Glutamicum ATCC Research Articles

Multi-step metabolic engineering Corynebacterium glutamicum ATCC13032 to produce L-methionine

Multi-step metabolic engineering Corynebacterium glutamicum ATCC13032 to produce L-methionine

Comparative Genomic and Genetic Evidence on a Role for the OarX Protein in Thiamin Salvage.

Salvage pathways for thiamin and its thiazole and pyrimidine moieties are poorly characterized compared to synthesis pathways. A candidate salvage gene is oarX, which encodes a short-chain dehydrogenase/reductase. In diverse bacteria, oarX clusters on the chromosome with genes of thiamin synthesis, salvage, or transport and is preceded by a thiamin pyrophosphate riboswitch. Thiamin and its moieties can undergo oxidations that convert a side-chain hydroxymethyl group to a carboxyl group, or the thiazole ring to a thiazolone, causing a loss of biological activity. To test if OarX participates in salvage of the carboxyl or thiazolone products, we used a genetic approach in Corynebacterium glutamicum ATCC 14067, which is auxotrophic for thiamin's pyrimidine moiety. This strain could not utilize the pyrimidine carboxyl derivative. This excluded a role in salvaging this product and narrowed the function search to metabolism of the carboxyl or thiazolone derivatives of thiamin or its thiazole moiety. However, a ΔthiG (thiazole auxotroph) strain was not rescued by any of these derivatives. Nor did deleting oarX affect rescue by the physiological pyrimidine and thiazole precursors of thiamin. These findings reinforce the genomic evidence that OarX has a function in thiamin metabolism and rule out five logical possibilities for what this function is.

Production of bilirubin via whole-cell transformation utilizing recombinant Corynebacterium glutamicum expressing a β-glucuronidase from Staphylococcus sp. RLH1.

Bilirubin, a key active ingredient of bezoars with extensive clinical applications in China, is produced through a chemical process. However, this method suffers from inefficiency and adverse environmental impacts. To address this challenge, we present a novel and efficient approach for bilirubin production via whole-cell transformation. In this study, we employed Corynebacterium glutamicum ATCC13032 to express a β-glucuronidase (StGUS), an enzyme from Staphylococcus sp. RLH1 that effectively hydrolyzes conjugated bilirubin to bilirubin. Following the optimization of the biotransformation conditions, a remarkable conversion rate of 79.7% in the generation of bilirubin was obtained at temperate 40°C, pH 7.0, 1mMMg2+ and 6mM antioxidant NaHSO3 after 12h. These findings hold significant potential for establishing an industrially viable platform for large-scale bilirubin production.

Efficient biosynthesis of creatine by whole-cell catalysis from guanidinoacetic acid in Corynebacterium glutamicum

Creatine is a naturally occurring derivative of an amino acid commonly utilized in functional foods and pharmaceuticals. Nevertheless, the current industrial synthesis of creatine relies on chemical processes, which may hinder its utilization in certain applications. Therefore, a biological approach was devised that employs whole-cell biocatalysis in the bacterium Corynebacterium glutamicum, which is considered safe for use in food production, to produce safe-for-consumption creatine. The objective of this study was to identify a guanidinoacetate N-methyltransferase (GAMT) with superior catalytic activity for creatine production. Through employing whole-cell biocatalysis, a gamt gene from Mus caroli (Mcgamt) was cloned and expressed in C. glutamicum ATCC 13032, resulting in a creatine titer of 3.37 g/L. Additionally, the study employed a promoter screening strategy that utilized nine native strong promoters in C. glutamicum to enhance the expression level of GAMT. The highest titer was achieved using the P1676 promoter, reaching 4.14 g/L. The conditions of whole-cell biocatalysis were further optimized, resulting in a creatine titer of 5.42 g/L. This is the first report of successful secretory creatine expression in C. glutamicum, which provides a safer and eco-friendly approach for the industrial production of creatine.

Establishment of synthetic microbial consortia with Corynebacterium glutamicum and Pseudomonas putida: Design, construction, and application to production of γ-glutamylisopropylamide and l-theanine.

Microbial synthetic consortia are a promising alternative to classical monoculture for biotechnological applications and fermentative processes. Their versatile use offers advantages in the degradation of complex substrates, the allocation of the metabolic burden between individual partners, or the division of labour in energy utilisation, substrate supply or product formation. Here, stable synthetic consortia between the two industrially relevant production hosts, Pseudomonas putida KT2440 and Corynebacterium glutamicum ATCC13032, were established for the first time. By applying arginine auxotrophy/overproduction and/or formamidase-based utilisation of the rare nitrogen source formamide, different types of interaction were realised, such as commensal relationships (+/0 and 0/+) and mutualistic cross-feeding (+/+). These consortia did not only show stable growth but could also be used for fermentative production of the γ-glutamylated amines theanine and γ-glutamyl-isopropylamide (GIPA). The consortia produced up to 2.8 g L-1 of GIPA and up to 2.6 g L-1 of theanine, a taste-enhancing constituent of green tea leaves. Thus, the advantageous approach of using synthetic microbial consortia for fermentative production of value-added compounds was successfully demonstrated.

Utilization of sweet sorghum juice as a carbon source for enhancement of itaconic acid production in engineered Corynebacterium glutamicum

Itaconic acid is a promising biochemical building block that can be used in polymer synthesis. Itaconic acid is currently produced in industry by the natural producer fungus Aspergillus terreus using glucose as a main carbon source. Most research for itaconic acid production using lignocellulosic-based carbon sources was carried out by A. terreus. Engineered Corynebacterium glutamicum strain which can grow in presence of fermentation inhibitors without effect on growth, was used for production of itaconic acid using sweet sorghum juice and bagasse sugar lysate (BSL). BSL contains many inhibitors unlike sorghum juice. C. glutamicum could grow in the media containing both types of lignocellulose-based carbon sources without showing any growth inhibition, however, sorghum juice was better in itaconic acid production than BSL. Different constructed strains of C. glutamicum were used for itaconic acid production, however, C. glutamicum ATCC 13032 pCH-Tad1optAdi1opt strain expressing Adi1/Tad1 genes (trans-pathway) from Ustilago maydis proved to be better in itaconic acid production giving final titer of 8.4 and 4.02 g/L using sweet sorghum juice and BSL as the sole carbon sources by fed-batch fermentation. Our study is the first for production of itaconic acid using sweet sorghum juice and BSL. The present study also proved that C. glutamicum can be used for enhancing itaconic acid production using lignocellulosic-based carbon sources.

Can Genome Sequencing Coupled to Flux Balance Analyses Offer Precision Guidance for Industrial Strain Development? The Lessons from Carbon Trafficking in Corynebacterium glutamicum ATCC 21573.

Systems biology tools offer new prospects for industrial strain selection. For bacteria that are significant for industrial applications, whole-genome sequencing coupled to flux balance analysis (FBA) can help unpack the complex relationships between genome mutations and carbon trafficking. This work investigates the l-tyrosine (l-Tyr) overproducing model system Corynebacterium glutamicum ATCC 21573 with an eye to more rational and precision strain development. Using genome-wide mutational analysis of C. glutamicum, we identified 27,611 single nucleotide polymorphisms and 479 insertion/deletion mutations. Mutations in the carbon uptake machinery have led to phosphotransferase system-independent routes as corroborated with FBA. Mutations within the central carbon metabolism of C. glutamicum impaired the carbon flux, as evidenced by the lower growth rate. The entry to and flow through the tricarboxylic acid cycle was affected by mutations in pyruvate and α-ketoglutarate dehydrogenase complexes, citrate synthase, and isocitrate dehydrogenase. FBA indicated that the estimated flux through the shikimate pathway became larger as the l-Tyr production rate increased. In addition, protocatechuate export was probabilistically impossible, which could have contributed to the l-Tyr accumulation. Interestingly, aroG and cg0975, which have received previous attention for aromatic amino acid overproduction, were not mutated. From the branch point molecule, prephenate, the change in the promoter region of pheA could be an influential contributor. In summary, we suggest that genome sequencing coupled with FBA is well poised to offer rational guidance for industrial strain development, as evidenced by these findings on carbon trafficking in C. glutamicum ATCC 21573.

Design and evaluation of a 3D-printed, lab-scale perfusion bioreactor for novel biotechnological applications.

3D-printing increased in significance for biotechnological research as new applications like lab-on-a-chip systems, cell culture devices or 3D-printed foods were uncovered. Besides mammalian cell culture, only few of those applications focus on the cultivation of microorganisms and none of these make use of the advantages of perfusion systems. One example for applying 3D-printing for bioreactor development is the microbial utilization of alternative substrates derived from lignocellulose, where dilute carbon concentrations and harmful substances present a major challenge. Furthermore, quickly manufactured and affordable 3D-printed bioreactors can accelerate early development phases through parallelization. In this work, a novel perfusion bioreactor system consisting of parts manufactured by fused filament fabrication (FFF) is presented and evaluated. Hydrophilic membranes are used for cell retention to allow the application of dilute substrates. Oxygen supply is provided by membrane diffusion via hydrophobic polytetrafluoroethylene membranes. An exemplary cultivation of Corynebacterium glutamicum ATCC 13032 supports the theoretical design by achieving competitive biomass concentrations of 18.4gL-1 after 52h. As a proof-of-concept for cultivation of microorganisms in perfusion mode, the described bioreactor system has application potential for bioconversion of multi-component substrate-streams in a lignocellulose-based bioeconomy, for in-situ product removal or design considerations of future applications for tissue cultures. Furthermore, this work provides a template-based toolbox with instructions for creating reference systems in different application scenarios or tailor-made bioreactor systems.

Crystal Structures of 6-Phosphogluconate Dehydrogenase from Corynebacterium glutamicum.

Corynebacterium glutamicum (C. glutamicum) has been considered a very important and meaningful industrial microorganism for the production of amino acids worldwide. To produce amino acids, cells require nicotinamide adenine dinucleotide phosphate (NADPH), which is a biological reducing agent. The pentose phosphate pathway (PPP) can supply NADPH in cells via the 6-phosphogluconate dehydrogenase (6PGD) enzyme, which is an oxidoreductase that converts 6-phosphogluconate (6PG) to ribulose 5-phosphate (Ru5P), to produce NADPH. In this study, we identified the crystal structure of 6PGD_apo and 6PGD_NADP from C. glutamicum ATCC 13032 (Cg6PGD) and reported our biological research based on this structure. We identified the substrate binding site and co-factor binding site of Cg6PGD, which are crucial for understanding this enzyme. Based on the findings of our research, Cg6PGD is expected to be used as a NADPH resource in the food industry and as a drug target in the pharmaceutical industry.

Effect of different metabolic pathways on itaconic acid production in engineered Corynebacterium glutamicum

Itaconic acid (IA), a C5-dicarboxylic acid, is a potential bio-based building block for the polymer industry. There are three pathways for IA production from natural IA producers; however, most of the engineered strains were used for IA production by heterologous expression of cis-aconitate decarboxylase gene (cadA) from Aspergillus terreus. In this study, IA was produced by an engineered Corynebacterium glutamicum ATCC 13032 expressing two different types of genes from two distinct pathways. The first involves the mammalian immunoresponsive gene1 (Irg1) derived from Mus musculus. The second (termed here the trans-pathway) involves two genes from the natural IA producer Ustilago maydis which are aconitate-delta-isomerase (Adi1) and trans-aconitate decarboxylase (Tad1) genes. The constructed strains developing the two distinct IA production pathways: C.glutamicum ATCC 13032 pCH-Irg1opt and C.glutamicum ATCC 13032 pCH-Tad1optadi1opt were used for production of IA from different carbon sources. The results reflect the possibility for IA production from C.glutamicum expressing the trans-pathway (Adi1/Tad1 genes) and cis-pathway (Irg1 gene) other than the well-known cis-pathway that depends mainly on cadA gene from A.terreus. The developed strain expressing trans-pathway from U.maydis; however, proved to be better at IA production with high titers of 12.25, 11.34, and 11.02g/L, and a molar yield of 0.22, 0.42, and 0.43mol/mol from glucose, maltose, and sucrose, respectively, via fed-batch fermentation. The present study suggests that trans-pathway is better than cis-pathway for IA production in engineered C.glutamicum.

Heterologous Biosynthesis of Hyaluronic Acid Using a New Hyaluronic Acid Synthase Derived from the Probiotic Streptococcus thermophilus

Hyaluronic acid (HA) is a natural linear polysaccharide extensively used in many fields, including the food, medicine, and cosmetics industries. Currently, species that produce HA synthetase (HAS) from microbial sources are relatively small and mainly pathogenic, such as Streptococcus pyogenes and Pasteurella multicide. Moreover, there is limited research on the safe microbial sources of HAS. Thus, we characterized SthasA, a HAS derived from the probiotic Streptococcus thermophilus, and used it for the de novo synthesis of HA in a chassis strain of Bacillus amyloliquefaciens. Metabolic engineering of the precursor supply modules suggested that hasB (encoding UDPG dehydrogenase), which was derived from Corynebacterium glutamicum ATCC 13032, effectively promoted the accumulation of HA products. Furthermore, by combining the expression of the global regulatory factor CcpA, HA yield from the recombinant strain reached 3.20 g/L. Finally, we obtained a yield of 5.57 g/L HA with a molecular weight of 1.7 × 106 Da using various process optimization strategies in a 5 L bioreactor. This study enriches our understanding of obtaining HAS from non-pathogenic bacteria and provides a safe and effective process for producing HA, which has the potential to promote the industrial applications of HA further.

Experimental kS estimation: A comparison of methods for Corynebacterium glutamicum from lab to microfluidic scale.

Knowledge about the specific affinity of whole cells towarda substrate, commonly referred to as kS , is a crucial parameter for characterizing growth within bioreactors. State-of-the-art methodologies measure either uptake or consumption rates at different initial substrate concentrations. Alternatively, cell dry weight or respiratory data like online oxygen and carbon dioxide transfer rates can be used to estimate kS . In this work, a recently developed substrate-limited microfluidic single-cell cultivation (sl-MSCC)method is applied for the estimation of kS values under defined environmental conditions. This method is benchmarked with two alternative microtiter plate methods, namely high-frequency biomass measurement (HFB)and substrate-limited respiratory activity monitoring (sl-RA).As a model system, the substrate affinity kS of Corynebacterium glutamicum ATCC 13032 regarding glucose was investigated assuming a Monod-type growth response. A kS of <70.7 mg/L(with 95% probability) with HFB, 8.55 ± 1.38 mg/Lwith sl-RA, and 2.66 ± 0.99 mg/L with sl-MSCC was obtained. Whereas HFB and sl-RA are suitable for a fast initial kS estimation, sl-MSCC allows an affinity estimation by determining tD at concentrations less or equal to the kS value. Thus, sl-MSCC lays the foundation for strain-specific kS estimations under defined environmental conditions with additional insights into cell-to-cell heterogeneity.

Metabolic engineering of Corynebacterium glutamicum for acetate-based itaconic acid production

BackgroundItaconic acid is a promising platform chemical for a bio-based polymer industry. Today, itaconic acid is biotechnologically produced with Aspergillus terreus at industrial scale from sugars. The production of fuels but also of chemicals from food substrates is a dilemma since future processes should rely on carbon sources which do not compete for food or feed. Therefore, the production of chemicals from alternative substrates such as acetate is desirable to develop novel value chains in the bioeconomy.ResultsIn this study, Corynebacterium glutamicum ATCC 13032 was engineered to efficiently produce itaconic acid from the non-food substrate acetate. Therefore, we rewired the central carbon and nitrogen metabolism by inactivating the transcriptional regulator RamB, reducing the activity of isocitrate dehydrogenase, deletion of the gdh gene encoding glutamate dehydrogenase and overexpression of cis-aconitate decarboxylase (CAD) from A. terreus optimized for expression in C. glutamicum. The final strain C. glutamicum ΔramB Δgdh IDHR453C (pEKEx2-malEcadopt) produced 3.43 ± 0.59 g itaconic acid L−1 with a product yield of 81 ± 9 mmol mol−1 during small-scale cultivations in nitrogen-limited minimal medium containing acetate as sole carbon and energy source. Lowering the cultivation temperature from 30 °C to 25 °C improved CAD activity and further increased the titer and product yield to 5.01 ± 0.67 g L−1 and 116 ± 15 mmol mol−1, respectively. The latter corresponds to 35% of the theoretical maximum and so far represents the highest product yield for acetate-based itaconic acid production. Further, the optimized strain C. glutamicum ΔramB Δgdh IDHR453C (pEKEx2-malEcadopt), produced 3.38 ± 0.28 g itaconic acid L−1 at 25 °C from an acetate-containing aqueous side-stream of fast pyrolysis.ConclusionAs shown in this study, acetate represents a suitable non-food carbon source for itaconic acid production with C. glutamicum. Tailoring the central carbon and nitrogen metabolism enabled the efficient production of itaconic acid from acetate and therefore this study offers useful design principles to genetically engineer C. glutamicum for other products from acetate.

Production of Trehalose from Maltose by Whole Cells of Permeabilized Recombinant Corynebacterium glutamicum

Trehalose (α-D-glucopyranosyl-1,1-α-D-glucopyranoside) is a stable and nonreducing disaccharide; can be used as sweetener, stabilizer, and humectant; and has many applications in the food, pharmaceutical, and cosmetic industries. Trehalose production from maltose catalyzed by trehalose synthase (TreS) is simple and economically feasible for industrial-scale application. Reducing the cost and enhancing the efficiency of TreS synthesis and the conversion of maltose to trehalose is critical for trehalose production. In this study, the homologous TreS was constitutively overexpressed in Corynebacterium glutamicum ATCC13032 by removing the repressor gene lacIq fragment in the plasmid, and TreS expression could be exempt from the inducer addition and induction process. For cell permeabilization, Triton X-100 was used as a permeabilization agent, and the treatment time was 3 h. In the conversion system, the permeabilized cells of recombinant C. glutamicum were used as biocatalysts, 300 g/L maltose was used as a substrate, and 173.7 g/L trehalose was produced within 12 h under 30 °C and pH 7.0 conditions. In addition, the whole-cell biocatalysts showed promising reusability. This study provides a safe, convenient, practical, and low-cost pathway for the production of trehalose.

The role of trehalose biosynthesis on mycolate composition and L-glutamate production in Corynebacterium glutamicum

Corynebacterium glutamicum has been widely utilized for the industrial production of various amino acids. Trehalose is a prerequisite for the biosynthesis of mycolates which are structurally important constituents of the cell envelope in C. glutamicum. In this study, C. glutamicum mutant ΔSYA, which is unable to synthesize trehalose was constructed by deleting genes treS, treY and otsA in the three pathways of trehalose biosynthesis. In the fermentation medium, ΔSYA grew as well as the control C. glutamicum ATCC13869, synthesized similar levels of glucose monocorynomycolate, trehalose dicorynomycolate, and phospholipids to ATCC13869, but produced 12.5 times more L-glutamate than ATCC13869. Transcriptional levels of the genes relevant to L-arginine biosynthesis, encoding ODHC and relevant to the biosynthesis of sulfur-containing amino acids were down-regulated in ΔSYA. In minimal medium with different concentrations of glucose, ΔSYA grew worse than ATCC13869 but excreted more L-glutamate. When grown in minimal medium, phospholipids are the major lipid in ΔSYA, while glucose monocorynomycolate, trehalose dicorynomycolate, and phospholipids are the major lipid in ATCC13869. The transcriptional levels of mscCG in ΔSYA was significantly up-regulated when grown in minimal medium.

Optimization of L-Citrulline Operon in Corynebacterium glutamicum for L-Citrulline Production

L-citrulline plays important roles in many physiological processes, and its application range is expanding rapidly. Corynebacterium glutamicum strains have the potential to be efficient L-citrulline producers. In this study, we performed optimization of L-citrulline biosynthesis operon in C. glutamicum ATCC13032 for L-citrulline production. Chromosomal integration of the integral argBEc gene from Escherichia coli (encoding natively insensitive N-acetylglutamate kinase), the deletion of the argR gene (encoding repressor ArgR), and the deletion of the argG gene (encoding argininosuccinate synthase) were achieved simultaneously by one-step genome modification and by obtaining the L-citrulline-producing strain. Then, plasmid-based overexpression of the optimized L-citrulline operon was carried out and the L-citrulline production was further improved. In fed-batch fermentation, the L-citrulline production and yield from glucose of the final strain reached 26.7 g/L and 0.18 g/g, respectively. These results indicate that optimization of L-citrulline operon in C. glutamicum is effective to construct the L-citrulline over-producing strain.

Tyramine Derivatives Catalyze the Aldol Dimerization of Butyraldehyde in the Presence of Escherichia coli.

Biogenic amine organocatalysts have transformed the field of synthetic organic chemistry. Yet despite their use in synthesis and to label biomolecules in vitro, amine organocatalysis in vivo has received comparatively little attention – despite the potential of such reactions to be interfaced with living cells and to modify cellular metabolites. Herein we report that biogenic amines derived from L‐tyrosine catalyze the self‐aldol condensation of butanal to 2‐ethylhexenal – a key intermediate in the production of the bulk chemical 2‐ethylhexanol – in the presence of living Escherichia coli and outperform many amine organocatalysts currently used in synthetic organic chemistry. Furthermore, we demonstrate that cell lysate from E. coli and the prolific amine overproducer Corynebacterium glutamicum ATCC 13032 catalyze this reaction in vitro, demonstrating the potential for microbial metabolism to be used as a source of organocatalysts for biocompatible reactions in cells.

Hot isopropanol quenching procedure for automated microtiter plate scale 13C-labeling experiments

BackgroundCurrently, the generation of genetic diversity for microbial cell factories outpaces the screening of strain variants with omics-based phenotyping methods. Especially isotopic labeling experiments, which constitute techniques aimed at elucidating cellular phenotypes and supporting rational strain design by growing microorganisms on substrates enriched with heavy isotopes, suffer from comparably low throughput and the high cost of labeled substrates.ResultsWe present a miniaturized, parallelized, and automated approach to 13C-isotopic labeling experiments by establishing and validating a hot isopropanol quenching method on a robotic platform coupled with a microbioreactor cultivation system. This allows for the first time to conduct automated labeling experiments at a microtiter plate scale in up to 48 parallel batches. A further innovation enabled by the automated quenching method is the analysis of free amino acids instead of proteinogenic ones on said microliter scale. Capitalizing on the latter point and as a proof of concept, we present an isotopically instationary labeling experiment in Corynebacterium glutamicum ATCC 13032, generating dynamic labeling data of free amino acids in the process.ConclusionsOur results show that a robotic liquid handler is sufficiently fast to generate informative isotopically transient labeling data. Furthermore, the amount of biomass obtained from a sub-milliliter cultivation in a microbioreactor is adequate for the detection of labeling patterns of free amino acids. Combining the innovations presented in this study, isotopically stationary and instationary automated labeling experiments can be conducted, thus fulfilling the prerequisites for 13C-metabolic flux analyses in high-throughput.

In silico analysis of nitrilase-3 protein from Corynebacterium glutamicum for bioremediation of nitrile herbicides

BackgroundThe nitrile compounds are produced either naturally or synthetically and are highly used in many manufacturing industries such as pharmaceuticals, pesticides, chemicals, and polymers. However, the extensive use and accumulation of these nitrile compounds have caused severe environmental pollution. Nitrilated herbicides are one such toxic substance that will persist in the soil for a long time. Therefore, effective measures must be taken to avoid its pollution to the environment. A variety of nitrile-converting bacterial species have the ability to convert these toxic substances into less toxic ones by using enzymatic processes. Among the bacterial groups, actinobacteria family members show good degradation capacity on these pollutants. The soil-dwelling Gram-positive industrial microbe Corynebacterium glutamicum is one such family member and its nitrile-degradation pathway is not well studied yet. In order to understand the effectiveness of using C. glutamicum for the degradation of such nitrile herbicides, an in silico approach has been done. In this perspective, this work focus on the structural analysis and molecular docking studies of C. glutamicum with nitrilated herbicides such as dichlobenil, bromoxynil, and chloroxynil. ResultsThe bioinformatics analysis using different tools and software helped to confirm that the genome of C. glutamicum ATCC 13032 species have genes (cg 3093) codes for carbon-nitrogen hydrolase enzyme, which specifically act on non-peptide bond present in the nitrile compounds. The conserved domain analysis indicated that this protein sequence was nitrilase-3 and comes under the nitrilase superfamily. The multiple sequence alignment analysis confirmed that the conserved catalytic triad residues were 40E, 115K, and 151C, and the existence of nitrilase-3 protein in the genome of Corynebacterium sp. was evaluated by a phylogenetic tree. The analysis of physico-chemical properties revealed that alanine is the most abounded amino acid (10.20%) in the nitrilase-3 protein, and these properties influence the substrate specificity of aliphatic and aromatic nitrile compounds. The homology modelled protein showed better affinity towards nitrile herbicides such as 2,6-dichlorobenzamide (BAM) and 3,5-dichloro-4-hydroxy-benzamide (CIAM) with the affinity value of − 5.8 and − 5.7 kcal/mol respectively. ConclusionsThe in silico studies manifested that C. glutamicum ATCC 13032 is one of the promising strains for the bioremediation of nitrilated herbicides contaminated soil.

Acetate-based production of itaconic acid with Corynebacterium glutamicum using an integrated pH-coupled feeding control

To date, most bio-based products of industrial biotechnology stem from sugar-based carbon sources originating from food and feed competing resources. Exemplary for bioproducts converted from glucose, the potential C5 platform chemical itaconic acid is presently produced by the filamentous fungus Aspergillus terreus. Here, an engineered strain of the industrial platform organism Corynebacterium glutamicum ATCC 13032 was used for acetate-based production of itaconic acid to overcome current production difficulties. For this purpose, C. glutamicum ICDR453C (pEKEx2-malEcadopt) with a mutated icd variant for reduced isocitrate dehydrogenase activity was constructed harbouring pEKEx2-malEcadopt, that includes a cis-aconitate dehydrogenase gene originating from A. terreus. Overall, a peak volumetric productivity of 1.01 gL−1h−1 was achieved resulting in an itaconate titer of 29.2 g/L, by using an integrated pH-coupled acetate feeding control in a fed-batch process without base titration. The results support the high potential of acetate as alternative substrate for bioproduction.