Oxygen influence on the ß-oxidative metabolism of methyl ricinoleate for lactones production by the yeast Yarrowia lipolytica

The yeast Yarrowia lipolytica is able to carry out the peroxisomal β-oxidative catabolism of methyl ricinoleate, a process leading notably to the production of γ-decalactone, a high-value aroma compound. In fact, this metabolic pathway gives rise to different C10 lactones and their accumulations report the efficiency of the peroxisomal β-oxidation enzymes. γ-Decalactone or 3-hydroxydecan-4-olide accumulate when acyl- CoA oxidase or 3-hydroxyacyl-CoA dehydrogenase, respectively, control the flux within the pathway. We investigated the accumulation of C10 lactones in various aeration conditions. An important accumulation of 3-hydroxydecan-4-olide was observed when increasing the aeration up to a certain point, above it its concentration was lowered, which indicates a stimulation of the activity of 3-hydroxyacyl-CoA dehydrogenase. Cultures under high-pressure were performed in order to increase the oxygen in the medium by an alternative mean. Y. lipolytica growth in glucose medium was accelerated at 0.5 MPa of total air pressure. A decrease in γ-decalactone production was observed with the increase in pressure. Curiously, applying a pressure of 0.5 MPa during growth and then during biotransformation resulted in high decenolides concentrations.Fundação para a Ciência e a Tecnologia (FCT)

Oil-in-water emulsions characterization by laser granulometry and impact on γ-decalactone production in Yarrowia lipolytica

Oil-in-water emulsions composed of methyl ricinoleate (MR) or castor oil (CO) as the organic phase, stabilized by Tween 80, are in the basis of the biotechnological production of gama-decalactone. Y. lipolytica was used due to its ability to grow on hydrophobic substrates and to carry out that biotransformation. The characterization of oil droplets size distribution by laser granulometry was performed under different oil concentrations. The impact of the presence of cells on droplets size was also analyzed, as well as the relevance of washing cells. Furthermore, the granulometric characterization of the emulsions was related with gama-decalactone production for non-washed cells, the smaller droplets disappeared, using both oils, which increased gama-decalactone concentration. This suggests that the access of cells to the substrate occurs by their adhesion around larger oil droplets.The authors acknowledge Fundacao para a Ciencia e Tecnologia (FCT) for the financial support provided (SFRH/BD/28039/2006) and CRUP (Cooperation project F-41/06)

Impact of the surface properties of lactic bacteria on the stability of emulsions

Bacteria have physicochemical surface properties which depend on the chemical composition of the cell surface. These characters proceed from several type of physicochemical interactions and are involved in attachment processes of microorganisms to surfaces. Thus they are of interest in several areas, as biomedicine, formation of biofilms and adhesion to apolar surfaces. Moreover, food matrix are complex heterogeneous media, which structure settles on interaction forces between molecules (van der Waals, electrostatic or structural forces…). When bacteria are present in a matrix, it is probable that their surface interacts with the other constituents. So far, few studies have mentioned this subject. In order to understand the involvement of cells surface properties in a food matrix, the effect of surface properties of lactic bacteria on the stability of model emulsions were studied. The results showed that the choice of a bacterium according to its surface properties may have a strong impact on the stability and on the behavior of an emulsion

The Use of Enzymes and Microorganisms for the Production of Aroma Compounds from Lipids

Lipids are an important source of aroma compounds. In foods, lipids are degraded or modified by enzymatic activities that are originally present in the raw materials or that develop later due to the growth of microorganisms. Mimicking these natural pathways, some processes have been developed to produce aroma compounds in bioreactors. In this review we describe the production of aroma compounds from different families: lactones, green notes and ionones. We focus on points that are specific to these reactions in heterogeneous media: physicochemical forces involved in the interactions between the substrate, product and biocatalyst, transfers between the phases and, as the degradation of lipids often requires an oxidation step, on the problems of oxygenation of the reactors

Prospects for Food Fermentation in South-East Asia, Topics From the Tropical Fermentation and Biotechnology Network at the End of the AsiFood Erasmus+Project

Fermentation has been used for centuries to produce food in South-East Asia and some foods of this region are famous in the whole world. However, in the twenty first century, issues like food safety and quality must be addressed in a world changing from local business to globalization. In Western countries, the answer to these questions has been made through hygienisation, generalization of the use of starters, specialization of agriculture and use of long-distance transportation. This may have resulted in a loss in the taste and typicity of the products, in an extensive use of antibiotics and other chemicals and eventually, in a loss in the confidence of consumers to the products. The challenges awaiting fermentation in South-East Asia are thus to improve safety and quality in a sustainable system producing tasty and typical fermented products and valorising by-products. At the end of the “AsiFood Erasmus+ project” (www.asifood.org), the goal of this paper is to present and discuss these challenges as addressed by the Tropical Fermentation Network, a group of researchers from universities, research centers and companies in Asia and Europe. This paper presents current actions and prospects on hygienic, environmental, sensorial and nutritional qualities of traditional fermented food including screening of functional bacteria and starters, food safety strategies, research for new antimicrobial compounds, development of more sustainable fermentations and valorisation of by-products. A specificity of this network is also the multidisciplinary approach dealing with microbiology, food, chemical, sensorial, and genetic analyses, biotechnology, food supply chain, consumers and ethnology

Generation of flavors and fragrances through biotransformation and de novo synthesis

Flavors and fragrances are the result of the presence of volatile and non-volatile compounds, appreciated mostly by the sense of smell once they usually have pleasant odors. They are used in perfumes and perfumed products, as well as for the flavoring of foods and beverages. In fact the ability of the microorganisms to produce flavors and fragrances has been described for a long time, but the relationship between the flavor formation and the microbial growth was only recently established. After that, efforts have been put in the analysis and optimization of food fermentations that led to the investigation of microorganisms and their capacity to produce flavors and fragrances, either by de novo synthesis or biotransformation. In this review, we aim to resume the recent achievements in the production of the most relevant flavors by bioconversion/biotransformation or de novo synthesis, its market value, prominent strains used, and their production rates/maximum concentrations.We would like to thank the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469 unit, COMPETE 2020 (POCI-01-0145FEDER-006684), and BiotecNorte operation (NORTE-01-0145FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020—Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

Rôle et perspectives des études microbiologiques pour la sécurité alimentaire

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Asia: Introduction

International audienc

Chương IV - VẤN ĐỀ SỬ DỤNG KHÁNG SINH TRONG CHĂN NUÔI VÀ TƯƠNG LAI CỦA NGHIÊN CỨU VI SINH VẬT ĐỐI VỚI AN TOÀN THỰC PHẨM

International audienceTrung tâm Quy trình Thực phẩm và Vi sinh vật, AgroSup Dijon, Đại học Bourgogne-Franche Comté 4�1� GIỚI THIỆU Chăn nuôi là một ngành nông nghiệp được công nghiệp hóa rất nhiều trong những thập kỷ vừa qua. Những trang trại chăn nuôi có quy mô lớn dần thay đổi bức tranh hệ thống sản xuất nông nghiệp của nhiều nước trên thế giới, trong đó có Việt Nam. Lợi thế của sản xuất quy mô là tăng năng suất và giảm chi phí đơn vị trên đầu gia súc, hiệu quả cạnh tranh cao, đáp ứng nhu cầu của thị trường về số lượng. Thế nhưng điểm yếu là mức độ an toàn, do sử dụng thức ăn công nghiệp và do rủi ro dịch bệnh lây nhiễm. Một trong những vấn đề lớn là sử dụng kháng sinh trong chăn nuôi. Tại châu Âu, việc dùng kháng sinh trong thức ăn gia súc đã hoàn toàn bị cấm. Tại Việt Nam, các cơ sở chăn nuôi dường như chưa hiểu các tác hại của kháng sinh và đang lún sâu vào phương pháp thực hành này. Việc sản xuất nông nghiệp sử dụng cùng một loại kháng khuẩn như trong y khoa và thú y sẽ gây ra những vấn đề nghiêm trọng gián tiếp cho xã hội. Trong chương 4 của cuốn sách, chúng tôi trước hết sẽ trình bày những tác hại và chứng minh việc lạm dụng kháng sinh l