Biofouling remains as a major operational challenge in membrane-based processes, and non-oxidizing biocides have emerged as practical tools to control microbial growth and biofilm formation. Alternatives to the conventional biocide 2,2-dibromo-3-nitrilepropionamide (DBNPA) requires evaluation of both antimicrobial efficiency and membrane compatibility, particularly under realistic seawater conditions. This study assessed the effects of sodium benzoate (SB) and 2-methyl-4-isothiazolin-3-one (MIT) on polyamide nanofiltration (NF) membranes and their performance against mixed marine bacterial communities. Membrane–biocide compatibility was examined by scanning electron microscopy, Fourier transform infrared spectroscopy, atomic force microscopy, and contact angle measurements. No significant morphological and chemical changes were observed after exposure to SB, MIT, or DBNPA. Long-duration performance tests confirmed the compatibility of these biocides and the polyamide membrane. Antimicrobial efficiency was determined by minimum inhibitory concentration (MIC) assays against total anaerobic heterotrophic bacteria obtained from the effluent of offshore sulfate removal units. SB exhibited limited antimicrobial activity despite its membrane compatibility. In contrast, MIT showed the lowest MIC values (80 ± 20 mg/L), outperforming DBNPA while maintaining membrane integrity. These findings highlight MIT as a promising biocide for controlling biofouling in NF processes. Moreover, combining MIT with DBNPA could provide synergistic effects, enhance biofouling control while preserve membrane integrity.

IntroductionMicrobiologically influenced corrosion (MIC) poses a persistent challenge in industrial systems, particularly in oilfield infrastructure, where biofilm-forming microorganisms accelerate metal degradation. This study evaluated the anticorrosive, antibiofilm, and biocidal properties of two bioproducts—a bioemulsifier from Psychrobacillus antarcticus Val9 and a surfactin from Bacillus velezensis H2O-1— simulating water injection header conditions.MethodsThe bioproducts were produced and characterized through emulsification indices, surface tension, and oil displacement assays. Their protective effects against biocorrosion were assessed via carbon steel mass loss, scanning electron microscopy, epifluorescence microscopy, surface roughness analysis, ATP quantification, and molecular profiling of microbial communities.Results and DiscussionThe compounds demonstrated desirable physicochemical properties and maintained stability under the tested conditions. All the treatments significantly reduced the carbon steel mass loss over 96 h, with protection rates ranging from 58.2% ± 11.3 to 94.6% ± 2.0. Microscopic analyses revealed diminished biofilm roughness and disrupted extracellular matrix cohesion, indicating impaired biofilm maturation. ATP assays and qPCR data revealed selective microbial suppression without triggering metabolic rebound, suggesting the destabilization of biofilm homeostasis. Furthermore, 16S rRNA gene sequencing and absolute quantification revealed a shift in the microbial community structure, with a reduced abundance of corrosion-associated taxa and enrichment of fewer metal-aggressive genera.ConclusionThese findings highlight the dual action of the tested bioproducts: direct surface protection and strategic microbial community modulation. This integrated approach offers a sustainable alternative to conventional chemical biocides, with potential applications in offshore pipelines and industrial water systems.

Magnetoreception is a remarkable ability found across a diverse range of organisms, including bacteria, birds, fish, insects, and mammals, enabling them to detect and harness the Earth's geomagnetic field. Recently, the recruitment of biomineralizing ectosymbionts by euglenozoans was evidenced as an ecological strategy for microeukaryotes to acquire this sense. Here, we report a case of magnetosymbiosis involving a ciliate and four populations of endosymbiotic bacteria experiencing genome reduction. Among these bacteria, one group of sulphate-reducing Desulfovibrionales was found to biomineralize bundles of bullet-shaped magnetite crystals. The ciliate's magnetotaxis mirrors that of free-living magnetotactic bacteria and euglenozoans, enabling efficient navigation in chemically stratified aquatic environments. However, in this case, magnetotaxis arises from an endosymbiotic interaction. Using a combination of optical-, confocal-, electron- and X-ray-based microscopy techniques, together with genomic analyses, these findings demonstrate that magnetosymbiosis can emerge in unicellular eukaryotic lineages through endosymbiotic integration, expanding our understanding of such interactions in aquatic ecosystems. More broadly, this work contributes to the ongoing debate on the origins of magnetoreception in eukaryotes.

Membrane models are available for the in vitro investigation of drug-membrane interactions. One potential new model for this purpose is bacterial magnetosomes, nanometric magnetic crystals surrounded by a protein-rich bilayer isolated from magnetotactic bacteria. In this work, we evaluated the relationship between the hydrophobicity of three drugs with different partition coefficients, and their adsorption into the magnetosome membrane. Adsorption values showed a clear positive trend with the partition coefficients (log P), suggesting that membrane association increases with compound lipophilicity. We also compared loading capacities between the magnetosomes of prismatic and cuboctahedral morphologies. Despite their larger volume and the smaller specific area, prismatic magnetosomes could adsorb a 1.6 times greater concentration of fluorescent-labeled poly-l-lysine. Different protein denaturation protocols were also tested to investigate their effects on membrane functionalization. In this brief communication, we propose a novel and facile utilization of magnetosomes as low-cost and magnetically responsive nanotools for drug characterization.

The biotechnological potential of microalgae is significant in various industrial sectors, but inefficient and expensive harvesting techniques hinder its widespread use. Regarding cell separation and concentration, few works used magnetic materials to harvest the cells. In general, the interaction between the mineral particles and cells is greatly influenced by pH and salinity conditions, which can limit their range of applications. Biogenic magnetite nanoparticles (BMs) produced by magnetotactic bacteria have unique magnetic properties and surface chemistry that can be applied for microalgae harvesting. In our experimental procedure, it was defined that 80 mu g BMs center dot mL- 1 under a more acidic pH was ideal for the process with cell density ranging from 3 center dot 103 to 1,2 center dot 104 cells/ mL. At pH 3.1, it was possible to magnetically concentrate up to 80.08 +/- 2.08 % and 75.26 +/- 2.45 % of Scenedesmus sp. and Desmodesmus sp. biomass, respectively. BMs also showed a reasonable recovery rate (52.08 %) when challenged under hypersaline conditions (40 g NaCl center dot L- 1) at pH 3.1 for Nannochloropsis sp. In this condition, synthetic magnetite nanoparticles (SMPs) and flocculants are ineffective in biomass harvesting. Thus, this work describes the process and efficiency of a magnetic nanotool capable of magnetically concentrating microalgae for downstream applications.

Biotechnology and sustainable strategies are the way forward for increasing global food production. The use of plant growth-promoting bacteria to increase the productivity of important food crops helps reduce the need for land expansion, improves soil fertility and plant tolerance to adverse abiotic conditions, and increases the ability to combat phytopathogens. Paenibacillus brasilensis strain PB24 is an endospore-forming bacterium that promotes plant growth through various direct and indirect mechanisms. To improve the understanding of its ability to inhibit the fungus Fusarium oxysporum, which causes numerous agricultural pathologies, the potential of P. brasilensis PB24 as a producer of antifungal compounds was investigated. In vitro assays demonstrated fungicidal activity against F. oxysporum hyphae. Additionally, genome mining of P. brasilensis PB24 was conducted to identify biocontrol and plant growth-promoting traits. For the first time, these traits were compared with those of other Paenibacillus species, and several genetic similarities were identified. Genome mining revealed that strain PB24 produces several antimicrobial compounds, similar to fusaricidin and sevadicin, but retains substantial differences in their monomers, suggesting that they may be novel lipopeptides. A unique genetic cluster was characterized in the PB24 genome as a potential resource for the discovery of new compounds. The results demonstrate the biotechnological potential of P. brasilensis PB24 for plant growth and biocontrol of phytopathogens and provide a basis for the future development of sustainable biocontrol strategies and commercial bacterial formulations.

Magnetotactic bacteria (MTB) are microorganisms that biomineralize intracellular magnetic nanoparticles inside a membrane vesicle/invagination. The set membrana + magnetic nanoparticle is known as magnetosome and generally magnetosomes are organized in linear chains in the cytoplasm, conferring a magnetic moment to the MTB. Due to their magnetic properties, MTB swim by following local magnetic field lines. This property makes MTB a suitable model to study bacterial movement. There are theoretical models to analyze the swimming of MTB, but the majority consider monotrichous bacteria. Only one model is related to the swimming of bilophotrichous bacteria, but they do not report the resultant trajectory parameters as a function of the magnetic field. Also, the literature lacks an experimental analysis of the trajectories of bilophotrichous MTB. The present study analyzes the movement of the bilphotrichous MTBMagnetofaba australisstrain IT-1 exposed to different magnetic field intensities. The trajectories are composed of two oscillations, one of low frequency and large amplitude and another of high frequency and small amplitude. The amplitudes show a magnetic field dependency, and the frequencies show to be magnetic field independent. The analysis of the trajectory orientation relative to the magnetic field direction shows that magnetotaxis ofM. australisfor low magnetic fields is not as efficient as expected, perhaps due to living in a liquid culture medium rich in nutrients. As far as we know, this is the first time that these movement data have been obtained, and they will be important to validate future theoretical models of movement for bilophotrichous MTB.

Magnetotactic bacteria (MTB) are Gram-negative, ubiquitous, aquatic, flagellated, microaerophilic, or anaerobic microorganisms exhibiting magnetotactic behaviour based on magnetosomes, which are the structural signature of the group. Magnetosomes are ferrimagnetic nanocrystals surrounded by a lipid bilayer, usually aligned in chain(s) within the cell. Environmental abiotic conditions such as salinity, dissolved oxygen, pH, and oxidation-reduction potential may drive the diversity of MTB populations in environments. Our results reported the first evidence of MTB in sediments sampled from the Araguaia River floodplain in the Amazon-Cerrado biome. Light microscopy showed at least six morphotypes of South-seeking MTB. Transmission electron microscopy and energy-dispersive X-ray spectroscopy observations demonstrated magnetite cuboctahedral, prismatic, and anisotropic magnetosomes. PCA ordination demonstrated a more significant influence of depth, ORP (oxidation-reduction potential), and transparency in sampled data from the river main channel (MC). Non-metric multidimensional scaling (NMDS) ordination and correlation analysis demonstrated a difference between MTB populations inhabiting MC and lakes and affluent (LA). NGS and bioinformatic analysis revealed higher richness and diversity among magnetotactic cocci and the majority phylogenetic assignment of MTB affiliated to Pseudomonadota phylum. Hence, the complete acquisition of these results will provide further insight into magnetotaxis characterisation and the abiotic factors that impact MTB spatial distribution.

Magnetotactic bacteria (MTB) are microorganisms that biomineralize intracellular magnetic nanoparticles inside a membrane vesicle/invagination. The set membrana + magnetic nanoparticle is known as magnetosome and generally magnetosomes are organized in linear chains in the cytoplasm, conferring a magnetic moment to the MTB. Due to their magnetic properties, MTB swim by following local magnetic field lines. This property makes MTB a suitable model to study bacterial movement. There are theoretical models to analyze the swimming of MTB, but the majority consider monotrichous bacteria. Only one model is related to the swimming of bilophotrichous bacteria, but they do not report the resultant trajectory parameters as a function of the magnetic field. Also, the literature lacks an experimental analysis of the trajectories of bilophotrichous MTB. The present study analyzes the movement of the bilphotrichous MTB Magnetofaba australis strain IT-1 exposed to different magnetic field intensities. The trajectories are composed of two oscillations, one of low frequency and large amplitude and another of high frequency and small amplitude. The amplitudes show a magnetic field dependency, and the frequencies show to be magnetic field independent. The analysis of the trajectory orientation relative to the magnetic field direction shows that magnetotaxis of M. australis for low magnetic fields is not as efficient as expected, perhaps due to living in a liquid culture medium rich in nutrients. As far as we know, this is the first time that these movement data have been obtained, and they will be important to validate future theoretical models of movement for bilophotrichous MTB.

Cutaneous leishmaniasis remains a neglected tropical disease with limited treatment options. Available therapies include costly and toxic drugs for which recurrent cases of resistance are reported. Drug delivery systems based on the association of approved drugs and nanoparticles have improved pharmacological properties of the drug, such as targeted therapy, enhanced drug solubility, reduced side effects, and potentially lower doses required for effective treatment. In this study, we explored the in vitro potential use of the nanobiomagnetite produced by magnetotactic bacteria functionalized with amphotericin B against promastigotes of Leishmania amazonensis, one of the main pathogens of cutaneous leishmaniasis. Additionally, the antileishmanial activity of the nanoformulation was significantly increased in association with alternating magnetic field (AMF) exposure, indicating an advantage in the therapeutic efficacy of the drug, potentially leading to a combined therapy. In addition, to assess the preliminary safety of the nanoformulation, we assessed its cytotoxicity on HaCaT, hFB, and J774.16 cell lines; none of the tested nanoformulations were cytotoxic toward these cell lines, suggesting their potential for biocompatible therapeutic applications. Moreover, no significant nitric oxide production was detected with the nanoparticle’s interaction on J774.16 macrophages. This finding is vital for further clinical considerations, as it reduces the risk of inflammatory responses. Thus, we demonstrated the biocompatibility and parasitic potential of functionalized nanobiomagnetite as an alternative AMF-responsive therapy in in vitro models. However, in vivo testing is still necessary to assess the nanoformulation activity against Leishmania.

Introduction: Anaerobic digestion integrates waste treatment, energy generation, and nutrient recycling, producing methane mainly through acetoclastic (AM) and hydrogenotrophic methanogenesis (HM). Methanogenic pathway management can improve biogas productivity and quality. The balance between pathways is influenced by environmental and physicochemical conditions, with conflicting results on the effect of different factors often reported. This systematic review aims to clarify the influence of various parameters on methanogenic pathways in anaerobic digesters. Methods: Literature search was conducted in the Web of Science and Scopus databases. The effects of different parameters on the predominant methanogenic pathway were evaluated using Kruskal-Wallis tests and Spearman's rank correlation. Results: Thermophilic temperatures and high free ammonia nitrogen concentrations (>300 mg L- 1) increase HM, with a strong combined effect of these variables. Conversely, under moderate temperature and ammonia concentrations, the primary feedstock influences the methanogenic pathway, with algae biomass, pig manure, and food industry wastewater showing the lowest contribution of hydrogenotrophic methanogens. pH effect varied with temperature, with acidic and alkaline pH favoring HM in mesophilic and thermophilic digesters, respectively. Furthermore, higher levels of volatile fatty acids (>2000 mg L- 1), carbohydrates (>10 g/L) and lipids (>10 g/L) also appeared to favor HM over AM, while most metals - especially Cr, Se and W - promoted AM. Conclusion: This study emphasizes the role of various factors in methanogenic pathway selection, highlighting the impact of previously overlooked parameters, such as inorganic elements and organic matter composition. These insights are essential for understanding the methanogenic pathway balance and optimizing biogas processes.

Magnetotactic bacteria (MTB) are a broad and diverse group of Gram-negative prokaryotes that biomineralize magnetosomes, organelles composed of a magnetic nanocrystal of magnetite (Fe3O4) or greigite (Fe3S4) and enveloped by a biological membrane. Magnetosomes are arranged in one or more chains intracellularly, which impart a magnetic moment to the cell. These structures permit a passive orientation of the MTB with the geomagnetic field lines (GML), which, when associated with swimming propelled by flagella, originate a phenomenon called magneto-aerotaxis, an important life strategy in a chemical stratified environment. There is a classical model based on elongated cells as vibrios and rods that tries to explain the magneto-aerotaxis. Still, this model raises questions when applied to other morphologies other than elongated cells. Here, we observe the spatial disposition of magnetosomes, motility behavior, and influence of magneto-aerotaxis in Magnetofaba australis strain IT-1, an MTB that achieves high swimming speeds and has some peculiarity in its motility. The three-dimensional reconstruction showed that Mf. australis strain IT-1's magnetosome chain is misaligned with the swimming axis, which makes it impossible to use the classical model to explain magneto-aerotaxis in this MTB. Despite this, Mf. australis strain IT-1 was capable of swimming aligned to the GML. Also, this work studied the influence of the magnetosome and magneto-aerotaxis between populations of Mf. australis strain IT-1 with and without magnetosomes. Our results indicated that the magnetosome presence not only positively influences the movement in Mf.australis strain IT-1 but also can positively impact population growth in these MTB.

AIMS:This study aimed to assess the antimicrobial potential of Bp1-AdE, produced by Bacillus pumilus 64-1, and to investigate its mode of action against Staphylococcus aureus and methicillin-resistant S. aureus (MRSA). METHODS AND RESULTS:Bp-1AdE, derived from sponge-associated B. pumilus, exhibited bactericidal activity at 1 550 µg ml-1 against S. aureus ATCC29213 and MRSA strains. Light and fluorescence microscopy revealed drastic cell lysis of S. aureus treated with Bp-1AdE. Scanning and transmission electron microscopy suggested that Bp-1AdE disrupts the cytoplasmic membrane. Toxicity assays showed that Bp-1AdE was non-toxic to Tenebrio molitor larvae. Liquid chromatography-mass spectrometry and Global Natural Product Social spectral libraries identified four substances within Bp-1AdE, including aliphatic alcohols [3,4-dipentylhexane-2,5-diol and 1,1'-(4,5-dibutyl-3,6-dimethylcyclohexane-1,2-diyl)bis(ethan-1-one)] and terpenoids (cholic acid and canrenone). CONCLUSIONS:Bp-1AdE demonstrated selective toxicity and bactericidal activity, highlighting its potential for controlling infections caused by multidrug-resistant S. aureus strains.

Disposed plastics in oceans provide a substrate to which microbes can adhere and structure the biofilm, namely the plastisphere. In this study, we showed that the mesoplastic density-based separation, routinely used in quantification assays, is detrimental to studying the microbiome diversity and ecology as it underestimates the real microbial diversity within these samples. Based on SEM and microbiome observations, we propose that chemically fixing samples before density separation preserves cellular diversity (2.32-fold change) and richness (1.12-fold change) that would be naturally lost due to the current methodology. OTUs assigned to Gram-negative bacterial species are the most negatively affected by omitting fixation and polymer composition was not decisive in shifting microbiome composition. Considering our findings, the formaldehyde-fixation step should be incorporated into the current methodology described in most studies as this is crucial to promote a deeper understanding of the microbial community in this ecosystem and biofilm-adhered scattering through aquatic ecosystems.

ABSTRACT In semi-arid regions, the use of brackish water for irrigation can reduce crop yields. However, the use of mineral fertilizer has been tested to mitigate salt stress. In this context, the objective was to evaluate the effect of salt stress at different phenological stages on the yield of peanut under potassium fertilization. The experiment was carried out from August to November 2021, in the experimental area of the Universidade da Integração da Lusofonia Afro-Brasileira (UNILAB), Redenção, Ceará, Brazil. The experimental design was completely randomized (CRD), in a 6 × 3 factorial scheme, with 6 replicates. Six strategies of irrigation with brackish water were applied from the following stages: vegetative (S1); flowering (S2); gynophore appearance (S3); pod formation (S4); fruiting (S5) and without salt stress (S6), and three doses of potassium: 0, 50 and 100% of the recommended dose. The use of brackish water in the vegetative stage led to lower pod length, pod mass, number of pods, number of marketable pods and yield. The dose corresponding to 100% of the recommended potassium dose mitigated salt stress in the pod formation and flowering stages, promoting a greater number of marketable pods, number of non-marketable pods, total number of pods and pod mass. The use of water with lower salinity throughout the cycle promoted greater pod mass, number of marketable pods and yield.

Magnetotactic bacteria are microorganisms that produce intracellular magnetic nanoparticles organized in chains, conferring a magnetic moment to the bacterial body that allows it to swim following the geomagnetic field lines. Magnetotactic bacteria usually display two swimming polarities in environmental samples: the South-seeking (SS) polarity and the North-seeking (NS) polarity, characterized by the bacteria swimming antiparallel or parallel to the magnetic field lines, respectively. It has been observed that in the presence of inhomogeneous magnetic fields, NS magnetotactic bacteria can change their swimming polarity to SS or vice versa. The present study analyzes populations of NS cocci obtained from SS cocci isolated in the presence of a magnet. The aim was to study differences in the swimming characteristics and magnetic moment among both populations of cocci. For that, trajectories were recorded and the velocity and angle among the velocity and the applied magnetic field were calculated. In addition, micrographs from both SS and NS cocci were obtained and their magnetosomes were measured to analyze their length, width, aspect ratio and magnetic moment, to finally obtain the magnetic moment for each coccus. The results showed the following properties of NS relative to SS cocci: higher velocities, narrow bacterial magnetic moment distribution, higher dispersion in the distribution of angles among the velocity and the applied magnetic field and lower magnetic field sensibility. Those differences cannot be explained by the simple change in magnetic polarity of the magnetosome chain and can be related to the existence of an active magnetoreceptive process in magnetotactic bacteria.

The detection of magnetic fields by animals is known as magnetoreception. The ferromagnetic hypothesis explains magnetoreception assuming that magnetic nanoparticles are used as magnetic field transducers. Magnetite nanoparticles in the abdomen of Apis mellifera honeybees have been proposed in the literature as the magnetic field transducer. However, studies with ants and stingless bees have shown that the whole body of the insect contain magnetic material, and that the largest magnetization is in the antennae. The aim of the present study is to investigate the magnetization of all the body parts of honeybees as has been done with ants and stingless bees. To do that, the head without antennae, antennae, thorax, and abdomen obtained from Apis mellifera honeybees were analyzed using magnetometry and Ferromagnetic Resonance (FMR) techniques. The magnetometry and FMR measurements show the presence of magnetic material in all honeybee body parts. Our results present evidence of the presence of biomineralized magnetite nanoparticles in the honeybee abdomen and, for the first time, magnetite in the antennae. FMR measurements permit to identify the magnetite in the abdomen as biomineralized. As behavioral experiments reported in the literature have shown that the abdomen is involved in magnetoreception, new experimental approaches must be done to confirm or discard the involvement of the antennae in magnetoreception.

Two microbial pathways are responsible for most of the methane produced during anaerobic digestion: acetoclastic methanogenesis (AM) and hydrogenotrophic methanogenesis (HM) coupled with syntrophic acetate oxidation (SAO). Identifying the dominant methanogenic pathway active in a system provides the information necessary to manage and optimize productivity, stability, process control, and gas quality in biogas reactors. In this study, a modified method is proposed to estimate methanogenic pathways in different biogas systems via short-term parallel incubations with methyl-labeled acetate (2-13C-acetate). Cavity ring-down spectroscopy was applied to measure the δ13C–CH4 and δ13C–CO2 isotopic signatures of produced biogas. Preliminary experiments demonstrated that longer incubation times led to significant variations in δ13C–CH4 and δ13C–CO2 and consequently interfered with the calculated fraction of CH4 produced from HM (fHM). This variability is likely caused by the dilution of 13CH4 and 13CO2 as 2-13C-acetate is consumed, along with potential changes in organic matter quality and quantity, microbial community composition, and environmental factors such as pH, volatile fatty acid content, and ammonia levels, during longer incubations. We applied this new approach to sludge from six full-scale reactors (three mesophilic and three thermophilic) and validated its potential with consistent estimates of fHM with minimal variation. Mesophilic reactors exhibited AM dominance, while HM was the dominant pathway in thermophilic reactors, aligning with reports in the literature.

Endocrine-disrupting compounds (EDCs) are a group of emergent pollutants that affect the endocrine system. EDCs can cause harm to humans and animals and unbalance the aquatic ecosystem even at low concentrations. Several methods are applied to remove EDCs, and recently, magnetic nanoparticles (MNPs), a low-cost and magnetically-responsive approach, have been introduced as modern innovative tools for this purpose. Thus, we conducted a systematic analysis to determine the characteristics of MNPs required to optimize EDCs removal in water/waste treatments. Most studies used magnetite (Fe3O4) nanoparticles, a low-cost and easily acquired material, followed by other metallic oxides nanoparticles (MOPs) like zinc, copper, and nickel oxides. Short adsorption time (0.5–15 min) and small MNP (10–80 nm) were the most prominent and successful in EDCs recovery approaches. After analyzing data published in the last decade, results showed that, in general, processes that apply lower concentrations of MNP seem to achieve a significant higher removal rate. For instance, MNPs formulations are able to successfully remove >90% of bisphenols and phthalates. However, depending on the EDCs type, the concentration of MNPs have to be adjusted to increase EDCs recovery rates, possibly due to their different chemical compositions and properties. Our results indicate that MNPs are an efficient, with potential to be a relatively cheap way to extract or eliminate EDCs from wastewater and should be considered an innovative tool to be included in waste treatment protocols.