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Existing models of the human skin have aided our understanding of skin health and disease. However, they currently lack a microbial component, despite microbes demonstrated connections to various skin diseases. Here, we present a robust, standardized model of the skin microbial community (SkinCom) to support in vitro and in vivo investigations. Our methods lead to the formation of an accurate, reproducible, and diverse community of aerobic and anaerobic bacteria. Subsequent testing of SkinCom on the dorsal skin of mice allowed for DNA and RNA recovery from both the applied SkinCom and the dorsal skin, highlighting its practicality for in vivo studies and -omics analyses. Furthermore, 66% of the responses to common cosmetic chemicals in vitro were in agreement with a human trial. Therefore, SkinCom represents a valuable, standardized tool for investigating microbe-metabolite interactions and facilitates the experimental design of in vivo studies targeting host-microbe relationships.

Significant progress has recently been made in the biosynthesis of germacrene A using microbial cell factories. Germacrene A is a crucial precursor for the synthesis of anti‐cancer active compounds. However, its hydrophobic characteristics lead to its aggregation in cell membranes and cause severe cytotoxicity. In the present study, we found that rhamnolipids (RLs), as toxicity antidotes, could promote the production of germacrene A. An optimal RLs concentration of 1.25 g L−1 resulted in an increase of over 30% in the germacrene A titer at both shake flask and bioreactor scales. Mechanistic analysis showed that the addition of RLs could dramatically reduce aqueous‐phase surface tension and cell surface hydrophobicity (CSH), and increase the cell membrane permeability. This, in turn, promoted an efficient transfer of germacrene A from cell membrane to extraction phases. The addition of RLs also increased the adenosine triphosphate (ATP) concentration and the nicotinamide adenine dinucleotide (NAD+/NADH) ratio, while reducing reactive oxygen species (ROS) levels. Correspondingly, gene transcripts for key enzymes associated with germacrene A biosynthesis, the respiratory chain, and ROS scavenging were upregulated significantly. This study provides an effective RLs‐regulated fermentation method for the biosynthesis of hydrophobic natural products. [ABSTRACT FROM AUTHOR]

Biopurification systems designed for pesticide treatment are a source of diverse bacteria with environmental and biotechnological applications, including Pseudomonas marginalis C9, which has been reported as a biosurfactant-producing bacterium. The optimization of biosurfactant produced from P. marginalis C9 to enhance the solubility of a hydrophobic pesticide of environmental interest was investigated. The response surface methodology (RSM) was used to optimize the combined effect of the initial pH (5–9), agitation (100–300 rpm), and temperature (24–32 °C) on biosurfactant production. A DASbox® automated mini-bioreactor system was used to evaluate the critical factors in biosurfactant production using a full factorial design (FFD). The results showed that the optimal culture conditions using RSM were a pH of 8.5, a temperature of 25 °C, and agitation at 200 rpm. The extraction yield of the biosurfactant was 7.40 g L−1, the surface tension was reduced to 27.45 mN m−1, and the critical micelle concentration (CMC) was 48.9 mg L−1. The FFD analysis indicated that a high agitation rate (300 rpm) strongly influenced the biosurfactant activity, regardless of the inlet oxygen supply (0.5–1.5 vvm). The rhamnolipid increased the water solubility of chlorpyrifos by 11.2- and 21.7-fold at the CMC and twice the CMC, respectively. [ABSTRACT FROM AUTHOR]

Grapevines constitute a very important crop in Greece and ochratoxin A (OTA) contamination of grapes is one of the most serious problems. The main aim of this study was to investigate the fungicidal activity of the fungicide Switch 62.5WG (37.5% v/v cyprodinil + 25% v/v fludioxonil) and Rhapynal (80% rhamnolipids) to reduce the black Aspergillus spp. (section Nigri) population and OTA contamination of grapes grown in Greece. Applications with the above products were conducted both at the harvesting stage and after cold storage. The results showed that pre-harvest applications with Switch 62.5WG or Switch 62.5WG + Rhapynal generally reduced the black Aspergillus spp. population, but not the OTA contamination of grapes. However, a repeated application after cold storage further reduced the black Aspergillus spp. population and significantly reduced the OTA contamination of grapes. Generally, this study showed that it is possible to reduce the black Aspergillus spp. population, but not the ochratoxin A contamination of grapes by spray applications with the fungicide Switch 62.5WG. However, fungicide application to grapes immediately after cold storage (2 months) could reduce ochratoxin A contamination of grapes and further reduce the black Aspergillus spp. population. [ABSTRACT FROM AUTHOR]

The micellar solubilization of naphthalene from its saturated aqueous solutions using the biosurfactant rhamnolipid was studied. Using the NMR diffusion method, selective measurements of the self‐diffusion coefficients of molecules of all components of the solution—naphthalene, rhamnolipid, and water—were carried out at various rhamnolipid concentrations from 0.06 to 100 g/L. Based on the results of diffusometry, the distribution of naphthalene molecules between the states free in solution and states bound by micelles was found. With an increase in the concentration of rhamnolipids, the proportion of bound naphthalene molecules increases from 50% at CRL = 2 g/L to 100% at CRL ≥ 50 g/L. The micelle‐water partition coefficient Km and the molar solubilization ratio MSR were calculated. [ABSTRACT FROM AUTHOR]

Rhamnolipids (RLs) are bioactive compounds that have gained a lot of attention for their potential applications in agriculture. However, the exploration of RLs in passion fruit plants remains limited. This study aimed to investigate the role of RLs in passion fruit plants growth and defense responses. Firstly, the results demonstrated that RLs act as plant growth regulators, significantly enhancing the survival rate and root system development of passion fruit seedlings propagated by cutting. Further analyses suggested that RLs may enhance photosynthetic capacity and modulate the accumulation of indoleacetic acid (IAA) and cytokinin (CTK) in passion fruit cuttings, thereby promoting plant growth and development. Additionally, this study revealed that RLs effectively reduced susceptibility to viral pathogen telosma mosaic virus (TeMV) in passion fruit plants compared to distilled water-pretreated controls, resulting in alleviated disease symptoms. Significant up-regulation of antioxidative enzyme activities and reducing substances were observed in RL's-pretreated plants upon TeMV-inoculation compared to distilled water-pretreated ones. Moreover, RLs were found to promote other defense-related signaling pathways upon TeMV-inoculation in passion fruit plants, including salicylic acid (SA) accumulation and expression levels of defense-related genes such as pathogenesis-related gene (PR3), phenylalanine ammonia-lyase (PAL), transcription factors (TFs) WRKY and NAC. Collectively, these findings underscored the positive roles played by RLs both in promoting growth and eliciting defense responses within passion fruit plants. These results provided valuable insights for designing environment-friendly management strategies for cutting propagation as well as prevention and control measures against viral diseases in passion fruits. [ABSTRACT FROM AUTHOR]

BACKGROUND: The oil industry has a big impact on the environment by itself and by using chemically synthesized surfactants. Biosurfactants are an ecofriendly alternative, especially rhamnolipids produced by Pseudomonas aeruginosa. Rhamnolipids in a determined concentration decrease the liquid surface tension, and this allows access oil hydrocarbon to be degraded. The objective of this research is to characterize the biosurfactant produced by the native strain P. aeruginosa 6K‐11 by determining its critical micelle concentration (CMC), Krafft point, and emulsifying activity. RESULTS: Experiments were initially performed with rhamnolipid produced by P. aeruginosa 6K‐11 growing on Siegmund‐Wagner medium with 1% of waste oil as carbon source and at 31.26 °C, 186 rpm after 42 h of incubation. After that, the biosurfactant was purified according to acid precipitation methodology. The first conductivity measurement, 34 μS/cm, was obtained with 12.5 g/L of rhamnolipid by using an APERA conductivity meter. The rhamnolipid CMC was 5.86 g/L due to the conductivity measurements graph and 0.49 was the dissociation degree. The equations of both lines were found by the method of least squares. The rhamnolipid has produced 1.97 Units of Emulsifying Activity (UEA) and 50% stability was observed based on the E24 Index. The highest conductivity achieved under 39 °C, as calculated from a conductivity against temperature graph, was the Krafft point. CONCLUSION: These findings give important parameters to characterize the P. aeruginosa 6K‐11 biosurfactant activity that can be used to accelerate oil biodegradation in bioremediation processes. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

BACKGROUND: Rhamnolipids are biosurfactants that have their main application in bioremediation processes. They are able to increase the biodegradation and detoxification rates from industrial effluents. The north of Peru and Iquitos have been not only major oil producers but also have been responsible for oil spills. This study therefore focused on the optimization of mineral nutrients such as nitrogen, phosphorous, calcium and iron to improve rhamnolipids production by Pseudomonas aeruginosa 6 K‐11, which was isolated from oil soil in Peru. RESULTS: Pseudomonas aeruginosa 6 K‐11 was reactivated in Trypticase Soy Broth by scaling from 5 to 200 mL of culture medium for 8 h at each stage. The culture was centrifuged and placed in 100 mL Siegmund–Wagner medium for 36 h in a 500 mL Erlenmeyer flask. First, it was determined that sodium nitrate, monopotassium phosphate, calcium chloride and iron sulfate were the best sources of mineral nutrients. Then, by using corn oil as carbon source, the ratios obtained for carbon‐to‐nitrogen and carbon‐to‐phosphorous were 21.172 and 16.279, respectively. In addition, it was found that the optimal concentration for calcium was 0.046 g L−1 and for iron was 0.003 g L−1. The most influential variables were carbon‐to‐nitrogen and carbon‐to‐phosphorus ratio. Finally, 35.124 g L−1 rhamnolipids was produced after 168 h of fermentation with the optimal parameters. CONCLUSION: The optimization of mineral nutrients was an important achieved goal for rhamnolipid production. In addition, this optimization can be used for modifying the culture medium to grow the biosurfactant producer strain. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Polyethylene (PE) is the most commonly used plastic type in the world, contributing significantly to the plastic waste crisis. Microbial degradation of PE in natural environments is unlikely due to its inert saturated carbon‐carbon backbones, which are difficult to break down by enzymes, challenging the development of a biocatalytic recycling method for PE waste. Here, we demonstrated the depolymerization of low‐molecular‐weight (LMW) PE using an enzyme cascade that included a catalase‐peroxidase, an alcohol dehydrogenase, a Baeyer Villiger monooxygenase, and a lipase after the polymer was chemically pretreated with m‐chloroperoxybenzoic acid (mCPBA) and ultrasonication. In a preparative experiment with gram‐scale pretreated polymers, GC‐MS and weight loss determinations confirmed ~27 % polymer conversion including the formation of medium‐size functionalized molecules such as ω‐hydroxycarboxylic acids and α,ω‐carboxylic acids. Additional analyses of LMWPE‐nanoparticles using AFM showed that enzymatic depolymerization reduced the sizes of these mCPBA‐ and enzyme‐treated LMWPE‐nanoparticles. This multi‐enzyme catalytic concept with distinct chemical steps represents a unique starting point for future development of bio‐based recycling methods for polyolefin waste. [ABSTRACT FROM AUTHOR]

Environmental concerns and rising biosurfactant demand emphasize the need for this study. The objective is to maximize rhamnolipid-biosurfactant production by Pseudomonas aeruginosa (SSL-4) utilizing waste engine oil (WEO) as the sole substrate for use in soil bioremediation and commercial production. Using an L16 Taguchi orthogonal array, a signal-to-noise ratio, and an analysis of variance (ANOVA), the effects of environmental (pH, incubation temperature) and dietary parameters (carbon source concentration, carbon/nitrogen (C/N) and carbon/phosphorus (C/P) ratio) are examined. Variations of the following parameters were made within a carefully selected range: incubation temperature of 25–40℃, pH range of 5–11, WEO concentration of 1–7% (v/v), and C/N and C/P ratios of 10–40. Response variables in this batch study include surface tension reduction (mN/m), dry cell biomass (DCBM) (g/L), and rhamnolipids yield based on substrate consumption, YP/S (g/g). Rhamnolipid was synthesized under optimal conditions, providing a yield of 21.42 g/g. The oil recovery of 74.05 ± 1.481% was achieved from oil-contaminated soil at a CMC of ∼70 mg/L. FTIR, 1H NMR, and UPLC-MS techniques were utilized for the characterization of rhamnolipids, and AAS for determining heavy metals concentration in WEO and residual waste engine oil (RWEO). The Germination Index (GI) of ∼82.55% indicated no phytotoxicity associated with synthesized rhamnolipid. [ABSTRACT FROM AUTHOR]

Introduction: The ability to produce biosurfactants plays a meaningful role in the bioavailability of crude oil hydrocarbons and the bioremediation efficiency of crude oil-degrading bacteria. This study aimed to characterize the produced biosurfactants by Pseudomonas oryzihabitans during the biodegradation of crude oil hydrocarbons. Methods: The biosurfactants were isolated and then characterized by Fourier transform infrared (FTIR), liquid chromatography-mass-spectrometry (LC-MS), and nuclear magnetic resonance spectroscopy (NMR) analyses. Results: The FTIR results revealed the existence of hydroxyl, carboxyl, and methoxyl groups in the isolated biosurfactants. Also, the LC-MS analysis demonstrated a main di-rhamnolipid (l-rhamnopyranosyll-rhamnopyranosyl-3- hydroxydecanoyl-3-hydroxydecanoate, Rha-Rha-C10-C10) along with a monorhamnolipid (l-rhamnopyranosyl-b-hydroxydecanoylb-hydroxydecanoate, Rha-C10-C10). In agreement with these findings, the NMR analysis confirmed the aromatic, carboxylic, methyl, sulfate moieties, and hexose sugar in the biosurfactants. The emulsion capacity of the biosurfactants decreased the surface tension of the aqueous system from 73.4 mN m-1 to around 33 mN m-1 at 200  mg  L-1 as the critical micelle concentration. The emulsification capacity of the biosurfactants in the formation of a stable microemulsion for the diesel-water system at a wide range of pH (2-12), temperature (0-80°C), and salinity (2-20  g  L-1 of NaCl) showed their potential use in oil recovery and bioremediation through the use of microbial enhancement. Discussion: This work showed the ability of Pseudomonas oryzihabitans NC392 cells to produce rhamnolipid molecules during the biodegradation process of crude oil hydrocarbons. These biosurfactants have potential in bioremediation studies as eco-friendly and biodegradable products, and their stability makes them optimal for areas with extreme conditions. [ABSTRACT FROM AUTHOR]

Green surfactants–based bioremediation of polycyclic aromatic hydrocarbons (PAHs) from the environment is a promising technique. Rhamnolipids are a class of glycolipid surfactants that belong to the category of green surfactants and have distinctive characteristics. PAHs, which are hazardous toxins, are commonly found in polluted soil, water, and air. PAHs are difficult to break down because they are resistant to degradation and typical methods of cleaning up pollution are not very effective. In recent years, there has been a growing interest in the capacity of specific microorganism species to produce rhamnolipids, which can enhance the process of PAH biodegradation. Rhamnolipids can dissolve and enhance the accessibility of PAHs, thereby boosting the effectiveness of microorganisms that break down PAHs. The presence of rhamnolipids can be attributed to the equilibrium between hydrophobic and hydrophilic properties, as well as their positive charge. Rhamnolipids have biosurfactant properties, making them beneficial for the bioremediation of polluted soil and water. In general, rhamnolipids have proven to be a highly efficient means of removing PAHs from the environment, providing a viable alternative to conventional chemical approaches. Nevertheless, additional investigation is necessary to gain a deeper comprehension of the fundamental principles behind rhamnolipid‐assisted bioremediation and to enhance its implementation in larger real‐world scenarios. This study provides a concise overview of recent research on the utilization of rhamnolipids for bioremediating PAHs in the environment. The article covers the underlying mechanisms, the specific microorganisms employed, and the overall efficacy of the bioremediation process. The utilization of rhamnolipids as a bioremediation tool is examined, along with the difficulties and restrictions of its implementation. The review's conclusion is followed by a discussion on the future directions for studying this topic. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate the effect of dietary supplementation with rhamnolipids (RLs) on the growth performance, slaughter performance, apparent digestibility and fat metabolism of broilers. Broiler chicks were randomly divided into 3 groups: control (C) group, 100 mg/kg (L) and 1,000 mg/kg (H) RL supplementation groups. The results, after dietary supplementation with RLs for 42 days, revealed a RL dose-dependent promoting effect on feed intake, and an increase of the evisceration index of 42-day-old broilers, but a decrease in the rate of abdominal fat gain. The dietary supplementation with RLs significantly increased the digestibility of protein and fat in broilers. The serum total cholesterol and high-density lipoprotein cholesterol levels of the H group were significantly higher than those of the C group (p

Introduction: Pseudomonas aeruginosa is a ubiquitous pathogen that causes various infectious diseases through the regulation of quorum sensing (QS). The strategy of interfering with the QS systems of P. aeruginosa, coupled with a reduction in the dosage of conventional antibiotics, presents a potential solution to treating infection and mitigating antibiotic resistance. In this study, seven cinnamoyl hydroxamates were synthesized to evaluate their inhibitory effects on QS of P. aeruginosa. Among these cinnamic acid derivatives, we found cinnamoyl hydroxamic acid (CHA) and 3-methoxy-cinnamoyl hydroxamic acid (MCHA) were the two most effective candidates. Furtherly, the effect of CHA and MCHA on the production of virulence factors and biofilm of P. aeruginosa were evaluated. Ultimately, our study may offer promising potential for treating P. aeruginosa infections and reducing its virulence. Methods: The disc diffusion test were conducted to evaluate inhibitory effects on QS of seven cinnamoyl hydroxamates. The influence of CHA and MCHA on the production of virulence and flagellar motility of P. aeruginosa was furtherly explored. Scanning electron microscopy (SEM) experiment were conducted to evaluate the suppression of CHA and MCHA on the formed biofilm of P. aeruginosa. RT-qPCR was used to detect rhlI, lasA, lasB, rhlA, rhlB, and oprL genes in P. aeruginosa. In silico docking study was performed to explore the molecular mechanism of CHA and MCHA. The synergistic effects of CHA with gentamicin were detected on biofilm cell dispersal. Result: After treatment of CHA or MCHA, the production of multiple virulence factors, including pyocyanin, proteases, rhamnolipid, and siderophore, and swimming and swarming motilities in P. aeruginosa were inhibited significantly. And our results showed CHA and MCHA could eliminate the formed biofilm of P. aeruginosa. RT-qPCR revealed that CHA and MCHA inhibited the expression of QS related genes in P. aeruginosa. Molecular docking indicated that CHA and MCHA primarily inhibited the RhlI/R system in P. aeruginosa by competing with the cognate signaling molecule C4-HSL.Additionally, CHA exhibited potent synergistic effects with gentamicin on biofilm cell dispersal. Discussion: P. aeruginosa is one of the most clinically and epidemiologically important bacteria and a primary cause of catheter-related urinary tract infections and ventilator-associated pneumonia. This study aims to explore whether cinnamoyl hydroxamates have inhibitory effects on QS. And our results indicate that CHA and MCHA, as two novel QSIs, offer promising potential for treating P. aeruginosa infections and reducing its virulence. [ABSTRACT FROM AUTHOR]

Garlic suffers from frequent pathogenic diseases, seriously affecting its yield and quality. Biosurfactants have been reported with high antimicrobial activity and wide antimicrobial spectrum. Biosurfactant-producing bacteria existing in garlic farmland soil are expected to be used in control of garlic diseases. In this study, strain FA1 having high yield of biosurfactants was isolated from garlic farmland soil. Combined with morphological analysis and its 16S rDNA sequences analysis, the strain FA1 was identified as Pseudomonas aeruginosa. HPLC-MS analysis showed that biosurfactants produced from P. aeruginosa FA1 were presented rhamnolipids, mainly Rha-C8-C10, Rha-Rha-C8-C10, Rha-C10-C10 and Rha-Rha-C10-C10. The proportion of mono-rhamnolipids and di-rhamnolipids was about 1 : 1. P. aeruginosa FA1 can produce 7.96 g/L of rhamnolipids. The FA1 rhamnolipids can decrease the air-water surface tension to 27.5 mN/m with a critical micelle concentration of 50 mg/L. Through the agar diffusion method, P. aeruginosa FA1 exhibited high antimicrobial activity with diameters of inhibition zones larger than 20 mm to both the garlic potential pathogenic bacteria and fungi. Rhamnolipids produced from P. aeruginosa FA1 induced the potential pathogens to generate higher level of intracellular Reactive Oxygen Species (ROS), thus, exerting antimicrobial effects. P. aeruginosa FA1 can highly produce rhamnolipids biosurfactants and exhibit high antimicrobial effect to the garlic potential pathogens. This study verified that indigenous biosurfactant-producing bacteria from garlic farmland soil were feasible and effective to control garlic potential pathogens. [ABSTRACT FROM AUTHOR]

Lubricant oils are largely responsible for environmental contamination and surfactants can hopefully improve the bioremediation process in soils contaminated with this kind of waste. However, to date only a few studies have elucidated how different surfactants affect the bioremediation process in oil-contaminated soils using the bioaugmentation technique. Thus, this study aimed to compare the effects of surfactants on the bioremediation process of waste lubricant oil in soil in association or not with bioaugmentation. Three biostimulating agents were tested: a chemical detergent, a synthetic surfactant, and a biosurfactant (rhamnolipid). The bioaugmentation process with Pseudomonas aeruginosa showed a faster biodegradation activity with total biodegradation on 181 day after application. The biosurfactant increased the number of microbial and fungal colonies leading to high biodegradation levels and a quicker treatment with or without the bioaugmentation. Bioaugmentation associated with biosurfactant reached 30.43 mg of CO2 of production on 181 day (90% of total biodegradation of waste lubricant oil) and reduced soil toxicity to 30%. Therefore, results showed that the association of biosurfactant and bioaugmentation with P. aeruginosa represents an ecologically viable strategy for bioremediation of soils contaminated with waste lubricant oil. [ABSTRACT FROM AUTHOR]

Foam can effectively improve reservoir heterogeneity, increase gas–liquid flow rate, reduce viscous fingering, and help to improve sweep efficiency. This paper mainly studies the characteristics and performance of microbial foam production, and proposes an enhanced oil recovery method for profile control by in situ microbial foam production. By optimizing the carbon and nitrogen sources of the medium, Pseudomonas aeruginosa PAO1 produced single and double rhamnolipids and biogas composed of N2, CO2, and CH4, and it could also produce foam in high salt, weak acid, and weak alkali environments. Gas injection experiments were carried out using self-produced biogas, the foaming effect is good in the range of gas–liquid ratio 1:1–3:1 and gas injection speed 20–40 ml/min, which was 71.43%–91.25% more than the foam volume produced by CO2 injection, and the foam production was positively correlated with the protein concentration of the foam. In the early stage of incubation, the foam was 20–100 μm in diameter, with high protein concentration and strong foam stability, which slowed down the drainage, polymerization, and disproportionation of the liquid film of the foam system. The foam performance test results show that the foam half-lifetime is long, up to 109 min. Foam culture medium has good viscosity reduction effect, emulsifying properties and less corrosive. The displacement experiment shows that the foam generated in situ by PAO1 in the core has good stability, reproducibility, and profile control performance, which can reduce the permeability of the core to half of the initial permeability and improve the reservoir heterogeneity. Therefore, microbial in situ foam production can be an effective method to enhance oil recovery in heterogeneous reservoirs, which is low cost, low pollution, and simple operation. [ABSTRACT FROM AUTHOR]

Surfactants are amphiphilic molecules that are capable of mixing water and oil. Biosurfactants are eco-friendly, low-toxicity, and stable to a variety of environmental factors. Optimizing conditions for microorganisms to produce biosurfactants can lead to improved production suitable for scaling up. In this study, we compared heterologous expression levels of the luminescence system luxCDABE operon controlled by regulatable promoters araC-PBAD and its strong version araC-PBAD-SD in Escherichia coli K12, Pseudomonas aeruginosa PAO1, and P. putida KT2440. Real-time monitoring of luminescence levels in the three strains indicated that luxCDABE controlled by araC-PBAD-SD promoter with 0.2% arabinose supplementation in P. putida produced the highest level of luminescence. By using the araC-PBAD-SD promoter-controlled rhlAB expression in P. putida, we were able to produce mono-rhamnolipid at a level of 1.5 g L−1 when 0.02% arabinose was supplemented. With the same system to express olsB, lyso-ornithine lipid was produced at a level of 10 mg L−1 when 0.2% arabinose was supplemented. To our knowledge, this is the first report about optimizing conditions for lyso-ornithine lipid production at a level up to 10 mg L−1. Taken together, our results demonstrate that regulatable araC-PBAD-SD promoter in P. putida KT2440 is a useful system for heterologous production of biosurfactants. [ABSTRACT FROM AUTHOR]

Rhamnolipids, simply divided into mono‐rhamnolipids and di‐rhamnolipids, their physicochemical properties are structure‐dependent. This study explored to increase the proportion of di‐rhamnolipids biosynthesized from Pseudomonas aeruginosa and evaluate the relationship between activity and di‐rhamnolipids proportions. P. aeruginosa SGrhlC was constructed by increasing the rhlC gene in P. aeruginosa SG. HPLC‐MS results indicated that SGrhlC produced more di‐rhamnolipids (62.32%) than that of the wild‐type strain SG (45.24%). Both the species and proportion of di‐rhamnolipids were increased, mainly Rha‐Rha‐C8‐C10 and Rha‐Rha‐C10‐C10. The rhamnolipids produced by SGrhlC was thermostable and salt‐tolerant. The SGrhlC rhamnolipids decreased surface tension of water to 27.0 mN/m with a critical micelle concentration (CMC) of 50 mg/L and emulsified crude oil with an emulsification index of 66.9 ± 1.5%. The SGrhlC rhamnolipids exhibited antimicrobial activity against Staphylococcus aureus and Cladosporium sp. with IC50 (half maximal inhibitory concentration) values less than 15 mg/L, and washed 73.02% ± 1.77% of oil from petroleum‐contaminated soil. Physicochemical activities of three bacterial rhamnolipids varied with their di‐rhamnolipids proportions. Results indicated that the higher proportions of di‐rhamnolipids were, the lower CMC, better surface activity and higher washing oil rate were, while the weaker emulsifying activity and lower antimicrobial activity were. The SGrhlC rhamnolipids showed better surface activity and a lower critical micelle concentration, which was superior for wetting, foaming, desorbing and dispersing. This study revealed that P. aeruginosa can be genetically regulated to biosynthesize rhamnolipids with specific structure. Perspectives of the customized biosynthesis and applications of rhamnolipids were also discussed. [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa is a Gram-negative pathogenic bacterium commonly found in healthcare centers, and is known for its ability to form biofilms, its virulence controlled by quorum sensing systems (QS). The aim of this study was to investigate the antimicrobial synergistic potential of sulfated polysaccharides (SPs) extracted from the green alga Enteromorpha intestinalis and to examine the effect of SPs on the QS phenotype and biofilm formation ability of Pseudomonas aeruginosa ATCC 10145. The extracted SPs combined with ceftazidime exhibited a significant antibiotic effect against P. aeruginosa, increasing its bactericidal activity up to nine times. In addition, concentrations below the minimum inhibitory concentration (MIC) of the extracted SPs (5 and 10 µg/ml) successfully reduced pyocyanin and rhamnolipid production, swimming motility, protease activity, and biofilm formation ability compared to the control group (P < 0.05). It appears that SPs extracted from green algae have significant potential as a coating agent for surgical equipment, effectively preventing hospital-acquired infections caused by the pathogenic bacterium P. aeruginosa. [ABSTRACT FROM AUTHOR]

Aims Microbial enhanced oil recovery (MEOR) is cost-effective and eco-friendly for oil exploitation. Genetically modified biosurfactants-producing high-yield strains are promising for ex-situ MEOR. However, can they survive and produce biosurfactants in petroleum reservoirs for in-situ MEOR? What is their effect on the native bacterial community? Methods and results A genetically modified indigenous biosurfactants-producing strain Pseudomonas aeruginosa PrhlAB was bioaugmented in simulated reservoir environments. Pseudomonas aeruginosa PrhlAB could stably colonize in simulated reservoirs. Biosurfactants (200 mg l−1) were produced in simulated reservoirs after bio-augmenting strain PrhlAB. The surface tension of fluid was reduced to 32.1 mN m−1. Crude oil was emulsified with an emulsification index of 60.1%. Bio-augmenting strain PrhlAB stimulated the MEOR-related microbial activities. Hydrocarbon-degrading bacteria and biosurfactants-producing bacteria were activated, while the hydrogen sulfide-producing bacteria were inhibited. Bio-augmenting P. aeruginosa PrhlAB reduced the diversity of bacterial community, and gradually simplified the species composition. Bacteria with oil displacement potential became dominant genera, such as Shewanella, Pseudomonas , and Arcobacter. Conclusions Culture-based and sequence-based analyses reveal that genetically modified biosurfactants-producing strain P. aeruginosa PrhlAB are promising for in-situ MEOR as well. [ABSTRACT FROM AUTHOR]

The need to improve the physicochemical properties of sea buckthorn juice and the bioavailability of carotenoids is a major challenge for the field. The effects of different natural emulsifiers, such as medium-chain triglycerides (MCTs), tea saponins (TSs) and rhamnolipids (Rha), on the physical and chemical indexes of sea buckthorn juice were studied. The particle size of sea buckthorn juice and the carotenoids content were used as indicators for evaluation. The effects of different addition levels of MCT, Rha and TS on the bioavailability of carotenoids in sea buckthorn juice were investigated by simulating human in vitro digestion tests. The results showed that those emulsifiers, MCT, Rha and TS, can significantly reduce the particle size and particle size distribution of sea buckthorn juice, improve the color, increase the soluble solids content, turbidity and physical stability and protect the carotenoids from degradation. When the addition amount of Rha was 1.5%, the total carotenoids content (TCC) of sea buckthorn juice increased by 45.20%; when the addition amount of TS was 1.5%, the total carotenoids content (TCC) of sea buckthorn juice increased by 37.95%. Furthermore, the bioaccessibility of carotenoids was increased from 36.90 ± 2.57% to 54.23 ± 4.17% and 61.51 ± 4.65% through in vitro digestion by Rha and TS addition, respectively. However, the total carotenoids content (TCC) of sea buckthorn juice and bioaccessibility were not significantly different with the addition of MCT. In conclusion, the findings of this study demonstrate the potential of natural emulsifiers, such as MCT, Rha and TS, to significantly enhance the physicochemical properties and bioavailability of carotenoids in sea buckthorn juice, offering promising opportunities for the development of functional beverages with improved nutritional benefits. [ABSTRACT FROM AUTHOR]

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Pseudomonas aeruginosa is a commonly found Gram-negative bacterium in healthcare facilities and is renowned for its ability to form biofilms and its virulence factors that are controlled by quorum sensing (QS) systems. The increasing prevalence of multidrug-resistant strains of this bacterium poses a significant challenge in the field of medicine. Consequently, the exploration of novel antimicrobial agents has become a top priority. This research aims to optimize chitosan derived from white shrimp (Metapenaeus affinis) using the Response Surface Methodology (RSM) computational approach. The objective is to investigate chitosan's potential as a solution for inhibiting QS activity and biofilm formation in P. aeruginosa ATCC 10,145. Under optimized conditions, chitin was treated with NaOH (1.41 M) for 15.75 h, HCl (7.49% vol) for 2.01 h, and at a deacetylation temperature of 81.15 °C. The resulting chitosan exhibited a degree of deacetylation (DD%) exceeding 93.98%, as confirmed by Fourier-transform infrared (FTIR) spectral analysis, indicating its high purity. The extracted chitosan demonstrated a significant synergistic antibiotic effect against P. aeruginosa when combined with ceftazidime, enhancing its bactericidal activity by up to 15-fold. In addition, sub-MIC (minimum inhibitory concentration) concentrations of extracted chitosan (10 and 100 µg/mL) successfully reduced the production of pyocyanin and rhamnolipid, as well as the swimming motility, protease activity and biofilm formation ability in comparison to the control group (P < 0.05). Moreover, chitosan treatment downregulated the RhlR and LasR genes in P. aeruginosa when compared to the control group (P < 0.05). The optimized chitosan extract shows significant potential as a coating agent for surgical equipment, effectively preventing nosocomial infections caused by P. aeruginosa pathogens. [ABSTRACT FROM AUTHOR]

Plasticulture has revolutionised Farming production. In salad cultivation, the snail is the main pest that can cause significant economic losses. The present study focuses on the design of a new industrial mulching material co-extruded separately with three essential oils: cade, turmeric and cumin oil. Experimental tests carried out on a pilot system confirmed the repellent effect against this mollusc and the protection of lettuce weight loss by about 30%. Adhesion tests by Escherichia coli and Pseudomonas aeruginosa demonstrate anti-adhesion properties of 80% when bioactive oils are incorporated into the industrial formulation of the plastic film. Application of the predictive theoretical approach confirms that the adhesion scores cannot be explained by the total adhesion energy and total hydrophobicity energy. This proves that these effects are the result of bioactive activity. This research work offers an innovative, practical and ecologically responsible alternative to protect lettuce crops against nuisances and pests. [ABSTRACT FROM AUTHOR]

Introduction: Ceftazidime/avibactam (CZA) is indicated against multidrugresistant Pseudomonas aeruginosa, particularly those that are carbapenem resistant. CZA resistance in P. aeruginosa producing PER, a class A extendedspectrum β-lactamase, has been well documented in vitro. However, data regarding clinical isolates are scarce. Our aim was to analyze the contribution of PER to CZA resistance in non-carbapenemase-producing P. aeruginosa clinical isolates that were ceftazidime and/or carbapenem non-susceptible. Methods: Antimicrobial susceptibility was determined through agar dilution and broth microdilution, while blaPER gene was screened through PCR. All PERpositive isolates and five PER-negative isolates were analyzed through Whole Genome Sequencing. The mutational resistome associated to CZA resistance was determined through sequence analysis of genes coding for PBPs 1b, 3 and 4, MexAB-OprM regulators MexZ, MexR, NalC and NalD, AmpC regulators AmpD and AmpR, and OprD porin. Loss of blaPER-3 gene was induced in a PER-positive isolate by successive passages at 43°C without antibiotics. Results: Twenty-six of 287 isolates studied (9.1%) were CZA-resistant. Thirteen of 26 CZA-resistant isolates (50%) carried blaPER. One isolate carried blaPER but was CZA-susceptible. PER-producing isolates had significantly higher MICs for CZA, amikacin, gentamicin, ceftazidime, meropenem and ciprofloxacin than non-PER-producing isolates. All PER-producing isolates were ST309 and their blaPER-3 gene was associated to ISCR1, an insertion sequence known to mobilize adjacent DNA. PER-negative isolates were classified as ST41, ST235 (two isolates), ST395 and ST253. PER-negative isolates carried genes for narrow-spectrum blactamases and the mutational resistome showed that all isolates had one major alteration in at least one of the genes analyzed. Loss of blaPER-3 gene restored susceptibility to CZA, ceftolozane/tazobactam and other β-lactamsin the in vitro evolved isolate. Discussion: PER-3-producing ST309 P. aeruginosa is a successful multidrugresistant clone with blaPER-3 gene implicated in resistance to CZA and other β-lactams. [ABSTRACT FROM AUTHOR]

The beauty and body care industry is searching for environmentally friendly and sustainable solutions for surfactants and conditioning agents in hair care products. Glycolipids and esterquats have proven to be promising substitutes. Glycolipids are natural and renewable surfactants with low environmental impact. Rhamnolipids and sophorolipids are advanced glycolipids used in body care products. Plant oil-based esterquats are used as a sustainable alternative in hair care products. They offer improved conditioning properties and allow manufacturers to reduce their ecological footprint. [Extracted from the article]

The human paraoxonase 2 (PON2) is the oldest member of a small family of arylesterase and lactonase enzymes, representing the first line of defense against bacterial infections and having a major role in ROS-associated diseases such as cancer, cardiovascular diseases, neurodegeneration, and diabetes. Specific Post-Translational Modifications (PTMs) clustering nearby two residues corresponding to pon2 polymorphic sites and their impact on the catalytic activity are not yet fully understood. Thus, the goal of the present study was to develop an improved PON2 purification protocol to obtain a higher amount of protein suitable for in-depth biochemical studies and biotechnological applications. To this end, we also tested several compounds to stabilize the active monomeric form of the enzyme. Storing the enzyme at 4 °C with 30 mM Threalose had the best impact on the activity, which was preserved for at least 30 days. The catalytic parameters against the substrate 3-Oxo-dodecanoyl-Homoserine Lactone (3oxoC12-HSL) and the enzyme ability to interfere with the biofilm formation of Pseudomonas aeruginosa (PAO1) were determined, showing that the obtained enzyme is well suited for downstream applications. Finally, we used the purified rPON2 to detect, by the direct molecular fishing (DMF) method, new putative PON2 interactors from soluble extracts of HeLa cells. [ABSTRACT FROM AUTHOR]

This study aimed to explore the inhibitory effects of dried fruit ethanol extracts of Sterculia lychnophora Hance (SLHe), a traditional medicinal plant known as Pangdahai, on biofilm formation and virulence factors of Pseudomonas aeruginosa. Screening of bioactive compounds extracted from Sterculia lychnophora revealed a strong binding affinity to anthranilate-CoA ligase (PqsA), which regulates genes involved in pyocyanin production and biofilm formation. The experimental investigation confirmed the inhibitory effects of SLHe on biofilm formation and its ability to disrupt existing biofilms. Additionally, SLHe exhibited reductions in pyocyanin production and protease activity of Pseudomonas aeruginosa. These findings indicate the therapeutic potential of SLHe as a natural alternative for treating bacterial infections, particularly those associated with bacterial biofilm formations. [ABSTRACT FROM AUTHOR]

In this study, an Actinomycetota Streptomyces mediolani strain CF51DZ was isolated from a beetle Protaetia morio collected in a cork oak forest in northeast Algeria, to extract, purify and characterize the antibacterial compound. The strain was isolated in specific ISP culture media, identified via morphological, biochemical, physiological and molecular characteristics and then studied its antibacterial activities against pathogenic bacteria using the well diffusion technique. The extraction, purification and characterization of the bioactive compound was carried out using chromatographic and spectroscopic methods. Morphological, physiological, and biochemical properties, as well as the 16S ribosomal DNA sequence of the strain, were found close to those of Streptomyces mediolani. The isolated strain produced an active compound having potent antibacterial properties against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. This compound was isolated and purified with thin layer chromatography and high-performance liquid chromatography, and chemically identified by mass spectroscopy and NMR spectroscopy. In addition, the chemical structure elucidation of the antibacterial metabolite by APCI-MS analysis revealed a peak at m/z 375 [M+H]+, a molecular formula of C19H18O8 . This compound was identified as methyl rosarinate: 3-(3,4-dihydroxyphenyl)-1-methoxy1-oxopropan-2-yl (E)-3-(3,4-dihydroxyphenyl)acrylate based on the IUPAC nomenclature. Moreover, the antibacterial agent was purified from Streptomyces mediolani strain CF51DZ that was for the first time, in Algeria, isolated from the beetle Protaetia morio. This supports further characterization of this promising chemical to ensure the best use for antibacterial applications. [ABSTRACT FROM AUTHOR]

The pyoverdine siderophore is produced by Pseudomonas aeruginosa to access iron. Its synthesis involves the complex coordination of four nonribosomal peptide synthetases (NRPSs), which are responsible for assembling the pyoverdine peptide backbone. The precise cellular organization of these NRPSs and their mechanisms of interaction remain unclear. Here, we used a combination of several single-molecule microscopy techniques to elucidate the spatial arrangement of NRPSs within pyoverdine-producing cells. Our findings reveal that PvdL differs from the three other NRPSs in terms of localization and mobility patterns. PvdL is predominantly located in the inner membrane, while the others also explore the cytoplasmic compartment. Leveraging the power of multicolor single-molecule localization, we further reveal co-localization between PvdL and the other NRPSs, suggesting a pivotal role for PvdL in orchestrating the intricate biosynthetic pathway. Our observations strongly indicates that PvdL serves as a central orchestrator in the assembly of NRPSs involved in pyoverdine biosynthesis, assuming a critical regulatory function. [ABSTRACT FROM AUTHOR]

Water–ethanol mixtures are largely exploited for many different applications, from industrial processes to pharmaceutical formulations. Surfactants are often added to tune their interfacial properties. Sustainability concerns require redesigning such blends to minimize their environmental impact. A successful approach is to replace synthetic oil-based components with affordable unpurified bio-derived alternatives. In this respect, we have characterized aqueous mixtures of bioethanol, obtained by the fermentation of algae, and rhamnolipids, biosurfactants of microbial origin. The physico-chemical characterization of water–bioethanol binary mixtures in terms of refractive index, density, viscosity, and surface tension indicates that bioethanol behaves like pure ethanol with negligible effects of impurities. Analysis of tensiometric titrations shows that, at bioethanol contents higher than 20–30% bioethanol mass percent, rhamnolipid aggregation is impaired, whereas surface adsorption at the water–air interface remains poorly affected. Overall, bio-derived components can be proposed as a promising alternative to oil-derived chemicals in eco-sustainable formulations. [ABSTRACT FROM AUTHOR]

Dialium guineense essential oil possesses various biological and biochemical activities. The present study is based on determination of antimicrobial, anti-diabetic, anti-cholinesterase, anti-biofim, anti-antibiotic resistance modifying activities and anti-quorum sensing potential of essential oil. Chemical compounds in essential oil were recognised by retention indices using gas chromatograph-mass spectroscopy (GC-MS). A total of 45 compounds were present in the essential oil of which 12 are most active. Essential oil of D. guineense showed highest anti-bacterial activity in the form of zone of inhibition, produced 23 mm zone against Staphylococcus aureus and 15 mm against Escherichia coli. D. guineense oil at various concentrations showed excellent anti-diabetic and anti-cholinesterase activities. Since many active compounds were present in D. guineense oil so authors of this study planned to observe effect of D. guineense oil on quorum sensing regulated virulence factors and thus bio-film formation in pathogens Essential oil reduced bio-film formation considerably at all concentrations against E. coli, Staphylococcus aureus and Pseudomonas aeruginosa. Determination of quorum sensing (QS) inhibitory activity was demonstrated by reduction in pyocyanin (73.93%), total protease (68.59%) and chitinase activity (66.18%) in Pseudomonas aeruginosa at 1 mg/mL of D. guineense oil compared to control. Essential oil at all concentrations tested showed synergistic effect. Since essential oil showed anti-microbial, anti-biofilm and quorum sensing regulated anti-pathogenic activities. Based on results mentioned above, it is concluded that bioactive chemicals from D. guineense oil can act as an anti-infective agent by controlling growth, bio-film formation and signalling pathways of pathogenic microbes as well as other diseases. [ABSTRACT FROM AUTHOR]

Coriander (Coriandrum sativum L.) is an annual herb belonging to the Apiaceae family that is grown worldwide. This aromatic herb has been used for its nutritional value and biological properties. In this study, we compared the essential oil composition and antibacterial activity of coriander seeds from nine Iranian and Iraqi populations for the first time. The seed oils were extracted using a Clevenger‐type apparatus, and their chemical composition was determined using GC and GC/MS Agilent apparatuses. The antimicrobial activity of the oils was tested against three infectious bacteria (Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa) using the agar well diffusion method. The experiments were repeated three times, and the results were analyzed using PAST, SAS, and SPSS software. The results showed that oxygenated monoterpenes, especially linalool, were the major compounds in the oils, followed by α‐pinene, γ‐terpinene, and geranyl acetate. The proportions of these compounds varied among the populations. Trace amounts of other compounds were also detected, some of which were only found in certain populations. The populations were detected as linalool chemotype, and classified into four groups based on their chemical constituents in the UPGMA tree. The PCA‐Biplot showed that these groups were characterized by the presence and percentage of specific compounds. The essential oils showed bacterial growth inhibitory properties only at 100% concentration. S. aureus was the most sensitive bacterium to the coriander essential oil, while the essential oils of all populations inhibited the growth of this bacterium. Additionally, the essential oils were more effective than antibiotics against E. coli. These findings contribute to our understanding of coriander seed essential oil by providing data on antibacterial activity and chemical characteristics. Furthermore, the study highlights the importance of selecting populations based on their specific essential oil profiles for antibacterial applications. [ABSTRACT FROM AUTHOR]

Swarming is a collective bacterial behavior in which a dense population of bacterial cells moves over a porous surface, resulting in the expansion of the population. This collective behavior can guide bacteria away from potential stressors such as antibiotics and bacterial viruses. However, the mechanisms responsible for the organization of swarms are not understood. Here, we briefly review models that are based on bacterial sensing and fluid mechanics that are proposed to guide swarming in the pathogenic bacterium Pseudomonas aeruginosa. To provide further insight into the role of fluid mechanics in P. aeruginosa swarms, we track the movement of tendrils and the flow of surfactant using a novel technique that we have developed, Imaging of Reflected Illuminated Structures (IRIS). Our measurements show that tendrils and surfactants form distinct layers that grow in lockstep with each other. The results raise new questions about existing swarming models and the possibility that the flow of surfactants impacts tendril development. These findings emphasize that swarm organization involves an interplay between biological processes and fluid mechanics.

Background. The development of highly effective and environmentally safe composite drugs with antimicrobial properties is an important challenge in biotechnology and pharmacy. Objective. To determine the antimicrobial activity of new composite preparations based on rhamnolipids combined with heterocyclic amine-containing derivatives of 1,4-naphthoquinone against the test-bacteria Escherichia coli B-906, Staphylococcus aureus 209-P, Mycobacterium luteum B-917, and fungi Candida tenuis UCM Y-70 and Aspergillus niger UCM F-1119. Methods. The in vitro antimicrobial activity of heterocyclic amine-containing derivatives of 1,4-naphtho­quinone, biosurfactants, and composite preparations based on them was tested against cultures of Escherichia coli B-906, Staphylococcus aureus 209-P, Mycobacterium luteum B-917, and fungi Candida tenuis UCM Y-70 and Aspergillus niger UCM F-1119 using the agar diffusion method on solid nutrient media, as well as the serial dilution method (minimum inhibitory and bactericidal concentrations). The toxicity of the heterocyclic amine-containing derivatives of 1,4-naphthoquinone was predicted using in silico methodology via the ProTox-II software. Results. It was found that 2-chloro-3-((1-methyl-1H-pyrazol-3-yl)amino)naphthalene-1,4-dione 3.2 and 2-chloro-3-((3-(n-tolyl)- 1H-pyrazol-5-yl) amino) naphthalene-1,4-dione 3.3 exhibit antimicrobial activity. Their composite preparations, due to the combination with rhamnolipids, demonstrated improved solubility and enhanced antimicrobial effects. Based on the results of the calculated assessment, the studied heterocyclic amine-containing derivatives of 1,4-naphthoquinone are predicted to fall into toxicity class IV. Conclusions. The antimicrobial activity of 2-chloro-3-((1-methyl-1H-pyrazol-3-yl)amino)naphthalene-1,4-dione 3.2 and 2-chloro-3-(3-( 3-(p-tolyl)-1H-pyrazol-5-yl)amino)naphthalene-1,4-dione 3.3 is enhanced. This suggests the potential of the proposed biotechnological approaches in the development of new biocidal preparations.

Water–ethanol mixtures are largely exploited for many different applications, from industrial processes to pharmaceutical formulations. Surfactants are often added to tune their interfacial properties. Sustainability concerns require redesigning such blends to minimize their environmental impact. A successful approach is to replace synthetic oil-based components with affordable unpurified bio-derived alternatives. In this respect, we have characterized aqueous mixtures of bioethanol, obtained by the fermentation of algae, and rhamnolipids, biosurfactants of microbial origin. The physico-chemical characterization of water–bioethanol binary mixtures in terms of refractive index, density, viscosity, and surface tension indicates that bioethanol behaves like pure ethanol with negligible effects of impurities. Analysis of tensiometric titrations shows that, at bioethanol contents higher than 20–30% bioethanol mass percent, rhamnolipid aggregation is impaired, whereas surface adsorption at the water–air interface remains poorly affected. Overall, bio-derived components can be proposed as a promising alternative to oil-derived chemicals in eco-sustainable formulations.

The antibacterial activity and mechanism of rhamnolipids (RLs) against Bacillus cereus spores were analyzed from the aspects of appearance, morphology, and cell membrane state. The results showed that minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of RLs were 80.0 and 160.0 mg/L, respectively. Both concentrations of RLs caused severe shrinkage and depression on the surface of spores, and disrupted the integrity and permeability of the spore cell membrane, leading to the leakage of intracellular electrolytes, DNA and proteins. In addition, RLs inhibited and inactivated B. cereus spores by various mechanisms such as decreasing heat resistance, generating oxidative stress, reducing surface adhesion, and binding to and interfering with DNA molecules. The results of this study will contribute to the development and application of RLs in the field of food safety.

Introduction: Periodontal diseases are known to be associated with polymicrobial biofilms and inflammasome activation. A deeper understanding of the subgingival cytological (micro) landscape, the role of extracellular DNA (eDNA) during periodontitis, and contribution of the host immune eDNA to inflammasome persistence, may improve our understanding of the mechanisms underlaying severe forms of periodontitis. Methods: In this work, subgingival biolfilms developing on biologically neutral polyethylene terephthalate films placed in gingival cavities of patients with chronic periodontitis were investigated by confocal laser scanning microscopy (CLSM). This allowed examination of realistic cytological landscapes and visualization of extracellular polymeric substances (EPS) including amyloids, total proteins, carbohydrates and eDNA, as well as comparison with several single-strain in vitro model biofilms produced by oral pathogens such as Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus gordonii, S. sanguinis and S. mitis. Fluorescence in situ hybridization (FISH) analysis was also used to identify eDNA derived from eubacteria, streptococci and members of the Bacteroides-Porphyromonas-Prevotella (BPP) group associated with periodontitis. Results: Analysis of subgingival biofilm EPS revealed low levels of amyloids and high levels of eDNA which appears to be the main matrix component. However, bacterial eDNA contributed less than a third of the total eDNA observed, suggesting that host-derived eDNA released in neutrophil extracellular traps may be of more importance in the development of biofilms causing periodontitis. Discussion: eDNA derived from host immunocompetent cells activated at the onset of periodontitis may therefore be a major driver of bacterial persistence and pathogenesis. [ABSTRACT FROM AUTHOR]

This comprehensive and critical review explores the synthesis and applications of carbohydrate‐based surfactants within the biorefinery concept, focusing on biobased sugar‐head molecules suitable for use across several manufacturing sectors, including cosmetics, pharmaceuticals, household products, detergents, and foods. The main focus relies on sustainable alternatives to conventional surfactants, which could reduce the final manufacturing carbon footprint of several industrial feedstocks and products. A thorough analysis of raw materials, highlighting the significance of feedstock sources, and the current biobased surfactants and rhamnolipid biosurfactants production trends, is presented. Key organic reactions for the production of sorbitan esters, sucrose esters, alkyl polyglycosides, and fatty acid glucamines, such as glycosidation, acylation, and etherification, as well as the production of rhamnolipids through fermentation are described. Given the scarce literature on the characterization of these surfactant types within the hydrophilic–lipophilic deviation (HLD) framework, the surfactant contribution parameter (SCP) in the HLD equation for sugar‐head surfactants is critically assessed. The economic landscape is also discussed, noting the significant growth in the biobased surfactants and biosurfactant market, driven by environmental awareness and regulatory changes, with projections indicating a substantial market increase in the forthcoming years. Finally, the promising potential of generative artificial intelligence (AI) in developing customized surfactant molecules, with optimized properties for targeted applications, is emphasized as a promising avenue for future research. [ABSTRACT FROM AUTHOR]

Biosurfactants represent a promising choice for the development of environmentally friendly and gentle personal care cleansers. Building viscosity is one of the major challenges to apply biosurfactants. In this study, sodium lauroyl sarcosinate (LS) and sodium lauroamphoacetate (LA) were used as bases to build wormlike micelles, and subsequently rhamnolipids were introduced to build mild surfactant systems. The LS‐LA mixture had the highest viscosity at the mass ratio of 1:5 and pH 6.0. After adding 1 wt% and less rhamnolipid, relatively high viscosity can be maintained. The viscosity of LS‐LA‐rhamnolipid can be increased by adding NaCl and more significantly by the addition of carrageenan due to its synergistic interactions with the surfactant mixture. In addition, the foaming properties of the systems are characterized with different amounts of rhamnolipid and carrageenan, which are correlated with the bulk viscosity and interfacial elasticity of the diluted solution used for the foaming test. Rhamnolipids have both high mildness and cleaning efficacy and adding rhamnolipids can significantly increase the mildness of the system. This study offers practical solutions for the incorporation of rhamnolipids or other biosurfactants in the formulation of personal care cleansers. [ABSTRACT FROM AUTHOR]

Rhamnolipids (RLs) are highly valuable molecules in the cosmetic, pharmaceutic, and agricultural sectors with outstanding biosurfactant properties. In agriculture, due to their potential to artificially stimulate the natural immune system of crops (also known as elicitation), they could represent a critical substitute to conventional pesticides. However, their current synthesis methods are complex and not aligned with green chemistry principles, posing a challenge for their industrial applications. In addition, their bioproduction is cumbersome with reproducibility issues and expensive downstream processing. This work offers a more straightforward and green access to RLs, crucial to decipher their mechanisms of action and design novel potent and eco-friendly elicitors. To achieve this, we propose an efficient seven-step synthetic pathway toward (R)-3- hydroxyfatty acid chains present in RLs, starting from cellulose-derived levoglucosenone, with Michael addition, Baeyer-Villiger oxidation, Bernet-Vasella reaction, and cross-metathesis homologation as key steps. This method allowed the production of (R)-3-hydroxyfatty acid chains and derivatives with an overall yield ranging from 24% to 36%. [ABSTRACT FROM AUTHOR]

Growing evidence suggests that biofilm formation in Pseudomonas aeruginosa (PA) results from quorum sensing, reducing bacterial sensitivity to antibiotics and fostering the development of antibiotic-resistant strains. Addressing the need for a compound that can inhibit quorum sensing signals to mitigate biofilm formation in PA, this study screened 40 essential oils for their potential as quorum sensing inhibitors against PA ATCC9027. Utilizing the agar well diffusion assay, the antibacterial activity of these essential oils was compared with levofloxacin, revealing that 25 out of 40 essential oils exhibited antibacterial activity against PA ATCC9027. The highest antibacterial activity was exhibited by essential oils from Cinnamomum burmannii (Cinnamon Bark Oil), Cananga odorata (Ylangylang Oil), and Eucalyptus globulus (Eucalyptus Oil), confirmed by respective MIC values of 0.09765% (v/v), 0.390625% (v/v), and 1.5625% (v/v), and MBC values of 0.09765% (v/v), > 1.5625% (v/v), and > 1.5625% (v/v). Growth curve inhibition assay followed by crystal violet biofilm formation assay revealed that only Ylang-ylang Oil exhibited biofilm formation inhibition at 1/4 MIC concentration. Docking analysis of compounds from these essential oils against quorum sensing enzymes (LasR, PqsR, and QscR) revealed that Ylang-ylang Oil compounds exhibited the highest binding affinity. In conclusion, among the 40 essential oils tested, 25 show potential as antibacterials against PA ATCC9027, with Ylang-ylang Oil standing out as a promising candidate for quorum sensing inhibitor development. The use and development of quorum sensing inhibitors from Ylang-ylang Oil compounds are expected to reduce the burden of antibiotic resistance, especially in Pseudomonas aeruginosa. [ABSTRACT FROM AUTHOR]

Sulfate surfactants in cosmetic products raise concerns due to their skin irritating impact and sustainability. Rhamnolipid, a green and safe biosurfactant, was studied from the perspective of rheology to help develop a formulation with natural and effective ingredients for cosmetics. The viscosity of rhamnolipids was investigated by changing pH, concentration and adding additives like inorganic salts (NaCl, MgCl2) and polymers (Carbopol® Ultrez 20, Carbopol® Aqua SF‐1, Carbopol® 940 and cationic guar gum), showing that the viscosity of rhamnolipid had a positive correlation with the increase of concentration, a negative correlation with the increase of pH, and that polymers instead of inorganic salts were suitable for thickening rhamnolipid. Further rheology tests indicated that Carbopol® Aqua SF‐1 imparted gel properties of rhamnolipid while cationic guar gum determined the liquid properties. In addition, the rhamnolipid‐containing moisturizing cream consisting of stearic acid/squalane ratios all showed shear‐thinning and gel behavior the same as the commercial ones. Visual appearance and particle size analysis indicated that all formulations exhibited high storage stabilities. The knowledge gained from this study may be useful for designing "sulfonate‐free" shampoo and cream with rheological properties that can be tailed for specific commercial cosmetic applications. [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa is an opportunistic pathogen that usually causes chronic infections and even death in patients. The treatment of P. aeruginosa infection has become more challenging due to the prevalence of antibiotic resistance and the slow pace of new antibiotic development. Therefore, it is essential to explore non-antibiotic methods. A new strategy involves screening for drugs that target the quorum-sensing (QS) system. The QS system regulates the infection and drug resistance in P. aeruginosa. In this study, veratryl alcohol (VA) was found as an effective QS inhibitor (QSI). It effectively suppressed the expression of QS-related genes and the subsequent production of virulence factors under the control of QS including elastase, protease, pyocyanin and rhamnolipid at sub-inhibitory concentrations. In addition, motility activity and biofilm formation, which were correlated with the infection of P. aeruginosa, were also suppressed by VA. In vivo experiments demonstrated that VA could weaken the pathogenicity of P. aeruginosa in Chinese cabbage, Drosophila melanogaster, and Caenorhabditis elegans infection models. Molecular docking, combined with QS quintuple mutant infection analysis, identified that the mechanism of VA could target the LasR protein of the las system mainly. Moreover, VA increased the susceptibility of P. aeruginosa to conventional antibiotics of tobramycin, kanamycin and gentamicin. The results firstly demonstrate that VA is a promising QSI to treat infections caused by P. aeruginosa. [ABSTRACT FROM AUTHOR]

Copyright of Baghdad Science Journal is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)