Single cell protein and oil production from solid cocoa fatty acid distillates co-fed ethanol.

The use of solid lipid sidestreams have been overlooked as a feedstock for the production of microbial biomass for food and feed applications and little to no recent work has examined the utilization of solid fatty acid distillates (FADs), which are a significant residue from vegetable oil processing. Yarrowia lipolytica and Rhodosporidium toruloides cultivated on cocoa fatty acid distillates (CFAD) generated final cell dry weight values > 40 g/L, with strong productivity (3.3 g/L·h) and rich protein (>45%) and lipid content (>25%).

Aromatic Yeasts: Interactions and Implications in Coffee Fermentation Aroma Profiles.

Nontraditional yeasts prevalent in tropical agricultural fermentations such as coffee and cocoa are known to contribute to aroma profiles, yet the functional roles and interactions between the associated microbial consortia in a farm fermentation are unclear. Here, boiled green bean extract (GBE) from green coffee beans was developed as a rich screening medium to deconstruct the microbial consortia and their interactions during the fermentation of dried green coffee beans. When cultivated in coculture with on GBE, strain-specific groupings with distinct volatile organic profiles were observed for nontraditional yeasts (e.

Exploring linker's sequence diversity to fuse carotene cyclase and hydroxylase for zeaxanthin biosynthesis.

Fusion of catalytic domains can accelerate cascade reactions by bringing enzymes in close proximity. However, the design of a protein fusion and the choice of a linker are often challenging and lack of guidance. To determine the impact of linker parameters on fusion proteins, a library of linkers featuring various lengths, secondary structures, extensions and hydrophobicities was designed.

β-Cryptoxanthin Production in by Optimization of the Cytochrome P450 CYP97H1 Activity.

Cytochromes P450, forming a superfamily of monooxygenases containing heme as a cofactor, show great versatility in substrate specificity. Metabolic engineering can take advantage of this feature to unlock novel metabolic pathways. However, the cytochromes P450 often show difficulty being expressed in a heterologous chassis.

Cytochrome P450 Surface Domains Prevent the β-Carotene Monohydroxylase CYP97H1 of from Acting as a Dihydroxylase.

Molecular biodiversity results from branched metabolic pathways driven by enzymatic regioselectivities. An additional complexity occurs in metabolites with an internal structural symmetry, offering identical extremities to the enzymes. For example, in the terpene family, β-carotene presents two identical terminal closed-ring structures.

Challenges to Ensure a Better Translation of Metabolic Engineering for Industrial Applications.

Metabolic engineering has evolved towards creating cell factories with increasingly complex pathways as economic criteria push biotechnology to higher value products to provide a sustainable source of speciality chemicals. Optimization of such pathways often requires high combinatory exploration of best pathway balance, and this has led to increasing use of high-throughput automated strain construction platforms or novel optimization techniques. In addition, the low catalytic efficiency of such pathways has shifted emphasis from gene expression strategies towards novel protein engineering to increase specific activity of the enzymes involved so as to limit the metabolic burden associated with excessively high pressure on ribosomal machinery when using massive overexpression systems.

Metabolic Engineering Strategies for Sustainable Terpenoid Flavor and Fragrance Synthesis.

Terpenoids derived from plant material are widely applied in the flavor and fragrance industry. Traditional extraction methods are unsustainable, but microbial synthesis offers a promising solution to attain efficient production of natural-identical terpenoids. Overproduction of terpenoids in microbes requires careful balancing of the synthesis pathway constituents within the constraints of host cell metabolism.

A "plug-n-play" modular metabolic system for the production of apocarotenoids.

Apocarotenoids, such as α-, β-ionone, and retinol, have high commercial values in the food and cosmetic industries. The demand for natural ingredients has been increasing dramatically in recent years. However, attempts to overproduce β-ionone in microorganisms have been limited by the complexity of the biosynthetic pathway.

A Functional Tricarboxylic Acid Cycle Operates during Growth of Bordetella pertussis on Amino Acid Mixtures as Sole Carbon Substrates.

It has been claimed that citrate synthase, aconitase and isocitrate dehydrogenase activities are non-functional in Bordetella pertussis and that this might explain why this bacterium's growth is sometimes associated with accumulation of polyhydroxybutyrate (PHB) and/or free fatty acids. However, the sequenced genome includes the entire citric acid pathway genes. Furthermore, these genes were expressed and the corresponding enzyme activities detected at high levels for the pathway when grown on a defined medium imitating the amino acid content of complex media often used for growth of this pathogenic microorganism.

U300 Insulin Glargine: A Novel Basal Insulin for Type 1 and Type 2 Diabetes.

To review clinical efficacy and safety of insulin glargine 300 units/mL (Gla-300), a novel high-concentration basal insulin. A MEDLINE search was performed to identify relevant articles published 1960 through February 2015 using the search term glargine 300. Published abstracts from conference proceedings of the American Diabetes Association 74th Scientific Sessions were identified.

Fructose and glucose mediates enterotoxin production and anaerobic metabolism of Bacillus cereus ATCC14579(T).

Aims: To determine the effects of carbohydrates on Bacillus cereus ATCC14579(T) anaerobic metabolism and enterotoxin production in amino acids rich medium.

Methods And Results: Bacillus cereus anaerobic growth on different carbohydrates (glucose, fructose, sucrose or glucose-fructose mixture) was examined in synthetic mMOD medium under continuous cultures (mu = 0.2 h(-1)).

Formation and metabolism of methylmalonyl coenzyme A in Corynebacterium glutamicum.

Genome sequence information suggests that B(12)-dependent mutases are present in a number of bacteria, including members of the suborder Corynebacterineae like Mycobacterium tuberculosis and Corynebacterium glutamicum. We here functionally identify a methylmalonyl coenzyme A (CoA) mutase in C. glutamicum that is retained in all of the members of the suborder Corynebacterineae and is encoded by NCgl1471, NCgl1472, and NCgl1470.

In silico strategy to rationally engineer metabolite production: A case study for threonine in Escherichia coli.

Genetic engineering of metabolic pathways is a standard strategy to increase the production of metabolites of economic interest. However, such flux increases could very likely lead to undesirable changes in metabolite concentrations, producing deleterious perturbations on other cellular processes. These negative effects could be avoided by implementing a balanced increase of enzyme concentrations according to the Universal Method [Kacser and Acerenza (1993) Eur J Biochem 216:361-367].

Phosphodiesterase type 5 inhibition coupled to strong reinforcement results in two periods of transient retention loss in the young chick.

Previous behavioural studies which have administered phosphodiesterase type-5 (PDE5) inhibitors have consistently demonstrated improved retention. However, when young chicks were trained on a strongly reinforced passive avoidance task 100microM zaprinast caused two periods of transient retention loss. This is opposed to past findings and may suggest an effect on retrieval.

Response of the central metabolism of Escherichia coli to modified expression of the gene encoding the glucose-6-phosphate dehydrogenase.

The deletion of the zwf gene encoding G6PDH activity led to restructuring of the carbon flux through central metabolism in Escherichia coli, though over-expression of this gene had only minor consequences for overall carbon flux. The modified carbon flux seen in the zwf deletion mutant enabled alternative routes of anabolic precursor formation and an adequate supply of NADPH synthesis via a modified TCA cycle to be generated so as to sustain growth rates comparable to the WT.

Degradation of aromatic compounds by Acinetobacter radioresistens S13: growth characteristics on single substrates and mixtures.

Acinetobacter radioresistens S13 is able to grow on phenol or benzoate as the sole carbon and energy source: both these compounds are catabolized through the beta-ketoadipate pathway. Genes encoding the catabolic enzymes for degradation of aromatic compounds are localized on A. radioresistens S13 chromosome and organized in, at least, two distinct sets, one for benzoate degradation and another for phenol catabolism.

Rational design of a Corynebacterium glutamicum pantothenate production strain and its characterization by metabolic flux analysis and genome-wide transcriptional profiling.

A "second-generation" production strain was derived from a Corynebacterium glutamicum pantothenate producer by rational design to assess its potential to synthesize and accumulate the vitamin pantothenate by batch cultivation. The new pantothenate production strain carries a deletion of the ilvA gene to abolish isoleucine synthesis, the promoter down-mutation P-ilvEM3 to attenuate ilvE gene expression and thereby increase ketoisovalerate availability, and two compatible plasmids to overexpress the ilvBNCD genes and duplicated copies of the panBC operon. Production assays in shake flasks revealed that the P-ilvEM3 mutation and the duplication of the panBC operon had cumulative effects on pantothenate production.

Metabolic network analysis during fed-batch cultivation of Corynebacterium glutamicum for pantothenic acid production: first quantitative data and analysis of by-product formation.

A first generation genetically modified strain of Corynebacterium glutamicum has been assessed for its potential to synthesise and accumulate the vitamin pantothenic acid in the medium using fed-batch cultivation technology, with biomass concentration controlled by isoleucine limitation. Kinetic analysis of specific rates throughout the process has been used to model carbon flux through both central metabolism and the specific pathways involved in product formation. Flux towards pantothenic acid is potentially high but much of this flux is dissipated as by-products within associated pathways, notably linked to amino acid synthesis.

Ketopantoate reductase activity is only encoded by ilvC in Corynebacterium glutamicum.

Ketopantoate reductase catalyzes the second step of the pantothenate pathway after ketoisovalerate, common intermediate in valine, leucine and pantothenate biosynthesis. We show here that the Corynebacterium glutamicum ilvC gene is able to complement a ketopantoate reductase deficient Escherichia coli mutant. Thus ilvC, encoding acetohydroxyacid isomeroreductase, involved in the common pathway for branched-chained amino acids, also exhibits ketopantoate reductase activity.

Osmotic stress, glucose transport capacity and consequences for glutamate overproduction in Corynebacterium glutamicum.

Glucose uptake by Corynebacterium glutamicum is predominantly assured by a mannose phosphotransferase system (PTS) with a high affinity for glucose (Km=0.35 mM). Mutants selected for their resistance to 2-deoxyglucose (2DG) and lacking detectable PEP-dependent glucose-transporting activity, retained the capacity to grow on media in which glucose was the only carbon and energy source, albeit at significantly diminished rates, due to the presence of a low affinity (Ks=11 mM) non-PTS uptake system.

Transcriptional, translational and metabolic regulation of glycolysis in Lactococcus lactis subsp. cremoris MG 1363 grown in continuous acidic cultures.

The physiological behaviour of Lactococcus lactis subsp. cremoris MG 1363 was characterized in continuous culture under various acidic conditions (pH 4.7-6.

Development of a phenomenological modeling approach for prediction of growth and xanthan gum production using Xanthomonas campestris.

An unstructured kinetic model for xanthan production is described and fitted to experimental data obtained in a stirred batch reactor. The culture medium was composed of several nitrogen sources (soybean hydrolysates, ammonium and nitrate salts) consumed sequentially. The model proposed is able to describe this sequential consumption of nitrogen sources, the consumption of inorganic phosphate and carbon, the evolution of biomass, and production of xanthan.

The influence of metabolic network structures and energy requirements on xanthan gum yields.

The metabolic network of Xanthomonas campestris is complex since a number of cyclic pathways are present making simple stoichiometric yield predictions difficult. The influence of certain pathway configurations and the resulting variations in flux have been examined as regards the maximum yield potential of this bacteria for xanthan gum production. These predictions have been compared with experimental results showing that the strain employed is functioning close to its theoretical maximum as regards yield criteria.

Anaerobic sugar catabolism in Lactococcus lactis: genetic regulation and enzyme control over pathway flux.

Lactic acid bacteria and particularly Lactococcus lactis are widely used for the production of lactic acid in fermented foods. Control of the catabolic rate in L. lactis, i.

Carbon flux analysis in a pantothenate overproducing Corynebacterium glutamicum strain.

Carbon flux analysis during a pseudo-stationary phase of metabolite accumulation in a genetically engineered strain of Corynebacterium glutamicum, containing plasmids leading to over-expression of the ilvBNCD and panBC operons, has identified the basic metabolic constraints governing the potential of this bacterium to produce pantothenate. Carbon flux converging on pyruvate (75% of glucose uptake) is controlled by anabolic precursor requirements and NADPH demand provoking high carbon loss as CO2 via the pentose pathway. Virtually all the flux of pyruvate is directed into the branched pathway leading to both valine and pantothenate production, but flux towards valine is tenfold higher than that transformed to pantothenate, indicating that significant improvements will only be obtained if carbon flux at the ketoisovalerate branchpoint can be modulated.