Bacterial Strains Research Articles

In Vitro Efficacy Testing of TONS504-Based Photodynamic Antimicrobial Chemotherapy (TONS504-PACT) Under a 405-nm Light-Emitting Diode Against Antimicrobial-Resistant Bacteria Causing Canine Keratitis.

To evaluate the invitro efficacy of photodynamic antimicrobial chemotherapy (PACT) using TONS504, a newly developed hydrophilic and cationic photosensitizer, under a blue light emitting diode (LED) against antimicrobial-resistant bacteria isolated from dogs with keratitis. Three bacterial strains (i.e., methicillin-resistant Staphylococcus pseudintermedius, extended-spectrum beta-lactamase-producing Escherichia coli, and Pseudomonas aeruginosa), isolated from two dogs with keratitis, were used in this study after antimicrobial susceptibility tests. PACT using TONS504 (0.1-100 mg/L) was performed under a 405-nm LED at 30 J/cm2 (20 mW/cm2, 25 min) against bacterial suspensions (1.0 × 107-8 CFU). Bacterial strains that were unexposed, exposed to TONS504 only, or exposed to blue light only served as controls. Antimicrobial effects were assessed by calculating the survival fraction based on the assessment of colony-forming units (CFU) on agar plates. Exposure to TONS504 or blue light only did not decrease the bacterial survival fraction against any of the strains. After TONS504-PACT under blue light against S. pseudintermedius, no colonies were observed at any TONS504 concentration, resulting in an approximate reduction of 2.3 × 108 in the survival fraction. TONS504-PACT under blue light against E. coli and P. aeruginosa at 10 mg/L of TONS504 showed the greatest reduction in survival fraction, and the reduction was substantially lower than those of the respective controls. TONS504-PACT under blue light exhibited satisfactory activity against antimicrobial-resistant bacteria invitro. Further research on the safety and clinical efficacy of TONS504-PACT under blue light is required; however, it is a potential treatment for antimicrobial-resistant bacterial keratitis in veterinary ophthalmology.

In vivo inhibition of Helicobacter pylori through probiotics and gastrointestinal commensals: a critical review

Introduction: Helicobacter pylori eradication is increasingly challenged, due to high antibiotic resistance rates in H. pylori and treatment failure. Consequently, new treatment regimens are needed. Probiotic and gastrointestinal bacteria exert anti-H. pylori activity in vivo, thus being potential add-on candidates for future eradication strategies. Methods: In this review we summarized the currently available literature for in vivo inhibition of H. pylori. Included studies address anti-H. pylori effects in mouse and rat models caused by potentially beneficial bacteria. Research on literature was further extended to clinical eradication studies in humans. Results: Several bacterial strains, mainly belonging to the Lactobacillus-genus, inhibited H. pylori in vivo. In animal studies probiotic bacteria and commensals reduced H. pylori colonisation and the inflammatory response. Certain probiotic species lead to a decrease of H. pylori colonisation. However, H. pylori eradication with current probiotic therapy is not obtained. Conclusion: Probiotic and gastrointestinal commensals are beneficial in H. pylori eradication therapy. Their current role is the reduction of adverse events and H. pylori load.

A Mini Review: Key Applications and Advances of Photodynamic Inactivation Against Bacteria in the Food Industry

ABSTRACTWith the increasingly severe global food safety issues, food‐borne pathogenic bacteria pose a significant threat. The traditional thermal inactivation approach has drawbacks such as high energy consumption and potential damage to food quality. Moreover, the advantages of current non‐thermal inactivation techniques need to be further enhanced and extended. Photodynamic inactivation (PDI), an innovative non‐thermal inactivation approach, has garnered significant interest in the realm of food preservation owing to its eco‐friendly nature and remarkable antimicrobial efficacy. This paper aims to discuss the applications of PDI technology in the food antibacterial field. It encompasses the capacity to eliminate planktonic bacteria and biofilms, along with its potential for application in antibacterial packaging films. Furthermore, this study systematically examines the utilization of various natural photosensitizers within PDI systems, analyzes their distinct antimicrobial activities against both Gram‐positive and Gram‐negative bacterial strains, and evaluates innovative approaches to optimize the bactericidal performance of PDI technology. Overall, PDI technology exhibits a broad‐spectrum antibacterial effect. However, its inactivation potency against Gram‐negative bacteria and biofilms is relatively weak. Through measures such as optimizing photosensitizer performance, adding adjuvants, and adjusting the reaction environment, the inactivation efficiency of PDI technology can be notably enhanced. This comprehensive review aims to provide groundbreaking perspectives and strategic guidance for the implementation of PDI technology in food safety applications, as well as to inspire the advancement of next‐generation antimicrobial solutions. Significantly, this contributes to effectively addressing food microbial contamination issues and safeguarding food safety. Moreover, it holds promise for promoting the widespread application and in‐depth development of PDI technology in related fields like food packaging.

Serratia marcescens G4 as a novel biocontrol strain against Sclerotinia sclerotiorum infection in soybean.

Sclerotinia is a soil-borne disease of soybean caused by Sclerotinia sclerotiorum, which seriously endangers the yield and quality of soybean. The purpose of this study was to explore effective biocontrol bacteria for controlling soybean Sclerotinia. In this study, we isolated 32 strains of bacteria from soybean rhizosphere soil. The inhibition rate of strain G4 on Sclerotinia sclerotiorum was the highest (82.27%). Strain G4 was identified as Serratia marcescens by morphological, physiological, biochemical and 16S rDNA sequence analysis. The strain G4 could inhibit the growth of Sclerotinia sclerotiorum and change the mycelial morphology. Under the conditions of 5.0 × 105 CFU/mL, pH 7 and 30 °C, the antibacterial rate of strain G4 was the highest, which was 92.10%. After the treatment of strain G4, the content of reducing sugar and soluble protein of Sclerotinia sclerotiorum showed a downward trend, which inhibited its growth. In addition, strain G4 could reduce the activity of cell wall degrading enzymes of Sclerotinia sclerotiorum. In vitro and pot experiments showed that Serratia marcescens had an inhibitory effect on Sclerotinia sclerotiorum. After treatment with strain G4, the content of defense-related enzymes and malondialdehyde in plants increased. The results showed that Serratia marcescens G4 isolated from soybean rhizosphere soil was an effective biocontrol strain against soybean Sclerotinia. Serratia marcescens G4 has a strong inhibitory effect on Sclerotinia sclerotiorum and can be used as a biocontrol bacterium to control the infection of soybean Sclerotinia. © 2025 Society of Chemical Industry.

Multi-strain Native Probiotics from the Asian Stinging Catfish (Heteropneustes fossilis) Enhance Growth, Blood Health, and Organ Morphology in the Host.

Probiotics are promising substitute to synthetic agrochemicals for improving fish health in the aquaculture system. The probiotics used in the aquaculture sector of Bangladesh are mostly imported. While these probiotics can offer benefits, probiotic-supplemented diet sometimes shows inconsistent results mainly due to incompatibility between the probiotic strains and local aquatic environment or fish species. Therefore, the development of probiotics from native fish species could be an alternative to mitigate the possible detrimental effects of imported probiotics on aquaculture production in Bangladesh. Thus, this study aimed to isolate and identify potential probiotic bacteria from the gut of Asian stinging catfish and to evaluate their efficiency in improving physiological parameters and organ morphology of the host fish. Following morphological and biochemical screening of the bacterial isolates, five isolates having potential probiotic traits were identified as Bacillus safensis (HF8), Bacillus altitudinis (HF10), Bacillus pacificus (HF19), Bacillus cereus (HF20), and Bacillus cereus (HF21) using 16S rRNA sequencing through the Barcode-Tagged Sequencing™ (BTSeq™) platform. Five probiotic bacteria, either individually or as a consortium, showed varying degrees of susceptibility to the thirteen antibiotics tested. Isolates HF8, HF19, and HF21 and the probiotic consortium demonstrated antagonistic activity against Aeromonas hydrophila, with strain HF8 exhibiting better inhibition efficiency. Application of a consortium of probiotic bacterial strains (1.15 × 109 to 2 × 1.15 × 109CFU/kg feed) through feed supplementation significantly improved the growth of the Asian stinging catfish compared to the untreated control after 60days of the feeding trial. Similarly, probiotic-fortified diet significantly enhanced the hepatosomatic index and relative intestine weight in the studied fish. The hematobiochemical parameters showed varying responses to the probiotic-supplemented diets. Moreover, the probiotic consortium had positive effects on the morphological parameters of the intestine and liver compared to the control. Principal component analysis (PCA) and Pearson's correlation of the histomorphology indices demonstrated a positive impact of the laboratory-based probiotic-fortified diet on the intestine of the host fish. The gonadosomatic index and developmental stages of the ovary were also improved in the fish treated with probiotic consortium compared to the group fed with normal feed. Multi-location field-level trials should be done before applying this probiotic-fortified diet at the farmers' level, which could substantially improve the commercial fish production in an ecofriendly manner.

Sorption of Microbial Electrogenic Bacterium Strain Micrococcus luteus on Charged Carbon Surface

Sorption of Microbial Electrogenic Bacterium Strain Micrococcus luteus on Charged Carbon Surface

Effects of Combined Chemical and Biofertiliser Application on Sweet Potato Growth and Yield

Due to its wide application in human food production and industrial uses sweet potato has a high economic value. The proper fertilization of the sweet potato is quite important and includes both inorganic and organic fertilisers. Sweet potato (Ipomoea batatas L.) is gaining popularity as a functional food with increasing global demand because of its health benefits, thus there is a need to enhance on its production and quality. The effectiveness of applying biofertilisers in conjunction with chemical fertilisers and the effect of various beneficial bacterial strains on the Lembayung sweet potato variety was established in this study. A factorial experiment was established using five treatments which included two bacterial strains (Bacillus subtilis and Pseudomonas fluorescens), a commercial biofertiliser and chemical fertiliser. The experiment was conducted in RCBD with four replications. The results of the experiment revealed that the use of biofertilisers in combination with chemical fertilisers significantly increased the tuber yield, growth of the plants and resistance to disease as compared to the other treatments. The treatment that produced the highest tuber yield and growth was the treatment with the use of biofertiliser. The use of biofertilisers greatly reduced the incidence and severity of viral diseases thus revealing their role in disease suppression. This approach not only improves the quality of production, but also promotes sustainable farming, which is in line with the efforts of enhancing soil fertility and increasing production.

Bioactivity and chemical screening of endophytic fungi associated with seaweeds Gracilaria sp. and Sargassum sp. of the Bay of Bengal, Bangladesh

This study explored the great potential of endophytic fungi associated with red seaweed Gracilaria sp. and brown seaweed Sargassum sp. of the Bay of Bengal, Bangladesh, for the first time. Endophytic fungi were identified taxonomically by morphological features and molecular characterisation (ITS sequence). The identification of six fungal isolates revealed five different fungal species belonging to four genera, namely, Aspergillus subversicolor, A. terreus and Cladosporium halotolerans isolated from Gracilaria sp. and Chaetomium globosum, A. terreus and Curvularia perotidis isolated from Sargassum sp. The ethyl acetate extracts of fungal endophytes were evaluated for antimicrobial activity, DPPH radical scavenging activity, and brine shrimp lethality bioassay. Amongst all the fungal extracts evaluated in this study, four showed mild to moderate inhibitory activity (10–14 mm) against the tested bacterial strains. Exceptionally, Chaetomium globosum exerted significant antibacterial activity with the highest zone of inhibition (21 ± 0.3 mm) against the Gram-negative bacterial strain Pseudomonas aeruginosa and also showed moderate antifungal activity (13 ± 0.9 mm) against A. niger. Sargassum sp.-derived A. terreus exhibited the strongest DPPH radical scavenging activity (IC50 value of 7.88 ± 0.09 µg/mL). All the fungal extracts have significant lethality against brine shrimp nauplii (LC50 value of ≤ 20.39 ± 4.04 µg/mL), while Curvularia perotidis and Cladosporium halotolerans were the most effective (LC50 values of 9.30 ± 2.96 µg/mL and 9.94 ± 3.49 µg/mL, respectively). Gas chromatography-mass spectrometry (GC-MS) analysis of the crude extracts identified the presence of several chemical compounds. These bioactive chemical constituents might contribute to the exhibited bioactivity in this study. The current study’s findings support the beneficial impacts of the fungal endophytes on exerting biological activities and consequently as valuable resources of bioactive compounds.

Characterizing the essential oil composition and assessing the antioxidant and antimicrobial properties of two compositae taxa: Gerbera delavayi Franch. and Gerbera piloselloides (L.) Cass

IntroductionGerbera piloselloides (L.) Cass. and Gerbera delavayi Franch. are increasingly recognized for their medicinal properties, particularly among ethnic minority communities in southern China, where they are used for heat-clearing, detoxification, cough relief, lung expulsion, and asthma alleviation. Despite their traditional use, these species have been subjected to limited research regarding their biological activities, leaving a gap in scientific understanding. MethodsThis study was designed to investigate the essential oil (EO) compositions, as well as the antioxidant and antimicrobial properties of G. piloselloides and G. delavayi. The EOs were extracted via hydrodistillation and analyzed using gas chromatography-mass spectrometry (GC-MS). The antioxidant potential was assessed through ABTS and DPPH free radical scavenging assays, along with the ferric reducing antioxidant power (FRAP) method. The antimicrobial activity was evaluated against five bacterial strains, including two Gram-positive (Staphylococcus aureus, Listeria) and three Gram-negative (Salmonella, Escherichia coli, Pasteurella multocida) species, using the broth microdilution technique.ResultsThe essential oil from G. piloselloides (EOgp) yielded 0.14% and was found to contain 24 compounds. It demonstrated high antioxidant activity in the ABTS assay and exhibited the strongest antibacterial effect against Listeria in vitro. In contrast, the essential oil from G. delavayi (EOgd) had a higher yield of 0.26% and contained a more complex composition with 100 compounds. It showed superior antioxidant activity in both the DPPH and FRAP assays and also demonstrated the highest antibacterial activity against Listeria.DiscussionThe findings of this study confirm that both G. piloselloides and G. delavayi possess significant potential as natural sources of antioxidants and antibacterial agents, warranting further exploration for their development into therapeutic products.

Comparison of Cytotoxicity and Antioxidant, Antibacterial, and Anti-Inflammatory Activity of Aqueous and Ethanolic Extracts from Malus domestica, Prunus armeniaca, and Prunus cerasus Leaves

This study presents a comprehensive evaluation of the biological properties of aqueous and aqueous–ethanolic leaf extracts from Malus domestica, Prunus armeniaca, and Prunus cerasus, which are plant waste materials. Phytochemical profiles were analyzed using HPLC, and antioxidant potential was assessed via DPPH, ABTS, FRAP, and superoxide dismutase (SOD) activity assays. Extracts showed concentration-, plant-, and extract type-dependent radical scavenging effects exceeding 80%, significant Fe3+ ion reduction, and up to 40% enhancement of SOD activity. In vitro studies on HDF and HaCaT cells revealed reduced intracellular ROS levels, indicating antioxidant potential. Cytotoxicity assays (Alamar Blue, Neutral Red) demonstrated increased skin cell viability by up to 35% at ≤50 or 125 µg/mL, while higher doses reduced viability by up to 70%, depending on the extract. Antibacterial activity varied among plant species and was effective against seven bacterial strains. ELISA assays showed anti-inflammatory effects, with IL-1β and IL-6 levels reduced by 48% and 40%, respectively, and IL-10 increased by up to 27%. These findings suggest that the tested leaf extracts support both enzymatic and non-enzymatic antioxidant defense mechanisms and may be valuable as functional ingredients in dermatological or cosmetic applications.

Rational search for natural antimicrobial compounds: relevance of sesquiterpene lactones

Antimicrobial resistance is one of the most pressing global health challenges, as many pathogens are rapidly evolving to evade existing treatments. Despite this urgent need for new solutions, natural plant-derived compounds remain relatively underexplored in the development of antimicrobial drugs. This report highlights an innovative approach to discovering potent antimicrobial agents through bioguided fractionation of numerous plant species from the rich Argentinean flora. By systematically screening 60 species (over 177 extracts) for antimicrobial activity against representative strains of gram-positive and gram-negative bacteria, we identified promising bioactive compounds within the Asteraceae family—particularly sesquiterpene lactones from the Xanthium genus. Building on this basis, we synthesized semi-synthetic derivatives by chemically modifying plant sub-extracts, focusing on structures incorporating heteroatoms and/or heterocycles containing oxygen and nitrogen (important for the bioavailability and bioactivity that they are capable of providing). These modifications were evaluated for their potential to enhance antimicrobial efficacy against bacteria and Candida species, including resistant strains. Our findings suggest that tailoring natural metabolites from Xanthium and related Asteraceae species can significantly improve their antimicrobial properties. This strategy offers a promising pathway for the development of novel therapeutic agents to combat bacterial and fungal infections in an era of rising drug resistance.Graphical

Poly-β-hydroxybutyrate Production from Bread Waste via Sequential Dark Fermentation and Photofermentation

This study explores the valorization of bread waste for poly-β-hydroxybutyrate (PHB) production through a combined dark fermentation (DF) and photofermentation (PF) process. DF, performed using Lactobacillus amylovorus DSM 20532, efficiently converted bread waste into a lactate- and acetate-rich substrate within 120 h. The resulting fermented bread broth (FBB) was enriched with essential nutrients by adding digestate from anaerobic digestion, replacing the need for chemical supplements. Six purple non-sulfur bacteria (PNSB) strains were screened for PHB production in the FBB. Cereibacter johrii Pisa7 demonstrated the highest PHB accumulation (50.73% w PHB/w cells), and biomass increase (+1.26 g L−1) over 336 h, leading to its selection for scale-up. Scale-up experiments were conducted in a 5 L photobioreactor with LED lights optimized for PNSB growth. C. johrii Pisa7 accumulated PHB at 15.17% and 11.51% w PHB/w cells in two independent trials, corresponding to productivities of 2.03 and 0.89 mg PHB L−1 h−1. These results confirm the scalability of the process while maintaining competitive PHB yields. This study highlights the potential of bread waste as a low-cost carbon source for bioplastic production, contributing to a circular bioeconomy by converting food waste into sustainable materials.

Microbial consortium involving Pseudomonas and Bacillus: strain selection and the effect of co-cultivation on biocontrol activity against phytopathogens and the composition of metabolic extracts.

Agricultural sustainability is vital to meet the growing global demand for food; therefore, the search for more sustainable options to replace traditional chemical products has gained attention due to their benefits. The sector has applied innovative microbial consortium approaches as a niche for exploring new bioproducts and metabolic pathways through microbial interactions. Thus, this study sought to select two endophytic bacterial strains with biocontrol activity to study their metabolic interactions in culture. For this, co-cultivation and axenic culture assays were carried out to evaluate the inhibition of Corynespora cassiicola, Sclerotinia sclerotiorum, Moniliophthora perniciosa, and Colletotrichum truncatum. After the production of antiphytopathogenic compound tests, two strains were selected: P. putida MG36 and B. amyloliquefaciens SS14. These bacteria were cultivated under three distinct conditions: axenic cultivation of SS14, axenic cultivation of MG36, and co-cultivation. The metabolites were extracted and analyzed by liquid chromatography coupled with mass spectrometry (UHPLC-MS/MS). The results showed that both strains exhibited significant antifungal activity. B. amyloliquefaciens SS14 demonstrated 65% inhibition against C. truncatum, while P. putida MG36 showed 58% inhibition against S. sclerotiorum. Analysis of the chemical profiles revealed the presence of exclusive and shared metabolites, such as iturin A4 (antifungal lipopeptide) and macrolactin A (bioactive polyketide), under different culture conditions. In conclusion, P. putida MG36 and B. amyloliquefaciens SS14 show promise as biocontrol agents against phytopathogens, contributing to more sustainable agricultural practices.

Isolation and characterization of a bioactive compound from Sphingomonas sanguinis DM with cytotoxic and molecular docking analysis

Datura metel, a common plant in the Solanaceae family, is known for its valuable medicinal properties. The metabolites created by its rhizosphere bacterium, Sphingomonas sanguinis DM, have garnered interest for their potential biological effects. This study will discuss the steps involved in fermenting and processing a bacterial strain to extract potent secondary metabolites. The ethyl acetate extract of the propagated strain was subjected to fractionation and purification through various chromatographic techniques. The purified compound was characterized through multiple spectroscopic methods for structure elucidation, including UV, MS, 1D, and 2D-NMR. Its cytotoxic activity was assessed on malignant skin cells (A-431) using the MTT test compared with normal melanocytes (HFB 4). Furthermore, A-431 cells were double-stained with PI and annexin V-FITC and analyzed by flow cytometry to detect Apoptosis. Molecular investigations include PCR screening to detect genes related to the biosynthesis of bioactive metabolites, such as NRPS and lipopeptide ItuD genes. A prospective effective strategy to overcome tumor plasticity in melanoma is to target the Wnt signaling pathways. Molecular docking studies were conducted in the different proteins (Fz4-CRD, LRP6, GSK3β) of the Wnt signaling pathway and Protein Kinase B/Akt for the isolated compound to investigate the possible pathway to inhibit melanoma. Sphingomonas sanguinis DM produced bis (2-methylheptyl) benzene-1,4-dicarboxylate isolated for the first time from a natural source. It was cytotoxic against the A-431 human skin carcinoma cell line (IC50 = 191.61 µg/mL) but less effective against HFB 4 human normal melanocytes (IC50 = 416.23 µg/mL; selectivity index = 2.17). The A-431 cells showed a significant increase in early Apoptosis and a moderate rise in late Apoptosis. PCR amplification confirmed genes encoding A domain and Iturin A. Bacterial sequences are available in NCBI GenBank with accession codes OR597597 and OR597598. Consequently, Sphingomonas sanguinis DM synthesized a cytotoxic natural terephthalate diester derivative, along with the host specificity of the strain.

Estimation of the average molecular weight of microbial polyesters from FTIR spectra using artificial intelligence.

In this paper, we present a method for calculating the average molecular weight of microbial polyesters using Fourier transform infrared spectroscopy (FTIR) data as input. FTIR spectra provide the necessary quantitative information, as the impact of chain ends on the spectra is influenced by the average molecular weight of the polymer. Since FTIR data can be collected rapidly and is available in abundance, it serves as an ideal input for machine learning algorithms, such as artificial neural networks. The robustness and reliability of the model are improved by designing the neural network to use absorbance ratios instead of absolute absorbances as input. We also propose a new feature selection method that facilitates the identification of absorbance ratio regions best suited to serve as input for the neural network. Our approach ensures that variations in sample preparation do not compromise the accuracy of the model. The proposed computational method is demonstrated using a microbial polyester [poly(3-hydroxybutyrate), PHB], which is a biopolymer natively synthesized by multiple bacterial strains. Although the computational method has been tested with PHB, the underlying concept can be extended to other polymers. To facilitate broader application, a step-by-step guide for developing similar models is also provided.

Optimizing Whole-Cell Biosensors for the Early Detection of Crop Infections: A Proof-of-Concept Study

This study presents a proof-of-concept evaluation of optimized whole-cell biosensors designed for the real-time detection of crop infections. Genetically engineered luminescent bacterial strains were used to detect volatile organic compounds (VOCs) emitted by crops during spoilage. Key factors investigated include bacterial uniformity, nutrient supply, and temperature effects. The results demonstrated that lower temperatures (+4 °C) yielded higher sensor sensitivity and prolonged bacterial viability. A proof-of-concept evaluation was conducted in storage-like conditions, showing effective infection detection in potatoes. These findings underscore the potential of whole-cell-based biosensors for monitoring postharvest production in cold storage environments.

Methicillin-Resistant Staphylococcus aureus Inhibitory Activity of some New Thiazole-Based Schiff Bases: One-pot Synthesis and In Vitro Screening.

Twelve thiazole-based Schiff bases derived from salicylaldehyde derivatives are efficiently prepared in the current study. A typical Hantzsch thiazole reaction was used to prepare the targeted molecules in 80%-92%. Therefore, a one-pot protocol was developed involving the reaction of salicylaldehydes, thiosemicarbazide, and the appropriate hydrazonyl chlorides in dioxane at reflux for 5-6h in the presence of one equivalent of triethylamine. The new products were tested against six different American Type Culture Collection bacterial strains with the reference ciprofloxacin. In general, integrating an aryldiazenyl unit into the structure of the tested 4-methylthiazole-based Schiff bases at thiazole-C5 resulted in improved antibacterial activity. Moreover, Schiff bases linked to 5-((4-chlorophenyl)thio)methyl units outperformed their analogs linked to 5-(phenyl)thio)methyl units by 2-fold. Thiazole-based Schiff base linked to 5-((4-chlorophenyl)thio)methyl and 5-((4-methoxyphenyl)diazenyl) units showed the highest activity against all strains tested, particularly Staphylococcus aureus and Enterococcus faecalis. It had minimum inhibitory concentration/minimum bactericidal concentration (MIC/MBC) up to 7.4/14.9µM. Moreover, it demonstrated comparable Methicillin-resistant S. aureus (MRSA) inhibitory activity to linezolid against two MRSA strains with MIC/MBC up to 7.4/29.8µM.

Biofabrication of microstructured bacterial ecosystems using chaotic bioprinting: advancing in vitro research for microbial engineering.

Mixed microbial communities are essential for various ecosystems, with bacteria often exhibiting unique behaviors in structured environments. However, replicating these interactions in vitro remains challenging, as traditional microbiology techniques based on well-mixed cultures fail to capture the spatial organization of natural communities.
Chaotic 3D printing offers a versatile, high-throughput method for fabricating hydrogel constructs with multilayered microstructure in which different bacterial strains can coexist, closely mimicking the partial segregation seen in natural microbial ecosystems. Using a Kenics static mixer (KSM) printing nozzle, we bioprinted a bacterial consortium consisting of Lactobacillus rhamnosus, Bifidobacterium bifidum, and Escherichia coli as a simplified model for human gut microbiota. Chaotic bioprinting enabled the creation of microstructured cocultures with distinct niches, allowing all bacterial strains to coexist (without being scrambled) and reach a population equilibrium.
We characterized the cocultures through fluorescence microscopy, colony counting, and quantitative polymerase chain reactions (qPCR). Our results demonstrate that the microarchitecture of the printed fibers significantly influences bacterial growth dynamics. Stratified arrangements enhanced coculture viability and balance over 72 hours compared to well-mixed and suspension conditions. Chaotic printing also allows the rational arrangement of strict anaerobic bacteria, such as B. bifidum, by positioning them in construct layers that are more susceptible to hypoxia.
Chaotic bioprinting presents a powerful tool for engineering microbial ecosystems with precise spatial control. This approach holds promise for advancing our understanding of microbial interactions and has potential biomedical applications in antibiotic testing, microbiota research, bioremediation, and synthetic biology.&#xD.

Safety Evaluation of N-trans-caffeoyltyramine Derived From a Strain of Yarrowia lipolytica Through Precision Fermentation.

N-trans-caffeoyltyramine (NCT) is a phenolic hydroxycinnamic acid amide naturally present in many plant crop species and is associated with immune response and many development processes. Little research has been done on the potential safety of NCT for use as an ingredient in conventional foods and beverages. This study assessed the safety of NCT derived from caffeic acid and produced using a genetically engineered strain Yarrowia lipolytica strain 3599_7 via precision fermentation through in vitro genotoxicity assays and a 90-day dietary oral toxicity study in rats. The Ames test was performed in bacterial strains and the highest dose tested was 5000.0μg/plate in the presence and absence of S9. The in vitro mammalian micronucleus test was conducted in human peripheral blood lymphocytes in culture exposed to NCT at predetermined concentrations in the absence (4-hour and 24-hour exposure) and presence (4-hour exposure) of S9. NCT was not genotoxic as evident from the Ames and the in vitro micronucleus assay. NCT exhibited no adverse effects in the 90-day oral toxicity study up to the highest dose tested, where the no-observed-adverse-effect level was 1427 and 1983mg/kg body weight/day in males and females, respectively.

Characterization of a rapid 17β-estradiol-degrading strain, Microbacterium proteolyticum ZJSU01

Estrogens, particularly 17β-estradiol, are prevalent endocrine-disrupting chemicals in aquatic environments, posing risks to ecosystems and human health. Biodegradation is considered one of the most effective and environmentally friendly methods for removing estrogen. In this study, a novel bacterial strain, Microbacterium proteolyticum ZJSU01, was isolated from pig manure. It completely degraded 5 mg/L of 17β-estradiol (E2) within 4 h, as well as its major transformation product, estrone (E1). The strain ZJSU01 displayed strong adaptability to high temperatures (37℃, 42℃) and a broad pH range (6–11), E2 (5 mg/L) could be completely removed by the strain under these conditions. Transformation intermediates were analyzed using UHPLC and HPLC-Q-TOF–MS to identify key metabolites and trace the degradation pathways. Four potential degradation pathways were identified, including the 4,5-seco pathway, which is widely conserved in most E2-degrading bacteria. Whole-genome sequencing predicted a chromosome with a size of 3,828,432 bp, and a series of functional genes, and transcriptomics analysis identified several genes involved in E2 degradation. The budC gene, a member of the short-chain dehydrogenases/reductases (SDRs) family, was identified as critical for E2 degradation and exhibited a nearly 170-fold upregulation. Meanwhile, genes such as fdeE and catA were associated with downstream degradation. Microbacterium proteolyticum ZJSU01 demonstrated strong acid–base and high-temperature resilience, highlighting its strong potential for practical applications due to its degradation capability and adaptability. This strain could be applied in wastewater treatment to effectively remove estrogenic pollutants from contaminated water.Key points• Microbacterium proteolyticum ZJSU01 removed 100% of E2 (10、5、1 mg/L) within 4 h.• Strain ZJSU01 showed great tolerance to high temperature and acid–base conditions.• A novel gene, budC, was identified as the primary driver of E2 degradation by ZJSU01.