Search Results (902)

Surfactin is a lipopeptide biosurfactant with significant industrial potential, but high production costs have hindered its commercialization. In this study, we developed a sustainable and cost-effective bioprocess for surfactin biosynthesis using Bacillus subtilis 55033, utilizing kitchen waste as the primary fermentation substrate without any previous pretreatment—an advantage that simplifies the process and reduces costs compared to previous reports. To maximize productivity, the fermentation parameters were systematically optimized through single-factor and orthogonal experimental designs. The optimal conditions were as follows: a fermentation temperature of 31 °C, a duration of 48 h, a 5% v/v inoculum, a 7% w/v solid-to-liquid ratio, an initial pH of 7.5, and an agitation speed of 200 rpm. Under these conditions, the surfactin yield reached 371.67 mg/L, an increase of 100.5% from 185.4 mg/L prior to optimization. We performed a comparative analysis of the surfactin biosynthetic gene clusters between B. subtilis 55033 and the model strain B. subtilis 168. The produced surfactin exhibited potent antagonistic activity against aquatic pathogens, significantly inhibiting the growth of several species of Vibrio and the division and hatching of Cryptocaryon irritans Tomonts. These findings demonstrate that our platform not only provides a high-value valorization route for organic waste but also enables preliminary exploration of surfactin applications in aquaculture, in line with the principles of a circular bioeconomy. Full article

This study presents an integrated optimization framework for enhancing biogas and methane production through anaerobic digestion, addressing the challenge of identifying optimal operating conditions across multiple interacting parameters. Biochemical methane potential tests were conducted to evaluate the individual effects of four critical operational parameters: temperature, mixing regime, inoculum-to-substrate (I-S) ratio, and chemical oxygen demand load (COD-L). Experimental findings confirmed that thermophilic conditions, mixing once a day, I-S ratio of 1:2, and moderate COD loading consistently delivered the most favorable biogas and methane yields. Kinetic modeling, including the Modified Gompertz and Logistic models, showed strong predictive agreement with experimental data (R² > 0.90), reliably capturing production dynamics across all tested conditions. Polynomial response surface methodology further identified COD-L as the dominant driver of methane yield, with optimal operating conditions falling within moderate temperature and COD-L ranges. This revealed significant nonlinear interactions between parameters. Building on these findings, the Crayfish Optimization algorithm successfully determined global optimal conditions, achieving a maximum biogas production of 0.371 Nm³/kg.VS. These results highlight how combining experimental investigation with predictive modeling and metaheuristic optimization creates a powerful decision-support framework for improving the efficiency and stability of anaerobic digestion systems. Full article

Anaerobic digestion of municipal wastewater sludge is often limited by slow hydrolysis rates. This study evaluated the effects of ozone pretreatment on methane production during mesophilic batch digestion. Ozone was applied at 0–10% for 30–90 s, with inoculum-to-substrate ratios of 1.0–2.0. Methane production was monitored using the AMPTS II system. The maximum methane yield (736 NmL CH₄ g⁻¹ VS; 1381 NmL total) was obtained at 10% ozone for 30 s and I/S = 1.5. Kinetic modelling showed enhanced methane production rates and reduced lag phases, with the Gompertz and Logistic models providing the best fit. Full article

The quarantine pathogen Phytophthora ramorum has a high potential for dispersal due to its airborne inoculum, its wide range of hosts, and its ability to spread through the trade of nursery plants. For these reasons, it represents a serious threat to ornamental nursery production and, consequently, to urban, natural and semi-natural ecosystems. This oomycete pathogen (EU1 lineage, A1 mating type) has been detected on Viburnum tinus in a commercial nursery located in the Pistoia nursery district (PND) (Tuscany, central Italy), one of the main nursery areas for the production of ornamentals in Europe. Artificial inoculations were carried out in the laboratory under controlled conditions, following a standard detached-leaf assay protocol, on leaves of 16 ornamental shrub species commonly marketed by the PND. Disease severity was assessed, and susceptibility categories (high, moderate, low, and non-susceptible) were defined based on data collected at 7 and 14 days post-inoculation and validated through statistical analysis. Inoculated species exhibited variable levels of disease severity. The results confirmed the pathogen’s high virulence on Viburnum tinus and Rhododendron hybrid ‘Madame Masson’. The following species were also found to be highly susceptible: Ilex aquifolium, Loropetalum chinense, Magnolia stellata, Osmanthus fragrans, and Trachelospermum jasminoides. Camellia japonica, Nerium oleander, Osmanthus heterophyllus, Prunus laurocerasus, and Rhododendron obtusum showed moderate susceptibility. Arbutus unedo, Laurus nobilis, Photinia fraseri and Syringa vulgaris exhibited low susceptibility. At the end of the trial, no infected species fell into the non-susceptible categories. The oomycete proved particularly aggressive on Ilex aquifolium, the most susceptible host among those tested. This high susceptibility is a new finding that could have significant epidemiological implications. Our findings emphasize the need for rigorous phytosanitary surveillance in nursery systems, based on constant monitoring and the adoption of high-throughput diagnostic protocols, in order to implement effective and rapid control measures. Full article

Damping-off disease represents a major constraint in greenhouse tomato (Solanum lycopersicum) production, being primarily caused by soil-borne fungi and oomycetes whose persistence is intensified by intensive cultivation practices. This review synthesizes current knowledge on integrated disease management strategies targeting these pathogens in protected cropping systems. Cultural practices (e.g., substrate sanitation and irrigation control), physical and chemical soil disinfestation, deployment of resistant cultivars, and biological control agents (e.g., Trichoderma, Bacillus, and Pseudomonas) are critically evaluated. Available evidence indicates that integrated approaches consistently reduce pathogen inoculum, limit infection processes, and enhance seedling establishment and vigor, thereby outperforming single-method interventions. Synergistic interactions among practices strengthen rhizosphere resilience and contribute to sustained soil health. Overall, integrated disease management offers an effective and environmentally sound framework to mitigate damping-off, reduce reliance on chemical inputs, and ensure stable tomato production in protected cultivation systems. Full article

Young dairy ruminants often have limited rumen fermentative capacity, which can impair adaptation to solid diet during weaning. This study evaluated the effects of ruminant colostrum supplementation to enhance in vitro rumen fermentation at weaning. A batch culture system using rumen inoculum from artificially reared lambs was incubated with ovine, bovine, or reconstituted bovine colostrum at 4 and 20 mL/L. Sequential colostrum fractionation was used to identify the main functional components. Whole colostrum supplementation at high doses reduced ruminal pH (p < 0.001) and increased gas production (+18%), ammonia-N (+41%) and butyrate proportion (+10%) across colostrum sources, indicating enhanced microbial fermentation. Responses were dose-dependent and consistent across colostrum sources. Lipid removal had minimal effects, whereas depletion of high-molecular-weight molecules, mostly IgG, markedly reduced gas production and protein degradation. Removal of medium-size proteins such as lactoferrin produced minor changes. Residual activity in low-molecular-weight fractions was retained likely associated with the presence of fermentable substrates and bioactive compounds. These findings indicate that colostrum may exhibit both nutritional and modulatory effects on in vitro rumen fermentation, with IgG identified as a key component. These findings support the preservation of IgG in colostrum-derived products to enhance rumen fermentation, although further in vivo validation is required to evaluate the effects in weaned ruminants. Full article

Air-dried mutton is a traditional, culturally significant meat product, yet its spontaneous fermentation is inherently constrained by unstable microbial communities, leading to batch-to-batch quality inconsistency and potential food safety hazards. Elucidating whether composite starter cultures can modulate the microbiota and enhance product quality is therefore critical for standardized industrial processing. Herein, we investigated the effects of a defined starter culture (composed of Lactiplantibacillus plantarum and Pediococcus pentosaceus in a 2:1 ratio, with a total inoculum of 10⁸ CFU/g) on the quality and flavor of air-dried mutton, comparing inoculated samples (FJ) with naturally fermented controls (ZR). The fermentation was conducted at 30 °C and 95% relative humidity (RH) for 24 h, followed by air-drying at 4 °C for 21 d, with all assays performed in three biological and three technical replicates. Starter inoculation significantly reduced the pH, water activity (Aw), total volatile basic nitrogen (TVB-N), and thiobarbituric acid reactive substances (TBARS) values while improving sensory acceptability (p < 0.05). Amplicon sequencing analysis revealed a lactic acid bacteria (LAB)-dominated microbiota in FJ samples, with elevated abundances of Pediococcus and Lactobacillus and reduced abundance of Pseudomonas. The inoculated group also exhibited altered eicosapentaenoic acid content and a more diverse volatile flavor profile, with eight key aroma compounds positively correlating with LAB abundance. These findings demonstrate that composite starter inoculation improves physicochemical quality, stabilizes the microbial community, and enhances flavor in air-dried mutton. Further mechanistic validation and scale-up trials are required to confirm industrial applicability. Full article

Air–liquid interface (ALI) cultures recapitulate key features of the airway epithelium by driving basal cell differentiation into ciliated, club, and goblet cells and by generating a functional mucus barrier, thereby representing a highly relevant model of the human respiratory tract. Using a reduced factorial Design of Experiments (DoE) methodology, we simultaneously investigated the effects of seven variables on human coronavirus OC43 (HCoV-OC43) replication in air–liquid interface (ALI)-cultured primary human bronchial epithelial cells (pHBECs) to identify robust conditions that support infection and viral replication. Epithelial differentiation was monitored by measuring transepithelial electrical resistance and determining expression levels of marker genes for basal, goblet, club, and ciliated cells using reverse transcription quantitative PCR (RT-qPCR). HCoV-OC43 replication was monitored by quantifying genomic and subgenomic RNA by RT-qPCR. Viral RNA peaked three days post-infection in cell lysates and four days post-infection in apical washes. Initiation of ALI conditions induced epithelial differentiation, which was complete after 21 days and emerged as the strongest determinant of viral replication. Differentiated pHBEC cultures showed significantly reduced viral RNA compared with undifferentiated cultures, particularly following apical infection. In contrast, basal infection resulted in lower viral RNA levels in undifferentiated cultures than apical infection but was less dependent on epithelial differentiation. However, productive infection following basal exposure was less consistent and more strongly dependent on viral inoculum size. We further demonstrate that repeated mucus washes prior to infection increased HCoV-OC43 replication in mature cultures. In summary, our findings show that epithelial differentiation negatively affects HCoV-OC43 replication and we identify conditions that maximize viral replication in fully differentiated pHBEC cultures. Full article

Anaerobic digestion (AD) of food waste is strongly influenced by substrate characteristics and operating conditions, particularly substrate composition, particle size, and substrate-to-inoculum (S/I) ratio. In this study, a modified ADM1-R3 model, incorporating a surface-based disintegration kinetics approach, was developed to evaluate the simultaneous influence of these factors on methane production. Sensitivity analysis identified the disintegration and hydrolysis constants as the most influential parameters, while principal component analysis supported a sequential calibration strategy. The model was calibrated using literature data and verified against independent datasets, achieving $R^2$ values of 0.9967 (calibration) and 0.9745–0.9880 (verification). Simulation results showed that optimal performance was observed at low S/I ratios (0.5–1) and intermediate particle sizes (1.4–4 mm), with maximum yields of 419, 744, and 581 $\mathrm{m}\mathrm{L}·{\mathrm{g}}^{-1} \mathrm{V}\mathrm{S}$ for carbohydrate-rich, protein- and lipid-rich, and mixed substrates, respectively. Overall, the model provides a consistent framework for analyzing AD behavior and identifying favorable operational conditions, although further validation under unstable operating conditions is required to fully assess its predictive capability. Full article

Indole-3-acetic acid (IAA) is an essential phytohormone that regulates several tropic responses in plants and serves as signaling molecule in plant–bacteria interactions. In this study, a high indolic-compound-producing actinobacterial strain, designated OP15, was isolated from the roots of Opuntia ficus-indica as an endophyte and identified as a member of the Streptomyces genus based on 16S rRNA gene sequence analysis. Synthetic dairy wastewater (SDWW) was used as a low-cost fermentation substrate for the production of IAA-equivalent compounds, providing a sustainable approach that links microbial metabolite production with agro-industrial waste valorization. Fermentation conditions were optimized using a Box–Behnken design coupled with response surface methodology. To address model overfitting, a backward elimination procedure was applied, yielding a reduced statistical model (R² = 0.658, adjusted R² = 0.628, predicted R² = 0.583) with adequate predictive performance. Under the optimized conditions (1 g/L NaCl, 1 g/L L-tryptophan, 100% SDWW, 7.5% inoculum, 4.5 days), the model predicted a maximum response of 278.2 µg/mL (95% prediction interval: 230.0–326.4 µg/mL). Experimental validation yielded a response of 296.838 µg/mL, falling within the prediction interval and confirming the model’s reliability within the experimental domain. This agreement supports the model’s utility for process optimization within the experimental domain. In addition, treatment of wheat seeds with the culture supernatant of OP15 isolate significantly (p < 0.05) promoted root length and root dry weight. Overall, these findings highlight the potential of the OP15 strain for the sustainable production of IAA-equivalent compounds using SDWW and support the valorization of dairy effluents as low-cost substrates for biotechnological applications. Full article

Mesenchymal stromal cells derived from adipose tissue (ASCs) are widely used in regenerative medicine, requiring scalable expansion strategies that preserve both cellular function and biological quality. However, current bioprocess optimization approaches are primarily guided by proliferation and phenotypic stability, often overlooking genomic integrity as a critical attribute. In this study, we developed a stirred-tank bioreactor system for ASC expansion on microcarriers and applied a genotoxicity-informed optimization strategy by integrating growth kinetics, metabolic profiling, and DNA damage assessment across multiple operational conditions (B₁–B₅), including variations in dissolved oxygen, agitation, inoculum density, and medium renewal. Optimized culture conditions (B5) enabled high cell productivity within a reduced cultivation period (9 days), while maintaining high viability (>90%), mesenchymal immunophenotype, and differentiation capacity. Distinct metabolic profiles were associated with enhanced proliferation, with increased glycolytic activity observed under optimized conditions. Despite these favorable outcomes, genotoxic analyses revealed a progressive, time-dependent accumulation of DNA damage and increased micronucleus frequency during expansion. Notably, these alterations did not impair cell proliferation, phenotype, or differentiation potential, indicating that conventional optimization metrics may not fully capture underlying genomic changes. Collectively, our findings demonstrate that bioprocess optimization based solely on classical performance parameters may overlook relevant biological alterations. By incorporating genotoxic endpoints into the evaluation framework, this study provides a refined approach for assessing large-scale stem cell expansion and contributes to improving the robustness and reliability of biomanufacturing strategies for therapeutic applications. Full article

Caproic acid (CA) production through ethanol-driven chain elongation (CE) is a promising pathway to valorize organic wastes. However, the effect of pH and inoculum source on substrate conversion properties and microbial communities was not fully explored. In this study, performance of caproic acid production with anaerobic methanogenic sludge (AMS), aerobic sludge (AS) and chain elongation sludge (CES) at different pH conditions (uncontrolled (UN), 5, 6, and 7) were investigated. It was found that microorganisms in all inocula could degrade ethanol, but the consumption rate was different. The AS mainly used substrate for biogas production, without CA accumulation, while AMS and CES could synthesize butyrate and caproate with ethanol and acetate as substrates. At pH UN and 5, excessive ethanol oxidation (EEO) was activated and transformed ethanol into acetate resulting in low CA yield. Increasing pH to 7, the AMS produced more caproate and achieved a higher CA yield (0.36 g-COD/g-COD) than that of CES (0.33 g-COD/g-COD). Microbial communities in raw inocula were different, which led to distinct substrate conversion pathways. After fermentation, Anaerolineaceae was the dominate family in AMS, while Corynebacteriaceae and Dysgonomonadaceae dominated in the reactor with CES, explaining the distinct caproate yield in both reactors. The results of this study provided useful information for constructing ethanol-driven CE processes from organic wastes. Full article

Hydrogenotrophic denitrification (H₂Den) is a promising strategy for NO₃⁻ removal from a supply water with low or negligible organic carbon content. However, its performance may be affected by emerging contaminants (ECs), which pose increasing risks to the environment and human health. This study investigates the acute effect of two widely detected ECs, acetaminophen (ACN) and chloramphenicol (CHP), at a 200 mg/L concentration, on H₂Den using anaerobic granular sludge (AnGS) as inoculum. Acute exposure to ACN enhanced NO₃⁻ removal, likely due to the formation of oxidizable metabolites serving as electron donors through the heterotrophic pathway. On day 3, the residual NO₃⁻ concentration had already dropped below the regulatory limit of 50 mg/L, reaching 4.3 mg NO₃⁻/L. In contrast, CHP initially inhibited the denitrification process, resulting in limited NO₃⁻ removal, i.e., a residual concentration of 145.4 mg NO₃⁻/L on day 3. Nevertheless, short-term microbial adaptation likely enabled performance recovery under CHP exposure. On day 6, both EC exposure tests allowed a NO₃⁻ removal above 97%, although CHP resulted in residual NO₂⁻, i.e., 37 mg NO₂⁻/L. In the presence of ACN, the accumulation of gaseous denitrification intermediates was observed, with NO concentration in the headspace peaking at 9.5% (i.e., 16.2 × 10⁻² µg NO/min/g VS) on day 6. Thus, in terms of either the production of gaseous intermediates or the presence of residual nitrogen in the liquid phase, ACN and CHP significantly influenced the denitrification performance, highlighting the importance of considering their presence in the operation of the denitrification process. Full article

Lignocellulose is degraded in the rumen by diverse microorganisms. This study aimed to select the top ruminal microbes associated with an anaerobic fungus (AF) capable of forming consortia that facilitate biogas production from wheat straw. The workflow included the following steps: (1) batch reactors, divided into three compartments with porous membrane bags containing wheat straw, were assembled. The outermost compartment was inoculated with freshly collected rumen content. The first microbes colonizing the wheat straw in the innermost compartment within 72 h were identified. (2) Synthetic consortia were assembled comprising the following identified microbes: an anaerobic fungus (AF) (Neocallimastix lanati); methanogenic archaea (M) (Methanobrevibacter ruminantium or Methanobrevibacter gottschalkii); bacteria (B) (Butyrivibrio hungatei or Succinoclasticum ruminis). (3) Wheat straw was subjected to 7-day pretreatments with these synthetic consortia. (4) The pretreated straw served as substrate in biochemical methane potential (BMP) tests that used a biogas reactor digestate as the inoculum. The pretreated straw produced elevated biomethane yields; nonetheless, this process needs further optimization. The cross-kingdom AF + M + B consortia increased methane production by 35–70%, and superior volatile fatty acid production was confirmed via HPLC. The results suggest novel strategies for advanced practical biogas/biomethane technologies. Full article

Alsophila spinulosa is a tree fern designated as a second-class nationally protected species in China and valued for its medicinal and ornamental properties. Its slow growth and susceptibility to environmental stresses pose challenges to its cultivation. Plant-growth-promoting rhizobacteria (PGPR) can enhance plant development by producing phytohormones, such as indole-3-acetic acid (IAA). In this study, 39 IAA-producing strains were isolated from the rhizosphere of A. spinulosa. Morphological and molecular analyses identified the highest IAA-producing strain, R74, as Burkholderia pyrrocinia. Its optimal inoculum age was determined to be 12–20 h, and its optimal culture conditions for IAA production were 24 h of incubation, 32 °C and pH 7.0. Whole-genome sequencing revealed that the genome of strain R74 is 8,347,169 bp in size with a GC content of 67%, comprising 7543 genetic elements. Further genomic analysis showed that IAA biosynthesis in R74 involves the tryptophan side-chain oxidase (TSO) pathway and the tryptophan-independent pathway. Pot experiments revealed that inoculation with R74 increased the height, root length, stem diameter, and biomass of A. spinulosa seedlings. It also increased antioxidant enzyme activities, elevated soluble protein and chlorophyll contents, and reduced malondialdehyde levels. This study provides an empirical basis for the development of Burkholderia-based biofertilizers to promote A. spinulosa growth. Full article