Tricomicosis palmelina causa poco frecuente de afectación del tallo piloso / Trichomycosis palmelina: rare cause of hair shaft affection

Resumen La tricomicosis o tricobacteriosis palmelina es un motivo de consulta poco frecuente en los servicios de dermatología, es importante reconocerla y diferenciarla de otras patologías ya que puede ser difícil de diagnosticar. La tricomicosis o tricobacteriosis es una condición infecciosa superficial asintomática, rara, causada en la mayoría de los casos por Corynebacterium flavescens (también llamada Corynebacterium tenuis), perteneciente a la familia corinebacteriaceae, las cuales, son bacterias gram positivas, pleomórficas, inmóviles, no encapsuladas, aerobias o anaerobias facultativas. Afecta pelos de la región axilar, zona púbica, escrotal e interglutea; se debe al aumento de la población bacteriana de la microbiota normal, adherida a la cutícula del pelo. Esta afectación es propia de climas húmedos, afectando predominantemente a adultos jóvenes, de sexo masculino, deportistas y homosexuales en un entorno de pobreza y hacinamiento. El objetivo del presente reporte es comunicar un caso de tricomicosis palmelina flava en región púbica en un adulto joven y describir las características clínicas de esta patología relativamente poco conocida.

Abstract Trichomycosis or palmelin trichobacteriosis it is an infrequent reason for consultation in dermatology services, important to recognize and differentiate it from other pathologies since it can be difficult to diagnose. Trichomycosis or trichobacteriosis is a rare, asymptomatic superficial infectious condition, caused in most cases by Corynebacterium flavescens (also called Corynebacterium tenuis), belonging to the Corynebacteriaceae family, which are gram-positive, pleomorphic, immobile, non-encapsulated bacteria, aerobic or facultative anaerobic. It affects hairs in the axillary region, pubic, scrotal and intergluteal area; It is due to the increase in the bacterial population of the normal microbiota, attached to the hair cuticle. This affectation is typical of humid climates, predominantly affecting young adults, males, athletes and homosexuals in an environment of poverty and overcrowding. The objective of this article is to report a case of trichomycosis palmellina flava in the pubic region present in a young adult and to present the clinical characteristics of this relatively unrecognized condition.

Corynebacterium falsenii Bacteremia Occurring in a Term Neonate Causing Late Onset Neonatal Sepsis

Isolated from blood and Cerebrospinal Fluid (CSF) cultures of Leukemia and Lymphoma patients, Corynebacterium falsenii was first identified in 1998 as a new Corynebacterium species. In 2010, it was reported as a cause of Bacteremia in a 13-month-old infant on Vancomycin therapy. We are hereby describing a Corynebacterium falsenii bacteremia occurring in a 15-day-old term neonate causing late onset Sepsis.

Analysis of susceptibility factors and curative effect of corynebacterium striatum detected in sputum of lower respiratory tract the elderly / 中华老年医学杂志

Objective:To observe the susceptibility factors of elderly patients with corynebacterium striata in sputum of lower respiratory tract and analyze its clinical therapeutic effect.Methods:The clinical data of 192 elderly inpatients infected with corynebacterium striatum detected in sputum of lower respiratory tract were retrospectively analyzed in Quanzhou First Hospital Affiliated to Fujian Medical University from January 2019 to June 2021.The detection rate of corynebacterium striata was calculated, and the susceptibility factors and clinical efficacy were compared between the infection group(n=102)and the colonization group(n=90).Results:The detection rate of corynebacterium striata(detected cases / numbers of qualified lower respiratory tract sputum specimen)was 0.8%(72/8976)from January to December 2019, 2.3%(134/5877)from January to December 2020, and 3.0%(121/4 039)from January to June 2021, the difference was statistically significant( χ2=93.93, P<0.01). The detection rates of corynebacterium striatum during three corresponding periods in elderly patients were 0.6%(57/8 976), 1.4%(81/5 877)and 1.9%(78/4 039), respectively, with statistically significant differences( χ2=45.57, P<0.01). The incidences or values of following indexes were higher in infection group than in colonization group: age of patients, admission of intensive care unit, malnutrition, use of hormones, combined use of antibiotics, use of invasive mechanical ventilation, use of fiber bronchoscope, reduced cough reflex, other basic diseases, and so on, but the differences were not statistically significant(all P>0.05). The clinical effective rates were 41.2%(42/102)in the infection group and 48.9%(44/90)in the colonization group, respectively, and the differences was not statistically significant( P>0.05). Only 25 patients(24.5%)in the infected group were treated on corynebacterium striatum according to drug sensitivity results.Among them, the clinical effective rate of the treatment group and the untreated group was 68.0%(17/25)and 32.5%(25/77), respectively, the difference was statistically significant( χ2=9.84, P<0.01). The clinical effective rate of untreated group was lower than that of colonization group, the difference was statistically significant( χ2=4.62, P<0.05). Conclusions:The detection rate of corynebacterium striatum in elderly patients is high, and increases year by year.Patients infected with corynebacterium striatum usually has a variety of susceptibility factors, if not taking effective treatment measures, may have adverse outcomes.In clinical work, it is necessary to pay attention to and reduce the susceptibility factors of corynebacterium striatum, and to correctly interpret the etiological reports, so as to adopt a reasonable and effective therapeutic schedule.

Construction and application of a synthetic promoter library for Corynebacterium glutamicum / 生物工程学报

Promoter is an important genetic tool for fine-tuning of gene expression and has been widely used for metabolic engineering. Corynebacterium glutamicum is an important chassis for industrial biotechnology. However, promoter libraries that are applicable to C. glutamicum have been rarely reported, except for a few developed based on synthetic sequences containing random mutations. In this study, we constructed a promoter library based on the native promoter of odhA gene by mutating the -10 region and the bystanders. Using a red fluorescent protein (RFP) as the reporter, 57 promoter mutants were screened by fluorescence imaging technology in a high-throughput manner. These mutants spanned a strength range between 2.4-fold and 19.6-fold improvements of the wild-type promoter. The strongest mutant exhibited a 2.3-fold higher strength than the widely used strong inducible promoter Ptrc. Sequencing of all 57 mutants revealed that 55 mutants share a 1-4 bases shift (4 bases shift for 68% mutants) of the conserved -10 motif "TANNNT" to the 3' end of the promoter, compared to the wild-type promoter. Conserved T or G bases at different positions were observed for strong, moderate, and weak promoter mutants. Finally, five promoter mutants with different strength were employed to fine-tune the expression of γ-glutamyl kinase (ProB) for L-proline biosynthesis. Increased promoter strength led to enhanced L-proline production and the highest L-proline titer of 6.4 g/L was obtained when a promoter mutant with a 9.8-fold higher strength compared to the wild-type promoter was used for ProB expression. The use of stronger promoter variants did not further improve L-proline production. In conclusion, a promoter library was constructed based on a native C. glutamicum promoter PodhA. The new promoter library should be useful for systems metabolic engineering of C. glutamicum. The strategy of mutating native promoter may also guide the construction of promoter libraries for other microorganisms.

Optimization of CRISPR/Cas9-based multiplex base editing in Corynebacterium glutamicum / 生物工程学报

As a new CRISPR/Cas-derived genome engineering technology, base editing combines the target specificity of CRISPR/Cas and the catalytic activity of nucleobase deaminase to install point mutations at target loci without generating DSBs, requiring exogenous template, or depending on homologous recombination. Recently, researchers have developed a variety of base editing tools in the important industrial strain Corynebacterium glutamicum, and achieved simultaneous editing of two and three genes. However, the multiplex base editing based on CRISPR/Cas9 is still limited by the complexity of multiple sgRNAs, interference of repeated sequence and difficulty of target loci replacement. In this study, multiplex base editing in C. glutamicum was optimized by the following strategies. Firstly, the multiple sgRNA expression cassettes based on individual promoters/terminators was optimized. The target loci can be introduced and replaced rapidly by using a template plasmid and Golden Gate method, which also avoids the interference of repeated sequence. Although the multiple sgRNAs structure is still complicated, the editing efficiency of this strategy is the highest. Then, the multiple gRNA expression cassettes based on Type Ⅱ CRISPR crRNA arrays and tRNA processing were developed. The two strategies only require one single promoter and terminator, and greatly simplify the structure of the expression cassette. Although the editing efficiency has decreased, both methods are still applicable. Taken together, this study provides a powerful addition to the genome editing toolbox of C. glutamicum and facilitates genetic modification of this strain.

Mastitis granulomatosa idiopática. Características clínicas, imagenológicas, patológicas y su correlación con la respuesta al tratamiento - Hospital Dr. Cosme Argerich / Idiopathic granulomatous mastitis: clinical, imagenological, pathological characteristics and their correlation with treatment response

Introducción: La mastitis granulomatosa idiopática (MGI) es una patología inflamatoria benigna que se presenta típicamente como tumoración dolorosa. Recientemente, un subconjunto con patrón histológico neutrofilico quístico (MGNQ) fue asociado al corynebacterium. Objetivo: Revisión bibliográfica y evaluación de nuestra casuística. Material y método: Se seleccionaron 24 mujeres con MGI diagnosticada entre 2000-2019. Variables analizadas: demográficas, antecedentes, clínica, imágenes, cultivos, patología, tratamientos y evolución. Resultados: Edad media: 40.7 años. 50% tuvo ≥4 gestas y 91.6% lactó. Presentación clínica: Tumor abscedado palpable 58.33%, Palpable asintomático 25%, Palpable doloroso 12.5%. Lesión no palpable 4.17%. Tamaño promedio de lesión: 3.5 cm. Imágenes BIRADS 4/5: 87.5% Cultivo de corynebacterium 25%. Patología: Polimorfonucleares intraductales (PMNID) 62.5%, Vacuolas quísticas 50% (2 casos con baci- los). Tratamiento: Antibióticoterapia 79.1%, Inmunosupresión 79.1%, Drenaje de abscesos 45.8%. Tumorectomía 41.6%. Tiempo de resolución: 5.5 meses Tiempo libre de enfermedad: 33.6 meses. Recurrencias: 31.%. Conclusiones: Debe sospecharse en toda mujer joven con tumor mamario asociado a abscesos, fistulas y/o úlceras. El diagnóstico de MGNQ y PM- NID tienen asociación estadísticamente significativa con recurrencia. Es esencial el abordaje multidisciplinario y el tratamiento multimodal

Introduction: Idiopathic granulomatous mastitis (IGM) is a benign inflammatory disease that typically presents as a painful mass. Recently, a subset with cystic neutrophilic histological pattern (CNGM) was related to corynebacterium. Objetive: Bibliographic review and evaluation of our casuistry. Material and method: During 2000-2019, 24 women diagnosed with IGM were selected. Variables analyzed: Demographic, background, clinical, images, cultures, pathology, treatment and evolution. Results: Average age: 40.7 years. 50% had ≥ 4 gestations and 91.6% lactated. Clinical presentation: Palpable abscessed tumor 58.33%, Palpable asymptomatic 25%, Palpable painful 12.5%. Non palpable lesion 4.17%. Average lesion size: 3.5 cm. BIRADS images 4/5: 87.5% Corynebacterium culture 25%. Findings: Intraductal polymorphonuclear cells (IDPMNC) (62.5% ), Cystic vacuoles (50%) (With bacilli in 2 cases). Treatment: Antibiotic therapy 79.1%, Immunosuppression 79.1%, Drainage of abscesses 45.8%. Lumpectomy 41.6%. Resolution time: 5.5 months Diseasefree time: 33.6 months. Recurrences: 31.8%. Conclusions: It should be suspected in any young woman with a breast tumor associated with abscesses, fistulas and/or ulcers. The diagnosis of CNGM and IDPMNC has statistically significant association with recurrence. A multidisciplinary approach and multimodal treatment is essential

Corynebacterium kroppenstedtii y patología mamaria / Corynebacterium kroppenstedtii and breast pathology

Resumen Corynebacterium kroppenstedtii es un bacilo gram positivo corineforme lipofílico, poco frecuente en la clínica humana. Forma parte de la microbiota cutánea de los seres humanos y, por esta razón, su interpretación clínica es compleja. La mastitis granulomatosa es una enfermedad inflamatoria de origen incierto con baja incidencia. Se presentan dos casos clínicos en los que se describe la asociación de C. kroppenstedtii con mastitis granulomatosa. El tejido mamario es rico en lípidos. El carácter lipofílico de este microorganismo podría explicar su presencia en dicho tejido.

Abstract Corynebacterium kroppenstedtii is a rare lipophilic coryneform gram-positive bacillus. It is part of the human skin microbiota and, for this reason, its clinical interpretation is complex. Granulomatous mastitis is an inflammatory disease of uncertain origin with a low incidence. The association of C. kroppenstedtii with granulomatous mastitis was described in two clinical case reports. The lipophilic characteristics of this microorganism explains why it can be found in lipid-rich breast tissue.

Resumo Corynebacterium kroppenstedtii é um bacilo gram-positivo corineforme lipofílico poco frecuente. Faz parte da microbiota do seres humanos, por isso sua interpretação clínica é complexa. A mastite granulomatosa é uma doença inflamatória de origem incerta com baixa incidência. Foram apresentados dois casos clínicos nos quais é descrita a associação de C. kroppenstedtii com mastite granulomatosa. O tecido mamário é rico em lipídios. O caráter lipofílico desse microrganismo pode explicar sua presença em tal tecido.

Tricuspid valve repair with autologous pericardium in a patient with infective endocarditis

Abstract Infective endocarditis is a rather uncommon disease, but it has significant mortality rates in the pediatric population (5% to 10%). We report a case of an infant patient with multiple vegetation in the tricuspid valve secondary to infective endocarditis caused by Corynebacterium diphtheriae. A tricuspid valvuloplasty was performed with a fenestrated autologous pericardium patch, providing satisfactory outcomes. This technique is simple, innovative, effective, and it could be applied in similar cases.

Engineering the C4 pathway of Corynebacterium glutamicum for efficient production of 5-aminolevulinic acid / 生物工程学报

5-aminolevulinic acid (5-ALA) plays an important role in the fields of medicine and agriculture. 5-ALA can be produced by engineered Escherichia coli and Corynebacterium glutamicum. We systematically engineered the C4 metabolic pathway of C. glutamicum to further improve its ability to produce 5-ALA. Firstly, the hemA gene encoding 5-ALA synthase (ALAS) from Rhodobacter capsulatus and Rhodopseudomonas palustris were heterologously expressed in C. glutamicum, respectively. The RphemA gene of R. palustris which showed relatively high enzyme activity was selected. Screening of the optimal ribosome binding site sequence RBS5 significantly increased the activity of RphemA. The ALAS activity of the recombinant strain reached (221.87±3.10) U/mg and 5-ALA production increased by 14.3%. Subsequently, knocking out genes encoding α-ketoglutarate dehydrogenase inhibitor protein (odhI) and succinate dehydrogenase (sdhA) increased the flux of succinyl CoA towards the production of 5-ALA. Moreover, inhibiting the expression of hemB by means of sRNA reduced the degradation of 5-ALA, while overexpressing the cysteine/O-acetylserine transporter eamA increased the output efficiency of intracellular 5-ALA. Shake flask fermentation using the engineered strain C. glutamicum 13032/∆odhI/∆sdhA-sRNAhemB- RBS5RphemA-eamA resulted in a yield of 11.90 g/L, which was 57% higher than that of the original strain. Fed-batch fermentation using the engineered strain in a 5 L fermenter produced 25.05 g/L of 5-ALA within 48 h, which is the highest reported-to-date yield of 5-ALA from glucose.

Characteristics of skin microbiota in an atopic dermatitis-like mouse model induced by 2,4-dinitrochlorobenzene / 中华皮肤科杂志

Objective:To investigate characteristics and changes of skin microbiota in atopic dermatitis-like mouse models induced by different concentrations of 2,4-dinitrochlorobenzene (DNCB) .Methods:Totally, 30 male specific-pathogen-free BALB/c mice were randomly divided into 3 groups by using a random number table: negative control group topically treated with 200 μl of mixture of acetone and olive oil at a volume ratio of 3∶1 on the back twice a week for 6 consecutive weeks; high-and low-concentration DNCB groups both topically treated with 200 μl of 1% DNCB on the first and third day at the first week, followed by topical application of 200 μl of 0.5% and 0.1% DNCB, respectively, twice a week for 5 weeks from the second week. Twenty-four hours after the last treatment, the severity of skin lesions was evaluated, and the transepidermal water loss and stratum corneum hydration were measured. After the experiment, the mice were sacrificed, and skin tissues were resected from the back of the mice for histopathological examination. Full-thickness skin tissue samples were obtained from the back of 3 mice in each group. Illumina Miseq PE300 high-throughput sequencing was performed to sequence the V3-V4 variable region of 16S rRNA gene of skin microbiota on the back of the mice, and the composition and structure of the skin microbiota and changes in the relative abundance of different genera were analyzed. One-way analysis of variance was used to analyze differences in indices among the 3 groups, and the Games-Howell method was used for multiple comparisons.Results:The severity scores of skin lesions were significantly higher in the high-and low-concentration DNCB groups (9.83 ± 2.45 points, 2.71 ± 0.56 points, respectively) than in the negative control group (0.51 ± 0.12 points, t=-7.19,-2.85, respectively, both P < 0.05) . Compared with the negative control group, the high-and low-concentration DNCB groups showed significantly increased transepidermal water loss ( t=-7.72,-2.68, respectively, both P < 0.05) , but significantly decreased stratum corneum hydration ( t=6.77, 5.99, respectively, both P < 0.05) ; the transepidermal water loss was significantly higher in the high-concentration DNCB group than in the low-concentration DNCB group ( t=2.76, P < 0.05) , while no significant difference in the stratum corneum hydration was observed between the high-and low-concentration DNCB groups ( P > 0.05) . There was a significant difference in the relative abundance of Corynebacterium among the 3 groups ( F=249.85, P < 0.001) , which was highest in the high-concentration DNCB group. No significant differences in the observed species and Chao1 index of the skin samples were observed among the 3 groups (both P > 0.05) , and the Shannon index was significantly lower in the high-concentration DNCB group than in the low-concentration DNCB group and negative control group ( t=6.96,-6.37, respectively, both P < 0.05) . Conclusion:DNCB could induce atopic dermatitis-like dermatitis in mice, and the severity of skin lesions and degree of barrier function impairment were related to the concentration of DNCB; the species diversity of skin microbiota markedly decreased in the high-concentration DNCB group, indicating that high-concentration DNCB modeling has more advantages in studying microbiological changes associated with atopic dermatitis.

Adult-onset nasopharyngeal diphtheria: an uncommon but rapidly progressive and potentially fatal infection

@#Nasopharyngeal diphtheria is an acute infectious upper respiratory tract disease caused by toxigenic strains of Corynebacterium diphtheriae. We report a case of a young adult who presented to us with a short history of fever, sore throat, hoarseness of voice and neck swelling. He claimed to have received all his childhood vaccinations and had no known medical illnesses. During laryngoscopy, a white slough (or membrane) was seen at the base of his tongue. The epiglottis was also bulky and the arytenoids were swollen bilaterally. The membrane was sent to the microbiology laboratory for culture. A diagnosis of nasopharyngeal diphtheria was made clinically and the patient was treated with an antitoxin together with erythromycin, while awaiting the culture result. Nevertheless, the patient’s condition deteriorated swiftly and although the laboratory eventually confirmed an infection by toxin-producing C. diphtheriae, the patient had already succumbed to the infection.

Adult Diphteria: Possible Transmission of Corynebacterium diphtheriae from Unvaccinated Child?

@#A case of a toxigenic strain of Corynebacterium diphtheriae in an immunocompetent adult is presented, with the possibility of the adult acquiring the infection from her unvaccinated child. The abovementioned adult is a 29-year-old housewife who was previously immunised with diphtheria, tetanus, and pertussis (DTaP) vaccination in childhood, who presented fever, cough, sore throat, hoarseness of voice, odynophagia, and bilaterally enlarged tonsils. A throat swab confirmed the presence of toxigenic Corynebacterium diphtheriae. The patient was given 80,000 international units (IU) dose of diphtheria antitoxin (DAT) and treated with 2.4 million units (MU) QID intravenous penicillin and oral erythromycin 800 mg twice daily for two weeks. The patient responded well to the treatment and recovered with no cardiovascular or neurotoxicity.

Roles and action mechanisms of skin microbiota in the occurrence of rosacea / 中华皮肤科杂志

The role of skin microbiota in the occurrence of rosacea remains unclear. This review summarizes several important skin microorganisms that have been reported to be possibly related to the occurrence of rosacea, including Demodex, Bacillus oleronius, Propionibacterium acnes, Corynebacterium kroppenstedtii, etc., and further elaborates on the potential mechanisms of action.

Advances and prospects in metabolic engineering for the production of amino acids / 生物工程学报

Fermentative production of amino acids is one of the pillars of the fermentation industry in China. Recently, with the fast development of metabolic engineering and synthetic biology technologies, the metabolic engineering for production of amino acids has been flourishing. Conventional forward metabolic engineering, reversed metabolic engineering based on omics data and in silico simulation, and evolutionary metabolic engineering mimicking the natural evolution, have shown increasingly promising applications. A series of highly efficient and robust amino acids-producing strains have been developed and applied in the industrial production of amino acids. The increasingly fierce market competition has put forward new requirements for strain breeding and selection, such as developing high value-added amino acids, dynamic regulation of cellular metabolism, and adapting to the requirements of new process. This review summarizes the advances and prospects in metabolic engineering for the production of amino acids.

Recent advances in developing enabling technologies for Corynebacterium glutamicum metabolic engineering / 生物工程学报

Corynebacterium glutamicum is an important workhorse of industrial biotechnology, especially for amino acid bioindustry. This bacterium is being used to produce various amino acids at a level of over 6 million tons per year. In recent years, enabling technologies for C. glutamicum metabolic engineering have been developed and improved, which accelerated construction and optimization of microbial cell factoriers, expanding spectra of substrates and products, and facilitated basic researches on C. glutamicum. With these technologies, C. glutamicum has become one of the ideal microbial chasses. This review summarizes recent key technological developments of enabling technologies for C. glutamicum metabolic engineering and focuses on establishment and applications of CRISPR-based genome editing, gene expression regulation, adaptive laboratory evolution, and biosensor technologies.

Advances in stress tolerance mechanisms and synthetic biology for the industrial robustness of Corynebacterium glutamicum / 生物工程学报

As a model industrial host and microorganism with the generally regarded as safe (GRAS) status, Corynebacterium glutamicum not only produces amino acids on a large scale in the fermentation industry, but also has the potential to produce various new products. C. glutamicum usually encounters various stresses in the process of producing compounds, which severely affect cell viability and production performance. The development of synthetic biology provides new technical means for improving the robustness of C. glutamicum. In this review, we discuss the tolerance mechanisms of C. glutamicum to various stresses in the fermentation process. At the same time, we highlight new synthetic biology strategies for boosting C. glutamicum robustness, including discovering new stress-resistant elements, modifying transcription factors, and using adaptive evolution strategies to mine stress-resistant functional modules. Finally, prospects of improving the robustness of engineered C. glutamicum strains ware provided, with an emphasis on biosensor, screening and design of transcription factors, and utilizing the multiple regulatory elements.

Endocarditis secundaria a corynebacterium tras implante de válvula aórtica transcatéter: Informe de un caso / Endocarditis due to corynebacterium after transcatheter aortic valve implantation: A case report

RESUMEN Se presenta un caso de endocarditis valvular protésica secundaria a un organismo infrecuente (Corynebacterium sp.) tras la implantación de una protésis valvular aórtica percutánea. La menor sensibilidad del ecocardiograma transesofágico para detectar signos de endocarditis en éstos pacientes puede retrasar el diagnóstico. El uso de otras técnicas de imagen complementarias como la tomografía por emisión de positrones, puede ser de utilidad. El aumento de implantes de prótesis percutánea en los últimos años va asociado a un aumento de complicaciones como la endocarditis.

ABSTRACT We present a case of prosthetic valve endocarditis secondary to an infrequent organism (Corynebacterium sp.) after percutaneous aortic valve implantation. The lower sensitivity of transesophageal echocardiogram to detect signs of endocarditis in these patients may delay diagnosis. Implementing other ancillary imaging techniques such as positron emission tomography may be helpful. The increase in percutaneous prosthetic implants in recent years is associated with an upsurge in complications such as endocarditis

Umbilical Diphtheria: Resurgence of a Forgotten Entity

Diphtheria has had a resurgence in India over the past decade.We present a case of umbilical diphtheria in a neonate, who had agood outcome with administration of anti-toxin and antibiotics.

Optimization of base editing in Corynebacterium glutamicum / 生物工程学报

In recent years, CRISPR/Cas9-mediated base editing has been developed to a powerful genome editing tool, providing advantages such as without introducing double-stranded DNA break, a donor template and relying on host homologous recombination repair pathway, and has been widely applied in animals, plants, yeast and bacteria. In previous study, our group developed a multiplex automated base editing method (MACBETH) in the important industrial model strain Corynebacterium glutamicum. In this study, to further optimize the method and improve the base editing efficiency in C. glutamicum, we first constructed a green fluorescent protein (GFP) reporter-based detection system. The point mutation in the inactivated GFP protein can be edited to restore the GFP fluorescence. By combining with flow cytometry analysis, the base-editing efficiency can be quickly calculated. Then, the base editor with the target gRNA was constructed, and the editing efficiency with the initial editing condition was (13.11±0.21)%. Based on this result, the editing conditions were optimized and the result indicated that the best medium is CGXII, the best initial OD₆₀₀ of induction is 0.05, the best induction time is 20 h, and the best IPTG concentration is 0.01 mmol/L. After optimization, the editing efficiency was improved to (30.35±0.75)%, which was 1.3-fold of that in initial condition. Finally, endogenous genomic loci of C. glutamicum were selected to assess if the optimized condition can improve genome editing in other loci. Editing efficiency of different loci in optimized condition were improved to 1.7-2.5 fold of that in original condition, indicating the effectiveness and versatility of the optimized condition. Our research will promote the better application of base editing technology in C. glutamicum.

Advances in gene editing of Corynebacterium glutamate / 生物工程学报

Corynebacterium glutamicum, an important microorganism to produce amino acids and organic acids, has been widely applied in food and medicine fields. Therefore, using editing tools to study the function of unknown genes in C. glutamicum has great significance for systematic development of industrial strain with efficient and novel production capability. Recently, gene editing has been greatly developed. Traditional gene editing based on homologous recombination and gene editing mediated by nuclease are successfully applied in C. glutamicum. Among these, the CRISPR system has been developed to be a main tool used for gene knockout of C. glutamicum due to its advantages of efficiency, simplicity and good target specificity. However, more efficient and reliable knockout system is still urgently demanded, to help develop high-performing strains in industrial application.