A remix in microbiology: enabling microbial ester production through the engineering of enzymes, pathways and genomes

Abstract

Saccharomyces bayanusKefir fermentation; juice and wine fermentation S. cerevisiae Beer, bread S. sake Sake fermentation Schizosaccharomyces pombe Wine Zygosaccharomyces rouxii Soy sauce Filamentous moulds Aspergillus niger Beverages; industrial production of citric acid; amyloglucosidases, pectinase, cellulase, glucose oxidase, protease (food additives) A. oryzae, A. sojae Soy sauce, beverages; α-amylases, amyloglucosidase, lipase (food additives) Penicillium camemberti White mold cheeses (camembert type) P. roqueforti Blue mold cheeses Rhizopus oligosporus Tempe fermentation R. oryzae Soy sauce, kojiAlthough old-school biotechnology has been exploiting microorganisms for millennia, the existence, functionality and importance of microorganisms in F&B was not realized until the 1660s-1670s. Who was the first to conceptualize the existence of microorganisms or the first to observe microorganisms is not a clear-cut story (7) but, frequently, literature refers to Antonie van Leeuwenhoek as "the Father of Microbiology" who discovered the "microcosmos" through his microscopic lenses around 1670. Later, around 1837, Charles Cagniard de la Tour, Theodor Schwann and Friedrich Traugott Kützing, independently described that the "metabolic activity of yeast cells is the cause of fermentation, and demonstrated that sugar and wort is used for growth and multiplication of the yeast" (8). Following, in the mid-1850s, Louis Pasteur further described the presence and importance of bacteria in milk products and developed the wellknown process of pasteurization (a process where packaged and non-packaged food is heated to around 50-60 o C for a short time to kill most microorganisms and extend the shelf life of a product). In 1897 a real turning point occurred in the world of microbiology, when Eduard Buchner demonstrated that yeast extract (with no living yeast) can form alcohol from a sugar solution, which led to the conclusion that fermentation is the result of enzymes (proteins capable in catalyzing a chemical conversion) produced by the microorganisms present in the F&B production process (9). Eduard Buchner's observations marked the birth of biochemistry as a discipline and in 1907 Eduard Buchner was awarded the Nobel prize in chemistry.Advances in microbiology, biochemistry and fermentation technologies in the 19 th century led to a plethora of novel applications and the generation of new products. This marked the birth of new-school biotechnology. New-school biotechnology is essentially the controlled and bn by 2028 with a compound annual growth rate of 4.9%) (11). Also, due to their volatile nature, flavors and fragrances can be captured and purified efficiently, hence decreasing their purification costs and increasing their purity levels. Interestingly, microbially-produced flavors and fragrances can "by-pass" any strict genetically modified organism (GMO) related regulation which is attributed again to the volatile nature of fragrance compounds and the absence of GMO material during their purification. Important players i...