Amino Acids in Human and Animal Nutrition

Karau, Andreas; Grayson, Ian

doi:10.1007/10_2014_269

Cited by 45 publications

(33 citation statements)

References 80 publications

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“…For example, they found that L-glutamine regulates small intestinal bacterial metabolism of arginine, serine, and aspartate, and reduced the catabolism of essential and non-essential amino acids. This is especially relevant given the fact that modern food processing has a dramatic effect on the relative concentrations of amino acids present in commonly consumed processed foods and recent evidence for important physiological roles for both essential (e.g., tryptophan) and non-essential amino acids in mammalian nutrition [ 49 – 51 ].…”

Section: Proteinsmentioning

confidence: 99%

Gut microbiota functions: metabolism of nutrients and other food components

et al. 2017

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The diverse microbial community that inhabits the human gut has an extensive metabolic repertoire that is distinct from, but complements the activity of mammalian enzymes in the liver and gut mucosa and includes functions essential for host digestion. As such, the gut microbiota is a key factor in shaping the biochemical profile of the diet and, therefore, its impact on host health and disease. The important role that the gut microbiota appears to play in human metabolism and health has stimulated research into the identification of specific microorganisms involved in different processes, and the elucidation of metabolic pathways, particularly those associated with metabolism of dietary components and some host-generated substances. In the first part of the review, we discuss the main gut microorganisms, particularly bacteria, and microbial pathways associated with the metabolism of dietary carbohydrates (to short chain fatty acids and gases), proteins, plant polyphenols, bile acids, and vitamins. The second part of the review focuses on the methodologies, existing and novel, that can be employed to explore gut microbial pathways of metabolism. These include mathematical models, omics techniques, isolated microbes, and enzyme assays.

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Section: Proteinsmentioning

confidence: 99%

Gut microbiota functions: metabolism of nutrients and other food components

et al. 2017

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“…As one of the three branched‐chain amino acids (BCAAs), l ‐valine is an essential nutrient for humans and animals. It is used in infusion solutions and human dietary supplements (Karau & Grayson, ), commercial feed in the swine and poultry industries (Oldiges, Eikmanns, & Blombach, ), and as a precursor for herbicide and antibiotic synthesis (Oldiges et al, ). Traditional extraction of l ‐valine, and most other amino acids, from protein hydrolysate has been replaced by microbial production and/or enzymatic synthesis (Xie, Liang, Huang, & Xu, ).…”

Section: Introductionmentioning

confidence: 99%

Metabolic engineering of Bacillus subtilis forl‐valine overproduction

Westbrook

Ren

Moo‐Young

et al. 2018

Biotech & Bioengineering

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Bacillus subtilis has been commonly applied to industrial enzyme production due to its genetic tractability, "generally recognized as safe (GRAS)" status, and robust growth characteristics. In spite of its ideal attributes as a biomanufacturing platform, B. subtilis has seen limited use in the production of other value-added biochemicals. Here, we report the derivation of engineered strains of B. subtilis for l-valine overproduction using our recently developed CRISPR (clustered regularly interspaced palindromic repeats)-Cas9 (CRISPR-associated [protein] 9) toolkit. We first manipulate the native l-valine biosynthetic pathway by relieving transcriptional and allosteric regulation, resulting in a >14-fold increase in the l-valine titer, compared to the wild-type strain. We subsequently identify and eliminate factors limiting l-valine overproduction, specifically increasing pyruvate availability and blocking the competing l-leucine and l-isoleucine biosynthetic pathways. By inactivating (a) pdhA, encoding the E1α subunit of the pyruvate dehydrogenase complex, to increase the intracellular pyruvate pool, and (b) leuA and ilvA, respectively encoding 2-isopropylmalate synthase and l-threonine dehydratase, to abolish the competing pathways, the l-valine titer reached 4.61 g/L in shake flask cultures. Our engineered l-valine-overproducing strains of B. subtilis are devoid of plasmids and do not sporulate due to the inactivation of sigF, encoding the sporulation-specific transcription factor σ , making them attractive for large-scale l-valine production. However, acetate dissimilation was identified as limiting l-valine overproduction in ΔpdhA B. subtilis strains, and improving acetate dissimilation or identifying alternate modes of increasing pyruvate pools to enhance l-valine-overproduction should be explored.

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“…Lys deficiency is also the major cause of the osteoporosis in humans [ 18 ]. Stress-induced anxiety in mice was reportedly caused by the lack of Lys in their daily diets [ 19 , 20 ]. A diet deficient in Met and Lys intake can reduce biological value of plant-based nutrition to 50-70%, compared to a balanced diet with high abundance of essential amino acids [ 21 ].…”

Section: Nutritional Roles Of Essential Amino Acidsmentioning

confidence: 99%

Improving Nutritional Quality of Plant Proteins Through Genetic Engineering

Chu

2016

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Humans and animals are unable to synthesize essential amino acids such as branch chain amino acids methionine (Met), lysine (Lys) and tryptophan (Trp). Therefore, these amino acids need to be supplied through the diets. Several essential amino acids are deficient or completely lacking among crops used for human food and animal feed. For example, soybean is deficient in Met; Lys and Trp are lacking in maize. In this mini review, we will first summarize the roles of essential amino acids in animal nutrition. Next, we will address the question: “What are the amino acids deficient in various plants and their biosynthesis pathways?” And: “What approaches are being used to improve the availability of essential amino acids in plants?” The potential targets for metabolic engineering will also be discussed, including what has already been done and what remains to be tested.

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Amino Acids in Human and Animal Nutrition

Cited by 45 publications

References 80 publications

Gut microbiota functions: metabolism of nutrients and other food components

Gut microbiota functions: metabolism of nutrients and other food components

Metabolic engineering of Bacillus subtilis forl‐valine overproduction

Improving Nutritional Quality of Plant Proteins Through Genetic Engineering

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