AMB Express最新文献

Bacillus subtilis is one of the most important production organisms in industrial biotechnology. However, there is still limited knowledge about the kinetics of fed-batch processes in bioreactors, as well as a lack of biological performance indicators, such as production yields, particularly regarding their variation over time. Understanding these kinetics and changes is crucial for optimizing the productivity in fed-batch processes. Fed-batch bioreactor cultures of Bacillus subtilis BMV9 in high cell density processes for surfactin production have been characterized with a kinetic model composed of first-order ordinary differential equations, describing the time course of biomass, substrate, surfactin and acetate. This model contributes to understanding critical restrictions and the knowledge gained was used to design and implement a model-based process. The model integrates biomass growth based on Monod kinetics, substrate consumption, surfactin synthesis and formation of the by-product acetate. After the model was parameterized for B. subtilis BMV9 using 12 different fed-batch bioreactor experiments, the kinetic model was able to accurately describe biomass accumulation, substrate consumption, product formation rates and, to some extent, the overflow metabolism involving acetate. Based on this, the kinetic model was used for a process design, in which the batch was omitted, which led to a product titre of 46.33 g/L and a space-time-yield of 2.11 g/(L*h) was achieved. The kinetic model developed in this study enables the description of the time course of biomass growth, substrate consumption and product formation and thus significantly improves process understanding. The computation of process parameters, which are not analytically accessible at any time, could be realized. A sensitivity analysis identified the maximum specific growth rate, substrate-related maintenance and the maximum acetate formation rate as key parameters influencing model outputs.

Many studies focus on optimizing the dark fermentative biohydrogen production. In the present work, static magnetic field (SMF) S pole and N pole were applied to the dark fermentation system of Clostridium pasteurianum to evaluate the effect of magnetic field direction on biohydrogen production process of Clostridium pasteurianum. The experimental results showed that the magnetic S pole application was more effective than the magnetic N pole application in improving microbial hydrogen production progress parameters. The maximum hydrogen production 2.47 ± 0.010 mol H₂/mol glucose was achieved in the magnetic S pole application group. Meanwhile, the maximum biomass, carbon conversion efficiency and energy conversion efficiency in magnetic S pole application group were increased by 93%, 27.7% and 28.3%, respectively, compared with the control group. The results provided a new information for further exploring the application of magnetic field in dark fermentative biohydrogen production process.

This study explores the microbial-assisted synthesis of nanoparticles from chalcopyrite ore and its tailings, emphasizing their potential applications in sustainable agriculture. Addressing the gap between research and practical field applications, the study employs microbial diversity to recover valuable elements as nanoparticles through green methods. Organic acids and metabolites produced by microorganisms facilitated the breakdown of mineral ores into nanoparticles. Optimal conditions (28 °C, pH 3.8) yielded nanoparticles (15-200 nm) after 72 h, as analysed by Dynamic Light Scattering and Scanning Electron Microscopy. Glycine encapsulation was confirmed via UV spectroscopy. In vitro experiments on Cicer arietinum (L.) demonstrated enhanced plant growth, including increased seed germination, branching, and early flowering, highlighting the potential of these nanoparticles in agricultural enhancement.

Drug-resistant Pseudomonas aeruginosa poses a significant clinical challenge due to its intrinsic antibiotic resistance and the formation of metabolically dormant persister cells. Here, we evaluated the antibacterial and anti-persister activities of a novel 20-amino-acid cationic antimicrobial peptide (RRFFKKAAHVGKHVGKAARR) alone and in combination with silver nanoparticles (AgNPs) against P. aeruginosa PAO1. Minimum inhibitory concentrations (MICs) were determined by broth microdilution (128 µg/mL for the peptide; 8 µg/mL for AgNPs), and checkerboard assays revealed a strong synergistic interaction (fractional inhibitory concentration index (FICI) = 0.25). Treatment of colistin-induced persister populations with the peptide-AgNP combination reduced viable cells by 94.3 ± 2.1% (p < 0.01), markedly outperforming either agent alone. MTT assays in Caco-2 cells demonstrated > 85% viability at concentrations up to the MIC, indicating low host cytotoxicity. Mechanistic insights suggest that membrane disruption by the peptide, coupled with reactive oxygen species (ROS) generation and intracellular interference by AgNPs, underlies the enhanced eradication of both active and dormant bacterial cells. These findings support further in vivo investigation of AMP-AgNP co-therapy as a promising strategy to overcome antibiotic tolerance in P. aeruginosa.

The mechanisms driving age-related macular degeneration (AMD) progression into two major but distinct vision-threatening subtypes, geographic atrophy (GA) and choroidal neovascularization (CNV), are unclear. This study identifies causal gut microbiota (GM) taxa involved in AMD and their connections to biological aging phenotypes, including epigenetic clock acceleration, telomere length, mitochondrial DNA copy number, 731 immune cell traits, and 91 inflammatory proteins through genetic prediction. Analyzing 207 GM taxa and 205 functional pathways alongside AMD progression GWAS data, we found that class_Gammaproteobacteria significantly influences both CNV and GA, and a bidirectional gut-retina axis involving Erysipelotrichaceae was also identified. Genus_Flavonifractor, species_Ruminococcus_obeum, and species_Streptococcus_thermophilus may attenuate AMD progression. Mediation analysis revealed pathways linking Ruminococcus obeum to GA progression via SSC-A expression on CD4 + T cells, and a CNV-associated pathway mediated by CD33dim HLA-DR + CD11b- cell counts. This study provides novel genetic evidence linking GM to dynamic AMD progression, offering genetic insights for future experimental research and clinical strategies.