Yarrowia lipolytica: a model yeast for citric acid production

Abstract

Every year more than 2 million tons of citric acid (CA) are produced around the world for industrial uses. Although initially extracted from citrus, the low profitability of the process and the increasing demand soon stimulated the search for more efficient methods to produce CA. Currently, most world CA demand (99%) is satisfied by fermentations with microorganisms, especially filamentous fungi and yeasts. CA production with yeasts has certain advantages over molds (e.g. higher productivity and easier cultivation), which in the last two decades have triggered a clear increase in publications and patents devoted to the use of yeasts in this field. Yarrowia lipolytica has become a model yeast that proved to be successful in different production systems. Considering the current interest evidenced in the literature, the most significant information on CA production using Y. lipolytica is summarized. The relevance on CA yields of key factors such as strains, media formulation, environmental conditions and production regimes is thoroughly discussed, with particular focus on increasing CA productivity. Besides, the possibility of tuning the mentioned variables to reduce concomitant isocitric acid production-the biggest disadvantage of using yeasts-is analyzed. Available methods for CA purification/quantification are also discussed.

Screening various Yarrowia lipolytica strains for citric acid production

“…As food additives, it is employed as acidifier, antioxidant, emulsifier, flavouring agent, stabilizer, and preservative. Due to its Generally Regarded as Safe (GRAS) status, CA has also usage in manufacturing pharmaceutical drugs, cosmetic, and detergent products (see also reviews; Apelblat, ; Cavallo, Charreau, Cerrutti, & Foresti, ; Ciriminna et al, ; Show et al, ).…”

“…However, the interest in CA production by yeast in the last 35 years has been increased due to the numerous advantages they offer as compared with mould. For instance, yeast has a good tolerance to high substrate concentrations and impurities such as metal ions that enable them to grow on a wide range of unrefined substrates and waste products (Cavallo et al, ). Conversion yield of substrates to CA by yeasts is also comparable with that of A .…”

“…lipolytica has been described as the most promising producer. It has numerous advantages for CA production over other microorganisms such as GRAS status, high productivity, wide range of substrate usage (hydrophilic and hydrophobic), high tolerance to metal ions, and salt solutions, capability to grown at the low and high pH (from 4 to 8) and wide range of temperatures (from 18°C to 32°C) (Cavallo et al, ; Fickers et al, ; Goncalves, Colen, & Takahashi, ; Groenewald et al, ; Rywinska et al, ; Zinjarde, Apte, Mohite, & Kumar, ). Furthermore, it is also convenient yeast for genetic modification (Forster et al, ; Holz et al, ).…”

Citric Acid Production by Yarrowia lipolytica Yeast on Different Renewable Raw Materials

“…The volume of citric acid globally exceeds two million tons per year and its production is annually increased by 5% [1].…”

“…Over the past 40 years, the interest of researchers has focused on yeast as a producer of CA; the yeast Yarrowia lipolytica has been the most used CA producer [1][2][3]. Initially, this kind of yeast attracted the attention of researchers due to its ability to grow and synthesize CA in media with n alkanes-an available and cheap substrate [2].…”