Bacillus thuringiensis, a facultatively aerobic, endospore-forming Gram-positive bacterium, is widely distributed across diverse natural environments. This bacterium is recognized as a cell factory producing insecticidal Cry (crystalline) toxins, also known as δ-endotoxins. However, during the stationary phase of growth, non-insecticidal B. thuringiensis strains synthesize inclusions composed of precursors of toxins called parasporins, which exhibit selective cytotoxicity toward cancer cells without harming normal cells. To date, six B. thuringiensis parasporins (PS1-PS6) have been identified and categorized into the three-domain toxin type (PS1, PS3, PS6) and the β-pore-forming toxin type (PS2, PS4, PS5). The anticancer activity of parasporins is primarily due to the induction of apoptotic pathways in cancer cells or to the formation of transmembrane pores that lead to necrosis. Among the characterized parasporins, PS2Aa1, PS4Aa1, and PS5Aa1 exhibit the highest anticancer potential, especially against leukemia, cervical, uterine, lung, colon, and hepatocellular cancer cells. Additionally, parasporins have been shown to exert cytotoxic effects on animal-derived cancer cell lines. The discovery of parasporin proteins synthesized by B. thuringiensis that exhibit non-hemolytic and non-insecticidal properties but display selective antitumor effects without harming normal cells underscores their potential biomedical significance and the possibility of novel applications of B. thuringiensis in human and veterinary medicine. Recent studies suggest that the molecular modifications of parasporins, such as conjugation with silver nanoparticles or maltose-binding proteins, represent a promising research direction and may facilitate future advances in anticancer therapy.

Nanoplastics are increasingly recognized as emerging environmental contaminants, yet the physicochemical mechanisms governing their interactions with bacterial cells remain insufficiently understood. In this study, we investigated the interactions between Gram-negative Escherichia coli and polystyrene nanoparticles (PS and PS-NH2; 100 and 200 nm) using electrophoretic light scattering (ELS), Fourier-transform infrared (FTIR) spectroscopy, and atomic force microscopy (AFM). Zeta potential measurements revealed concentration-, pH-, and time-dependent shifts in the electrokinetic behavior of bacteria-nanoparticle mixtures, reflecting composite signals arising from nanoparticle attachment and surface-level interactions rather than direct measurements of bacterial surface charge. FTIR and AFM analyses confirmed nanoparticle surface adhesion and localized envelope perturbations; however, evidence for nanoparticle penetration remained indirect and subject to methodological limitations. Microbiological assays showed growth inhibition at nanoparticle concentrations ≥50 μg/mL, but no bactericidal activity was conclusively confirmed under the applied conditions. Overall, the results demonstrate that polystyrene nanoparticles induce measurable physicochemical and sublethal biological effects on E. coli without reaching cytotoxic thresholds, underscoring the importance of cautious interpretation when linking nanoparticle-induced surface perturbations to biological outcomes.

Antibiotic resistance among bacteria represents a major challenge in modern medicine. The absence of antibiotics effective against multidrug-resistant pathogens triggers interest in reviving older antibiotics. This review aims to provide a focused and updated perspective on the reintroduction of polymyxin antibiotics, with a particular emphasis on colistin, a cyclic oligopeptide initially used in the 1950s and 1960s. We analyze colistin from multiple perspectives, including (i) its historical and contemporary clinical applications, (ii) pharmacokinetic and pharmacodynamic properties, and (iii) use in veterinary medicine and animal husbandry. Key unresolved issues are highlighted, such as colistin toxicity, challenges in susceptibility testing, the emergence of resistance, including the mcr gene variants, and inconsistent clinical evidence supporting combination therapy. By integrating historical background with current data, this review provides a comprehensive overview of the therapeutic relevance, limitations, and ongoing challenges associated with colistin in the era of multidrug-resistant Gram-negative infections.

Primary temperate forests serve as a natural framework for studying linkages between vegetation, soil properties and microbial communities under minimal human disturbance. Here, we characterize how soil bacterial communities and functional potential vary across five dominant forest types of the Białowieża National Park, representing a natural mosaic of vegetation and edaphic conditions. Using full-length 16S rRNA Oxford Nanopore sequencing, functional profiling via BIOLOG EcoPlates, and applying multivariate analyses, we detected clear differences in bacterial composition and carbon-substrate utilization profile among forest types. Distance-based redundancy analysis (dbRDA) identified soil pH as the primary abiotic gradient shaping bacterial communities, while RLQ, fourth-corner and multiblock sPLS analyses consistently supported bacteria-soil-vegetation linkages. Three consistent ecological clusters emerged across the forest mosaic. Coniferous forests with acidophilic bacterial assemblages linked to strongly acidic soils and ericaceous understoreys, broadleaf forests with bacterial genera associated with moderately acidic, nutrient-depleted soils and shade-tolerant vegetation, and alder forests characterized by richer, more metabolically active microbial communities occurring in less acidic soils with tall-herb understoreys. Mixed forests displayed broad internal variability, reflecting their wide range of vegetation and soil conditions. Overall, environmental filtering structures distinct bacterial communities of this primary temperate forest, providing a valuable baseline for future plant-soil-microbiome studies.

A significant driving force in nanotechnology development is the environmentally friendly synthesis of nanomaterials using natural extracts as reducing and stabilizing agents. In this study, silver and copper nanoparticles were synthesized and compared using two approaches: (1) a green synthesis pathway employing beetroot extract as a natural bio-reductant and stabilizer, and (2) a conventional chemical reduction method. The resulting nanoparticles were extensively characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-Vis spectroscopy, and dynamic light scattering (DLS). The study revealed that the green synthesis route produced nanoparticles with well-defined morphology, high stability, and strong antimicrobial potential, outperforming those obtained via conventional chemical synthesis. Copper nanoparticles synthesized using beetroot extract exhibited particularly enhanced fungicidal and bactericidal properties, demonstrating the effectiveness of plant-based reducing agents in producing functional nanostructures. To further evaluate potential applications, the green-synthesized nanoparticles were incorporated into a polypropylene matrix, confirming their integrity and activity within the composite system. This work emphasizes the role of green synthesis in designing high-performance nanomaterials and highlights the promising capabilities of beetroot extract as a sustainable and efficient reducing and stabilizing medium for silver and copper nanoparticle production.

Nowadays, there is a growing need to develop environmentally friendly procedures that reduce the use of toxic chemicals in synthesis. Green synthesis methods have an advantage over conventional chemical methods because they do not pollute the environment significantly. This has generated more interest in using readily available plants to create nanomaterials. In this work, silver nanoparticles were obtained through green chemistry using natural reducing agents present in apple extract. The research focused on optimizing the synthesis conditions to obtain predictable structures. The characterization of the nanoparticles was performed using transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction (XRD), UV–Vis spectroscopy, and infrared spectroscopy (IR). The achieved results led to the conclusion that the use of apple extract was suitable for obtaining homogenous and spherical silver nanoparticles at a wide range of core precursor concentrations and a variable pH. The diameter of the studied nanoparticles ranged from 6 to 22 nm. The nanoparticles obtained with apple extract were highly active against Gram-positive bacteria and fungus, but less active against Gram-negative bacteria. The development of nanotechnology in green chemistry processes will gradually increase with technological advances, being a key component in developing new synthesis processes for nano-object formation.

The Pseudomonas genus includes species present in various environments and known for antibiotic resistance. However, only hospital-associated Pseudomonas aeruginosa have been extensively studied regarding antibiotic resistance. Thus, to fill the gap in knowledge on antibiotic resistance among other Pseudomonas spp., we investigated 41 isolates from soil samples taken in the Białowieża National Park in Northeastern Poland. This unique forest without notable anthropogenic influence, provides excellent conditions for research of antibiotic resistance from the perspective of natural environments. The phylogeny trees obtained based on the nucleotide sequence of the 16S rRNA gene and gyrB gene grouped the isolates into clusters belonging to the Pseudomonas fluorescens, Pseudomonas koreensis, and Pseudomonas putida groups, originating from the P. fluorescens lineage. All isolates under study demonstrated resistance to at least 12 out of the 24 antibiotics tested. Resistance to colistin, cefotaxime, and imipenem was detected in 73, 73, and 17% of the isolates, respectively. Most isolates showing resistance to imipenem and colistin clustered within the P. fluorescens group. Seven isolates were highly multi-resistant, to up to 18 of the 24 antibiotics tested. The presence of resistance genes related to intrinsic resistance of P. aeruginosa has been confirmed in environmental isolates.

Metals are natural components of the lithosphere, whose amounts and bioavailability are increasing in many areas due to their continuous release from both natural sources and intensive human activities. Some metals are essential or beneficial for living organisms, while others are non-essential and potentially toxic. When present at higher concentrations, even essential and beneficial metal ions can become harmful to all forms of life. Bacteria, unicellular organisms that have been exposed to metals since the earliest stages of life on Earth, have evolved metabolic pathways involving essential metals as well as diverse strategies to cope with metal toxicity. In the domain Bacteria, two main strategies have been identified: (i) metal exclusion, which includes cell wall sequestration and immobilization of metals in extracellular exopolysaccharides, siderophores, and other soluble microbial products, as well as (ii) metal tolerance, involving intracellular sequestration of metals (e.g., by metallothioneins, or low molecular weight thiols) as well as enzymatic conversion of metals to less toxic forms and/or its active efflux. Microorganisms possessing such adaptive traits are considered valuable agents for potential application in medicine, environmental sciences, and bioengineering (e.g., bioremediation and/or biomining).

Microbiological enhanced oil recovery (MEOR) uses indigenous or exogenous microorganisms and nutrients to enhance oil production through synthesis of metabolites reducing oil viscosity and surface tension. In order to find bacteria suitable for MEOR, we studied 26 isolates from wells in the Akingen oilfield in West Kazakhstan. Six of them were selected for further analysis based on their ability to reduce surface tension to less than 40 mN/m, with the A9 isolate exhibiting tension reduction values of 32.76 ± 0.3 mN/m. Based on the morphological features, biochemical activities, and the 16S rRNA gene, the isolates were classified to the Bacillus subtilis group. In the phylogenetic analysis the isolates grouped into two main clusters. Genes encoding the surfactin synthetase subunits were found in A2, A8, A9, A12, PW2, only the PW2 strain had lchAA encoding lichenysin, while sacB encoding levan was noted in A2, A8, A9, and A12. The expression of srfAB, srfAC, and sacB tested with qPCR varied among strains. Nevertheless, whereas temperature moderately affects the expression level, with the highest level recorded at 40 °C, salinity significantly impacts the expression of the genes encoding biosurfactants. B. subtilis strains isolated in the study, especially A9, are promising for microbial-enhanced oil recovery.

Bacillus cereus sensu lato (B. cereus s.l.) comprises mesophilic and psychrotolerant bacteria commonly found in natural environments as well as in organic and conventional milk. Due to their potential toxigenicity and antibiotic resistance, these bacteria pose a significant threat to consumer health. Organic milk production, which prohibits the use of antibiotics and artificial additives, may influence the composition of microbiota between milk types. This study aimed to compare the antibiotic resistance profiles and enterotoxic potential of B. cereus s.l. isolates from organic and conventional milk. The results indicate that, although conventional milk contains on average 3 times fewer B. cereus s.l. isolates, it has 10-15% more resistant isolates to selected beta-lactams, macrolides, and aminoglycosides. Regarding drug resistance, 21% of B. cereus s.l. isolates were multidrug-resistant, and as many as 42% were non-susceptible to two classes of antibiotics. Even among the sensitive isolates, bacteria from conventional milk exhibited on average 2.05 times higher MICs (minimal inhibitory concentrations) for beta-lactams, 1.49 times higher for erythromycin, 1.38 times higher for vancomycin, and 1.38 times higher for azithromycin. Antibiotic resistance was mostly associated with the origin of the isolates. These findings underscore the need for ongoing monitoring of antibiotic resistance and enterotoxicity among opportunistic B. cereus s.l. strains, which may pose challenges for public health and veterinary medicine. The results highlight that selective pressure associated with antibiotic use can drive resistance development in bacteria that are not the primary targets of antimicrobial therapy.

Artykuł skupia się na rozwoju otwartej nauki w Uniwersytecie w Białymstoku. Nawiązuje do najważniejszych wydarzeń związanych z otwartym dostępem na świecie i w Polsce. Wskazuje na korzyści i problemy wynikające z otwierania wyników pracy naukowej. Przedstawia też decyzje i przedsięwzięcia realizowane w ramach funkcjonowania Repozytorium Uniwersytetu w Białymstoku, będącego centrum działań w zakresie otwartej nauki. Podsumowuje plany dalszych kroków ku otwartości na uczelni, zarówno w sferze otwierania publikacji, jak i danych badawczych, zgodnie z potrzebami i wymaganiami, pojawiającymi się w środowisku naukowym.

Polymer molecules, the main components of plastics, are an emerging pollutants in various environmental compartments (water, air, soil) that may induce several ecotoxicological effects on live organisms. Therefore, understanding how plastic particles interact with bacterial cell membranes is crucial in analysing their associated risks in ecosystems and human microbiota. However, relatively little is known about the interaction between nanoplastics and bacteria. The present work focuses on Staphylococcus aureus and Klebsiella pneumoniae, representing the Gram-positive and Gram-negative bacteria respectively, exposed to 100 nm diameter polystyrene nanoparticles (PS NPs). The nanoparticles attach to the cells' membranes of both bacteria, changing their electrical charge, but without the effect of killing the cells. PS NPs caused a change in zeta potential values (both species of bacterial strains), dependent on particle concentration, pH, as well as on exposure time of bacteria to them. Through the application of AFM and FTIR techniques, the presence of PS NPs on bacterial surfaces was detected, suggesting the affinity of the particles to bacterial components, but without any changes in the morphology of the tested bacteria. The zeta potential can be more widely used in the study of interactions between nanostructures and cells.

To identify metal adapted bacteria equipped with traits positively influencing the growth of two hyperaccumulator plant species Arabidopsis arenosa and Arabidopsis halleri , we isolated bacteria inhabiting rhizosphere and vegetative tissues (roots, basal and stem leaves) of plants growing on two old Zn–Pb–Cd waste heaps in Bolesław and Bukowno (S. Poland), and characterized their potential plant growth promoting (PGP) traits as well as determined metal concentrations in rhizosphere and plant tissues. To determine taxonomic position of 144 bacterial isolates, 16S rDNA Sanger sequencing was used. A metabolic characterization of isolated strains was performed in vitro using PGP tests. A. arenosa and A. halleri accumulate high amounts of Zn in their tissues, especially in stem leaves. Among in total 22 identified bacterial taxa, the highest level of the taxonomical diversity ( H’ = 2.01) was revealed in A. halleri basal leaf endophytes originating from Bukowno waste heap area. The 96, 98, 99, and 98% of investigated strains showed tolerant to Cd, Zn, Pb and Cu, respectively. Generally, higher percentages of bacteria could synthesize auxins, siderophores, and acetoin as well as could solubilize phosphate. Nine of waste heap origin bacterial strains were tolerant to toxic metals, showed in vitro PGP traits and are potential candidates for bioremediation.

Escherichia albertii is a new enteropathogen of humans and animals. The aim of the study was to assess the prevalence and pathogenicity of E. albertii strains isolated in northeastern Poland using epidemiological and genomic studies. In 2015–2018, a total of 1154 fecal samples from children and adults, 497 bird droppings, 212 food samples, 92 water samples, and 500 lactose-negative E. coli strains were tested. A total of 42 E. albertii strains were isolated. The PCR method was suitable for their rapid identification. In total, 33.3% of E. albertii isolates were resistant to one antibiotic, and 16.7% to two. Isolates were sensitive to cefepime, imipenem, levofloxacin, gentamicin, trimethoprim/sulfamethoxazole, and did not produce ESBL β-lactamases. High genetic variability of E. albertii has been demonstrated. In the PFGE method, 90.5% of the strains had distinct pulsotypes. In MLST typing, 85.7% of strains were assigned distinct sequence types (STs), of which 64% were novel ST types. Cytolethal distending toxin (CDT) and Paa toxin genes were found in 100% of E. albertii isolates. Genes encoding toxins, IbeA, CdtB type 2, Tsh and Shiga (Stx2f), were found in 26.2%, 9.7%, 1.7%, and 0.4% of E. albertii isolates, respectively. The chromosome size of the tested strains ranged from 4,573,338 to 5,141,010 bp (average 4,784,003 bp), and at least one plasmid was present in all strains. The study contributes to a more accurate assessment of the genetic diversity of E. albertii and the potential threat it poses to public health.

In this study, using bilayer lipid membrane technique, we report a novel facet of antihemolytic activity of two tannins (1,2,3,4,5-penta-O-galloyl-β-D-glucose (PGG) and 1,2-di-O-galloyl-4,6-valoneoyl-β-D-glucose (dGVG)), which consists in inhibiting the formation of α-hemolysin channels and blocking the conductivity of already formed channels. These effects were observed at tannin concentrations well below minimal inhibitory concentration values for S. aureus growth. Using spectroscopic methods, we show that these two tannins differing in molecular structure but having the same number of -OH groups and aromatic rings form firm complexes with hemolysin in aqueous solutions, which may underlie the disruption of its subsequent interaction with the membrane, thus preventing hemolysis of erythrocytes. In all experimental settings, PGG was the more active compound compared to dGVG, that indicates the important role of the flexibility of the tannin molecule in interaction with the toxin. In addition, we found that PGG, but not dGVG, was able to block the release of the toxin by bacterial cells. This toxin is a strong pathogenic factor causing a number of diseases and therefore is considered as a virulence target for treatment of S. aureus infection, so the data obtained suggest that PGG and possibly other tannins of similar structure have therapeutic potential in fighting the virulence of S. aureus.

Due to its great medical and pharmaceutical importance, honey bee venom is considered to be well characterized both chemically and in terms of biomedical activity. However, this study shows that our knowledge of the composition and antimicrobial properties of Apis mellifera venom is incomplete. In this work, the composition of volatile and extractive components of dry and fresh bee venom (BV) was determined by GC-MS, as well as antimicrobial activity against seven types of pathogenic microorganisms. One-hundred and forty-nine organic C1–C19 compounds of different classes were found in the volatile secretions of the studied BV samples. One-hundred and fifty-two organic C2–C36 compounds were registered in ether extracts, and 201 compounds were identified in methanol extracts. More than half of these compounds are new to BV. In microbiological tests involving four species of pathogenic Gram-positive and two species of Gram-negative bacteria, as well as one species of pathogenic fungi, the values of the minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC) were determined for samples of dry BV, as well as ether and methanol extracts from it. Gram-positive bacteria show the greatest sensitivity to the action of all tested drugs. The minimum MIC values for Gram-positive bacteria in the range of 0.12–7.63 ng mL−1 were recorded for whole BV, while for the methanol extract they were 0.49–125 ng mL−1. The ether extracts had a weaker effect on the tested bacteria (MIC values 31.25–500 ng mL−1). Interestingly, Escherichia coli was more sensitive (MIC 7.63–500 ng mL−1) to the action of bee venom compared to Pseudomonas aeruginosa (MIC ≥ 500 ng mL−1). The results of the tests carried out indicate that the antimicrobial effect of BV is associated with the presence of not only peptides, such as melittin, but also low molecular weight metabolites.

A proper understanding of silver (Ag) nanoparticles properties is fundamental for developing new antimicrobial agents. In this study, Ag nanoparticles were obtained by green synthesis methods using natural reducing agents present in extracts of apples, oranges, potatoes, red pepper, white onion, garlic and radish. The antimicrobial properties of respective nanoparticles, expressed as the minimum inhibitory concentration, were assessed against Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Candida krusei. Characterization of Ag nanoparticles was done with the application of transmission electron microscopy, X-ray diffraction and UV-vis spectroscopy. The obtained results led to the conclusions that in each extract (pH from 2.1 to 6.2) were obtained specific particles (size from 9 to 30 +/- 2 nm) with different antimicrobial activity. Our study indicates that plant extracts gives the Ag nanoparticles specific properties, yet the best antimicrobial properties show nanoparticles obtained in the presence of potato extract.

The chemical composition of propolis of four species of stingless bees (SLBs) from Argentina was determined, and its antibacterial and anticancer activity was evaluated on selected types of microbes and cancer cell lines. Volatile secretions of all propolis samples are formed by 174 C2–C15 organic compounds, mainly mono- and sesquiterpenes and their derivatives. The chromatograms of ether extracts showed 287 peaks, of which 210 were identified. The most representative groups in the extracts of various propolis samples were diterpenoids (mainly resin acids), triterpenoids and phenolic compounds: long-chain alkenyl phenols, resorcinols and salicylates. The composition of both volatile and extractive compounds turned out to be species-specific; however, in both cases, the pairwise similarity of the propolis of Scaptotrigona postica and Tetragonisca fiebrigi versus that of Tetragona clavipes and Melipona quadrifasciata quadrifasciata was observed, which indicated the similarity of the preferences of the respective species when choosing plant sources of resin. The composition of the studied extracts completely lacked flavonoids and phenolcarboxylic acids, which are usually associated with the biological activity and medicinal properties of propolis. However, tests on selected microbial species and cancer cell lines showed such activity. All propolis samples tested against Paenibacillus larvae, two species of Bacillus and E. coli showed biofilm inhibition unrelated to the inhibition of bacterial growth, leading to a decrease in their pathogenicity. Testing the anticancer activity of ether extracts using five types of cell cultures showed that all four types of propolis studied inhibit the growth of cancer cells in a dose- and time-dependent manner. Propolis harvested by T. clavipes demonstrated the highest cytotoxicity on all tested cell lines.

Polyphenols, including tannins, are phytochemicals with pronounced antimicrobial properties. We studied the activity of two hydrolysable tannins, (i) gallotannin—1,2,3,4,5-penta-O-galloyl-β-D-glucose (PGG) and (ii) ellagitannin—1,2-di-O-galloyl-4,6-valoneoyl-β-D-glucose (dGVG), applied alone and in combination with antibiotics against Staphylococcus aureus strain 8324-4. We also evaluated the effect of these tannins on bacterial membrane integrity and fluidity and studied their interaction with membrane proteins and lipids. A correlation between the antimicrobial activity of the tannins and their membranotropic action depending on the tannin molecular structure has been demonstrated. We found that the antibacterial activity of PGG was stronger than dGVG, which can be associated with its larger flexibility, dipole moment, and hydrophobicity. In addition, we also noted the membrane effects of the tannins observed as an increase in the size of released bacterial membrane vesicles.

Phenolic acids represent a class of drugs with mild antibacterial properties. We have synthesized iodinated gallic and ferulic acids and together with commercially available iodinated forms of salicylic acids studied their cytotoxicity, bacteriostatic and anti-virulence action. Out of these, iodogallic acid had lowest minimal inhibitory concentration (MIC) against Staphylococcus aureus (MIC = 0.4 mM/118.8 μg/ml). Yet, it had strong effect on erythrocyte membrane lipid ordering and on α-hemolysin secretion by the bacteria at lower non-bacteriostatic and non-cytotoxic concentrations (<0.1 mM). Iodogallic acid formed static complexes with α-hemolysin in solutions (logKb = 4.69 ± 0.07) and inhibited its nano-pore conduction in artificial lipid bilayers (IC50 = 37.9 ± 5.3 μM). These effects of iodogallic acid converged on prevention of hemolysis induced by α-hemolysin (IC50 = 41.5 ± 4.2 μM) and pointed to enhanced and diverse anti-virulence properties of some aryl iodides. The analysis of molecular surface electrostatic charge distribution, molecular hydrophilicity, electronegativity, and dipole moment of studied compounds suggested the importance of the number of hydroxyl groups and their proximity to iodine in anti-virulence activity manifestation. In iodogallic acid, charge redistribution resulted in higher hydrophilicity without concomitant change in overall molecular electronegativity and dipole moment compared to non-iodinated gallic acid. This study shows new directions for the development of antibacterial/antivirulence therapeutics.