Biofilms are multicellular communities of microbes that are encased within an extracellular matrix. Environmental factors induce bacteria to form biofilm. Bacteria have several regulatory mechanisms ...in response to environmental changes, and the two-component signal transduction system (TCS) is a major strategy in connecting changes in input signals to changes in cellular physiological output. The TCS employs multiple mechanisms such as cross-regulation, to integrate and coordinate various input stimuli to control biofilm formation. In this mini-review, we demonstrate the roles of TCS on biofilm formation, illustrating these input signals and modulation modes, which may be utilized by future investigations in elucidating the regulatory signals and underlying the mechanisms of biofilm formation.
Biofilms are communities of microorganisms that live in a self-produced extracellular matrix in order to survive in hostile environments. Second messengers, such as c-di-GMP and cAMP, participate in ...the regulation of biofilm formation. c-di-GMP is a major molecule that is involved in modulating the bacterial transition between a planktonic lifestyle and biofilm formation. Aside from regulating carbon catabolism repression in most bacteria, cAMP has also been found to mediate biofilm formation in many bacteria. Although the underlying mechanisms of biofilm formation mediated by cAMP-CRP have been well-investigated in several bacteria, the regulatory pathways of cAMP-CRP are still poorly understood compared to those of c-di-GMP. Moreover, some bacteria appear to form biofilm in response to changes in carbon source type or concentration. However, the relationship between the carbon metabolisms and biofilm formation remains unclear. This mini-review provides an overview of the cAMP-CRP-regulated pathways involved in biofilm formation in some bacteria. This information will benefit future investigations of the underlying mechanisms that connect between biofilm formation with nutrient metabolism, as well as the cross-regulation between multiple second messengers.
The influences of silica fume content and aging on the rheological properties of silica fume/styrene-butadiene-styrene composite-modified asphalts were investigated via rolling thin-film oven test ...simulations. The asphalts rheological properties before and after aging were measured using three-major-indices, dynamic shear rheology, and bending beam rheometer tests. Fourier transform infrared spectroscopy was used to examine the changes in the functional groups of the asphalt. The silica fume did not chemically react with the modified asphalt, and its original structure was maintained. The aging resistance improved significantly after adding the silica fume. At 6% silica fume content, the relaxation of the asphalt was the highest, indicating that the asphalt had the best low-temperature crack resistance at this mixing proportion. Furthermore, the carbonyl index value of this sample exhibited the smallest increment among all of the samples, and this asphalt sample had the strongest short-term aging resistance. Thus, the optimum silica fume content in the composite-modified asphalt was determined to be 6%. This information may be used to fabricate an asphalt mixture that can improve the service life and aging resistance of pavements.
Nucleotide second messengers, such as cAMP and c-di-GMP, regulate many physiological processes in bacteria, including biofilm formation. There is evidence of cross-talk between pathways mediated by ...c-di-GMP and those mediated by the cAMP receptor protein (CRP), but the mechanisms are often unclear. Here, we show that cAMP-CRP modulates biofilm maintenance in Shewanella putrefaciens not only via its known effects on gene transcription, but also through direct interaction with a putative c-di-GMP effector on the inner membrane, BpfD. Binding of cAMP-CRP to BpfD enhances the known interaction of BpfD with protease BpfG, which prevents proteolytic processing and release of a cell surface-associated adhesin, BpfA, thus contributing to biofilm maintenance. Our results provide evidence of cross-talk between cAMP and c-di-GMP pathways through direct interaction of their effectors, and indicate that cAMP-CRP can play regulatory roles at the post-translational level.
Seasonal erosion flooding events present a significant challenge for effective disaster monitoring and land degradation studies. This research addresses this challenge by harnessing the combined ...capabilities of time-series Landsat and MODIS images to achieve high spatiotemporal-resolution mapping of flooding during such events. The study underscores the critical importance of precise flood monitoring for disaster mitigation and informed land management. To overcome the limitations posed by the trade-off between spatial and temporal resolution in current satellite sensors, we emplyedand theflexible spatiotemporal data fusion (FSDAF) methods to produce synthetic flood images with enhanced spatiotemporal resolutions for mapping by using MODIS and Landsat data from August 29 to September 3, 2016. A comparison was made between flood maps from several post-disaster forecasts based on ground-obtained time-series images of the Tumen River flood in China. According to the FSDAF approach, the input Landsat image of March 25, 2016, and the fused results had a root mean square error (RMSE) of 0.0301, average difference of 0.001, r of 0.941, and structure similarity indexof 0.939, indicating that temporal variation data had been effectively incorporated into a forecast on August 16, 2016. Results also indicated that the FSDAF forecast values are lower than those from the actual Landsat image. The results of the study also showed that the generated images could be effectively used for flood mapping. By using our newly developed simulation model, we were able to produce a comprehensive map of the inundated areas during the event from August 29 to September 3, 2016. This shows that FSDAF holds great potential for flood prediction and study and has the potential to benefit further disaster-related land degradation by combining multi-source images to provide high temporal and spatial resolution remote sensing information.
A method for the simultaneous determination of eight quinoxalines and their metabolites in poultry feathers was developed in this study using ultra-performance liquid chromatography combine with ...quadrupole linear ion trap electrostatic field orbit trap high resolution mass spectrometer. Specificity, matrix effect, linearity, trueness, repeatability, reproducibility, and stability using the Commission of the European Communities, Regulation (EU) 2021/808. The correlation coefficients were all greater than 0.99. The average recoveries of the eight compounds ranged from 76.1% to 112.8%, with coefficient of variation of less than 15%. The limits of detection and quantification of the method were 0.04–0.1 μg/kg and 0.12–0.3 μg/kg, respectively. The method has been successfully applied to depletions of olaquindox and quincetone in feathers of laying hens. Methylquinoxaline-2-carboxylic acid and quincetone are the main metabolites in olaquindox and quincetone in feather, respectively.
•Simultaneous determination of eight quinoxalines and their metabolites in poultry feathers.•Analytes from feathers are effectively extracted by two complex extraction methods.•This method has been applied to depletion of olaquindox and quincetone in feathers.•Feathers are an acceptable substrate for monitoring quinoxaline residue levels.
In this paper, we aim to establish a mathematical model to design a maximizing social welfare intervention mechanism of healthcare service goods in China. The intervention mechanism is helpful to ...facilitate the adoption of the healthcare service goods. We consider a research problem that regulates the supply chain system for healthcare service goods by an intervention mechanism, and two intervention strategies composed of demand-growth strategy and subsidy strategy are used to the combination of intervention mechanism. Then this paper presents a new method based on fuzzy set and bilevel programming to design the intervention mechanism. To demonstrate the effectiveness of the proposed model, we conduct a case study for Wudang personalized health package and verify our model by the specific result analysis, the result indicates that our joint intervention mechanism is helpful to achieve the target and increase social welfare.
The gram-positive filamentous bacterium
is one of the largest resources for bioactive metabolites, particularly antibiotics. Antibiotic production and other metabolic processes are tightly regulated ...at the transcriptional level. Sigma (σ) factors are components of bacterial RNA polymerases that determine promoter specificity. In
, σ factors also play essential roles in signal transduction and in regulatory networks, thereby assisting in their survival in complex environments. However, our current understanding of σ factors in
is still limited. In this mini-review, we demonstrate the roles of
σ factors, illustrating that these serve as linkers of different metabolic pathways. Further investigations on σ factors may improve our knowledge of
physiology and benefit exploitation of
resources.
One-step fermentation is a cheap way to produce xylo-oligosaccharides (XOS), where production of xylanases and XOS is integrated into a single process. In spite of cost advantage, one-step ...fermentation is still short in yield so far due to the limited exploration. To cope with this issue, production of XOS from wheat bran by recombinant Escherichia coli through one-step fermentation was investigated in this study.
An endo-β-1,4-xylanase gene belonging to glycoside hydrolase family 11 of Bacillus agaradhaerens was employed to construct recombinant E. coli. This xylanase showed maximal activity at 60 °C and pH 8.0-8.5. Its activity retained more than 60% after incubation at 70 °C for 4 h, showing a good stability. The recombinant E. coli BL21(DE3) could secreted xylanases that directly hydrolyzed de-starched wheat bran to XOS in fermentation medium. The XOS generated from hydrolysis consisted of xylose, xylobiose and xylotriose accounting for 23.1%, 37.3% and 39.6%, respectively. Wheat bran concentration was found to be the most crucial factor affecting XOS production. The XOS concentration reached 5.3 mg/mL at 10% loading of wheat bran, which is higher than those of previous researches. Nitrogen source type could also affect production of XOS by changing extracellular xylanase activity, and glycine was found to be the best one for fermentation. Optimal fermentation conditions were finally studied using response surface optimization. The maximal concentration emerged at 44.3 °C, pH 7.98, which is affected by characteristics of the xylanase as well as growth conditions of E. coli.
This work indicates that the integrated fermentation using recombinant E. coli is highly competitive in cost and final concentration for producing XOS. Results can also provide theoretical basis for large-scale production and contribute to the wide adoption of XOS.
As a non-traditional sample matrix, feather samples can be used to effectively monitor antibiotic addition and organismal residue levels in poultry feeding. Therefore, an ultra-performance liquid ...chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed to simultaneously determine the residue levels of 26 quinolones in poultry feathers. The feather samples were extracted by sonication with a 1% formic acid and acetonitrile mixture in a water bath at 50 °C for 30 min, purified by the adsorption of multiple matrix impurities, dried with nitrogen, redissolved, and analyzed by UPLC-MS/MS. The linearity, limit of detection (LOD), limit of quantification (LOQ), recovery and precision were calculated. The 26 antibiotics demonstrated good linearity in the linear range. The recoveries and coefficients of variation were 78.9-110% and <13.7% at standard spiked levels of 10, 100 and 200 μg/kg, respectively. The LOD and LOQ were 0.12-1.31 and 0.96-2.60 μg/kg, respectively. The method also successfully identified quinolone residues in 50 poultry feather samples. The results showed that quinolones can accumulate and stabilize for a certain period of time after transferring from the body to the feathers of poultry.
PDF
