Baker’s yeast-catalyzed synthesis of optically pure 4-tert-butyl-3-hydroxy beta-lactam cis-(3R,4S) and trans-(3R,4R) diastereomers

2002 ◽  
Vol 80 (7) ◽  
pp. 796-800 ◽  
Author(s):  
Margaret M Kayser ◽  
Yan Yang ◽  
Marko D Mihovilovic ◽  
Anton Feicht ◽  
Fernande D Rochon

Baker's yeast (Saccharomyces cerevisiae) reductions were applied to the synthesis of the paclitaxel C-13 side-chain analogue. An easily synthesized alpha-keto-beta-lactam (1-(4-methoxyphenyl)-4-tert-butylazetidin-2,3-dione, 4) was reduced by yeast cells to give a mixture of enantiomerically pure cis and trans isomers. Both compounds were isolated and characterized, and their absolute configurations were confirmed by X-ray crystallographic analysis.Key words: Taxol®, C-13 side-chain, paclitaxel analogues, optically pure alpha-hydroxy-beta-lactams, baker's yeast-catalyzed reductions.

Author(s):  
Muhammad Asjad Khan ◽  
Muhammad Mohsin Javed ◽  
Asia Ahmed ◽  
Sana Zahoor ◽  
Kaleem Iqbal

Yeast extract is extensively applied in various food industries as a food additive to enhance to flavor of food products or as a vitamin supplement. It is also considered as a crucial component of microbiological media. The current study was conducted to optimize a process for the production of yeast extract by using Baker’s yeast (Saccharomyces cerevisiae). The cultivation of yeast biomass was performed in a stirred fermenter. The influence of numerous physical and chemical parameters such as carbon and nitrogen sources, temperature, pH and agitation were evaluated on the production of yeast cells by employing one factor at a time approach and optimum conditions for the production of maximum yeast biomass was determined. The maximum growth was attained using molasses as a substrate at 30ºC supplemented with urea at 150 rpm with pH 4.5. After fermentation, cells were separated by centrifugation and were ruptured by adopting different techniques and autolysis was found the most viable method. Various techniques were applied to dry the yeast extract and the spray dryer was appeared as most effective one. Yeast extract acquired after drying was subjected to various analysis including protein and solid content estimation and amino acid profiling and compared with commercial yeast extract. The dried yeast extract was incorporated in media preparations to grow various microorganisms including yeast, fungi and bacteria and considerable growth was observed. These promising results indicated that the developed process is a cost effective alternative approach for the production of yeast extract.


2009 ◽  
Vol 75 (9) ◽  
pp. 2765-2774 ◽  
Author(s):  
Esben H. Hansen ◽  
Birger Lindberg Møller ◽  
Gertrud R. Kock ◽  
Camilla M. Bünner ◽  
Charlotte Kristensen ◽  
...  

ABSTRACT Vanillin is one of the world's most important flavor compounds, with a global market of 180 million dollars. Natural vanillin is derived from the cured seed pods of the vanilla orchid (Vanilla planifolia), but most of the world's vanillin is synthesized from petrochemicals or wood pulp lignins. We have established a true de novo biosynthetic pathway for vanillin production from glucose in Schizosaccharomyces pombe, also known as fission yeast or African beer yeast, as well as in baker's yeast, Saccharomyces cerevisiae. Productivities were 65 and 45 mg/liter, after introduction of three and four heterologous genes, respectively. The engineered pathways involve incorporation of 3-dehydroshikimate dehydratase from the dung mold Podospora pauciseta, an aromatic carboxylic acid reductase (ACAR) from a bacterium of the Nocardia genus, and an O-methyltransferase from Homo sapiens. In S. cerevisiae, the ACAR enzyme required activation by phosphopantetheinylation, and this was achieved by coexpression of a Corynebacterium glutamicum phosphopantetheinyl transferase. Prevention of reduction of vanillin to vanillyl alcohol was achieved by knockout of the host alcohol dehydrogenase ADH6. In S. pombe, the biosynthesis was further improved by introduction of an Arabidopsis thaliana family 1 UDP-glycosyltransferase, converting vanillin into vanillin β-d-glucoside, which is not toxic to the yeast cells and thus may be accumulated in larger amounts. These de novo pathways represent the first examples of one-cell microbial generation of these valuable compounds from glucose. S. pombe yeast has not previously been metabolically engineered to produce any valuable, industrially scalable, white biotech commodity.


Author(s):  
Ida N Jamal ◽  
Reiny A Tumbol ◽  
Remy E.P Mangindaan

Motile Aeromonas Septicaemia disease (MAS) attacking tilapia has increased in recent years as a consequence of intensive aquaculture activities, which led to losses in aquaculture industry. The agent causing MAS disease is Aeromonas hydrophila. The disease can be controlled with the β-glucan. As immunostimulants, β-glucans can also increase resistance in farmed tilapia. Studies on the use of β-glucan extracted from baker's yeast Saccharomyces cerevisiae was intended to evaluate the non-specific immune system of tilapia that were challenged with Aeromonas hydrophila. The method used was an experimental method with a completely randomized design consisting of four treatments with three replicats. The dose of β-glucan used as treatments were 0 mg.kg-1 fish (Control), 5 mg.kg-1 fish (B), 10 mg.kg-1 fish (C) and 20 mg.kg-1 fish (D), each treatment as injected three times at intervals of 3 days, the injection volume of 0.5 ml/fish for nine days and resistance surveillance for seven days. The results showed that the difference in the amount of β-glucan and the frequency of the injected real influence on total leukocytes, phagocytic activity and resistance. Total leukocytes, phagocytic activity and resistance to treatment was best achieved by the administration of C a dose of  10 mg.kg-1 of the fish© Penyakit Motil Aeromonas Septicaemia (MAS) yang menyerang ikan nila mengalami peningkatan selama beberapa tahun terakhir sebagai konsekuensi dari kegiatan akuakultur intensif, yang menyebabkan kerugian dalam industri budidaya. Agen utama penyebab penyakit MAS adalah Aeromonas hydrophila. Untuk mengendalikan penyakit tersebut dapat dilakukan dengan pemberian β-glukan. Sebagai imunostimulan, β-glukan juga dapat  meningkatkan resistensi pada ikan nila yang dibudidayakan. Pengkajian mengenai pemanfaatan β-glukan yang diekstrak dari ragi roti Saccharomyces cerevisiae dimaksudkan untuk menguji sistem imun non spesifik ikan nila yang diuji tantang dengan bakteri Aeromonas hydrophila. Metode yang digunakan yaitu metode eksperimen dengan rancangan acak lengkap yang terdiri dari empat perlakuan dan tiga ulangan. Dosis β-glukan  yang digunakan sebagai perlakuan sebesar 0 mg.kg-1 ikan (Kontrol), 5 mg.kg-1 ikan (B), 10 mg.kg-1 ikan (C) dan 20 mg.kg-1 ikan (D), masing-masing perlakuan diinjeksi sebanyak 3 kali dengan interval waktu 3 hari selama 9 hari, volume injeksi 0,5 mL/ekor ikan dan pengamatan resistensi selama tujuh hari. Hasil penelitian menunjukkan perbedaan jumlah β-glukan dan frekuensi pemberian yang diinjeksikan memberikan pengaruh nyata terhadap total leukosit, aktivitas fagositosis dan resistensi. Total leukosit, aktivitas fagositosis dan resistensi terbaik dicapai pada perlakuan C dengan dosis 10 mg.kg-1 ikan©


2001 ◽  
Vol 12 (13) ◽  
pp. 1871-1879 ◽  
Author(s):  
Elisabetta Brenna ◽  
Claudia Dei Negri ◽  
Claudio Fuganti ◽  
Stefano Serra

1981 ◽  
Vol 45 (12) ◽  
pp. 2713-2721
Author(s):  
Youichi Tamai ◽  
Hiroshi Shinmoto ◽  
Masayoshi Takakuwa

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