alleviate continuous-cropping stress through distinct yet complementary mechanisms involving rhizosphere microbiome modulation and mungbean transcriptional reprogramming. This study provides a sustainable strategy for legume cultivation. Full article