Polycyclic aromatic sulfur heterocycles, such as dibenzothiophene (DBT), and their alkylated derivatives are recognized as persistent and toxic contaminants that pose major risks to the environment and human health. Here, a novel electroactive gram-positive bacterium, Lysinibacillus macroides AP, was isolated and identified from a microbial fuel cell (MFC) powered by aromatic compounds. An electricity generation performance with a maximum discharge voltage of 424.59 mV and a power density of 420.95 mW m⁻² was obtained using L. macroides AP in an MFC fueled with sodium formate. An analysis of the extracellular electron transfer (EET) mechanism indicated that the endogenous redox mediators produced by L. macroides AP were not detected, but exogenous redox mediators such as thionine acetate and anthraquinone-2, 6-disulfonate could temporarily enhance EET. The characterization of biofilm morphology revealed a dense network of microbial nanowires on the cell surface of L. macroides AP; the abundance of these nanowires was positively correlated with the discharge efficiency of the MFC, suggesting that the nanowires generated by L. macroides AP cells were likely to promote EET. Additionally, effective bioelectricity generation and simultaneous DBT degradation were successfully achieved using L. macroides AP in MFCs, with a power density of 385.20 mW m⁻² and 88.72 % DBT removal. This is the first report on a novel ecological role of L. macroides AP as a gram-positive electroactive bacterium, emphasizing its potential applications in environmental remediation and energy recovery.

Phytic acid, also known as inositol hexaphosphate (IP6), is one of the most abundant organophosphorus compounds in nature. Its degradation by phytase plays a key role in the natural phosphorus cycle. In addition, phytases are widely used in livestock and poultry feed to enhance phosphorus utilization. While most reported and commercial phytases are derived from terrestrial organisms, relatively few originate from marine microorganisms, and information on the diversity of phytase-producing marine bacteria remains limited. In this study, following enrichment with sodium phytate, we analyzed the bacterial diversity in seawater and sediment samples collected from the coast of Aoshan Bay in Qingdao, China, using 16S rRNA gene amplicon sequencing. A total of 138 OTUs representing 10 phyla, 15 classes, 37 orders, 55 families, and 70 genera were identified. Furthermore, 27 phytase-producing bacterial strains were isolated from the enrichment cultures, primarily belonging to the phyla Firmicutes (14/27) and Proteobacteria (12/27). Five extracellular phytase genes were identified through genome sequencing of three representative strains. These phytases were subsequently expressed and characterized. All were classified as histidine acid phosphatase-type phytases, exhibiting optimal activity at temperatures of 50-60 °C and pH values of 4.0-5.0. Notably, phytase 3919 showed a specific activity as high as 2485.25 U/mg, indicating strong potential for practical applications. This study provides insight into the diversity of coastal bacteria involved in phytic acid degradation, contributing to our understanding of bacterial-driven phosphorus cycling in coastal ecosystems and facilitating the discovery of phytases with industrial potential.

Bifidobacterium animalis subsp. lactis is a well-known probiotic with potential benefits for alleviating sub-health symptoms, including immune dysfunction and anxiety. Given the strain-specific nature of its probiotic effects, identifying effective strains for sub-health alleviation is crucial. In this study, we characterized 16 B animalis subsp. lactis isolates from fecal samples and probiotic sources. We assessed the genotype-phenotype correlations related to growth, carbon source utilization, and stress tolerance in vitro. Subsequently, we profiled 107 metabolites (including 28 alcohols and 17 esters) and quantified the levels of short-chain fatty acids and three other organic acids. Three B. animalis strains, GOLDGUT-BB21, WLBA7, and WLBA6, were selected and evaluated in a sleep-deprived mouse model. In vivo, WLBA3 reduced inflammation and oxidative stress by inhibiting the NLRP3 inflammasome pathway and modulating gut microbiota (e.g., Lactobacillus and Alistipes), which in turn significantly improved weight gain and fatigue resistance, attenuated cognitive function, and anxiety-like behavior. These findings provide insights into the diversity of B. animalis subsp. lactis strain resources and highlight the potential of WLBA3 as a candidate for alleviating sub-health symptoms.

The verrucomicrobial methanotroph, Methylacidiphilum sp. RTK17.1, and the microalgae, Galdieria sp. RTK37.1 are both thermoacidophilic microorganisms isolated from geothermally heated soils at Rotokawa, Aotearoa-New Zealand. In this work, we used cocultures of Methylacidiphilum sp. RTK17.1 and Galdieria sp. RTK37.1 in batch and continuous systems (45 °C, pH 2.5) to assess their biomass productivity and performance; with the goal of removing methane and carbon dioxide from simulated waste gas streams and assessing the resultant biomass for its potential use as single cell protein. Coculture performance was compared to corresponding axenic cultures and the nutritional suitability of resultant biomass was assessed as a single cell protein feedstock. Stable coculture was achieved in both batch and chemostat systems. In batch experiments, Galdieria sp. RTK37.1 significantly enhanced growth (29 %) and methane oxidation (300 %) rates of Methylacidiphilum sp. RTK17.1, and complete methane removal was achieved without formation of an explosive gas mixture. In steady state chemostat coculture experiments, Galdieria sp. RTK37.1 decreased net volumetric oxygen consumption by 46 %, but its oxygenic activity was unable to supply Methylacidiphilum sp. RTK17.1 with the O₂ required for complete CH₄ removal. Nevertheless, Methylacidiphilum sp. RTK17.1 benefited from the presence of Galdieria sp. RTK37.1 in a low O₂ environment; with O₂ algae-methanotroph cross-feeding playing a fundamental role on their interactions. Methylacidiphilum sp. RTK17.1, Galdieria sp. RTK37.1, and their coculture each displayed similar nutritional profiles, with protein quality comparable to soybean meal and fishmeal feeds used for animals. The biomass needed to meet the daily indispensable amino acid requirements of a 62 kg adult human was 568 g for Methylacidiphilum sp. RTK17.1, 804 g Galdieria sp. RTK37.1, and 754 g for the coculture, with histidine being the limiting amino acid. These thermoacidophilic cocultures, which have not previously been investigated, offer great potential to convert low (or negative) value industrial gas streams into valuable products (e.g. supplementary biofeedstocks).

Microcin J25 (MccJ25) has received substantial attention as a potential solution to the global threat of infection caused by antibiotic-resistant bacteria. However, the industrial fermentation of MccJ25 faces production bottlenecks. It is imperative to further explore the production optimization strategies for MccJ25 to formulate comprehensive approaches for its industrial-scale production and other downstream applications. Here, Fe²⁺ in tap water was identified as a critical inhibitor of MccJ25 biosynthesis, selectively repressing mcjA transcription, which was reversible via 2,2′-bipyridine-mediated chelation. To decouple production from growth phase dependency and Fe²⁺ interference, we engineered Escherichia coli BL21 cells by performing two genetic modifications. First, we replaced the native mcjA promoter with a constitutive promoter (P_Q) to allow its mid-log phase expression. Second, we replaced the native mcjBCD promoter with a medium-strength variant (P₂₂₂₃) that delayed production kinetics without affecting final yields. However, the genomic integration of mcjD alleviated plasmid-borne toxicity, increasing the expression timing and doubling the yield to 240 mg/L. Finally, we computationally optimized the mcjA ribosome-binding site (RBS) to enhance translation efficiency. RBS optimization revealed that a moderate translation initiation efficiency (550,584 arbitrary units [au]) maximized production, whereas excessive efficiency (2,019,712 au) impaired growth and output. These interventions synergistically increased the MccJ25 titer 10-fold, reaching 430 mg/L in batch culture. Our findings establish a robust platform for MccJ25 overproduction, highlighting promoter engineering and translational tuning as pivotal strategies for antimicrobial peptide biosynthesis. This study provides insights for overcoming metabolic constraints in microbial fermentation, advancing the development of peptide-based therapeutics against multidrug-resistant pathogens.

Polystyrene (PS) is a polyolefin plastic that is used extensively in food packaging. The chemical structure of PS is extremely stable owing to its C-C backbone and styrene rings, making it highly resistant to biodegradation, which causes serious environmental pollution and health threats. Although certain microorganisms have been reported to degrade PS waste, most studies have focused on the changes in the molecular weight and surface structure of plastics. These slight degradation phenomena make it extremely difficult to detect the degradation products, thus challenging the definitive demonstration of PS degradation. This study investigated the co-cultivation of the polyolefin plastic-degrading bacterium Raoultella sp. DY2415 and the benzoic acid bioconversion strain Pseudomonas putida KT2440-ΔRBC. BA is a possible degradation product of PS and can be converted by P. putida KT2440-ΔRBC into the high value-added compound muconic acid (MA). After co-cultivation, MA was detected in the medium, indicating that Raoultella sp. DY2415 degraded PS and generated BA, which was subsequently utilized by P. putida KT2440-ΔRBC for MA synthesis. This study demonstrated the biodegradation of PS and the synthesis of MA through a fully biological process, thereby promoting the circular economy of plastics.

Exporter protein systems play a crucial role in the efficient production of valuable chemicals. However, the lack of active exporters significantly limits the application of industrial bio-based production, making the identification and utilization of novel exporters highly important. In this study, we discovered a novel l-Homoserine exporter, Cg0701, in Corynebacterium glutamicum through homology analysis. First, tolerance assays revealed that the cg0701 overexpression strain (CgH-2) exhibited a 10.45% increase in cell growth compared to the control when cultivated with 30 g/L-Homoserine. Additionally, export assays demonstrated that the l-Homoserine export capacity of CgH-2 increased by approximately 30%. Furthermore, genomic overexpression of cg0701 in an l-Homoserine-producing chassis also enhanced both tolerance and export activity. As a result, the recombinant strain CgH-11 produced 10.79 g/L-Homoserine in shake flask cultures and 48.72 g/L in a 5 L fermenter, representing improvements of 19.89% and 24.44%, respectively. In summary, our results indicate that Cg0701 is a novel l-Homoserine exporter in C. glutamicum, enriching our understanding of amino acid export systems and providing a valuable target for the construction of l-Homoserine microbial cell factories.

Fighting against antibiotic resistance has an unexpected ally, archaea. Despite the extensive exploration of antimicrobial peptides in bacteria and eukaryotes, the archaeal domain has been overlooked. A recent study employed deep learning to screen archaeasins. The synthesized versions showed a 93 % success rate against pathogens by depolarizing the cytoplasmic membrane, not the outer membrane. This highlights the promise and deep learning power of archaea for antibiotic discovery and the culture of uncultured archaea.

Glutathione (GSH), an essential tripeptide thiol critical for cellular redox regulation, has significant value in the pharmaceutical and nutraceutical industries. To overcome limitations of traditional GSH extraction methods, this study established a microbial cell factory platform in Saccharomyces cerevisiae through integrated metabolic engineering strategies: (1) host strain screening identified NJ-SQYY with superior GSH accumulation (74.14 mg·L⁻¹, 8.27 mg·g^-1 dry cell weight [DCW]); (2) CRISPR/Cas9-mediated genomic integration of bacterial gshAB introduced with a bifunctional glutathione synthetase; (3) systematic optimization via promoter tuning and Gsh1-Gsh2 enzyme fusion, and CYS3 overexpression-resolved γ-glutamylcysteine bottlenecks. These interventions synergistically enhanced GSH synthesis to 339.3 mg·L⁻¹ in shake flasks (4.6-fold increase), representing the highest reported titer in chromosomally engineered S. cerevisiae. Scaling to dissolved oxygen-coupled fed-batch fermentation in a 5-L bioreactor produced 997.46 mg·L⁻¹ GSH at 33.85 mg·g⁻¹ DCW. This study demonstrated a holistic metabolic engineering-to-bioprocessing approach for industrial GSH biomanufacturing.