Applied Microbiology and Biotechnology最新文献

{"title":"Isolation and genomic characterization of a lytic bacteriophage against multidrug-resistant Proteus mirabilis.","authors":"Parmanand Kushwaha, Sovon Acharya, Manisha Behera, Shailesh Desai, Surajit Gandhi, Munindra Ruwali, Lakshminarasimhan Krishnaswamy, Sarika Chaturvedi, Sachinandan De, Prashanth Suravajhala, Gyaneshwer Chaubey","doi":"10.1007/s00253-026-13832-y","DOIUrl":"https://doi.org/10.1007/s00253-026-13832-y","url":null,"abstract":"<p><p>Multidrug-resistant (MDR) Proteus mirabilis is a significant opportunistic pathogen, largely due to its ability to form robust biofilms that are recalcitrant to conventional antibiotic therapy. Bacteriophages represent a promising alternative, yet their therapeutic potential is contingent on a thorough characterization of their biological functions and genomic architecture. This study details the isolation and comprehensive analysis of a novel bacteriophage targeting MDR P. mirabilis. A novel lytic bacteriophage, designated Proteus phage ram_arti_1324, was isolated from sewage. Transmission electron microscopy classified it as a member of the family Podoviridae. Functional assays demonstrated its potent efficacy against established P. mirabilis biofilms, achieving a 55% reduction in total biomass in vitro conditions. Whole-genome sequencing revealed a linear, double-stranded DNA genome of 91,735 bp with a GC content of 34.7%. Genomic annotation identified 146 putative coding sequences (CDS), including key lytic genes encoding two distinct endolysins, and four tRNA genes. Crucially, the genome lacks any identifiable virulence factors, antibiotic resistance genes, or markers indicative of a lysogenic life cycle. Comparative genomic analysis against 51 known Proteus phages confirmed its novelty. Proteus phage ram_arti_1324 shares less than 95% average nucleotide identity with its closest relatives, suggesting it represents a novel viral species. This uniqueness was further supported by whole-genome alignment, which revealed a distinct arrangement of locally co-linear blocks not observed in other related phages. The genomic and functional data establish that Proteus phage ram_arti_1324 is a novel, strictly lytic bacteriophage with significant therapeutic potential against both planktonic and biofilm-associated MDR P. mirabilis. Its potent anti-biofilm activity, combined with a genome free of deleterious genes, makes it a strong candidate for further development in phage-based clinical applications. The complete genome sequence provides a valuable resource for future research into phage-host dynamics and the bioengineering of next-generation antimicrobial agents. KEY POINTS: • Novel lytic bacteriophage Proteus phage ram_arti_1324 was isolated with genome size 91735 bp. • Proteus phage ram_arti_1324 displayed absence of virulence factors, antibiotic resistance genes (ARGs) and deleterious genes. • Proteus phage ram_arti_1324 displayed antibiofilm activity against MDR P. mirabilis.</p>","PeriodicalId":8342,"journal":{"name":"Applied Microbiology and Biotechnology","volume":" ","pages":""},"PeriodicalIF":4.3,"publicationDate":"2026-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147760850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Metagenomic insights into urolithin formation from rambutan rind extract by rat faecal-derived microbiome.","authors":"Wai-Kit Tow, Cindy Shuan Ju Teh, Chien Wei Ooi, Ronald F S Lee, Maalini Krishnasamy, Uma Devi Palanisamy, Usha Sundralingam","doi":"10.1007/s00253-026-13841-x","DOIUrl":"https://doi.org/10.1007/s00253-026-13841-x","url":null,"abstract":"<p><p>Ellagitannins and ellagic acid are microbially converted into urolithins, metabolites associated with antioxidant, anti-inflammatory, and mitochondrial-related activities. Although several human-derived urolithin-producing strains and their associated enzymes have recently been characterised, the diversity of microbial strategies across host systems remains poorly understood. This study investigated urolithin production in the Sprague-Dawley rat faecal-derived microbial communities supplemented with rambutan rind extract, an ellagitannin-rich agricultural by-product containing 35-40% geraniin. Rambutan rind extract supplementation was associated with reduced isobutyric acid levels at study endpoint. Ex vivo anaerobic fermentation of hydrolysed rambutan rind extract (113 µM ellagic acid equivalent) resulted in the formation of urolithin C (9.4 ± 0.6 µM) and Isourolithin A (12.5 ± 0.6 µM) by day 9. Shotgun metagenomics analysis revealed very low relative abundance of Actinobacteria (< 0.009%), despite this phylum encompassing most previously characterised urolithin-producing taxa. Canonical ellagic acid degradation genes and the MetaCyc EA degradation pathway were not detected. Comparative pathway analysis indicated overlap in general metabolic pathways with Ellagibacter isourolithinifaciens DSM 104140^T reflecting shared metabolic frameworks rather than conserved urolithin biosynthetic pathways, with highly divergent homologues (Eadh1, Eadh2, Eadh3, and Ucdh). Together, these findings demonstrate that rambutan rind extract can support urolithin formation in rat faecal-derived microbial consortia and highlight functional associations consistent with alternative or yet-uncharacterised microbial strategies for ellagitannin biotransformation. These findings support a discovery-driven framework for investigating urolithin biotransformation in non-human gut microbiomes using ellagitannin-rich agricultural substrates. KEY POINTS: • Rambutan rind extract supports urolithin formation in rat-derived gut microbiota. • Substrate concentration influences urolithin production under ex vivo conditions. • Rat gut microbiota shows homologues' divergence in urolithin-associated proteins.</p>","PeriodicalId":8342,"journal":{"name":"Applied Microbiology and Biotechnology","volume":" ","pages":""},"PeriodicalIF":4.3,"publicationDate":"2026-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147760773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bacteriophage survival and ARG dissemination from wastewater treatment plants to the environment.","authors":"Syeda Fazoon Kazmi, Fang Ru, Yinghua Zhang, Jun Feng, Dong Wu","doi":"10.1007/s00253-026-13815-z","DOIUrl":"https://doi.org/10.1007/s00253-026-13815-z","url":null,"abstract":"<p><p>The proliferation of antibiotic resistance genes (ARGs) represents a critical global health threat, with wastewater treatment plants (WWTPs) identified as major hotspots for resistance amplification and dissemination. While bacterial conjugation has been extensively studied, bacteriophages are emerging as significant but underestimated vectors for ARG transfer via transduction. We hypothesize that phages are capable of withstanding disinfection and exploiting diverse bacterial hosts in receiving environments, thereby functioning as active vectors of ARG dissemination rather than passive genetic reservoirs. Meta-analysis of disinfection efficacy data (n = 79 experimental observations, 6 technology categories) reveals significant differences in log₁₀ reduction across disinfection technologies (Kruskal-Wallis: H = 25.96, df = 5, p < 0.0001). Ozonation was significantly more effective than chlorination (p < 0.001), membrane processes (p = 0.003), UV irradiation (p = 0.005), and PAA/thermal treatment (p = 0.010). Phage persistence in receiving waters follows a 1-4 week timeline modulated by temperature (Q₁₀ ~ 2-3), solar UV, and water chemistry. Broad host range phages have the potential to transfer ARGs to environmentally dominant genera (Aeromonas, Pseudomonas, Vibrio), and sub-inhibitory antibiotics may induce prophages and enhance bacterial competence, creating synergistic conditions that could accelerate resistome evolution. This review underscores the need for integrated approaches combining phage-targeted disinfection with ecological monitoring to effectively restrain the spread of antibiotic resistance.</p>","PeriodicalId":8342,"journal":{"name":"Applied Microbiology and Biotechnology","volume":" ","pages":""},"PeriodicalIF":4.3,"publicationDate":"2026-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147760690","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mitigating protocatechuic acid toxicity in Vibrio natriegens enables poly-3-hydroxybutyrate production from an aromatic carbon source.","authors":"Anna Faber, Roland Politan, Angus Nicol, Simona Della Valle, Benjamin Jenkins, Gavin Flematti, Georg Fritz","doi":"10.1007/s00253-026-13831-z","DOIUrl":"https://doi.org/10.1007/s00253-026-13831-z","url":null,"abstract":"<p><p>3,4-Dihydroxybenzoic acid (protocatechuic acid, PCA) is a central intermediate in bacterial aromatic catabolism - a key node for processing aromatic waste streams such as lignin and polyethylene terephthalate (PET) and a compound of growing biotechnological interest for valorising complex aromatic feedstocks. Here, we present a proof-of-concept for upcycling of PCA as a sole carbon source into a non-aromatic, higher-value bioproduct. We show that Vibrio natriegens, an emerging microbial chassis, can use PCA to produce poly-3-hydroxybutyrate (PHB), with no additional carbon source such as yeast extract or peptone. Efficient growth on PCA required careful optimisation of substrate concentration, cultivation conditions, and medium composition, e.g. replacing Fe²⁺ with Fe³⁺. These strategies reduced PCA autoxidation and limited reactive oxygen species (ROS) toxicity. Adaptive laboratory evolution over ~ 1000 generations identified convergent mutations that reveal insights into the architecture of the oxidative stress response in V. natriegens, including catalytic enzymes such as a Dyp-type peroxidase, and multiple regulatory proteins including OxyR, MarR, RpoS, ToxS, and RseB. Further mutations implicate cell wall repair and protein quality control in the PCA stress response. Functionally, the adapted strains produced 2.5-fold more PHB in 80% of the time required by the parental strain. Overall, we demonstrate the potential and current limitations of V. natriegens for the sustainable upcycling of aromatic, waste-derived carbon into value-added bioproducts.</p>","PeriodicalId":8342,"journal":{"name":"Applied Microbiology and Biotechnology","volume":" ","pages":""},"PeriodicalIF":4.3,"publicationDate":"2026-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147760765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Understanding time-growth rate relationship for slow-growing microbial cells in retentostat culturing systems.","authors":"Beatriz Aranda, Juan M Gonzalez","doi":"10.1007/s00253-026-13817-x","DOIUrl":"https://doi.org/10.1007/s00253-026-13817-x","url":null,"abstract":"<p><p>Generally, microorganisms in nature are severely growth-limited because of nutrient availability, competition, or physico-chemical parameters. To simulate these growing conditions, the use of continuous culturing systems has been proposed. One modification of these systems is the so-called retentostat. It corresponds to a system closed to cells and open to nutrients, and a nutrient is limiting growth. In this system, cells are forced to reduce progressively their growth rate as a result of increasing biomass sharing the same resources. In these systems, near-zero growth rates (corresponding to long doubling times) can be achieved within relatively reasonable time frames. Nevertheless, in these systems, the relationship between growth rate and time remains to be further analyzed. Herein, we evaluate a retentostat culturing system for different prokaryotic species. We established a general relationship between growth rate and incubation time. This allows us to easily estimate either the growth rate reached after a given incubation time or the time required to obtain cells at a specific slow growth rate. The results suggested progressive adaptation of cells at decreasing growth rates. This contribution simplifies estimates for incubation time-dependent growth rates and shows a retentostat as a species-independent culturing system where growth rates depend on time and dilution rate.</p>","PeriodicalId":8342,"journal":{"name":"Applied Microbiology and Biotechnology","volume":" ","pages":""},"PeriodicalIF":4.3,"publicationDate":"2026-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147760138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Piezoelectric cold atmospheric plasma inactivates dairy cattle bacteria and potentiates antibiotics in vitro.","authors":"Jessica S Ghodke, Dayane Lemos Teixeira, Daniel Enriquez-Hidalgo, Matt J Bell, Olena Doran, Alexandros Ch Stratakos","doi":"10.1007/s00253-026-13843-9","DOIUrl":"https://doi.org/10.1007/s00253-026-13843-9","url":null,"abstract":"<p><p>Wound infection remains a major challenge in animal health and welfare, particularly in the farm environment, where skin injuries are prone to microbial contamination. However, reliance on antibiotics increases the risks of antimicrobial resistance and drug residues in animal products. Therefore, developing effective non-antibiotic-based approaches for wound decontamination is critically important and an emerging priority. In the current study, the antimicrobial efficacy of cold atmospheric plasma (CAP) was assessed against Escherichia coli P4, Staphylococcus aureus M60, and Staphylococcus epidermidis NCTC 11047 inoculated onto a bovine collagen-elastin matrix that approximates dermal tissue. Bacterial survivors (log CFU/cm²) were quantified after CAP exposure of 30-180 s at 1-2 cm source distances, alongside mechanistic assessments (viability staining, intracellular reactive oxygen species (ROS), extracellular lactate dehydrogenase (LDH), adenosine triphosphate (ATP) leakage, and lipid peroxidation). At 1 cm exposure distance, CAP reduced viable counts below detection limit after 120 s across all strains; at 2 cm, significant but distance-attenuated reductions were maintained. CAP exposure decreased viability in a treatment time-dependent manner, increased intracellular ROS, and compromised membrane integrity, consistent with envelope permeabilisation. A brief 30-s pre-exposure enhanced antibiotic susceptibility, approximately halving MICs and reducing MBCs by up to 75% for oxytetracycline (engemycin) and enrofloxacin. These findings indicate that piezoelectric CAP provides broad antimicrobial activity and potentiates antibiotic efficacy, supporting translational potential for on-farm wound hygiene and antibiotic stewardship. KEY POINTS: • Piezoelectric CAP effectively reduces bacterial log CFU/cm². • Piezoelectric CAP compromises bacterial cell integrity and causes oxidative damage. • CAP-pretreated bacteria showed enhanced antibiotic susceptibility.</p>","PeriodicalId":8342,"journal":{"name":"Applied Microbiology and Biotechnology","volume":" ","pages":""},"PeriodicalIF":4.3,"publicationDate":"2026-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147760136","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Leaf mold extract agar facilitates recovery of soil bacterial diversity beyond Bacillus dominance.","authors":"Fumiaki Tabuchi, Kazuhiro Mikami, Masaki Ishii, Jyunichiro Yasukawa, Masanobu Miyauchi, D P N De Silva, Atsushi Miyashita","doi":"10.1007/s00253-026-13826-w","DOIUrl":"https://doi.org/10.1007/s00253-026-13826-w","url":null,"abstract":"<p><p>Dominance of Bacillus species on conventional agar often hampers the recovery of diverse soil bacteria (\"Bacillus dominance\"). To address this, we developed an agar medium containing leaf mold extract (LME) and evaluated its effectiveness for soil microorganism isolation compared to conventional yeast malt extract agar (YME agar). The 16S rRNA gene sequencing revealed that YME agar cultures were dominated by Bacillus-related bacteria, while LME agar enabled the growth of a broader range of taxa, especially actinomycetes like Streptomyces. LME agar supported higher bacterial diversity even in samples with high Bacillus abundance. Some LME isolates had very low 16S rRNA gene similarity to known species or could not be amplified with universal primers, suggesting potentially novel taxa. One unidentified isolate proliferated only in liquid LME, indicating a unique nutrient requirement. We further screened LME-derived isolates (569 strains) for therapeutic activity using an insect (the silkworm, Bombyx mori) model infected with three pathogenic fungi (Rhizopus arrhizus, Aspergillus fumigatus, Candida albicans). Distinct extracts showed significant efficacy in each infection model, and the overall hit rate was 6.2%. Notably, the extract of the rare species Ancylobacter sonchi showed marked efficacy against R. arrhizus infection, underscoring LME agar's potential for accessing novel bioresources. These results suggest that LME agar suppresses Bacillus dominance and expands access to diverse, rare, and previously uncultured soil bacteria, providing a powerful platform for microbial library construction and novel drug discovery. KEY POINTS: • LME agar prevents Bacillus dominance, enabling recovery of diverse microbial colonies. • LME agar accesses rarer and more diverse microbiota than nutrient-rich media. • A strain from LME agar showed therapeutic activity in silkworms infected with R. arrhizus.</p>","PeriodicalId":8342,"journal":{"name":"Applied Microbiology and Biotechnology","volume":" ","pages":""},"PeriodicalIF":4.3,"publicationDate":"2026-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147760756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A katE katG double-knockout E. coli strain eliminates the risk of catalase contamination in recombinant proteins","authors":"Axel Tobias Scholz,&nbsp;Lucia Coppo,&nbsp;Edward Nolan,&nbsp;Michaella Hernandez,&nbsp;Xuan Wang,&nbsp;Pradeep Mishra,&nbsp;Robert Schnell,&nbsp;Zsuzsanna Anna Pató,&nbsp;Yifei Chen,&nbsp;Markus Dagnell,&nbsp;Attila Andor,&nbsp;Qing Cheng,&nbsp;Elias S. J. Arnér","doi":"10.1007/s00253-026-13820-2","DOIUrl":"10.1007/s00253-026-13820-2","url":null,"abstract":"<p>Recombinant protein expression in <i>E. coli</i> is a key methodology for modern biomedical research. Typically, a polyhistidine-tagged (“His-tagged”) protein is purified using immobilized metal affinity chromatography (IMAC), achieving close to apparently homogenous target protein preparations. However, contaminant host proteins may nonetheless be co-purified at trace amounts. This includes bacterial catalase, which can even be found crystallized instead of an intended target protein. Here, we found that less than 0.03% of the original endogenous bacterial catalase remaining in a final recombinant protein product can easily be detected in an enzymatic H₂O₂ (hydrogen peroxide) scavenging assay, because of the high inherent turnover of catalase and its lack of need for additional cofactors. If present in a recombinant protein preparation, this activity may give unintended effects, especially if the target protein is a redox active enzyme, such as glutathione peroxidase, glutaredoxin, ribonucleotide reductase, thioredoxin, or peroxiredoxin. Here, we found that genetic deletion of the two <i>katG</i> and <i>katE</i> genes in a bacterial expression host could fully eliminate catalase from the recombinant protein product without any appreciable loss of final yield. We suggest that this genetic approach is to be preferred for the removal of catalase instead of using more extensive purification schemes.</p><p>• <i>Catalase contaminates recombinant His-tagged proteins purified from E. coli.</i></p><p>• <i>A small amount of catalase yields substantial activity due to its high turnover.</i></p><p>• <i>Genetic knockout eliminates catalase contamination without compromising yields.</i></p>","PeriodicalId":8342,"journal":{"name":"Applied Microbiology and Biotechnology","volume":"110 1","pages":""},"PeriodicalIF":4.3,"publicationDate":"2026-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00253-026-13820-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147738633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vibrio proteolyticus DCF12.2 postbiotic modulates intestinal metabolic and immune pathways in zebrafish.","authors":"Jorge García-Márquez, Isabel Cerezo, Rafaela Santos, Rui Magalhães, António Paulo Carvalho, Salvador Arijo, Aires Oliva-Teles, Cláudia Serra, Miguel Ángel Moriñigo","doi":"10.1007/s00253-026-13825-x","DOIUrl":"https://doi.org/10.1007/s00253-026-13825-x","url":null,"abstract":"<p><p>Postbiotics have recently emerged as a promising alternative to probiotics in aquaculture due to their improved safety, stability, and ease of application; however, the biological effects of postbiotics derived from Vibrio proteolyticus remain largely unexplored. In this study, we evaluated the impact of dietary supplementation with ethanol-inactivated V. proteolyticus DCF12.2 on the intestinal microbiota composition and transcriptomic profile of zebrafish (Danio rerio). Fish were fed a control diet (CTRL group) or a diet supplemented with 1% lyophilized ethanol-inactivated V. proteolyticus DCF12.2 (VP group) for 21 days. Alpha and beta diversity analyses exhibited no significant differences in overall gut microbial composition between dietary groups, nor at the phylum or genus level. However, differential abundance analysis at the amplicon sequence variant (ASV) level identified significant differences in ASVs affiliated with the genera Aeromonas, Delftia, Ralstonia, Shewanella, and Stenotrophomonas, which were enriched in fish receiving the VP diet (p < 0.0001). Despite these ASV-level shifts, predicted microbial metabolic functions did not differ significantly between treatments. In contrast, transcriptomic analysis via Gene Set Enrichment Analysis (GSEA) detected a clear host response: a significant downregulation of the cytokine-cytokine receptor interaction pathway and the upregulation of pathways related to nutrient metabolism, oxidative phosphorylation, and cellular biosynthesis in fish fed the VP diet (adjusted p < 0.05). These results suggest that dietary supplementation with postbiotics from V. proteolyticus DCF12.2 modulates intestinal metabolic and immune pathways without inducing major restructuring of the gut microbiota composition. Collectively, these findings provide new insights into host-postbiotic interactions and support the potential application of postbiotics from V. proteolyticus DCF12.2 as functional feed additives for sustainable aquaculture. KEY POINTS: • Postbiotic diet did not alter gut microbial diversity but induced ASV-level differences • Postbiotic diet upregulated nutrient metabolism, oxidative phosphorylation, and cellular biosynthesis • Cytokine-cytokine receptor signaling was downregulated by the postbiotic diet.</p>","PeriodicalId":8342,"journal":{"name":"Applied Microbiology and Biotechnology","volume":" ","pages":""},"PeriodicalIF":4.3,"publicationDate":"2026-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147760128","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of a membrane-bound PQQ-dependent D-lactate dehydrogenase in Gluconobacter japonicus.","authors":"Naoya Kataoka, Shu Takeuchi, Shintaro Maeno, Minenosuke Matsutani, Kazunobu Matsushita, Toshiharu Yakushi","doi":"10.1007/s00253-026-13818-w","DOIUrl":"https://doi.org/10.1007/s00253-026-13818-w","url":null,"abstract":"<p><p>Membrane-bound pyrroloquinoline quinone (PQQ)-dependent quinoproteins are key components of the periplasmic oxidative metabolism of acetic acid bacteria, yet several predicted enzymes remain experimentally uncharacterized. Here, we identified and characterized Pqq5 from Gluconobacter japonicus NBRC 3271 as a membrane-bound PQQ-dependent D-lactate dehydrogenase (mLDH). Overexpression of mLDH in a strain lacking six major membrane bound dehydrogenases markedly increased D-lactate dehydrogenase activity in membrane fractions. The enzyme showed a clear preference for D-lactate over L-lactate, exhibited maximal activity at pH 6.0, and retained substantial activity at pH 4.0-6.0. Kinetic analysis using membrane fractions yielded an apparent K_M of 1.08 mM for D-lactate. Membrane fractions containing mLDH showed ubiquinone-1 reductase activity and D-lactate-dependent oxygen consumption, suggesting that the enzyme is involved in quinone-linked D-lactate oxidation. D-lactate dehydrogenase activity was decreased by EDTA treatment, and restored by supplementation with PQQ and CaCl₂, supporting the assignment of mLDH as a quinoprotein. In addition, pyruvate was produced from D-lactate in an mLDH-dependent manner. In an engineered background lacking known D-lactate-oxidizing enzymes, overexpression of mLDH helped growth on D-lactate medium. Together, these results support the identification of Pqq5 as a membrane-bound PQQ-dependent D-lactate dehydrogenase in G. japonicus and suggest that this enzyme contributes to quinone-linked D-lactate utilization. KEY POINTS: • Pqq5 is a membrane-bound PQQ-dependent D-lactate dehydrogenase, mLDH • mLDH catalyzes D-lactate oxidation and ubiquinone reduction in membrane fractions • mLDH helps growth on D-lactate in an engineered G. japonicus background.</p>","PeriodicalId":8342,"journal":{"name":"Applied Microbiology and Biotechnology","volume":" ","pages":""},"PeriodicalIF":4.3,"publicationDate":"2026-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147728281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}