unicellular 500 gr = 3,200 billion cells eukaryotic microorganism

ubiquitious Kingdom Fungi chemoorganotroph Mitosis, budding , spore

Able to convert carbohydrates to and alcohols

Old English gist , gyst Indo-European yes : b oil, foam, or bubble Kingdom : Fungi

archaeascomycetes Schizosaccharomyces pombe Saccharomyces cerevisiae Phyllum hemiascomycetes Candida albicans Ascomycota (budding ) Pischia pastoris Neurospora euascomycetes Aspergillus (filamentous Penicillium yeast) Benefits Negative sides

Food products Product spoilage Science Pathogen Bioremediation

Biofuel Hobby

Pharmaceutical Cattle feed •Genomic sequence of S.cerevisiae •Genetic improvements of industrial End of 20 th century-present

•Improvement of industrial strains •Yeast taxonomy study Late 1900s Isolation of single to- and bottom- Late 1800s fermenting yeast and employment as Yeast in malt: starter for and Saccaromyces cerevisiae Early 1800s Louis Pasteur, 1857 : Pasteur effect Late 1600s Microscopic observation (Anton van Leeuwenhoek, 1685) ‘globular structures’ •Wine making (Caucasia) 2000-6000BC •Beer (Sumeria, Babylonia) •Dough leavening (Egypt) 1755 Dictionary of the English language “the ferment put into drink to make it work and into to lighten and swell it.” Verstrepen et al. (2006) Synthetic biology

Systems biology Prospect of genome synthesis to create Molecular biology ‘ideal’ strain Exploitation of biological complexity of improved Genetics yeast (strains, processes) Metabolic engineering by directed genetic modification and Biochemistry reconstruction Genetics engineering by gene cloning and transformation of desirable traits Microbiology •Genetics breeding •Mutagenesis and selection •Clonal selection •Isolation and identification Probiotics S. boulardii Baking Alcoholic drinks leavening agent beer, wine, , brem Nutritional supplements Non alcoholic drinks deactivated yeast, S.cerevisiae, carbonated drinks (root beer, ) single cell proteins

Soy Yeast polysaccharides , tauco S.cerevisiae, Rhodotorula, Pichia holstii , etc.

Food additives/flavor Colorants yeast extract/autolysate Rhodotorula, Cryptococcus, Sporobolomyces, etc. Dairy fermentation Traditional food Tape Zymology/zymurgy

Glucose +++ 2 ADP +++ 2 P i = 2 +++ 2 CO 2 +++ 2 ATP +++ 2 H 2O

•Where ? •How ? •What metabolic pathway ? •Enzymatic reaction? •Secondary metabolites? •Monoterpenes •Thiols •Norisoprenoids •Ethyl acetate •Ester •Fatty acids •Hydrogen sulfide •Glycerol •Methanol Embden–Meyerhof–Parnas (EMP pathway)

•Preparatory phase •Pay-off phase wikipedia.org Brewer’s Yeast Harvest Wine Yeast Crushing (destemming)

Mixture of juice, skin, and seeds

Oenology Yeast addition The science of wine and Fermentation

Time on skins Extraction method Temperature Fermentation vessel Type of yeast

Malolactic fermentation

Pressing

Storage and aging

Bottling ‘Cultured’ yeast

Saccharomyces cerevisiae •Skin of fruits •Equipments •Surrounding environment •Leek of previous fermentation

•Brettanomyces •Saccharomyces bayanus •Candida •Saccharomyces beticus •Kloeckera (common wild yeast) •Saccharomyces fermentati •Saccharomycodes •Saccharomyces paradoxus •Schizosaccharomyces (fission yeast) •Saccharomyces pastorianus •Zygosaccharomyces (alcohol, high and SO tolerant) •Saccharomyces uvarum 2 •Aureobasidium Requirements of wine yeasts

•Non toxic •Quickly begin fermentation, out-competing other "wild yeasts” •Completely utilize all fermentable •High alcohol-tolerance (≥15%)

•Have a high SO 2 tolerance but low production of sulfur compounds •Produce minimum amount of residual pyruvate, acetic acid and acetaldehyde •Produce minimum foaming •Have high levels of flocculation and lees compaction •Produce flavoring compounds Product

•Organoleptik •Conversion rate of substrate to ethanol Quantity •Ethanol concentration •Residual sugar Quality •Sedimentation rate of yeast and lees •Titratable acidity •pH Safety •Sulfur concentration •Volatile compounds production •Growth rate of yeast •Contamination Distiller’s Yeast

totalpict.com Baker’s Yeast Purpose? +++

Alkohol ? Baker’s Yeast S.cerevisiae

Active Dry Yeast Warm liquid

Bread Machine / instant/rapid rise yeast Highly active, one rise only

Fresh Yeast Extremely perishable, tested prior use

Liquid Yeast Concentrated culture Raw materials

FERMENTATION STAGES Filtration

Flask fermentation Blending Pure culture fermentation Intermediate fermentation Extrusion and cutting Drying Stock fermentation Compressed yeast Dried yeast Pitch fermentation Trade fermentation Packaging

Food and Agric. Indust. Chapt.9 Steensels et al . (2014) Steensels et al . (2014) Steensels et al . (2014) •Fixed-state yeast •Two-step fermentation •Usage of previous leek •Ambient yeast •Harvesting time •Addition of fruit juice •Addition of sulphur / chilling •The list is endless… Exploration of new yeast strains sources: marine, endemic species/location/situation Creation of new strains GMO / natural process exploitation

Create your own branded starter yeast!!