Efficient enzymatic production of benzaldehyde from l-phenylalanine with a mutant form of 4-hydroxymandelate synthase.

Benzaldehyde is an organic compound with an almond-like aroma and one of the most important and widely used flavorings in the food industry. To develop an enzymatic process for the production of benzaldehyde from l-phenylalanine, four enzymes were expressed in Escherichia coli; l-amino acid deaminase, 4-hydroxymandelate synthase, (S)-mandelate dehydrogenase, and benzoylformate decarboxylase. Although each E. coli strain could be used to synthesize benzaldehyde from l-phenylalanine, the yield was low due to the accumulation of an intermediate, phenylpyruvic acid. We developed a second reaction step by engineering 4-hydroxymandelate synthase of Actinoplanes teichomyceticus. A quadruple mutant of 4-hydroxymandelate synthase (A199V/Q206R/I217V/K337Q) obtained by random and site-directed mutagenesis demonstrated 2.4-fold higher activity than wild type. Furthermore, the mutant-expressing strain was able to produce benzaldehyde from 100 mm l-phenylalanine at a conversion rate of 84% (wild type, 37%). We report the development of an efficient process for benzaldehyde production using l-phenylalanine as a substrate.

Influence of an elemental diet on 5-fluorouracil-induced morphological changes in the mouse salivary gland and colon.

PURPOSE: The elemental diet (ED) Elental® reportedly reduces adverse reactions to chemotherapy in digestive system cancer patients; however, the mechanism is unclear. Therefore, we verified the protective effect of ED against gastrointestinal disorders induced by the antineoplastic drug 5-fluorouracil (5-FU). METHODS: After 5 days of tail vein injections of 40 mg/kg/day 5-FU in female BALB/c mice, the mice were given oral ED (ED group) or dextrin with the same number of calories (control group). We measured the weight of salivary glands and the PAS-positive area of colonic mucosa and verified the antitumor effect in tumor-bearing mice given 5-FU and ED. RESULTS: Although body weight decreased after 5-FU treatment, ED group mice weighed more than control group mice. Additionally, although control mice developed diarrhea after 5-FU treatment, the ED group showed only loose stools. The control group saliva volume was approximately one sixth of the vehicle group volume after 5-FU treatment; this was improved to approximately half in the ED group. The area ratio of PAS-positive cells in the colonic mucosa was reduced by 5-FU treatment, with the ratio being higher in the ED group than that in the control group. Similar tumor growth suppression was observed in the 5-FU and ED groups. CONCLUSIONS: ED alleviated adverse reactions to 5-FU without affecting antitumor activity. Protection against 5-FU-induced weight loss was potentially due to both improved nutritional support with combined ingredients and prevention of diarrhea that is associated with reduced colonic goblet cells and decreased saliva production from reduced salivary gland contraction.

Vanillin production by Corynebacterium glutamicum using heterologous aromatic carboxylic acid reductases.

BACKGROUND: Vanillin is a flavoring substance derived from vanilla. We are currently developing a biotransformation method for vanillin production using glucose. This report describes the last step in vanillin production: the conversion of vanillic acid to vanillin. First, we selected Corynebacterium glutamicum as the host owing to its high vanillin resistance. The aromatic aldehyde reductase gene (NCgl0324) and vanillic acid demethylase protein subunits A and B gene (vanAB, NCgl2300-NCgl2301) were deleted in C. glutamicum genome to avoid vanillin degradation. Next, we searched for an aromatic carboxylic acid reductase (ACAR), which converts vanillic acid to vanillin. Seventeen ACAR homologs from various organisms were introduced into C. glutamicum. RESULTS: In vivo conversion experiments showed that eight ACARs were successfully expressed and produced vanillin. In terms of conversion activity and substrate specificity, the ACARs from Gordonia effusa, Coccomyxa subellipsoidea, and Novosphingobium malaysiense are promising candidates for commercial production. CONCLUSIONS: Corynebacterium glutamicum harboring Gordonia effusa ACAR produced 22 g/L vanillin, which is, to the best of our knowledge, the highest accumulation reported in the literature. At the same time, we discovered ACAR from Novosphingobium malaysiense and Coccomyxa subellipsoidea C-169 with high substrate specificity. These findings are useful for reducing the byproducts.

Food antigen-induced immune responses in Crohn's disease patients and experimental colitis mice.

BACKGROUND: In Crohn's disease (CD), the involvement of food antigens in immune responses remains unclear. The objective of this study was to detect immune responses against food antigens in CD patients and examine the mechanism in a mouse model of colitis. METHODS: We enrolled 98 CD patients, 50 ulcerative colitis patients, and 52 healthy controls (HCs) to compare the levels of serum immunoglobulin (Ig)Gs against 88 foods. The presence of serum IgGs against foods was also examined in interleukin (IL)-10 knockout (KO) mice in which CD4(+) T cell activation by antigenic food protein was assessed. Mice transferred with IL-10 KO cells received diets with or without food antigens, and the development of colitis was evaluated. RESULTS: The prevalence of IgGs against various foods, especially vegetables, grains, and nuts, was significantly higher in CD patients than in HCs. Similarly, the prevalence of IgGs against food proteins was higher in IL-10 KO mice than in BALB/c mice. Beta-conglycinin, identified as an antigenic food proteins in IL-10 KO mice, induced CD4(+) T cell production of interferon-γ and IL-17 through dendritic cell antigen presentation. Elimination of the food antigens ameliorated the development of colitis in mice without altering the composition of their intestinal microbiota. CONCLUSIONS: In CD colitis mice, intestinal inflammation via CD4(+) T cell hyperactivation was induced by food antigens associated with high serum IgG levels and was ameliorated by the elimination of food antigens. This disrupted immunological tolerance to food antigen, which might act as an exacerbating factor, remains to be elucidated in CD patients.