Search Results (398)

Microorganisms serve as a vital source of natural anticancer agents, with many of their secondary metabolites already employed in clinical oncology. In recent years, salt-adapted microbes, including halophilic and halotolerant species from marine, salt lake, and other high-salinity environments, have gained significant attention. Their unique adaptation mechanisms and diverse secondary metabolites offer promising potential for novel anticancer drug discovery. This review consolidated two decades of research alongside current global cancer statistics to evaluate the therapeutic potential of salt-adapted microorganisms. Halophilic and halotolerant species demonstrate significant promise, with their bioactive metabolites exhibiting potent inhibitory effects against major cancer cell lines, particularly in lung and breast cancer. Evidence reveals structurally unique secondary metabolites displaying enhanced cytotoxicity compared to conventional anticancer drugs. Collectively, salt-adapted microorganisms represent an underexplored yet high-value resource for novel anticancer agents, offering potential solutions to chemotherapy resistance and treatment-related toxicity. Full article

Antibiotic resistance is one of the most significant public health issues today. As a consequence, there is an urgent need for novel classes of antibiotics. This necessitates the development of highly efficient screening methods for the rapid identification of antibiotic-producing bacteria. Here, we describe a new method for high-throughput screening of antimicrobial compounds (AMC) producing halophilic bacteria. Our methodology used a newly designed 3D-printed Petri plate replicator used for drop deposition and colony replication. We employed this device in combination with a modified agar overlay assay to screen more than 7400 bacterial colonies. A total of 54 potential AMC producers were discovered at a success rate of 0.7%. Although 40% of them lost their antibacterial activity during the secondary screening, 22 strains retained inhibitory activity and were able to suppress the growth of one or more safe relatives of the ESKAPE group pathogens. The ethyl acetate extract from the most potent strain, Virgibacillus salarius POTR191, demonstrated moderate antibacterial activity against Enterococcus faecalis, Acinetobacter baumanii, and Staphylococcus epidermidis with minimal inhibitory concentrations of 128 μg/mL, 128 μg/mL, and 512 μg/mL, respectively. We propose that our replica plate assay could be used for target-based antimicrobial screening of various extremophilic bacteria. Full article

Accurate gene expression quantification using reverse transcription quantitative PCR (RT-qPCR) requires stable reference genes (RGs) for reliable normalization. However, few studies have systematically identified RGs suitable for simultaneous high salt, alkaline, and high-temperature conditions. This study addresses this gap by evaluating the stability of eight candidate RGs in the anaerobic halophilic alkalithermophile Natranaerobius thermophilus JW/NM-WN-LF^T under combined salt, alkali, and thermal stresses. The stability of these candidate RGs was assessed using five statistical algorithms: Delta CT, geNorm, NormFinder, BestKeeper, and RefFinder. Results indicated that recA exhibited the highest expression stability across all tested conditions and proved adequate as a single RG for normalization in both RT-qPCR and droplet digital PCR (ddPCR) assays. Furthermore, recA alone or combined with other RGs (sigA, rsmH) effectively normalized the expression of seven stress-response genes (proX, opuAC, mnhE, nhaC, trkH, ducA, and pimT). This work represents the first systematic validation of RGs under polyextreme stress conditions, providing essential guidelines for future gene expression studies in extreme environments and aiding research on microbial adaptation mechanisms in halophilic, alkaliphilic, and thermophilic microorganisms. Full article

Reported herein is a further expansion of the cooperatively catalyzed Koenigs–Knorr glycosylation reaction, known as “the 4K reaction”. It has been discovered that molecular iodine, along with a metal salt and an acid additive, can activate thioglycosides. Previous mechanistic studies showed the interaction of the anomeric sulfur with thiophilic iodine; this complex is stable until the halophilic metal salt and the acid additive are added. This new avenue has allowed for the investigation of halophilic promoters that would not activate thioglycosides without iodine. Presented herein is the recent discovery of iron(III) triflate as an efficient activator of thioglycosides via the 4K reaction pathway. Full article

Most large-scale crude oil spills occur in marine environments. We screened easily propagable/maintainable halophiles to develop agents for the bioremediation of marine spills. A bacterial strain isolated from a polluted region of the Great Salt Lake was characterized and tested for its ability to degrade crude oil. The strain (Salinivibrio costicola) is motile, catalase- and lipase-positive, a facultative anaerobe, and an obligate halophile. Its growth optimum and tolerance ranges are: NaCl (5%, 1.25–10%), pH (8, 6–10), and temperature (22 °C, 4–45 °C). Its genome (3,166,267 bp) consists of two circular chromosomes and a plasmid, containing 3197 genes, including some genes potentially relevant to hydrocarbon metabolism. The strain forms a biofilm but is considered nonpathogenic and is sensitive to some common antibiotics. Lytic bacteriophages infecting the strain are rare in the water samples we tested. The strain survived on desiccated agar media at room temperature for a year, grew optimally in complex media containing 0.1–1% crude oil, but failed to reduce total recoverable petroleum hydrocarbons from crude oil. Thus, a recalcitrant halophile may endure crude oil without mineralizing. Due to some of their advantageous attributes, such strains can be considered for genetic manipulation to develop improved agents for bioremediation. Full article

The strain of Oceanobacillus picturae DY09, as a typical halophilic microorganism, possesses distinctive salt adaptation mechanisms that hold significant application value in the fields of agriculture, industry, and biomedicine. To deeply analyze the salt-tolerance molecular mechanism of this strain, this research disclosed its salt-tolerance strategies under diverse salt concentrations through transcriptomics. In a low-salt environment, the DY09 strain adopted a “metabolic simplification” strategy, significantly reducing the metabolic load by promoting lysine degradation and inhibiting the biosynthesis of branched-chain amino acids and glycine betaine (GB) but upregulating the expression of the GB transporter gene betH and preferentially utilizing exogenous GB to maintain basic osmotic balance. When exposed to high-salt stress, this strain activated multiple regulatory mechanisms: it upregulated the expression of Na⁺/K⁺ antiporter proteins to maintain ionic homeostasis; the synthesis genes of amino acids such as arginine and proline were significantly upregulated, and the GB synthesis genes betA/B and the transporter gene betH were upregulated concurrently, which realized the synergistic operation of endogenous synthesis and exogenous uptake of osmoprotective substances. The expression level of the antioxidant enzyme systems is upregulated to scavenge reactive oxygen species. Simultaneously, the molecular chaperones groES/groEL and GB cooperate to maintain the functional stability of the protein. In this study, a trinity salt-tolerance-integrated strategy of “dynamic perception–hierarchical response–system synergy” of halophilic bacteria was initially proposed, which provided a research idea for exploring the salt–alkali-tolerant mechanism of halophilic bacteria and a theoretical basis for the further development and application of this strain. Full article

Small heat shock proteins (sHsps) are ubiquitous low-molecular-weight chaperones that prevent protein aggregation under cellular stress conditions. In the absence of stress, they assemble into large oligomers. In response to stress, such as elevated temperatures, they undergo conformational changes that expose hydrophobic surfaces, allowing them to interact with denatured proteins. At heat shock temperatures in bacteria, large sHsp oligomers disassemble into smaller oligomeric forms. Methanogens are a diverse group of microorganisms, ranging from thermophilic to psychrophilic and halophilic species. Accordingly, their sHsps exhibit markedly different temperature dependencies based on their optimal growth temperatures. In this study, we characterized sHsps from both hyperthermophilic and mesophilic methanogens to investigate the mechanisms underlying their temperature-dependent behavior. Using analytical ultracentrifugation, we observed the dissociation of sHsps from a mesophilic methanogen into dimers. The dissociation equilibrium of these oligomers was found to be dependent not only on temperature but also on protein concentration. Furthermore, by generating various mutants, we identified the specific amino acid residues responsible for the temperature dependency observed. The C-terminal region containing the IXI/V motif and the α-crystallin domain were found to be the primary determinants of oligomer stability and its temperature dependence. Full article

To date, the nitrogen metabolism pathways and salt-tolerance mechanisms of halophilic denitrifying bacteria have not been fully studied, and full-scale engineering trials with saline fly ash-washing wastewater have not been reported. In this study, we isolated and screened a halophilic denitrifying bacterium (Marinobacter sp.), GH-1, analyzed its nitrogen metabolism pathways and salt-tolerance mechanisms using whole-genome data, and explored its nitrogen removal characteristics under both aerobic and anaerobic conditions at different salinity levels. GH-1 was then applied in a full-scale engineering project to treat saline fly ash-washing leachate. The main results were as follows: (1) Based on the integration of whole-genome data, it is preliminarily hypothesized that the strain possesses complete nitrogen metabolism pathways, including denitrification, a dissimilatory nitrate reduction to ammonium (DNRA), and ammonium assimilation, as well as the following three synergistic strategies through which to counter hyperosmotic stress: inorganic ion homeostasis, organic osmolyte accumulation, and structural adaptations. (2) The strain demonstrated effective nitrogen removal under aerobic, anaerobic, and saline conditions (3–9%). (3) When applied in a full-scale engineering system treating saline fly ash-washing wastewater, it improved nitrate nitrogen (NO₃⁻-N), total nitrogen (TN), and chemical oxygen demand (COD) removal efficiencies by 31.92%, 25.19%, and 31.8%, respectively. The proportion of Marinobacter sp. increased from 0.73% to 3.41% (aerobic stage) and 2.86% (anoxic stage). Overall, halophilic denitrifying bacterium GH-1 can significantly enhance the nitrogen removal efficiency of saline wastewater systems, providing crucial guidance for biological nitrogen removal treatment. Full article

The genus Haloarcula is one of the most extensively studied genera within the class Halobacteria. In this study, analyses of average nucleotide identity (ANI), average amino acid identity (AAI), digital DNA–DNA hybridization (dDDH) values, and phylogenomic data indicated that “Haloarcula californiae” ATCC 33799 and “Haloarcula sinaiiensis” ATCC 33800 served as reference strains for Haloarcula marismortui. Furthermore, a halophilic archaeal strain, GH36^T, isolated from the inland Gahai Salt Lake in China, was subjected to comprehensive polyphasic taxonomic characterization. The ANI, AAI, and dDDH comparisons between strain GH36^T and other Haloarcula species were below the established thresholds for species demarcation. Strain GH36^T was assigned to a novel species within the genus Haloarcula based on phylogenetic, phylogenomic, and comparative genomic analyses. Moreover, distinct phenotypic differences were observed in strain GH36^T. In strain GH36^T, the primary phospholipids detected were phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), and phosphatidylglycerol sulfate (PGS), whereas the principal glycolipids were sulfated mannosyl glucosyl diether (S-DGD-1) and mannosyl glucosyl diether (DGD-1). Accordingly, the novel species Haloarcula montana sp. nov. is proposed to accommodate strain GH36^T (=CGMCC 1.62631^T = MCCC 4K00122^T). Full article

Skin photoaging, driven primarily by ultraviolet radiation, remains a critical dermatological concern. Carotenoids, a class of natural pigments with potent antioxidant properties, have emerged as promising agents for preventing and mitigating photoaging. This review comprehensively integrates current understanding regarding the triggers of skin photoaging, oxidative stress and their associated signal pathways, the photoprotective roles and mechanisms of carotenoids, as well as their bioavailability. Common C₄₀ carotenoids, such as β-carotene, lycopene, astaxanthin, lutein, and zeaxanthin demonstrate remarkable antioxidant activity, primarily attributed to their conjugated double bond structures. Many studies have demonstrated that both oral and topical administration of these C₄₀ carotenoids can effectively alleviate skin photoaging. Specifically, they play a crucial role in promoting the formation of a new skin barrier and enhancing the production of collagen and elastin, key structural proteins essential for maintaining skin integrity and elasticity. Mechanistically, these carotenoids combat photoaging by effectively scavenging reactive oxygen species and modulating oxidative stress responsive signal pathways, including MAPK, Nrf2, and NF-κB. Notably, we also anticipate the anti-photoaging potential of novel carotenoids, with a particular emphasis on bacterioruberin, a C₅₀ carotenoid derived from halophilic archaea. Bacterioruberin exhibits a superior radical scavenging capacity, outperforming the conventional C₄₀ carotenoids. Furthermore, when considering the application of carotenoids, aspects such as safe dosage, bioavailability, and possible long term usage issues, including allergies and pigmentation disorders, must be taken into account. This review underscores the anti-photoaging mechanism of carotenoids, providing strategies and theoretical basis for the prevention and treatment of photoaging. Full article

In Thailand, mangrove forests form a major component of the Andaman coastal ecosystems in the southern provinces. However, studies on their microbial assemblage largely revolved around groups of bacteria, fungi, and eukaryotic microalgae, while the diversity of cyanobacteria in these regions remains almost unknown. This taxonomic study applied the polyphasic approach to examine seven cyanobacterial strains collected from different mangrove environments (including soil crust, tree bark, wood, and rock surface) across Ranong, Phang-Nga, and Phuket provinces. The comprehensive analysis combining morphology, ecology, 16S rRNA phylogenetic relationships, genetic identity, ITS secondary structure, and ITS dissimilarity resulted in the first records of the genera Picosynechococcus, Allocoleopsis, and Sirenicapillaria in Thailand, and led to the description of a new species, Picosynechococcus mangrovensis sp. nov. This new species was differentiated from the type species P. fontinalis based on the distinct 16S rRNA gene phylogenetic position, low 16S rRNA genetic similarity, its slightly halophilic nature, and ability to form pseudo-filaments with up to 160 cells. Our research significantly expands the documented cyanobacterial diversity of Southeast Asian mangrove ecosystems, establishing a critical foundation for future ecological and biotechnological investigations in these understudied yet vital tropical habitats. Full article

Polyhydroxyalkanoates (PHAs), as biosynthetic and biodegradable polymers, serve as alternatives to petroleum-based plastics, yet face critical cost barriers in large-scale production. While magnetic field (MF) stimulation enhances microbial activity, the optimal MF parameters and metabolic mechanisms for PHA biosynthesis remain unexplored. This study optimized magnetic field parameters to increase PHA biosynthesis in Haloferax mediterranei. A custom-engineered electromagnetic system identified 110 mT of static magnetic field (SMF) as the optimal level for biosynthesis, reaching 77.97 mg/(L·h) PHA volumetric productivity. A pulsed magnetic field caused oxidative stress and impaired substrate uptake despite increasing PHA synthesis. Prolonged SMF exposure (72 h) maximized PHA productivity, while 48 h of exposure attained 90% efficiency. Metabolomics revealed that SMF-driven carbon flux redirection via regulated butanoate metabolism led to a 2.10-fold increase in (R)-3-hydroxybutanoyl-CoA), while downregulating acetoacetate (0.51-fold) and suppressing PHA degradation (0.15-fold). This study pioneers the first application of metabolomics in archaea to decode SMF-induced metabolic rewiring in Haloferax mediterranei. Our findings establish SMF as a scalable bioenhancement tool, offering sustainable solutions for the circular bioeconomy. Full article

Biodegradation is an advanced method for reducing plastic waste in the environment, involving the participation of microbial communities with plastic-degrading properties. Our study presents a novel halophilic community isolated from the plastic-contaminated region in Burgas Lake, Bulgaria. In a medium containing 15% sodium chloride, the community can degrade a significant amount of polycaprolactone (PCL) as a sole carbon source, as well as the plastics polystyrene (PS) and polypropylene (PP), albeit to a lesser extent. The community showed high hydrophobicity and the ability to form a biofilm on PCL beads, as well as high esterase activity and significant biodegradation capacity, as demonstrated by measuring the weight of the PCL material after cultivation for 4 and 8 weeks. Moreover, a scanning electron microscopy (SEM) analysis revealed visible cracks, craters, and holes in the surface of the polymer particles. The metagenomic study revealed that Halomonas profundus dominated the community with a proportion of 95.13%, followed by Alloalcanivorax venustensis (2.73%), Chromohalobacter marismortui (0.72%), and Halomonas caseinilytica (0.78%). However, most of the species in the community were not previously known as PCL-degrading. Thus, studying the diversity of the halophile community can significantly improve our fundamental understanding and clarify their potential applications for environmental and water–plastic remediation. Full article

Laccase production was evaluated in 108 fungal isolates recovered from the eastern coast of Saudi Arabia, a critical element in environmental biodegradation and biotransformation. The most active isolate was identified as Curvularia lunata MLK46 (GenBank accession no. PQ100161). It exhibited maximal productivity at pH 6.5, 30 °C, and incubation for 5 d, with 1% sodium nitrate and 1% galactose as the preferred nitrogen and carbon sources, respectively. Productivity was enhanced by NaCl, CuSO₄, and FeCl₃ supplementation, with a maximum at 0.3 mM, 0.2 mM, and 61.7 mM concentrations, respectively. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) for the purified enzyme through diethylaminoethyl (DEAE)-Sepharose chromatography revealed a prominent band at 71.1 kDa with maximum activity at pH 6 and stability at pH 6–9. Furthermore, it was optimally active at 50 °C and thermally stable at 50–80 °C with a half-life time (T_1/2) of 333.7 min to 80.6 min, respectively. Its activity was also enhanced by many metallic ions, especially Fe³⁺ ions; however, it was inhibited by Hg²⁺ and Ag⁺ ions. The enzyme demonstrated significant degradation of specific substrates such as 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), guaiacol, o-dianisidine, and 2,6-dichlorophenol, with a kinetic efficiency constant which ranged from 40.95 mM⁻¹ s⁻¹ to 238.20 mM⁻¹ s⁻¹. UV spectrophotometry confirmed efficient oxidation peaks by electron transition against guaiacol (at 300 nm), o-dianisidine (at 480 nm), ABTS (at 420 nm), and 2,6-dichlorophenol (at 600 nm). The results collectively demonstrate the potential of laccase from C. lunata MLK46 as a promising agent for the effective biodegradation of several industrial pollutants under extreme conditions. Full article

Vibrio parahaemolyticus, a halophilic Gram-negative bacterium commonly found in aquatic products, can colonize the human small intestine, causing gastroenteritis and potentially leukemia. As a major intestinal pathogen, it poses a significant threat to public health. This study aims to investigate the phenotypic heterogeneity of V. parahaemolyticus in the low-salinity and bile salt environments of the human intestinal tract and to elucidate its mechanisms of tolerance and pathogenicity using proteomics. The experimental results indicated that under the low salinity and bile salts conditions of the human intestinal environment, the growth, motility, and biofilm formation of the strains were significantly inhibited. Proteomics analysis revealed that, under these conditions, the energy metabolism, chemotaxis system, flagellar motor, and ribosome-related proteins of V. parahaemolyticus were significantly affected, thereby influencing its growth, motility, and biofilm formation. Furthermore, the activation of the secretion system, particularly the T2SS, enhanced the virulence of secreted factors on host cells. Additionally, the activation of the β-lactam resistance pathway increased resistance to the intestinal environment, thereby enhancing the pathogenicity of V. parahaemolyticus. Full article