Search Results (99)

Biofilms are structured communities of microorganisms encased in a self-produced extracellular matrix, and they represent one of the most widespread forms of microbial life on Earth. Their presence poses serious challenges in both environmental and clinical settings. In natural and industrial systems, biofilms contribute to water contamination, pipeline corrosion, and biofouling. Clinically, biofilm-associated infections are responsible for approximately 80% of all microbial infections, including endocarditis, osteomyelitis, cystic fibrosis, and chronic sinusitis. A particularly critical concern is their colonization of medical devices, where biofilms can lead to chronic infections, implant failure, and increased mortality. Implantable devices, such as orthopedic implants, cardiac pacemakers, cochlear implants, urinary catheters, and hernia meshes, are highly susceptible to microbial attachment and biofilm development. These infections are often recalcitrant to conventional antibiotics and frequently necessitate surgical revision. In the United States, over 500,000 biofilm-related implant infections occur annually, with prosthetic joint infections alone projected to incur revision surgery costs exceeding USD 500 million per year—a figure expected to rise to USD 1.62 billion by 2030. To address these challenges, surface modification of medical devices has emerged as a promising strategy to prevent bacterial adhesion and biofilm formation. This review focuses on recent advances in chemical surface functionalization using non-antibiotic agents, such as enzymes, chelating agents, quorum sensing quenching factors, biosurfactants, oxidizing compounds and nanoparticles, designed to enhance antifouling and mature biofilm eradication properties. These approaches aim not only to prevent device-associated infections but also to reduce dependence on antibiotics and mitigate the development of antimicrobial resistance. Full article

Soil contamination with petroleum hydrocarbons is a serious environmental issue, necessitating the development of effective and environmentally friendly remediation methods that align with the principles of sustainable development. This study investigated the impact of selected biosurfactants on the efficiency of the biodegradation of total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAHs) in contaminated soil. Six biosurfactants—poly-γ-glutamic acid (γ-PGA), rhamnolipid, surfactin, a mixture of γ-PGA, rhamnolipids, and surfactin (PSR), as well as two commercial formulations (JBR 425 and JBR 320)—were evaluated in combination with a bacterial consortium. Biodegradation experiments were conducted under laboratory conditions for a 90-day period. The effectiveness of the tested biosurfactants was assessed using respirometric analysis, the chromatographic determination of the residual hydrocarbon content, and toxicity assays. The results showed that the application of a bacterial consortium enriched with a mixture of biosurfactants PSR (a biosurfactant concentration in the inoculating mixture: 5 g/dm³) was the most effective approach, resulting in an oxygen uptake of 5164.8 mgO₂/dm³ after 90 days, with TPH and PAH degradation rates of 77.3% and 70.32%, respectively. Phytotoxicity values decreased significantly, with TU values ranging from 6.32 to 4.62 (growth inhibition) and 3.77 to 4.13 (germination). Toxicity also decreased in the ostracodtoxkit test (TU = 4.35) and the Microtox SPT test (TU = 4.91). Among the tested biosurfactants, surfactin showed the least improvement in its bioremediation efficiency. Under the same concentration as in the PSR mixture, the oxygen uptake was 3446.7 mgO₂/dm³, with TPH and PAH degradation rates of 60.64% and 52.64%, respectively. In the system inoculated with the bacterial consortium alone (without biosurfactants), the biodegradation efficiency reached 44.35% for TPH and 36.97% for PAHs. The results demonstrate that biosurfactants can significantly enhance the biodegradation of petroleum hydrocarbons in soil, supporting their potential application in sustainable bioremediation strategies. Full article

The growth of aquaculture production in recent years has revealed multiple challenges, including the rise of antimicrobial resistance (AMR) in aquatic animal production, which is currently attracting significant attention from multiple one-health stakeholders. While antibiotics have played a major role in the treatment of bacterial infections for almost a century, a major consequence of their use is the increase in AMR, including the emergence of AMR in aquaculture. The AMR phenomenon creates a situation where antibiotic use in one system (e.g., aquaculture) may impact another system (e.g., terrestrial–human). Non-prudent use of antibiotics in aquaculture and animal farming increases the risk of AMR emergence, since bacteria harboring antibiotic resistance genes can cross between compartments such as wastewater or other effluents to aquatic environments, including intensive aquaculture. Transferable antimicrobial resistance gene (AMG) elements (plasmids, transposons, integrons, etc.) have already been detected in varying degrees from pathogenic bacteria that are often causing infections in farmed fish (Aeromonas, Vibrio, Streptococcus, Pseudomonas, Edwardsiella, etc.). This review of current veterinary approaches for the prevention and control of AMR emergence in aquaculture focuses on the feasibility of alternatives to antimicrobials and supplemental treatment applications during on-farm bacterial disease control and prevention. The use of vaccines, bacteriophages, biosurfactants, probiotics, bacteriocins, and antimicrobial peptides is discussed. Full article

This study evaluated the acaricidal effects of biosurfactants produced by Serratia ureilytica against the two-spotted spider mite Tetranychus urticae and their compatibility with the predatory mite Ambliseus swirski. The biosurfactants were obtained via liquid cultures of the bacterial strains. In the laboratory, T. urticae was exposed via acaricide-immersed leaves and A. swirskii via acaricide-coated glass vials. In the greenhouse, mite-infested plants were sprayed with the biosurfactants. In the laboratory, biosurfactants produced by S. ureilytica NOD-3 and UTS exhibited strong acaricidal activity, causing 95% mortality in adults and reducing egg viability by more than 60%. In the greenhouse trial, all biosurfactants significantly suppressed T. urticae populations at all evaluated periods (7, 14, and 21 days post-application). Gas chromatography–mass spectrometry (GC-MS) analysis of the biosurfactants identified several fatty acids, including hexadecanoic acid, pentanoic acid, octadecanoic acid, decanoic acid, and tetradecanoic acid, as well as the amino acids L-proline, L-lysine, L-valine, and glutamic acid. These fatty acids and amino acids are known structural components of lipopeptides. Furthermore, the bioinformatic analysis of the genomes of the three S. ureilytica strains revealed nonribosomal peptide synthetase (NRPS) gene clusters homologous to those involved in the biosynthesis of lipopeptides. These findings demonstrate that S. ureilytica biosurfactants are promising eco-friendly acaricides, reducing T. urticae populations by >95% while partially sparing A. swirskii. Full article

The increasing resistance of pathogenic microorganisms to antimicrobials has driven the search for safe and sustainable alternatives. In this context, microbial biosurfactants have gained prominence due to their antimicrobial activity, low toxicity, and high stability under extreme conditions. This study presents the production and characterization of a biosurfactant with antimicrobial potential, obtained from Bacillus subtilis isolated from soil, for application in the control of resistant strains. Bacterial identification was performed using mass spectrometry (MALDI-TOF), confirming it as Bacillus subtilis. The strain B. subtilis UCP 1533 was cultivated using different carbon sources (glucose, soybean oil, residual frying oil, and molasses) and nitrogen sources (ammonium chloride, sodium nitrate, urea, and peptone), with evaluations at 72, 96, and 120 h. The best condition involved a mineral medium supplemented with 2% soybean oil and 0.12% corn steep liquor, resulting in the production of 16 g·L⁻¹ of biosurfactant, with a critical micelle concentration (CMC) of 0.3 g·L⁻¹ and a reduction in water surface tension to 25 mN·m⁻¹. The biosurfactant showed an emulsification index of 100% for used motor oil and ranged from 50% to 100% for different vegetable oils, maintaining stability across a wide range of pH, salinity, and temperature. FT-IR and NMR analyses confirmed its lipopeptide nature and anionic charge. Toxicity tests with Tenebrio molitor larvae showed 100% survival at all the tested concentrations. In phytotoxicity assays, seed germination rates above 90% were recorded for Solanum lycopersicum and Lactuca sativa. Antimicrobial tests revealed inhibitory activity against resistant strains of Escherichia coli and Pseudomonas aeruginosa, as well as against species of the genus Candida (C. glabrata, C. lipolytica, C. bombicola, and C. guilliermondii), highlighting the biosurfactant as a promising alternative in combating antimicrobial resistance (AMR). These results indicate the potential application of this biosurfactant in the development of antimicrobial agents for pharmaceutical formulations and sustainable strategies for phytopathogen control in agriculture. Full article

In this comprehensive study, we investigated the degradation capacity and tolerance of the bacterial strain Bacillus subtilis in culture media with high concentrations of heavy crude oil (HCO) as the sole carbon source. Using a meticulously designed experimental approach conducted at room temperature (25 °C), we systematically examined various culture media with HCO concentrations of 20%, 35%, and 50% v/v over a 10-week period. The results revealed the microorganism’s remarkable resistance to these HCO concentrations. Biotransformation capacity was confirmed by quantifying CO₂ production via gas chromatography, showing substantial bioconversion with a 42% increase in CO₂ production. Additionally, changes in surface tension were monitored using the Du Noüy ring method, showing a reduction in the aqueous phase tension from 72.3 to 47.43 mN/m. At the end of the bioconversion period, all treated samples exhibited visible emulsification, indicative of biosurfactant production. This phenomenon was consistent with the observed decrease in surface tension, providing further evidence of biosurfactant-mediated mechanisms. These findings highlight the immense biotechnological potential of B. subtilis to address HCO-related challenges, offering promising prospects for crude oil bioremediation and bioupgrading. Full article

The study is devoted to the analysis of the physicochemical parameters of formation waters, the metagenomic composition of the microbial community and the characteristics of bacterial isolates from the oil fields of Western Kazakhstan to assess their potential in microbial-enhanced oil recovery (MEOR) technologies. Analyses revealed an adaptation of local microorganisms to extreme conditions of high salinity, temperature and pressure, with the dominant presence of Proteobacteria, including the genus Marinobacter. Screening isolates for biosurfactant synthesis showed a high activity of strains M22-7, M93-8C and M142-2, capable of reducing surface tension to 28.81 ± 0.6 mN/m and forming emulsions. Genetic analysis confirmed the presence of key genes (srfAA, srfp) responsible for surfactin synthesis, but the absence of lchAA and rhlAA indicates that the synthesis of other types of biosurfactants is limited. The results highlight the promise of developing microbial consortia and using biosurfactants in high-salinity environments to enhance oil recovery. Full article

Microorganisms from saline environments have garnered significant interest due to their unique adaptations, which enable them to thrive under high-salt conditions and synthesize valuable biomolecules. This study investigates the biosynthesis of biomolecules, such as extracellular hydrolytic enzymes, biosurfactants, and carotenoid pigments, by four newly halotolerant bacterial strains isolated from saline environments in the Băicoi (soil, water) and Curmătura (mud) area (Prahova County, Romania). Isolation was performed on two selective culture media with different NaCl concentrations (1.7 M, 3.4 M). Based on their phenotypic and molecular characteristics, the four halotolerant bacteria were identified as Halomonas elongata SB8, Bacillus altitudinis CN6, Planococcus rifietoensis CN8, and Halomonas stenophila IB5. The two bacterial strains from the Halomonas genus exhibited growth in MH medium containing elevated NaCl concentrations (0–5 M), in contrast to the other two strains from Bacillus (0–2 M) and Planococcus (0–3 M). The growth of these bacteria under different salinity conditions, hydrocarbon tolerance, and biomolecule production were assessed through biochemical assays, spectrophotometry, and high-performance thin-layer chromatography. The antimicrobial properties of biosurfactants and carotenoids produced by H. elongata SB8, B. altitudinis CN6, P. rifietoensis CN8, and H. stenophila IB5 were evaluated against four reference pathogenic microorganisms from the genera Escherichia, Pseudomonas, Staphylococcus, and Candida. H. elongata SB8 showed the highest hydrocarbon tolerance. B. altitudinis CN6 exhibited multiple hydrolase activities and, along with H. elongata SB8, demonstrated biosurfactant production. P. rifietoensis CN8 produced the highest carotenoid concentration with antifungal and antimicrobial activity. Exploring these organisms opens new pathways for bioremediation, industrial bioprocessing, and sustainable biomolecule production. Full article

Enzymes and biosurfactants, often referred to as “green chemicals,” play pivotal roles in enhancing the washing performance of bio-based detergents—a growing trend driven by environmentally conscious consumers. However, the widespread adoption of such bio-based detergents faces challenges, including high costs, limited efficiency, and the need for ongoing innovations. Bacillus species have long been universally acknowledged and exploited for industrial applications, and Bacillus spp. are largely differentiated from other microorganisms for their enzymatic applications, particularly in detergent production. Recent developments in bio-surfactant production by Bacillus sp. support the adoption of green detergents, and these bacterial biosurfactants are a promising source for detergent manufacturing. This article provides an overview of the current understanding of promising Bacillus species and their potential to advance and accelerate the production of bio-based detergents. Full article

The present study investigated the combined effects of wheat straw biochar (BC) and biosurfactant rhamnolipid (RL) on the biodegradation kinetics of phenanthrene by indigenous microorganisms in agricultural soil, focusing on dynamic responses of both bioavailability and community structure. The combined treatment (BC + RL, 60.63%) significantly enhanced phenanthrene biodegradation compared to RL alone (54.74%) and the control (45.98%), while BC amendment alone (42.55%) notably inhibited biodegradation by reducing phenanthrene bioavailability despite increasing bacterial abundance, enzyme activity, and community diversity. Both RL and BC + RL treatments promoted bioavailability by transforming phenanthrene from tightly bound (very slowly desorbing fraction, F_vslow) to readily bioavailable fractions (rapidly and slowly desorbing fractions, F_rapid and F_slow), as revealed by sequential Tenax extraction. The RL-mediated increase in phenanthrene bioavailability to microbes by 11.93–17.90% via solubilization greatly enriched PAH-degrading bacterial genera and the nidA gene, contributing to enhanced biodegradation. The BC + RL combination outperformed the single application of RL in improving phenanthrene biodegradation due to their synergy in stimulating microbial population and activity (e.g., Bacillus, Massilia, Sphingomonas, and polyphenol oxidase) as a growth stimulus. These findings demonstrate that BC and RL co-application enhances PAH removal through improved bioavailability and optimized microbial communities, offering a promising strategy for soil bioremediation to ensure agricultural product safety. Full article

Citrus canker, caused by Xanthomonas citri subsp. citri, is a devastating disease that affects citrus production and trade worldwide. Traditional control methods, based on copper compounds, are effective but pose environmental and health risks due to their toxicity and potential for bioaccumulation. This study evaluates the synergistic potential of essential oils (EOs) and rhamnolipids as sustainable alternatives for disease management. Four EOS (citronella, palmarosa, geranium, and clove) were tested for their antibacterial activity. Citronella EO showed a 90% inhibitory concentration (IC 90) of 0.15% (v/v) and a minimum bactericidal concentration of 0.25% (v/v), while the other EOs showed IC 90 and bactericidal activity at 0.06% (v/v). Rhamnolipids (RHLs), biosurfactants produced by Pseudomonas aeruginosa, inhibited X. citri at a concentration of 0.3% (v/v). The combination of citronella EO and RHLs showed a synergistic effect, reducing the inhibitory concentration of citronella by 50% and that of RHLs by more than 90%. In addition, the combined formulation permeabilized more than 80% of bacterial membranes and reduced biofilm formation. In contrast, other oils tested in combination with rhamnolipid showed independent effects. These results indicate that EOs and rhamnolipids represent an environmentally safe strategy for the control of X. citri subsp. citri that overcomes the limitations of conventional methods while reducing environmental and health impacts. Full article

Biofilms formed by Candida albicans pose therapeutic challenges due to their resistance to conventional antimicrobials, highlighting the need for more effective treatments. Rhamnolipids (RLs) are biosurfactants with diverse antimicrobial properties. Bacteriophages are viruses that target specific bacterial strains. Recent studies have shown that they may affect biofilm formation by fungi and yeasts. This study investigated the combined antimicrobial effects of RLs and bacteriophages against C. albicans biofilms, focusing on their anti-adhesive and inhibitory effects on biofilm development. RT-PCR assays were used to analyze gene modulation in C. albicans biofilm formation in response to RLs and bacteriophage treatments, while hyphae formation was examined using microscopy. The results showed that RLs-bacteriophage combinations significantly reduced biofilm formation compared to individual treatments. A combination of 200 mg/L RLs with bacteriophage BF9 led to a 94.8% reduction in biofilm formation. In a subsequent model, the same RL concentration with bacteriophage LO5/1f nearly eliminated biofilm formation (~96%). Gene expression analysis revealed downregulation of key biofilm-associated genes when Candida cells were treated with 200 mg/L RLs and four bacteriophages (BF17, LO5/1f, JG004, FD). These results show the potential of RL and bacteriophage combinations in combating C. albicans biofilms, presenting a promising therapeutic approach against resilient infections. Full article

Biofilm formation on orthopedic joint implants complicates diagnosis of periprosthetic joint infections (PJIs). Sonication of explanted orthopedic implants for diagnostic enhances pathogen detection, but it shows limitations in sensitivity and handling. We investigated whether the biosurfactant saponin could improve bacterial recovery from orthopaedic implants and thereby enhance infection diagnosis ex vivo. Orthopaedic material discs of 1 cm diameter were contaminated with different clinical bacterial PJI isolates. Biofilms of Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, Cutibacterium avidum, and Cutibacterium acnes were grown on the discs, which were then treated with either saline solution or various concentrations of saponin. Next, the discs were vortexed or sonicated. Colony-forming units (CFUs) enumeration and time-to-positivity of liquid cultures were determined. Additionally, a novel 3D PJI soft tissue in vitro model was established to validate these findings in a more representative scenario. Median CFU enumeration showed that 0.001% (w/v) saponin as compared to saline solution increased CFUs recovery by 2.2 log₁₀ for S. epidermidis, 0.6 log₁₀ for S. aureus, 0.6 log₁₀ for C. avidum, 1.1 log₁₀ for C. acnes, and 0.01 log₁₀ for E. coli. Furthermore, saponin treatment resulted in a >1 log₁₀ increase in S. epidermidis CFU recovery from implants in the 3D tissue model compared to standard saline sonication. With that, we propose a novel two-component kit, consisting of a saponin solution and a specialized transportation box, for the efficient collection, transportation, and processing of potentially infected implants. Our data suggest that biosurfactants can enhance bacterial recovery from artificially contaminated orthopedic implants, potentially improving the diagnosis of PJIs. Full article

Aphids (Hemiptera: Aphididae) are cosmopolitan generalist pests of many agricultural crops. Their ability to reproduce rapidly through parthenogenesis allows them to quickly reach population sizes that are difficult to control. Their damage potential is further exacerbated when they act as vectors for plant pathogens, causing diseases in plants. Aphids are typically managed through the widespread use of insecticides, increasing the likelihood of short-term insecticide resistance. However, for the past few decades, entomopathogenic bacteria have been used as an alternative management strategy. Entomopathogenic bacteria have demonstrated their effectiveness for biologically suppressing insect pests, including aphids. In addition to identifying bacterial species that are pathogenic to aphids, research has been conducted on toxins such as Cry, Cyt, Vip, recombinant proteins, and other secondary metabolites with insecticidal activity. Most studies on aphids have been conducted in vitro, exposing them to an artificial diet contaminated with entomopathogenic bacteria or bacterial metabolites for periods ranging from 24 to 96 h. The discovery of new bacterial species with insecticidal potential, as well as the possibility of biotechnological applications through the genetic improvement of crops, will provide more alternatives for managing these agricultural pests in the future. This will also help address challenges related to field application. Full article

In countries with a long petroleum extraction and processing history, such as Romania, extensive soil areas are often polluted with petroleum and its derivatives, posing significant environmental and human health risks. This study explores the diesel biodegradation potential of two native bacterial consortia isolated from hydrocarbon-polluted soils, focusing on their phenotypic and molecular characteristics, growth kinetics, alkane hydroxylase activity, hydrolase production, and biosurfactant synthesis capabilities. The bacterial consortia, CoP1 and CoP2, were successfully obtained using the standard successive enrichment culture method from two soil samples collected from a region affected by petroleum pollution. The CoP1 and CoP2 consortia demonstrated efficient diesel-degrading capabilities, achieving 50.81−84.32% degradation when cultured in a minimal medium containing 1–10% (v/v) diesel as the sole carbon and energy source. This biodegradation potential was corroborated by their significant alkane hydroxylase activity and the detection of multiple catabolic genes in their genomes. The CoP1 consortium contains at least four catabolic genes (alkB, alkM, todM, ndoM) as well as rhamnosyltransferase 1 genes (rhlAB), while the CoP2 consortium contains only two catabolic genes (ndoM, C23DO). The RND transporter gene (HAE1) was present in both consortia. Secondary metabolites, such as glycolipid-type biosurfactants, as well as extracellular hydrolases (protease, amylase, cellulase, and lipase), were produced by both consortia. The CoP1 and CoP2 consortia demonstrate exceptional efficiency in diesel degradation and biosurfactant production, making them well suited for the bioremediation of soils contaminated with petroleum and its derivatives. Full article