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1.
Nat Biomed Eng ; 2024 Apr 19.
Article in English | MEDLINE | ID: mdl-38641710

ABSTRACT

Intracellular DNA sensors regulate innate immunity and can provide a bridge to adaptive immunogenicity. However, the activation of the sensors in antigen-presenting cells (APCs) by natural agonists such as double-stranded DNAs or cyclic nucleotides is impeded by poor intracellular delivery, serum stability, enzymatic degradation and rapid systemic clearance. Here we show that the hydrophobicity, electrostatic charge and secondary conformation of helical polypeptides can be optimized to stimulate innate immune pathways via endoplasmic reticulum stress in APCs. One of the three polypeptides that we engineered activated two major intracellular DNA-sensing pathways (cGAS-STING (for cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes) and Toll-like receptor 9) preferentially in APCs by promoting the release of mitochondrial DNA, which led to the efficient priming of effector T cells. In syngeneic mouse models of locally advanced and metastatic breast cancers, the polypeptides led to potent DNA-sensor-mediated antitumour responses when intravenously given as monotherapy or with immune checkpoint inhibitors. The activation of multiple innate immune pathways via engineered cationic polypeptides may offer therapeutic advantages in the generation of antitumour immune responses.

2.
Metab Eng ; 83: 160-171, 2024 May.
Article in English | MEDLINE | ID: mdl-38636729

ABSTRACT

Microbes have inherent capacities for utilizing various carbon sources, however they often exhibit sub-par fitness due to low metabolic efficiency. To test whether a bacterial strain can optimally utilize multiple carbon sources, Escherichia coli was serially evolved in L-lactate and glycerol. This yielded two end-point strains that evolved first in L-lactate then in glycerol, and vice versa. The end-point strains displayed a universal growth advantage on single and a mixture of adaptive carbon sources, enabled by a concerted action of carbon source-specialists and generalist mutants. The combination of just four variants of glpK, ppsA, ydcI, and rph-pyrE, accounted for more than 80% of end-point strain fitness. In addition, machine learning analysis revealed a coordinated activity of transcriptional regulators imparting condition-specific regulation of gene expression. The effectiveness of the serial adaptive laboratory evolution (ALE) scheme in bioproduction applications was assessed under single and mixed-carbon culture conditions, in which serial ALE strain exhibited superior productivity of acetoin compared to ancestral strains. Together, systems-level analysis elucidated the molecular basis of serial evolution, which hold potential utility in bioproduction applications.


Subject(s)
Carbon , Directed Molecular Evolution , Escherichia coli , Escherichia coli/genetics , Escherichia coli/metabolism , Carbon/metabolism , Escherichia coli Proteins/genetics , Escherichia coli Proteins/metabolism , Glycerol/metabolism , Lactic Acid/metabolism , Metabolic Engineering
3.
Methods Mol Biol ; 2760: 117-132, 2024.
Article in English | MEDLINE | ID: mdl-38468085

ABSTRACT

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9 system has enabled rapid advances in genomic engineering and transcriptional regulation. Specifically, CRISPR interference (CRISPRi) system has been used to systematically investigate the gene functions of microbial strains in a high-throughput manner. This method involves growth profiling using cells that have been transformed with the deactivated Cas9 (dCas9) and single-guide RNA (sgRNA) libraries that target individual genes. The fitness scores of each gene are calculated by measuring the abundance of individual sgRNAs during cell growth and represent gene essentiality. In this chapter, a process is described for functional genetic screening using CRISPRi at the whole-genome scale, starting from the synthesis of sgRNA libraries, construction of CRISPRi libraries, and identification of essential genes through growth profiling. The commensal bacterium Bacteroides thetaiotaomicron was used to implement the protocol. This method is expected to be applicable to a broader range of microorganisms to explore the novel phenotypic characteristics of microorganisms.


Subject(s)
Gene Expression Regulation , RNA, Guide, CRISPR-Cas Systems , Phenotype , Genetic Testing , CRISPR-Cas Systems
4.
Nat Nanotechnol ; 19(2): 255-263, 2024 Feb.
Article in English | MEDLINE | ID: mdl-37723279

ABSTRACT

Nanomedicines have been approved to treat multiple human diseases. However, clinical adoption of nanoformulated agents is often hindered by concerns about hepatic uptake and clearance, a process that is not fully understood. Here we show that the antitumour efficacy of cancer nanomedicine exhibits an age-associated disparity. Tumour delivery and treatment outcomes are superior in old versus young mice, probably due to an age-related decline in the ability of hepatic phagocytes to take up and remove nanoparticles. Transcriptomic- and protein-level analysis at the single-cell and bulk levels reveals an age-associated decrease in the numbers of hepatic macrophages that express the scavenger receptor MARCO in mice, non-human primates and humans. Therapeutic blockade of MARCO is shown to decrease the phagocytic uptake of nanoparticles and improve the antitumour effect of clinically approved cancer nanotherapeutics in young but not aged mice. Together, these results reveal an age-associated disparity in the phagocytic clearance of nanotherapeutics that affects their antitumour response, thus providing a strong rationale for an age-appropriate approach to cancer nanomedicine.


Subject(s)
Nanoparticles , Neoplasms , Humans , Mice , Animals , Neoplasms/therapy , Phagocytes/pathology , Nanomedicine/methods , Nanoparticles/therapeutic use , Kinetics
5.
Front Bioeng Biotechnol ; 11: 1267378, 2023.
Article in English | MEDLINE | ID: mdl-37929193

ABSTRACT

The past decade has seen growing interest in bacterial engineering for therapeutically relevant applications. While early efforts focused on repurposing genetically tractable model strains, such as Escherichia coli, engineering gut commensals is gaining traction owing to their innate capacity to survive and stably propagate in the intestine for an extended duration. Although limited genetic tractability has been a major roadblock, recent advances in systems and synthetic biology have unlocked our ability to effectively harness native gut commensals for therapeutic and diagnostic purposes, ranging from the rational design of synthetic microbial consortia to the construction of synthetic cells that execute "sense-and-respond" logic operations that allow real-time detection and therapeutic payload delivery in response to specific signals in the intestine. In this review, we outline the current progress and latest updates on microbial therapeutics, with particular emphasis on gut commensal engineering driven by synthetic biology and systems understanding of their molecular phenotypes. Finally, the challenges and prospects of engineering gut commensals for therapeutic applications are discussed.

6.
Nat Commun ; 14(1): 6610, 2023 10 19.
Article in English | MEDLINE | ID: mdl-37857647

ABSTRACT

The recent success of mRNA therapeutics against pathogenic infections has increased interest in their use for other human diseases including cancer. However, the precise delivery of the genetic cargo to cells and tissues of interest remains challenging. Here, we show an adaptive strategy that enables the docking of different targeting ligands onto the surface of mRNA-loaded small extracellular vesicles (sEVs). This is achieved by using a microfluidic electroporation approach in which a combination of nano- and milli-second pulses produces large amounts of IFN-γ mRNA-loaded sEVs with CD64 overexpressed on their surface. The CD64 molecule serves as an adaptor to dock targeting ligands, such as anti-CD71 and anti-programmed cell death-ligand 1 (PD-L1) antibodies. The resulting immunogenic sEVs (imsEV) preferentially target glioblastoma cells and generate potent antitumour activities in vivo, including against tumours intrinsically resistant to immunotherapy. Together, these results provide an adaptive approach to engineering mRNA-loaded sEVs with targeting functionality and pave the way for their adoption in cancer immunotherapy applications.


Subject(s)
Extracellular Vesicles , Glioblastoma , Humans , RNA, Messenger/genetics , Immunotherapy/methods , Extracellular Vesicles/genetics , Electroporation
7.
Nanomaterials (Basel) ; 13(19)2023 Oct 05.
Article in English | MEDLINE | ID: mdl-37836345

ABSTRACT

The continuous advancement of Artificial Intelligence (AI) technology depends on the efficient processing of unstructured data, encompassing text, speech, and video. Traditional serial computing systems based on the von Neumann architecture, employed in information and communication technology development for decades, are not suitable for the concurrent processing of massive unstructured data tasks with relatively low-level operations. As a result, there arises a pressing need to develop novel parallel computing systems. Recently, there has been a burgeoning interest among developers in emulating the intricate operations of the human brain, which efficiently processes vast datasets with remarkable energy efficiency. This has led to the proposal of neuromorphic computing systems. Of these, Spiking Neural Networks (SNNs), designed to closely resemble the information processing mechanisms of biological neural networks, are subjects of intense research activity. Nevertheless, a comprehensive investigation into the relationship between spike shapes and Spike-Timing-Dependent Plasticity (STDP) to ensure efficient synaptic behavior remains insufficiently explored. In this study, we systematically explore various input spike types to optimize the resistive memory characteristics of Hafnium-based Ferroelectric Tunnel Junction (FTJ) devices. Among the various spike shapes investigated, the square-triangle (RT) spike exhibited good linearity and symmetry, and a wide range of weight values could be realized depending on the offset of the RT spike. These results indicate that the spike shape serves as a crucial indicator in the alteration of synaptic connections, representing the strength of the signals.

8.
Plants (Basel) ; 12(15)2023 Jul 28.
Article in English | MEDLINE | ID: mdl-37570953

ABSTRACT

Efficient genetic transformation is a prerequisite for rapid gene functional analyses and crop trait improvements. We recently demonstrated that new T-DNA binary vectors with NptII/G418 selection and a compatible helper plasmid can efficiently transform maize inbred B104 using our rapid Agrobacterium-mediated transformation method. In this work, we implemented the non-integrating Wuschel2 (Wus2) T-DNA vector method for Agrobacterium-mediated B104 transformation and tested its potential for recalcitrant inbred B73 transformation and gene editing. The non-integrating Wus2 (NIW) T-DNA vector-assisted transformation method uses two Agrobacterium strains: one carrying a gene-of-interest (GOI) construct and the other providing an NIW construct. To monitor Wus2 co-integration into the maize genome, we combined the maize Wus2 expression cassette driven by a strong constitutive promoter with a new visible marker RUBY, which produces the purple pigment betalain. As a GOI construct, we used a previously tested CRISPR-Cas9 construct pKL2359 for Glossy2 gene mutagenesis. When both GOI and NIW constructs were delivered by LBA4404Thy- strain, B104 transformation frequency was significantly enhanced by about two-fold (10% vs. 18.8%). Importantly, we were able to transform a recalcitrant inbred B73 using the NIW-assisted transformation method and obtained three transgene-free edited plants by omitting the selection agent G418. These results suggest that NIW-assisted transformation can improve maize B104 transformation frequency and provide a novel option for CRISPR technology for transgene-free genome editing.

9.
Sci Data ; 10(1): 431, 2023 07 06.
Article in English | MEDLINE | ID: mdl-37414813

ABSTRACT

The genome of Populus davidiana, a keystone aspen species, has been sequenced to improve our understanding of the evolutionary and functional genomics of the Populus genus. The Hi-C scaffolding genome assembly resulted in a 408.1 Mb genome with 19 pseudochromosomes. The BUSCO assessment revealed that 98.3% of the genome matched the embryophytes dataset. A total of 31,862 protein-coding sequences were predicted, of which 31,619 were functionally annotated. The assembled genome was composed of 44.9% transposable elements. These findings provide new knowledge about the characteristics of the P. davidiana genome and will facilitate comparative genomics and evolutionary research on the genus Populus.


Subject(s)
Genome, Plant , Populus , Biological Evolution , Genomics/methods , Phylogeny , Populus/genetics , Chromosomes, Plant
10.
Pharmacol Res ; 194: 106836, 2023 08.
Article in English | MEDLINE | ID: mdl-37355147

ABSTRACT

Alzheimer's disease (AD) is the most prevalent type of dementia and is characterized by cognitive deficits and accumulation of pathological plaques. Owing to the complexity of AD development, paradigms for AD research and drug discovery have shifted to target factors that mediate multiple pathogenesis in AD. Increasing evidence suggests that the suppression of the Wnt/ß-catenin signaling pathway plays substantial roles in AD progression. However, the underlying mechanism for the suppression of Wnt/ß-catenin pathway associated with AD pathogenesis remains unexplored. In this study, we identified that CXXC5, a negative feedback regulator of the Wnt/ß-catenin pathway, was overexpressed in the tissues of AD patients and 5xFAD transgenic mice paired with the suppression of Wnt/ß-catenin pathway and its target genes related to AD. The level of CXXC5 was upregulated, upon aging of 5xFAD mice. AD characteristics including cognitive deficits, amyloid-ß (Aß) plaques, neuronal inflammation, and age-dependent increment of AD-related markers were rescued in Cxxc5-/-/5xFAD mice. 5-methoxyindirubin-3'-oxime (KY19334), a small molecule that restores the suppressed Wnt/ß-catenin pathway via interference of the CXXC5-Dvl interaction, significantly improved the overall pathogenic phenotypes of 5xFAD mice. Collectively, our findings revealed that CXXC5 plays a key role in AD pathogenesis and suggest inhibition of CXXC5-Dvl interaction as a new therapeutic approach for AD.


Subject(s)
Alzheimer Disease , Wnt Signaling Pathway , Animals , Mice , Alzheimer Disease/metabolism , Amyloid beta-Peptides/metabolism , beta Catenin/metabolism , Disease Models, Animal , DNA-Binding Proteins/metabolism , Mice, Transgenic , Transcription Factors , Humans
11.
Microbiol Resour Announc ; 12(6): e0127122, 2023 Jun 20.
Article in English | MEDLINE | ID: mdl-37133359

ABSTRACT

We report the high-quality genome sequence of Tricholoma matsutake strain 2001, which was isolated from a mushroom fruiting body in South Korea. The genome has 80 contigs, a size of 162.6 Mb, and an N50 value of 5,103,859 bp and will provide insight into the symbiotic association between T. matsutake and Pinus densiflora.

12.
J Dermatol ; 50(10): 1335-1338, 2023 Oct.
Article in English | MEDLINE | ID: mdl-37208851

ABSTRACT

Alopecia totalis (AT) and alopecia universalis (AU) is known to have a poor prognosis with high relapse rate, and treatment failure is observed in most patients, regardless of the type of therapy. Although treatment and the prognosis of AT and AU have improved in recent years, old data are routinely cited in recent review papers without questioning them. The authors aimed to study the clinical characteristics and prognosis of AT and AU to update and compare the results with those of previously reported studies. The authors retrospectively reviewed patients diagnosed with AT and AU from 2006 to 2017 in a single institution. Of the 419 patients, the mean age at first episode was 22.9 years, and 24.6% had early onset (≤13 years). During follow-up, 53.9% had more than 50% hair growth, and 19.6% of patients showed >90% hair growth. Among patients who showed >50% improvement, 36.7% had no recurrence. In early studies conducted in the 1950s and 1960s, the chance of full hair regrowth was reported to be <10%. In our study, patients with >90% improvement in AT and AU accounted for 19.6% of patients. The authors provide an update on data regarding the prognoses of AT and AU.


Subject(s)
Alopecia Areata , Humans , Retrospective Studies , Alopecia Areata/drug therapy , Alopecia/therapy , Alopecia/drug therapy , Prognosis , Hair
14.
Elife ; 122023 03 24.
Article in English | MEDLINE | ID: mdl-36961502

ABSTRACT

Cancer secretome is a reservoir for aberrant glycosylation. How therapies alter this post- translational cancer hallmark and the consequences thereof remain elusive. Here, we show that an elevated secretome fucosylation is a pan-cancer signature of both response and resistance to multiple targeted therapies. Large-scale pharmacogenomics revealed that fucosylation genes display widespread association with resistance to these therapies. In cancer cell cultures, xenograft mouse models, and patients, targeted kinase inhibitors distinctively induced core fucosylation of secreted proteins less than 60 kDa. Label-free proteomics of N-glycoproteomes identified fucosylation of the antioxidant PON1 as a critical component of the therapy-induced secretome (TIS). N-glycosylation of TIS and target core fucosylation of PON1 are mediated by the fucose salvage-FUT8-SLC35C1 axis with PON3 directly modulating GDP-Fuc transfer on PON1 scaffolds. Core fucosylation in the Golgi impacts PON1 stability and folding prior to secretion, promoting a more degradation-resistant PON1. Global and PON1-specific secretome de-N-glycosylation both limited the expansion of resistant clones in a tumor regression model. We defined the resistance-associated transcription factors (TFs) and genes modulated by the N-glycosylated TIS via a focused and transcriptome-wide analyses. These genes characterize the oxidative stress, inflammatory niche, and unfolded protein response as important factors for this modulation. Our findings demonstrate that core fucosylation is a common modification indirectly induced by targeted therapies that paradoxically promotes resistance.


Subject(s)
Protein Processing, Post-Translational , Secretome , Humans , Animals , Mice , Glycosylation , Aryldialkylphosphatase
15.
Int J Cardiovasc Imaging ; 39(1): 87-95, 2023 Jan.
Article in English | MEDLINE | ID: mdl-36598698

ABSTRACT

Accurate measurement of right ventricular (RV) size using transthoracic echocardiography (TTE) is important for evaluating the severity of congenital heart diseases. The RV end-diastolic area index (RVEDAi) determined using TTE is used to assess RV dilatation; however, the tracing line of the RVEDAi has not been clearly defined by the guidelines. This study aimed to determine the exact tracing method for RVEDAi using TTE. We retrospectively studied 107 patients with atrial septal defects who underwent cardiac magnetic resonance imaging (CMR) and TTE. We measured the RVEDAi according to isoechoic and high-echoic lines, and compared it with the RVEDAi measured using CMR. The isoechoic line was defined as the isoechoic endocardial border of the RV free wall, whereas the high-echoic line was defined as the high-echoic endocardial border of the RV free wall more outside than the isoechoic line. RVEDAi measured using high-echoic line (high-RVEDAi) was more accurately related to RVEDAi measured using CMR than that measured using isoechoic line (iso-RVEDAi). The difference in the high-RVEDAi was 0.3 cm2/m2, and the limit of agreement (LOA) was - 3.7 to 4.3 cm2/m2. With regard to inter-observer variability, high-RVEDAi was superior to iso-RVEDAi. High-RVEDAi had greater agreement with CMR-RVEDAi than with iso-RVEDAi. High-RVEDAi can become the standard measurement of RV size using two-dimensional TTE.


Subject(s)
Heart Defects, Congenital , Heart Septal Defects, Atrial , Humans , Adult , Retrospective Studies , Predictive Value of Tests , Echocardiography/methods , Heart , Heart Septal Defects, Atrial/diagnostic imaging , Hypertrophy, Right Ventricular/diagnostic imaging , Hypertrophy, Right Ventricular/etiology , Reproducibility of Results
16.
Comput Struct Biotechnol J ; 21: 563-573, 2023.
Article in English | MEDLINE | ID: mdl-36659921

ABSTRACT

Adaptive laboratory evolution (ALE) has long been used as the tool of choice for microbial engineering applications, ranging from the production of commodity chemicals to the innovation of complex phenotypes. With the advent of systems and synthetic biology, the ALE experimental design has become increasingly sophisticated. For instance, implementation of in silico metabolic model reconstruction and advanced synthetic biology tools have facilitated the effective coupling of desired traits to adaptive phenotypes. Furthermore, various multi-omic tools now enable in-depth analysis of cellular states, providing a comprehensive understanding of the biology of even the most genomically perturbed systems. Emerging machine learning approaches would assist in streamlining the interpretation of massive and multiplexed datasets and promoting our understanding of complexity in biology. This review covers some of the representative case studies among the 700 independent ALE studies reported to date, outlining key ideas, principles, and important mechanisms underlying ALE designs in bioproduction and synthetic cell engineering, with evidence from literatures to aid comprehension.

17.
Nat Nanotechnol ; 17(12): 1332-1341, 2022 12.
Article in English | MEDLINE | ID: mdl-36357792

ABSTRACT

Solid tumours display a limited response to immunotherapies. By contrast, haematological malignancies exhibit significantly higher response rates to immunotherapies as compared with solid tumours. Among several microenvironmental and biological disparities, the differential expression of unique immune regulatory molecules contributes significantly to the interaction of blood cancer cells with immune cells. The self-ligand receptor of the signalling lymphocytic activation molecule family member 7 (SLAMF7), a molecule that is critical in promoting the body's innate immune cells to detect and engulf cancer cells, is expressed nearly exclusively on the cell surface of haematologic tumours, but not on solid ones. Here we show that a bispecific nanobioconjugate that enables the decoration of SLAMF7 on the surface of solid tumours induces robust phagocytosis and activates the phagocyte cyclic guanosine monophosphate-adenosine monophosphate synthase-stimulator of interferon genes (cGAS-STING) pathway, sensitizing the tumours to immune checkpoint blockade. Our findings support an immunological conversion strategy that uses nano-adjuvants to improve the effectiveness of immunotherapies for solid tumours.


Subject(s)
Membrane Proteins , Neoplasms , Humans , Membrane Proteins/metabolism , Immunotherapy , Phagocytosis
18.
ACS Appl Bio Mater ; 2022 Oct 03.
Article in English | MEDLINE | ID: mdl-36191156

ABSTRACT

Biolistic transfection is a popular and versatile tool for plant transformation. A key step in the biolistic process is the binding of DNA to the heavy microprojectile using a delivery agent, usually a positively charged molecule containing amine groups. Currently, the choice of the commercial delivery agent is mostly limited to spermidine. In addition, the detailed delivery mechanism has not been reported. To help broaden the selection of the delivery agent and reveal the fundamental mechanisms that lead to high delivery performance, a library of amine-containing molecules was investigated. A double-barrel biolistic delivery device was utilized for testing hundreds of samples with much-improved consistency. The performance was evaluated on onion epidermis. The binding and release of DNA were measured via direct high-performance liquid chromatography analysis. This study shows that the overwhelming majority of the amine library performed at the same level as spermidine. To further interpret these results, correlations were performed with thousands of molecular descriptors generated by chemical modeling. It was discovered that the overall charge is most likely the key factor to a successful binding and delivery. Furthermore, even after increasing the amount of the DNA concentration 50-fold to stress the binding capacity of the molecules, the amines in the library continued to deliver at a near identical level while binding all the DNA. The increased DNA was also demonstrated with a Cas9 editing test that required a large amount of DNA to be delivered, and the result was consistent with the previously determined amine performance. This study greatly expands the delivery agent selection for biolistic delivery, allowing alternatives to a commercial reagent that are more shelf-stable and cheaper. The library also offers an approach to investigate more challenging delivery of protein and CRISPR-Cas via the biolistic process in the future.

19.
Biochim Biophys Acta Mol Cell Res ; 1869(12): 119361, 2022 Dec.
Article in English | MEDLINE | ID: mdl-36162649

ABSTRACT

Phospholipase D1 (PLD1) plays a crucial role in cell differentiation of different cell types. However, the involvement of PLD1 in astrocytic differentiation remains uncertain. In the present study, we investigate the possible role of PLD1 and its product phosphatidic acid (PA) in astrocytic differentiation of hippocampal neural stem/progenitor cells (NSPCs) from hippocampi of embryonic day 16.5 rat embryos. We showed that overexpression of PLD1 increased the expression level of glial fibrillary acidic protein (GFAP), an astrocyte marker, and the number of GFAP-positive cells. Knockdown of PLD1 by transfection with Pld1 shRNA inhibited astrocytic differentiation. Moreover, PLD1 deletion (Pld1-/-) suppressed the level of GFAP in the mouse hippocampus. These results indicate that PLD1 plays a crucial role in regulating astrocytic differentiation in hippocampal NSPCs. Interestingly, PA itself was sufficient to promote astrocytic differentiation. PA-induced GFAP expression was decreased by inhibition of signal transducer and activation of transcription 3 (STAT3) using siRNA. Furthermore, PA-induced STAT3 activation and astrocytic differentiation were regulated by the focal adhesion kinase (FAK)/aurora kinase A (AURKA) pathway. Taken together, our findings suggest that PLD1 is an important modulator of astrocytic differentiation in hippocampal NSPCs via the FAK/AURKA/STAT3 signaling pathway.


Subject(s)
Aurora Kinase A , Neural Stem Cells , Animals , Aurora Kinase A/metabolism , Focal Adhesion Protein-Tyrosine Kinases/metabolism , Glial Fibrillary Acidic Protein/genetics , Glial Fibrillary Acidic Protein/metabolism , Hippocampus/metabolism , Mice , Phosphatidic Acids/metabolism , Phospholipase D , RNA, Small Interfering/genetics , RNA, Small Interfering/metabolism , Rats , Signal Transduction/physiology
20.
Antibiotics (Basel) ; 11(8)2022 Jul 29.
Article in English | MEDLINE | ID: mdl-36009888

ABSTRACT

Bacteria can evade antibiotics by acquiring resistance genes, as well as switching to a non-growing dormant state without accompanying genetic modification. Bacteria in this quiescent state are called persisters, and this non-inheritable ability to withstand multiple antibiotics is referred to as antibiotic tolerance. Although all bacteria are considered to be able to form antibiotic-tolerant persisters, the antibiotic tolerance of extremophilic bacteria is poorly understood. Previously, we identified the psychrotolerant bacterium Pseudomonas sp. B14-6 from the glacier foreland of Midtre Lovénbreen in High Arctic Svalbard. Herein, we investigated the resistance and tolerance of Pseudomonas sp. B14-6 against aminoglycosides at various temperatures. This bacterium was resistant to streptomycin and susceptible to apramycin, gentamicin, kanamycin, and tobramycin. The two putative aminoglycoside phosphotransferase genes aph1 and aph2 were the most likely contributors to streptomycin resistance. Notably, unlike the mesophilic Pseudomonas aeruginosa PA14, this cold-adapted bacterium demonstrated reduced susceptibility to all tested aminoglycosides in a temperature-dependent manner. Pseudomonas sp. B14-6 at a lower temperature formed the persister cells that shows tolerance to the 100-fold minimum inhibitory concentration (MIC) of gentamicin, as well as the partially tolerant cells that withstand 25-fold MIC gentamicin. The temperature-dependent gentamicin tolerance appears to result from reduced metabolic activity. Lastly, the partially tolerant Pseudomonas sp. B14-6 cells could slowly proliferate under the bactericidal concentrations of aminoglycosides. Our results demonstrate that Pseudomonas sp. B14-6 has a characteristic ability to form cells with a range of tolerance, which appears to be inversely proportional to its growth rate.

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