Kluyveromyces fragilis is also known as Kluyveromyces marxianus, a fungus which belongs to the Ascomycetes class, a budding yeast having an oval or round shaped morphology [1]. This organism doesn’t go through urease hydrolysis, rather ferment starch and other saccharides [2,3]. Their genome constitutes 30-52 percent guanine-cytosine (GC) organization [4] and their hyphae is dimorphic either appear as a single cell or filaments [5,6]. Kluyveromyces fragilis cells range in size 3-5 m in width and exhibits oval morphology and reproduces through vegetative multiplication [7,8]. Kluyveromyces' filamentous stage might be useful for industrial point of view as Kluyveromyces fragilis hyphae, for instance, have a significantly large surface area than the yeast cell and may in this way be simpler to immobilize and the expanded surface might help to elevate the availability of released proteins [9,10]. Kluyveromyces fragilis have the ability to ferment lactose, xylose, galactose, maltose, and inulin [11].

Kluyveromyces fragilis in Food Biotechnology

Kluyveromyces fragilis offers numerous applications in food, synthesis of significant metabolites, food waste valorization etc [12,13]. Recent studies focused on genetically transforming Kluyveromyces fragilis using CRISPR-Cas9 gene editing technique [14]. Traits like thermotolerance, lipid synthesis etc incorporated into modifiesKluyveromyces fragilis for industrial benefits with intrinsically more vigorous features that proposition guarantee for modern environmentally friendly energy generation [15]. In addition, Kluyveromyces fragilis is a promising host for modern biotechnology for biosynthetic produced from plant biomass feedstock's since it produces at high temperatures and on an extensive variety of carbon sources [16,17]. In any case, significant limitations in hereditary designing have kept this yeast from displacing the generally utilized yeast Saccharomyces cerevisiae [18]. However, genetically altered Kluyveromyces fragilis possess a novel thermotolerant trait with promising unsaturated fat synthesis capability [19]. Kluyveromyces fragilis is also capable of lactose-fermenting and is widely used in dairy products fabrication [20,21]. Additionally, have mild proteolytic and lipolytic activity [22]. Kluyveromyces to metabolize milk constituents such as lactose, proteins, and fat makes them pivotal in fermented cheese/milk products [23]. Kluyveromyces fragilis assisted milk fermentation is impacted by temperature and secreted lipase content in milk in order to hydrolyze lactose into galactose, glucose, ethanol, and glycerol [24]. Following 12 days of metabolization at 25 °C, concentration of free unsaturated fats in milk increases essentially [25]. Kluyveromyces fragilis also known to produce ethanol, isoamyl liquor, and ethyl acetic acid derivatives [26]. Genetically designed Kluyveromyces fragilis produces high lactic acid because the transformant strains lacks pyruvate dehydrogenase and pyruvate decarboxylase activity [27].Besides the capacity of Kluyveromyces fragilis to adapt to the distressing circumstances brought about by the arrival of inhibitory synthetic substances during biomass handling is expected for the development of lignocellulosic bio refineries [28].Because of its thermotolerance and ability to metabolize xylose, Kluyveromyces fragilis has been examined as an industrially potent microbe [29]. Furfural and 5-hydroxymethylfurfural (HMF), both produced from lignocellulose, are respected appealing structural blocks required into assortments of high-esteem subordinates [30]. Xylose utilization and its tolerance from acids, and furfural, were studied in various Kluyveromyces fragilis strains acquired from cocoa fermentation [31,32]. Furfural-reducing ability of Kluyveromyces fragilis was related with NADH besides, the inhibitory effect of furans was improved when xylose was consumed [33]. Thus, these discoveries support Kluyveromyces fragilis as a reasonable microbial for lignocellulosic biorefineries [34].

Kluyveromyces fragilis K is a thermotolerant yeast with vast applications in food biotechnology and biorefineries.

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