###### Abstract  
Feed phytases are purchased as a dry culture medium of secreting producers, mostly micellar fungi. These preparations are required to withstand heating up to 75-80 \({}^{\circ}\)C because they are intended for mixing with feed components with subsequent granulation by spray drying. For this reason, many phytases that have a high specific activity at 37 \({}^{\circ}\)C and correspond to the optimal pH of intestinal chrome are not used in practice. A novel expression system allowing accumulation of the phytase from _Obesumbacterium proteus_ within yeast _Yarrowia lipolytica_ was proposed. Encapsulation increases thermal stability of the enzyme from 55 \({}^{\circ}\)C up to 70 \({}^{\circ}\)C. The obtained preparation exhibited a high impact on the daily weight gain of a weaned mouse model fed a phosphorus-deficient diet at a dosage 165 phytase activity units (FYT)/kg, whereas a commercial phytase preparation--Ladozyme Proxi derived from _Aspergillus ficutum_--did not improve the daily weight gain even at the dosage of 15,000 FYT/kg. pypase; microencapsulation; daily weight gain; weaning mice; _Obesumbacterium proteus; Yarrowia lipolytica Article  
A Feed Additive Containing Encapsulated 6-Phytase within Recombinant _Yarrowia lipolytica_  
[PERSON], [PERSON], E.  
phosphatases [19] from rats, humans, and other vertebrates. These phytases are intracellular proteins composed of 354-439 amino acids, with a molecular mass of -42-45 kDa. These monomeric proteins are not \(N\)-glycosated [13]. PhyC representatives typically have a single optimal pH (~5.0-6.0) and exhibit an optimal temperature of 40-60 \({}^{\circ}\)C.  
The PhyA and PhyC families differ in their substrate specificity. PhyA is a so-called 3-phytase--the maximal reaction rate is achieved when the phosphate moiety in the third position of the phytate is removed. By contrast, members of the PhyC family exhibit so-called 6-phytase specificity, hydrolysing predominantly phosphate moieties in the sixth (1-4) position [6]. Enzymes from the PhyB and PhyD families are rarely used in practice. Considering average daily weight gain (ADG), a comparison of diets containing phytases with phosphate-deficient diets indicated an unambiguous growth-stimulating effect of the enzymes during the entire period of the observation. However, comparison with a diet with adequate phosphorus revealed a high efficiency of the phytases only at early ages of the animals--the first month after weaning piglets from milk feeding [20]. As the slaughter time approaches, the efficiency of the mineral source of phosphorus in the diet is higher relative to the exogenous phytases. This drop in phytase efficiency can be prevented by increasing the phytase dosage. Both [PERSON] et al. [20] and [PERSON] et al. [5] reported that very high phytase dosages (3000-12,500 phytase activity units (FYT)/kg)--several times higher than dosages recommended by manufacturers--could adjust the ADG of the experimental group to the level of the group being fed a diet with adequate phosphorus or even somewhat surpass it. By contrast, standard phytase dosages (250-1000 FYT/kg) have no effect during this period, although they are efficient at an early age. When fed low-phytase diets during the finishing period, the slaughter weight of baryons was almost indistinguishable from that of animals fed a phosphorus-deficient diet. The efficiency of low phytase dosages in broiler feed is somewhat higher than in barrows [21]. One can speculate that this effect is due to elongation of the digestion time in the larger animals combined with insufficient stability of the exogenous phytases in the intestinal chrome. This conclusion leads to the hypothesis that using encapsulated phytase preparations that gradually release the enzyme from protective micro-containers--as a result of solubilising their surface coating--increases the enzyme efficiency. The phytase of _Obesumbacterium proteus_ (OPP) [16] is a typical representative of the PhyC family.