Current state of coenzyme Q10 production and its applications

Coenzyme Q₁₀ (CoQ₁₀), an obligatory cofactor in the aerobic respiratory electron transfer for energy generation, is formed from the conjugation of a benzoquinone ring with a hydrophobic isoprenoid chain. CoQ₁₀ is now used as a nutritional supplement because of its antioxidant properties and is beneficial in the treatment of several human diseases when administered orally. Bioprocesses have been developed for the commercial production of CoQ₁₀ because of its increased demand, and these bioprocesses depend on microbes that produce high levels of CoQ₁₀ naturally. However, as knowledge of the biosynthetic enzymes and the regulatory mechanisms modulating CoQ₁₀ production increases, approaches arise for the genetic engineering of CoQ₁₀ production in Escherichia coli and Agrobacterium tumefaciens. This review focused on approaches for CoQ₁₀ production, strategies used to engineer CoQ₁₀ production in microbes, and potential applications of CoQ₁₀.     

Increasing coenzyme Q10 yield from Rhodopseudomonas palustris by expressing rate-limiting enzymes and blocking carotenoid and hopanoid pathways

Coenzyme Q₁₀ (CoQ₁₀), a strong antioxidant, is used extensively in food, cosmetic and medicine industries. A natural producer, Rhodopseudomonas palustris, was engineered to overproduce CoQ₁₀. For increasing the CoQ₁₀ content, crtB gene was deleted to block the carotenoid pathway. crtB gene deletion led to 33% improvement of CoQ₁₀ content over the wild type strain. However, it was found that the yield of hopanoids was also increased by competing for the precursors from carotenoid pathway with CoQ₁₀ pathway. To further increase the CoQ₁₀ content, hopanoid pathway was blocked by deleting shc gene, resulting in R. palustris [Δshc, ΔcrtB] to produce 4·7 mg g⁻¹ DCW CoQ₁₀, which was 1·2 times higher than the CoQ₁₀ content in the wild type strain. The common strategy of co-expression of rate-limiting enzymes (DXS, DPS and UbiA) was combined with the pathway blocking method resulted in 8·2 mg g⁻¹ DCW of CoQ₁₀, which was 2·9 times higher than that of wild type strain. The results suggested a synergistic effect among different metabolic engineering strategies. This study demonstrates the potential of R. palustris for CoQ₁₀ production and provides viable strategies to increase CoQ₁₀ titer.     

Controlling the sucrose concentration increases Coenzyme Q10 production in fed-batch culture of <Emphasis Type="Italic">Agrobacterium tumefaciens</Emphasis>

The production yield of Coenzyme Q₁₀ (CoQ₁₀) from the sucrose consumed by Agrobacterium tumefaciens KCCM 10413 decreased, and high levels of exopolysaccharide (EPS) accumulated after switching from batch culture to fed-batch culture. Therefore, we examined the effect of sucrose concentration on the fermentation profile by A. tumefaciens. In the continuous fed-batch culture with the sucrose concentration maintained constantly at 10, 20, 30, and 40 g l⁻¹, the dry cell weight (DCW), specific CoQ₁₀ content, CoQ₁₀ production, and the production yield of CoQ₁₀ from the sucrose consumed increased, whereas EPS production decreased as maintained sucrose concentration decreased. The pH-stat fed-batch culture system was adapted for CoQ₁₀ production to minimize the concentration of the carbon source and osmotic stress from sucrose. Using the pH-stat fed-batch culture system, the DCW, specific CoQ₁₀ content, CoQ₁₀ production, and the product yield of CoQ₁₀ from the sucrose consumed increased by 22.6, 13.7, 39.3, and 39.3%, respectively, whereas EPS production decreased by 30.7% compared to those of fed-batch culture in the previous report (Ha SJ, Kim SY, Seo JH, Oh DK, Lee JK, Appl Microbiol Biotechnol, 74:974–980, 2007). The pH-stat fed-batch culture system was scaled up to a pilot scale (300 l), and the CoQ₁₀ production results obtained (626.5 mg l⁻¹ of CoQ₁₀ and 9.25 mg g DCW⁻¹ of specific CoQ₁₀ content) were similar to those obtained at the laboratory scale. Thus, an efficient and highly competitive process for microbial CoQ₁₀ production is available.     

Molecular,Physiological and Phenotypic Characterization of Paracoccus denitrificans ATCC 19367 Mutant Strain P-87 Producing Improved Coenzyme Q10

Coenzyme Q₁₀ (CoQ₁₀) is a blockbuster nutraceutical molecule which is often used as an oral supplement in the supportive therapy for cardiovascular diseases, cancer and neurodegenerative diseases. It is commercially produced by fermentation process, hence constructing the high yielding CoQ₁₀ producing strains is a pre-requisite for cost effective production. Paracoccus denitrificans ATCC 19367, a biochemically versatile organism was selected to carry out the studies on CoQ₁₀ yield improvement. The wild type strain was subjected to iterative rounds of mutagenesis using gamma rays and NTG, followed by selection on various inhibitors like CoQ₁₀ structural analogues and antibiotics. The screening of mutants were carried out using cane molasses based optimized medium with feeding strategies at shake flask level. In the course of study, the mutant P-87 having marked resistance to gentamicin showed 1.25-fold improvements in specific CoQ₁₀ content which was highest among all tested mutant strains. P-87 was phenotypically differentiated from the wild type strain on the basis of carbohydrate assimilation and FAME profile. Molecular differentiation technique based on AFLP profile showed intra specific polymorphism between wild type strain and P-87. This study demonstrated the beneficial outcome of induced mutations leading to gentamicin resistance for improvement of CoQ₁₀ production in P. denitrificans mutant strain P-87. To investigate the cause of gentamicin resistance, rpIF gene from P-87 and wild type was sequenced. No mutations were detected on the rpIF partial sequence of P-87; hence gentamicin resistance in P-87 could not be conferred with rpIF gene. However, detecting the mutations responsible for gentamicin resistance in P-87 and correlating its role in CoQ₁₀ overproduction is essential. Although only 1.25-fold improvement in specific CoQ₁₀ content was achieved through mutant P-87, this mutant showed very interesting characteristic, differentiating it from its wild type parent strain P. denitrificans ATCC 19367, which are presented in this paper.

Electronic supplementary material

The online version of this article (doi:10.1007/s12088-014-0506-4) contains supplementary material, which is available to authorized users.     

Improving coenzyme Q8 production in Escherichia coli employing multiple strategies

Coenzyme Q (CoQ) is a medically valuable compound and a high yielding strain for CoQ will have several benefits for the industrial production of CoQ. To increase the CoQ₈ content of E. coli, we blocked the pathway for the synthesis of menaquinone by deleting the menA gene. The blocking of menaquinone pathway increased the CoQ₈ content by 81 % in E. coli (ΔmenA). To study the CoQ producing potential of E. coli, we employed previous known increasing strategies for systematic metabolic engineering. These include the supplementation with substrate precursors and the co-expression of rate-limiting genes. The co-expression of dxs-ubiA and the supplementation with substrate precursors such as pyruvate (PYR) and parahydroxybenzoic acid (pHBA) increased the content of CoQ₈ in E. coli (ΔmenA) by 125 and 59 %, respectively. Moreover, a 180 % increase in the CoQ₈ content in E. coli (ΔmenA) was realized by the combination of the co-expression of dxs-ubiA and the supplementation with PYR and pHBA. All in all, CoQ₈ content in E. coli increased 4.06 times by blocking the menaquinone pathway, dxs-ubiA co-expression and the addition of sodium pyruvate and parahydroxybenzoic acid to the medium. Results suggested a synergistic effect among different metabolic engineering strategies.     

Enhanced production of CoQ<Subscript>10</Subscript> by newly isolated <Emphasis Type="Italic">Sphingomonas</Emphasis> sp. ZUTEO3 with a coupled fermentation–extraction process

The use of coenzyme Q₁₀ (CoQ₁₀) as a complementary therapy in heart failure will increase in proportion to the growth of the ageing population and the expansion of statins consumption. Economical production of CoQ₁₀ by microbes will become more important due to the growing demands of the pharmaceutical industry. Process simplification and integration might be one desirable pathway for economic production of CoQ₁₀ by microbial fermentation. In this report, the effect of a coupled fermentation–extraction process on CoQ₁₀ production by newly isolated Sphingomonas sp. ZUTEO3 was evaluated. It was found that the CoQ₁₀ yield of the coupled process was significantly higher than that of the traditional process. As optimal conditions in our experiment, 2% soybean oil was added to the original culture to enhance cell membrane permeability, and 50 mL hexane was added to the 30 h culture as an extracting solvent for the subsequent coupled fermentation–extraction process. The maximal yield of CoQ₁₀ reached 43.2 mg/L and 32.5 mg/g dry cell weight after 38 h of total fermentation period. The coupled process represents one potential pathway for CoQ₁₀ production with even higher yield and lower cost. This is the first report of CoQ₁₀ production by Sphingomonas sp. using a coupled fermentation–extraction process.     

L-鸟氨酸发酵菌种的代谢工程研究进展

L-鸟氨酸是一种非蛋白类氨基酸参与尿素代谢及生物多胺类的合成,其对人体具有治疗肝脏疾病、增强免疫力等作用,被广泛应用于医疗、保健、食品等领域。工业上生产鸟氨酸主要有化学法、酶法及工业发酵法。其中,发酵法因其生产成本及环境保护等方面的优势而逐渐成为研究的焦点。本文归纳了近年来采用基因工程技术选育鸟氨酸高产菌种最新研究进展,重点讨论了产鸟氨酸谷氨酸棒杆菌的代谢工程改造策略,并对未来的研究方向进行了预测。     

Microbial production of fatty alcohols

Fatty alcohols have numerous commercial applications, including their use as lubricants, surfactants, solvents, emulsifiers, plasticizers, emollients, thickeners, and even fuels. Fatty alcohols are currently produced by catalytic hydrogenation of fatty acids from plant oils or animal fats. Microbial production of fatty alcohols may be a more direct and environmentally-friendly strategy since production is carried out by heterologous enzymes, called fatty acyl-CoA reductases, able to reduce different acyl-CoA molecules to their corresponding primary alcohols. Successful examples of metabolic engineering have been reported in Saccharomyces cerevisiae and Escherichia coli in which the production of fatty alcohols ranged from 1.2 to 1.9 g/L, respectively. Due to their metabolic advantages, oleaginous yeasts are considered the best hosts for production of fatty acid-derived chemicals. Some of these species can naturally produce, under specific growth conditions, lipids at high titers (>50 g/L) and therefore provide large amounts of fatty acyl-CoAs or fatty acids as precursors. Very recently, taking advantage of such features, over 8 g/L of C₁₆–C₁₈ fatty alcohols have been produced in Rhodosporidium toruloides. In this review we summarize the different metabolic engineering strategies, hosts and cultivation conditions used to date. We also point out some future trends and challenges for the microbial production of fatty alcohols.     

Morphological and Molecular Differentiation of Sporidiobolus johnsonii ATCC 20490 and Its Coenzyme Q10 Overproducing Mutant Strain UF16

Coenzyme Q₁₀ (CoQ₁₀) is an industrially important molecule having nutraceutical and cosmeceutical applications. CoQ₁₀ is mainly produced by microbial fermentation and the process demands the use of strains with high productivity and yields of CoQ₁₀. During strain improvement program consisting of sequential induced mutagenesis, rational selection and screening process, a mutant strain UF16 was generated from Sporidiobolus johnsonii ATCC 20490 with 2.3-fold improvements in CoQ₁₀ content. EMS and UV rays were used as mutagenic agents for generating UF16 and it was rationally selected based on atorvastatin resistance as well as survival at free radicals exposure. We investigated the genotypic and phenotypic changes in UF16 in order to differentiate it from wild type strain. Morphologically it was distinct due to reduced pigmentation of colony, reduced cell size and significant reduction in mycelial growth forms with abundance of yeast forms. At molecular level, UF16 was differentiated based on PCR fingerprinting method of RAPD as well as large and small-subunit rRNA gene sequences. Rapid molecular technique of RAPD analysis using six primers showed 34 % polymorphic fragments with mean genetic distance of 0.235. The partial sequences of rRNA-gene revealed few mutation sites on nucleotide base pairs. However, the mutations detected on rRNA gene of UF16 were less than 1 % of total base pairs and its sequence showed 99 % homology with the wild type strain. These mutations in UF16 could not be linked to phenotypic or genotypic changes on CoQ₁₀ biosynthetic pathway that resulted in improved yield. Hence, investigating the mutations responsible for deregulation of CoQ₁₀ pathway is essential to understand the cause of overproduction in UF16. Phylogenetic analysis based on RAPD bands and rRNA gene sequences coupled with morphological variations, exhibited the novelty of mutant UF16 having potential for improved CoQ₁₀ production.     

Effects of introducing heterologous pathways on microbial metabolism with respect to metabolic optimality

Although optimality of microbial metabolism under genetic and environmental perturbations is well studied, the effects of introducing heterologous reactions on the overall metabolism are not well understood. This point is important in the field of metabolic engineering because heterologous reactions are more frequently introduced into various microbial hosts. The genome-scale metabolic simulations of Escherichia coli strains engineered to produce 1,4-butanediol, 1,3-propanediol, and amorphadiene suggest that microbial metabolism shows much different responses to the introduced heterologous reactions in a strain-specific manner than typical gene knockouts in terms of the energetic status (e.g., ATP and biomass generation) and chemical production capacity. The 1,4-butanediol and 1,3-propanediol producers showed greater metabolic optimality than the wild-type strains and gene knockout mutants for the energetic status, while the amorphadiene producer was metabolically less optimal. For the optimal chemical production capacity, additional gene knockouts were most effective for the strain producing 1,3-propanediol, but not for the one producing 1,4-butanediol. These observations suggest that strains having heterologous metabolic reactions have metabolic characteristics significantly different from those of the wild-type strain and single gene knockout mutants. Finally, comparison of the theoretically predicted and ¹³C-based flux values pinpoints pathways with non-optimal flux values, which can be considered as engineering targets in systems metabolic engineering strategies. To our knowledge, this study is the first attempt to quantitatively characterize microbial metabolisms with different heterologous reactions. The suggested potential reasons behind each strain’s different metabolic responses to the introduced heterologous reactions should be carefully considered in strain designs.     

L-valine production in Corynebacterium glutamicum based on systematic metabolic engineering: progress and prospects

L-valine is an essential branched-chain amino acid that cannot be synthesized by the human body and has a wide range of applications in food, medicine and feed. Market demand has stimulated people’s interest in the industrial production of L-valine. At present, the mutagenized or engineered Corynebacterium glutamicum is an effective microbial cell factory for producing L-valine. Because the biosynthetic pathway and metabolic network of L-valine are intricate and strictly regulated by a variety of key enzymes and genes, highly targeted metabolic engineering can no longer meet the demand for efficient biosynthesis of L-valine. In recent years, the development of omics technology has promoted the upgrading of traditional metabolic engineering to systematic metabolic engineering. This whole-cell-scale transformation strategy has become a productive method for developing L-valine producing strains. This review provides an overview of the biosynthesis and regulation mechanism of L-valine, and summarizes the current metabolic engineering techniques and strategies for constructing L-valine high-producing strains. Finally, the opinion of constructing a cell factory for efficiently biosynthesizing L-valine was proposed.

     

Plasma coenzyme Q10 concentrations are not decreased in male patients with coronary atherosclerosis

Coenzyme Q₁₀ (CoQ₁₀) is an important mitochondrial electron transfer component and has been postulated to function as a powerful antioxidant protecting LDL from oxidative damage. It could thus reduce the risk of cardiovascular disease. Thus far, beneficial effects of supplementation with CoQ₁₀ have been reported. To study the relation between unsupplemented concentrations of plasma CoQ₁₀ and coronary atherosclerosis, we performed a case-control study among 71 male cases with angiographically documented severe coronary atherosclerosis and 69 healthy male controls free from symptomatic cardiovascular disease and without atherosclerotic plaques in the carotid artery.

Plasma CoQ₁₀ concentrations (mean ± SE) were 0.86 ± 0.04 vs. 0.83 ± 0.04 μmol/l for cases and controls, respectively. The CoQ₁₀/LDL-cholesterol ratio (μmol/mmol) was slightly lower in cases than in controls (0.22 ± 0.01 vs. 0.26 ± 0.03). Differences in CoQ₁₀ concentrations and CoQ₁₀/LDL-cholesterol ratio did not reach significance. The odds ratios (95% confidence interval) for the risk of coronary atherosclerosis calculated per μmol/l increase of CoQ₁₀ was 1.12 (0.28–4.43) after adjustment for age, smoking habits, total cholesterol and diastolic blood pressure.

We conclude that an unsupplemented plasma CoQ₁₀ concentration is not related to risk of coronary atherosclerosis.     

Treatment of CoQ10 Deficient Fibroblasts with Ubiquinone,CoQ Analogs,and Vitamin C: Time- and Compound-Dependent Effects

Background

Coenzyme Q₁₀ (CoQ₁₀) and its analogs are used therapeutically by virtue of their functions as electron carriers, antioxidant compounds, or both. However, published studies suggest that different ubiquinone analogs may produce divergent effects on oxidative phosphorylation and oxidative stress.

Methodology/Principal Findings

To test these concepts, we have evaluated the effects of CoQ₁₀, coenzyme Q₂ (CoQ₂), idebenone, and vitamin C on bioenergetics and oxidative stress in human skin fibroblasts with primary CoQ₁₀ deficiency. A final concentration of 5 µM of each compound was chosen to approximate the plasma concentration of CoQ₁₀ of patients treated with oral ubiquinone. CoQ₁₀ supplementation for one week but not for 24 hours doubled ATP levels and ATP/ADP ratio in CoQ₁₀ deficient fibroblasts therein normalizing the bioenergetics status of the cells. Other compounds did not affect cellular bioenergetics. In COQ2 mutant fibroblasts, increased superoxide anion production and oxidative stress-induced cell death were normalized by all supplements.

Conclusions/Significance

These results indicate that: 1) pharmacokinetics of CoQ₁₀ in reaching the mitochondrial respiratory chain is delayed; 2) short-tail ubiquinone analogs cannot replace CoQ₁₀ in the mitochondrial respiratory chain under conditions of CoQ₁₀ deficiency; and 3) oxidative stress and cell death can be counteracted by administration of lipophilic or hydrophilic antioxidants. The results of our in vitro experiments suggest that primary CoQ₁₀ deficiencies should be treated with CoQ₁₀ supplementation but not with short-tail ubiquinone analogs, such as idebenone or CoQ₂. Complementary administration of antioxidants with high bioavailability should be considered if oxidative stress is present.     

Analysis of coenzyme Q in human blood and tissues

The major coenzyme Q species in humans is the decaprenyl quinoid derivative coenzyme Q₁₀ (CoQ₁₀), and its measurement is somewhat challenging owing to its hydrophobicity and tendency to be oxidized. There are three major methods which are suited for analysis of CoQ₁₀: HPLC-coupled UV or electrochemical detection, and tandem mass spectrometry. The techniques are discussed, and results of these applications to determine CoQ₁₀ concentrations in various human fluids and tissues are summarized.     

Lactate increases coenzyme Q10 production by Agrobacterium tumefaciens

By the optimization of nitrogen source for coenzyme Q₁₀ (ubiquinone, CoQ₁₀) production in Agrobacterium tumefaciens KCCM 10413 culture, the highest CoQ₁₀ production was achieved in medium containing corn steep powder (CSP). Components for a stimulatory effect on the production of CoQ₁₀ in CSP were screened, and lactate was found to increase dry cell weight (DCW) and the specific CoQ₁₀ content. In a fed-batch culture of A. tumefaciens, supplementation with 1.5 g of lactate l⁻¹ further improved DCW, the specific CoQ₁₀ content, and CoQ₁₀ production by 16.0, 5.8, and 22.8%, respectively. It has been reported that lactate stimulates cell growth and acts as an accelerator driving the tricarboxylic acid (TCA) cycle (Roberto et al. 2002, Biotechnol Let 24:427–431; Matsuoka et al. 1996, Biosci Biotechnol Biochem 60:575–579). In this study, lactate supplementation increased DCW and the specific CoQ₁₀ content in A. tumefaciens culture, probably by accelerating TCA cycle and energy production as reported previously, leading to the increase of CoQ₁₀ production.     

Pediatric reference intervals for muscle coenzyme Q10

Coenzyme Q₁₀ (CoQ₁₀) is present in humans in both the reduced (ubiquinol, CoQ₁₀H₂) and oxidized (ubiquinone, CoQ₁₀) forms. CoQ₁₀ is an essential cofactor in mitochondrial oxidative phosphorylation, and is necessary for ATP production. Total, reduced and oxidized CoQ₁₀ levels in skeletal muscle of 148 children were determined by HPLC coupled with electrochemical detection, and we established three level thresholds for total CoQ₁₀ in muscle. We defined as “severe deficiency”, CoQ₁₀ levels falling in the range between 0.82 and 4.88 μmol/g tissue; as “intermediate deficiency”, those ranging between 5.40 and 9.80 μmol/g tissue, and as “mild deficiency”, the amount of CoQ₁₀ included between 10.21 and 19.10 μmol/g tissue. Early identification of CoQ₁₀ deficiency has important implications in children, not only for those with primary CoQ₁₀ defect, but also for patients with neurodegenerative disorders, in order to encourage earlier supplementation with this agent also in mild and intermediate deficiency.     

Optimization of culture conditions and scale-up to pilot and plant scales for coenzyme Q<Subscript>10</Subscript> production by <Emphasis Type="Italic">Agrobacterium tumefaciens</Emphasis>

This report describes the optimization of culture conditions for coenzyme Q₁₀ (CoQ₁₀) production by Agrobacterium tumefaciens KCCM 10413, an identified high-CoQ₁₀-producing strain (Kim et al., Korean patent. 10-0458818, 2002b). Among the conditions tested, the pH and the dissolved oxygen (DO) levels were the key factors affecting CoQ₁₀ production. When the pH and DO levels were controlled at 7.0 and 0–10%, respectively, a dry cell weight (DCW) of 48.4 g l⁻¹ and a CoQ₁₀ production of 320 mg l⁻¹ were obtained after 96 h of batch culture, corresponding to a specific CoQ₁₀ content of 6.61 mg g-DCW⁻¹. In a fed-batch culture of sucrose, the DCW, specific CoQ₁₀ content, and CoQ₁₀ production increased to 53.6 g l⁻¹, 8.54 mg g-DCW⁻¹, and 458 mg l⁻¹, respectively. CoQ₁₀ production was scaled up from a laboratory scale (5-l fermentor) to a pilot scale (300 l) and a plant scale (5,000 l) using the impeller tip velocity (V _tip) as a scale-up parameter. CoQ₁₀ production at the laboratory scale was similar to those at the pilot and plant scales. This is the first report of pilot- and plant-scale productions of CoQ₁₀ in A. tumefaciens.     

An integrated computational and experimental study for overproducing fatty acids in Escherichia coli

Increasing demands for petroleum have stimulated sustainable ways to produce chemicals and biofuels. Specifically, fatty acids of varying chain lengths (C₆–C₁₆) naturally synthesized in many organisms are promising starting points for the catalytic production of industrial chemicals and diesel-like biofuels. However, bio-production of fatty acids from plants and other microbial production hosts relies heavily on manipulating tightly regulated fatty acid biosynthetic pathways. In addition, precursors for fatty acids are used along other central metabolic pathways for the production of amino acids and biomass, which further complicates the engineering of microbial hosts for higher yields. Here, we demonstrate an iterative metabolic engineering effort that integrates computationally driven predictions and metabolic flux analysis techniques to meet this challenge. The OptForce procedure was used for suggesting and prioritizing genetic manipulations that overproduce fatty acids of different chain lengths from C₆ to C₁₆ starting with wild-type E. coli. We identified some common but mostly chain-specific genetic interventions alluding to the possibility of fine-tuning overproduction for specific fatty acid chain lengths. In accordance with the OptForce prioritization of interventions, fabZ and acyl-ACP thioesterase were upregulated and fadD was deleted to arrive at a strain that produces 1.70 g/L and 0.14 g fatty acid/g glucose (～39% maximum theoretical yield) of C_14–16 fatty acids in minimal M9 medium. These results highlight the benefit of using computational strain design and flux analysis tools in the design of recombinant strains of E. coli to produce free fatty acids.     

Human Coenzyme Q10 Deficiency

Ubiquinone (coenzyme Q₁₀ or CoQ₁₀) is a lipid-soluble component of virtually all cell membranes and has multiple metabolic functions. Deficiency of CoQ₁₀ (MIM 607426) has been associated with five different clinical presentations that suggest genetic heterogeneity, which may be related to the multiple steps in CoQ₁₀ biosynthesis. Patients with all forms of CoQ₁₀ deficiency have shown clinical improvements after initiating oral CoQ₁₀ supplementation. Thus, early diagnosis is of critical importance in the management of these patients. This year, the first molecular defect causing the infantile form of primary human CoQ₁₀ deficiency has been reported. The availability of genetic testing will allow for a better understanding of the pathogenesis of this disease and early initiation of therapy (even presymptomatically in siblings of patients) in this otherwise life-threatening infantile encephalomyopathy. Special issue dedicated to John P. Blass.     

Factors affecting broth viscosity and coenzyme Q10 production by Agrobacterium species

Summary In the production of coenzyme Q₁₀ (CoQ₁₀) by Agrobacterium sp. the culture broth becomes highly viscous. In an attempt to improve the production process, the effects of chemical and physical factors on broth viscosity and CoQ₁₀ production were studied, using Agrobacterium sp. KY-8593. A particular concentration ratio of sugar to ammonium-nitrogen (NH₄–N) in the medium could effectively enhance CoQ₁₀ production without increasing broth viscosity. An increase in culture temperature to between 32°C and 34°C lowered broth viscosity without reducing CoQ₁₀ production. NH₄–N concentration and temperature had a correlative effect on broth viscosity. At a temperature of about 33°C, there was a wide range of NH₄–N concentration which was optimal for both broth viscosity and CoQ₁₀ production. In optimal conditions with 8% sugar the apparent broth viscosity was reduced to less than 10 pseudo-cP and CoQ₁₀ production was increased to more than 80 mg/l.