INTRODUCTIONThe modern concept of healthy diet means that therange of functional foods keeps expanding to satisfyvarious physiological needs of the human organism.There are many ways to balance the nutritionaland biological value of functional products, e.g.new formulations, specific raw materials, optimaltechnological processes, functional and biologicallyactive additives, etc. [1–3].The biotechnological processing of microbialbiomass proved to be a promising direction for theproduction of functional food and feed ingredients [4–6].Microbial biomass is a source of protein substances,vitamins, polysaccharides, and trace elements. Bacterialcell walls contain many valuable polysaccharides,including β-glucans, mannans, aminopolysaccharides,etc. [7–9]. Fungal biomass is known to producechitosanglucan biologics [10–12]. Certain componentsof cell walls possess sorption, antioxidant, and othervaluable properties, which makes it possible to usethem in food industry [13–16]. In addition, microbialcell protoplasm contains a biologically complete proteinwith the amino acid score approaching that of animalprotein [4, 6]. However, commercial use ofmicroorganisms in protein and amino acid productionstill requires further research.The Saccharomyces cerevisiae strain of yeast haslong been focus of scientific attention. Biotechnologyemploys it as a substrate for protein food andfeed additives. Enzyme systems can increase thebioavailability of cellular contents. They catalyzethe hydrolysis of subcellular structures and releasebiologically valuable components, e.g. proteins [6,17, 18]. The functional and biomedical propertiesof enzymatic hydrolysates depend on the degree ofbiocatalytic decomposition of intracellular proteins.Proteolytic enzymes owe their regulatory role to theirability to catalyze the hydrolytic degradation of theprotein by certain peptide bonds. This process resultsin physiologically active peptides, which, in turn, canbe bioregulators of certain biological processes [18–21].The primary structure of the peptides determines theirfunctions. Biologically active peptides (BAP) have alow molecular weight, and their amount of amino acidresidues can vary from 3 to 50 [21–24].Aspergillus fungal mycelial biomass has also beena popular subject of scientific studies. Aspergillusoryzae produces industrially significant metabolites,e.g. enzymes, organic acids, etc. [4, 10–12, 14, 25–27].Various studies of microbial biomass as a substratefor food and feed additives revealed differences inthe amount of proteins and polysaccharides. Theirstructure and biochemical composition also vary,which can affect the functional properties of biologicalproducts. The biomass of A. oryzae fungus containsalmost twice as little protein as the S. cerevisiae yeast.However, the fungal biomass proved a valuable sourceof polysaccharides [25]. A fungal and yeast biomassmix can improve the quality and biological value offunctional products and is a promising direction insubstrate production.Protein substances, e.g. polypeptides, low-molecularweightpeptides, and amino acids, are an importantcomponent of any balanced diet. Proteins and aminoacids are responsible for the formation of all tissues ina living organism. They also play a regulatory role inmetabolic processes. It is the composition and amountof key amino acids that matters. This fact provesthe relevance of studies aimed at obtaining variousfunctional ingredients of food and feed productsfrom microbial biomass as a source of biologicallycomplete protein.The research objective was to study the processesof enzymatic decomposition of proteins in fungal andyeast biomass. The project also focused on the effectof peptide and amino acid composition of microbialbiomass enzymatic hydrolysates on the functionalproperties of food and feed ingredients.STUDY OBJECTS AND METHODSThe research was performed on the premises ofthe Russian Research Institute of Food Biotechnology– branch of Federal Research Center of Nutrition,Biotechnology, and Food Safety (Moscow). It featuredthe biomass of the Aspergillus oryzae mycelial fungus,an industrial producer of hydrolytic enzymes for thefood industry, and the Sаcharomyces cerevisiae strain ofbaker’s yeast.The A. oryzae fungal biomass was obtained by a10-minute centrifugation at 5000 rpm. The resultingmycelial biomass was mixed with yeast in a ratioof 1:2. It served as a substrate for the biocatalyticdecomposition of intracellular polymers. Aftercentrifugation, the filtrate of the culture fluid was usedto obtain a complex enzyme preparation (CEP), whichserved as a source of proteinases and peptidases.The biocatalytic decomposition of the fungaland yeast biomass happened because of the autolyticprocesses caused by intracellular fungal enzymes. Theexogenous enzymatic systems of proteolytic (CEP) andβ-glucanase (Brewzyme enzyme preparation) actionwere introduced to increase the polymer hydrolysis.The enzymatic activity in the enzyme systems wasmeasured using standard methods. The mannanaseactivity was determined by the degree of mannanhydrolysis under certain conditions with the formationof reducing carbohydrates. The chitinase hydrolysiswas assessed according to the chitin hydrolysis. StateStandard R 53974-2010I was used to evaluate the generalproteolytic activity, while State Standard R 53973-2010IIserved to measure the β-glucanase activity.We determined the hydrolysis of the fungal andyeast biomass mix according to the concentration ofreducing substances, amine nitrogen, and amino acidsduring enzyme hydrolysis. The anthrone method madeit possible to measure the concentration of reducingsubstances, while the copper method helped to define theconcentration of amine nitrogen [28]III.We used high-pressure exclusion chromatographyto assess the mass distribution of peptide molecules inthe enzymatic hydrolysates. The superose 12 column(1.0×30 cm) was calibrated with standard globular watersolubleproteins provided by SERVA (Germany) [29].I State Standard 53974-2010. Enzyme preparations for foodindustry. Method for determination of proteolitic activity. Moscow:Standartinform; 2011. 16 p.II State Standard R 53973-2010. Enzyme preparations for foodindustry. Method for determination of β-glucanase activity. Moscow:Standartinform; 2011. 12 p.III OFS.1.2.3.0022.15 Opredelenie aminnogo azota metodamiformolʹnogo i yodometricheskogo titrovaniya [General PharmacopoeiaArticle No. 1.2.3.0022.15 Determination of amine nitrogen byformol and iodometric titration].270Serba Е.М. et al. Foods and Raw Materials, 2020, vol. 8, no. 2, pp. 268–2760.2 M sodium chloride served as an eluent at elutionrate = 0.4 cm3/min and a wavelength λ = 280 nmusing a UV132 flow-through ultraviolet detectorand a Multichrom 3.1 data processing software. Thechromatograms were integrated by the gravimetricmethod. The range of molecular weights varied fromfree to full volume of the chromatographic column.The research employed a KNAUER EUROCHROM2000 chromatograph to measure the amino acid contentin the microbial biomass and enzymatic hydrolysates.After that, the components were determined by aspectrophotometric Smartline UV Detector 2500 at awavelength of λ = 570 nm (Germany). The aminogramswere calculated by comparing the areas of the standardand the sample [30].RESULTS AND DISCUSSIONThe microbial biomass proved to vary in the aminoacid composition (Table 1). The content of essentialamino acids amounted to 53.13% of the total numberin the fungal protein, while it was only 41.30% in theyeast protein. The level of tryptophan and methioninein the fungal protein was 2.2 times higher, leucine andtyrosine – by 1.8 times, and valine – by 1.5 times. Asfor the yeast protein, it appeared to contain proline; theamount of glutamic acid was by 1.4 times higer, lysineand threonine – by 1.2 times.The yeast and fungal biomass mix had a total aminoacid content of 306.0 mg/g, which was 1.5 times higherthan that in the fungal biomass (202.8 mg/g). The yeastand fungal biomass had a slightly higher biological valueof proteins, while the share of essential amino acids was44.26% (Table 1).We conducted a comparative analysis of the aminoacid composition of the protein in the yeast and fungalbiomass mix with that of the reference protein approvedby the Food and Agricultural Organization (WHO). Thereference protein shows to what degree a certain proteinsatisfies the physiological need of the body for essentialamino acids [31].The amino acid score (ACS) was calculatedaccording to the formula:ACS = А : S × 100% (1)where ACS – amino acid score;А – essential amino acid content in a particularprotein;S – amino acid content in the reference protein.The yeast and fungal biomass demonstrated a highbiological value of the protein: the total content ofessential amino acids was 1.2 times higher than in thereference protein. The biomass contained two limitingamino acids, namely phenylalanine and methionine.Their amino acid score was 70% and 55% of thereference protein, respectively (Fig. 1). Tryptophan,lysine, threonine, and leucine proved to have the highestamino acid score.Therefore, the biomass fortified with essential aminoacids obtained from proteins of the S. cerevisiae yeaststrain and the A. oryzae fungus can be a promisingsubstrate for the production of new biologically activepeptide and amino acid additives with a wide range offunctional properties.The microbial biomass mix had a higher level ofprotein in the substrate, and its biological value alsoincreased. In addition, it demonstrated a higher contentof chitin-glucan and mannan polysaccharides, as well asintracellular enzymes.Table 1 Amino acids in the microbial biomass mix(Aspergillus oryzae and Sаcharomyces cerevisiae)Amino acids Amino acid content in microbial biomassYeast Fungal Mixmg/g % mg/g % mg/g %Aspartic acid 37.86 10.01 20.05 9.89 30.06 9.82Serine 22.15 5.86 11.04 5.44 19.25 6.29Threonine 18.57 4.91 8.40 4.14 15.63 5.11Glutamic acid 64.83 17.15 25.54 12.59 51.02 16.67Proline 36.05 9.54 – – 14.06 4.60Glycine 17.21 4.55 10.03 4.95 14.46 4.73Alanine 25.71 6.80 11.00 5.42 18.37 6.00Valine 14.85 3.93 11.85 5.84 14.38 4.70Methionine 5.51 1.46 6.62 3.26 5.92 1.94Isoleucine 13.00 3.44 6.31 3.11 11.02 3.60Leucine 23.66 6.26 22.92 11.30 23.25 7.60Tyrosine 6.45 1.71 6.09 3.00 6.02 1.97Phenylalanine 14.87 3.93 8.46 4.17 12.75 4.17Histidine 11.66 3.08 5.47 2.70 8.21 2.68Lysine 27.96 7.40 12.74 6.28 23.95 7.83Tryptophan 25.57 6.76 30.45 15.02 28.62 9.35Arginine 12.16 3.22 5.83 2.87 9.03 2.95Total amountof aminoacids378.07 100 202.80 100 306.00 100Essentialamino acids156.15 41.30 107.75 53.13 135.42 44.26Figure1 Essential amino acids in the protein of the microbialbiomass mix (Aspergillus oryzae and Sаcharomycescerevisiae) vs. reference protein0 2 4 6 8ThreonineValineMethionineIsoleucineLeucinePhenylalanineLysineTryptophanMicrobial protein Reference protein51015202530Reducing substances, NH2,free amino acids, %132Stage IBiocatalysis of the biomass mixby fungal endo-enzymes(τ = 2 h, t = 50°C)Biomass mix(1:2)hydrolysate IStage IIBiocatalysis of the biomass mix by fungalendo-enzymes and exogenous β-glucanaseBrewzyme 50 unitsof β-glucanase per gbiomass Saccharomyces cerevisiae biomass271Serba Е.М. et al. Foods and Raw Materials, 2020, vol. 8, no. 2, pp. 268–276The biocatalytic conversion made it possible toincrease the bioavailability of polymers in the microbialbiomass mix and to obtain easily digestible peptidesand amino acids. The biocatalytic conversion includedthree stages (Fig. 1). Stage I featured the fungal biomass,which contained residual proteolytic and β-glucanaseenzymes (Table 2). The autolytic decomposition ofthe microbial biomass polymers lasted 2 h at 50°C.Enzymatic hydrolysate I of the biomass mix appearedafter 2 h of autolysis under the effect of fungalintracellular enzymes.The Brewzyme BGX enzyme preparation is knownas a source of β-glucanases and other hydrolases(Table 2). The Brewzyme enzyme made it possible toincrease the decomposition rate of cell walls duringStage II. Mannans and β-glucans, as well as protein-Table 2 Enzymatic activity of enzyme preparations used for biocatalysis of the microbial biomass mix (Aspergillus oryzae andSаcharomyces cerevisiae)Source of enzymes Enzyme activity, unit/g (cm3)Protease β-glucanase Mannanase ChitinaseFungal biomass 5.10 1.44 0.12 0.02Brewzyme BGX enzyme 0 600.00 78.00 0.76Complex enzyme preparation (CEP) 450.00 113.00 48.00 1.98Figure 2 Biocatalytic conversion of the microbial biomass mix (Aspergillus oryzae and Sаcharomyces cerevisiae)0 2 ThreonineValineMethionineIsoleucineLeucinePhenylalanineLysineTryptophanMicrobial protein 0510152025300 2 4 6 Reducing substances, NH2,free amino acids, %Enzymolisis 1 – reducing substances, % 3 – free amino acids, %010203040502 Molecular weight distributionof peptide fractions, %Proteolyses 72.9–29.0 29.0–8.0–4.1 4.1–Stage IBiocatalysis of the biomass mixby fungal endo-enzymes(τ = 2 h, t = 50°C)Biomass mix(1:2)Enzymatic hydrolysate IStage IIBiocatalysis of the biomass mix by fungalendo-enzymes and exogenous β-glucanase(τ = 3 h, t = 40°C)Brewzyme 50 unitsof β-glucanase per gAspergillus oryzae biomass Saccharomyces cerevisiae biomassStage IIIBiocatalysis of the biomass mixby fungal endo-enzymes and exogenous proteases(τ = 13 h, t = 30°C)Enzymatic hydrolysate IICEP – a source of a complexof proteinases20 of protease per gEnzymatic hydrolysate III272Serba Е.М. et al. Foods and Raw Materials, 2020, vol. 8, no. 2, pp. 268–276Table 3 Composition of free amino acids in enzymatic hydrolysates of the microbial biomass mix(Aspergillus oryzae and Sаcharomyces cerevisiae)Amino acids Amino acid content, mg/gEnzymatic hydrolysate I Enzymatic hydrolysate II Enzymatic hydrolysate IIIAspartic acid 3.567 5.097 12.866Serine 4.246 5.560 9.824Threonine 6.960 10.476 10.968Glutamic acid 11.233 14.442 14.487Proline 2.611 3.439 7.810Glycine 1.712 2.850 7.264Alanine 6.304 7.517 9.130Valine 5.125 6.540 8.509Methionine 1.088 2.009 2.570Isoleucine 4.189 5.744 6.558Leucine 5.916 8.404 11.549Tyrosine 3.040 4.627 5.497Phenylalanine 3.575 5.346 6.648Histidine 3.696 10.053 10.803Lysine 6.111 9.240 9.527Tryptophan 6.435 8.044 11.295Arginine 4.829 7.249 7.714Total amount of amino acids, whereessential amino acids80.63739.398116.63755.803152.01967.624Content of free amino acids, % of total 26.4 38.1 49.70 2 4 6 8ThreonineValineMicrobial protein Reference protein0510152025300 2 4 6 8 10 12 14Reducing substances, NH2,free amino acids, %Enzymolisis time, h1 – reducing substances, % 2 – amino nitrogen, %3 – free amino acids, %132010203040502 5 18Molecular weight distributionof peptide fractions, %Proteolyses time, h72.9–29.0 29.0–14.6 14.6–8.08.0–4.1 4.1–1.6 менее 1.6 кДаStage IBiocatalysis of the biomass mixby fungal endo-enzymes(τ = 2 h, t = 50°C)Stage IIBiocatalysis of the biomass mix by fungalendo-enzymes and exogenous β-glucanase(τ = 3 h, t = 40°C)Brewzyme 50 unitsof β-glucanase per gStage IIIBiocatalysis of the biomass mixby fungal endo-enzymes and exogenous proteases(τ = 13 h, t = 30°C)IICEP – a source of a complexof proteinases20 of protease per gEnzymatic hydrolysate IIIFigure 3 Biochemical parameters of the enzymatichydrolysates during hydrolysis of the microbial biomassmix (Aspergillus oryzae and Sаcharomyces cerevisiae)mannan and chitin-glucan complexes, were the mainstructural polymers [8, 9]. The proportion was 50 unitsof β-glucanase per 1 g of biomass dry matters. Stage IIlasted 3 h at 40°С and produced enzymatic hydrolysateII after 5 h of hydrolysis (Fig. 2).Complex enzyme preparation CEP was introducedduring Stage III. It provided a deeper enzymatichydrolysis of the main subcellular polymers of themicrobial biomass, including protein substances. Thehydrolysis resulted in the formation of easily digestiblebiologically active products. The CEP served as asource of a complex of proteinases and peptidases.The proportion was 20 units of protease per 1 g ofbiomass solids (Fig. 2). Fungal proteolytic enzymes arethermolabile, so the temperature was reduced to 30°C.Stage III lasted 13 h; the total biocatalysis time was 18 h.Stage III produced enzymatic hydrolysate III.The enzyme system of the A. oryzae fungusand exogenous enzymes made it possible to obtainenzymatic hydrolysates from the yeast and fungalmicrobial biomass mix. The enzymatic hydrolysatesvaried in the degree of decomposition of intracellularpolymers (Fig. 2).The most intense formation of hydrolysis products ofprotein and carbohydrate polymers took place during thefirst 5 h. After 5 and 14 h, the concentration of solublereducing carbohydrates increased by 9.3 and 12.1 times(from 2.1% to 25.5%), respectively. The concentrationof amine nitrogen (NH2+) increased by 6.4 times and9.6 times (from 0.5% to 4.8%). The concentration of freeamino acids increased by 8.0 times and 12.2 times, from1.3% to 15.9% (Fig. 3).Table 3 illustrates the composition of the free aminoacids in the obtained enzymatic hydrolysates andtheir amount. 26.4% of free amino acids were releasedduring the hydrolysis of the microbial biomass mix byintracellular fungal enzymes (enzymatic hydrolysate I).After exogenous enzymes (β-glucanase and proteolyticeffects) were introduced and the process time wasprolonged, the release of amino acids increased by1.5–2.0 times. It reached 38.1% in enzymatic hydrolysateII and 49.7% in enzymatic hydrolysate III. The contentof free essential amino acids also increased (Table 3).The amount of essential free amino acids increased273Serba Е.М. et al. Foods and Raw Materials, 2020, vol. 8, no. 2, pp. 268–276by 1.7 times in enzymatic hydrolysate III, rising from39.398 mg/g to 67.624 mg/g, compared to enzymatichydrolysate I.Thus, controlling the enzymatic hydrolysis of thecombined microbial biomass allowed us to obtainenzymatic hydrolysates with the desired degree ofdecomposition of microbial cell proteins.We also measured the effect of process time onthe molecular weight of the peptide fractions in theenzymatic hydrolysates of the biomass mix. Averageyeast proteins consist of 466 amino acid residues andhave a molecular weight of 53 kDa. Fungal proteasesreduced the molecular weight of proteins after 2 h ofautolysis (Fig. 4).The molecular weight distribution of proteinfractions during the hydrolysis of the biomass mixconfirmed the effectiveness of the decompositionprocesses that produced lower-molecular-weightpeptides (Figs. 4 and 5). A longer enzymatic hydrolysislowered the content of high-molecular-weight peptidesand increased the number of low-molecular-weightpeptides.In enzymatic hydrolysate I, peptides in the rangeover 4.1 kDa accounted for 38.2% of the total amountof protein substances. Peptides in the range from 4.1 to1.6 kDa constituted 26.7%, while those under1.6 kDa made up 35.1%. The content of highmolecular-weight peptides decreased significantlyduring the hydrolysis of protein polymers. After5 hours of hydrolysis, the amount of peptides over29.0 kDa fell by 2.1 times, after 18 hours – by10.7 times (Fig. 5). In enzymatic hydrolysate II, thefraction of low-molecular-weight peptides reached45.4%. As for enzymatic hydrolysate III, the contentof low-molecular-weight peptides in the range up to4.1 kDa was 75.3%, while the share of those under1.6 kDa accounted for 52.4%.CONCLUSIONThe present research revealed the composition ofpeptides and amino acids in the enzymatic hydrolysatesof a new biomass mix that combined the Saccharomycescerevisiae yeast strain and the Aspergillus oryzaefungus. A set of experiments confirmed that theenzymatic hydrolysates could be used to fortify food andfeed products.The new biomass mix demonstrated a higher contentof proteins and essential amino acids, as well as other(a) Enzymatic hydrolysate I (2 h) (b) Enzymatic hydrolysate II (5 h) (c) Enzymatic hydrolysate III (18 h)Figure 4 Molecular weight distribution of bioconversion products of protein polymers in the enzymatic hydrolysates of themicrobial biomass mix (Aspergillus oryzae and Sаcharomyces cerevisiae)Figure 5 Molecular weight distribution of peptides duringthe enzymatic hydrolysis of the microbial biomass mix(Aspergillus oryzae and Sаcharomyces cerevisiae)0102 5 Molecular of Proteolyses time, 72.9–29.0 29.0–14.6 8.0–4.1 4.1–1.6 Enzymatic hydrolysate IIIIII.Microbial biomass mixEnzyme hydrolysis – 2 hSuperose 12 (1, 6 x 50 cm)Eluent – 0.2 MNaCl+azideElution rate – 2.0 mL/minUV detector (280 nm)At the x-axes – molecularweight, kDaEnzymolisis – 5 hSuperose 12 (1, 6 x 50 cm)Eluent – 0.2 MNaCl+azideElution rate – 2.0 mL/minUV detector (280 nm)At the x-axes – molecularweight, kDaAt the y-axes – opticalAt the y-axes – optical density at 280 nm, RUdensity at 280 nm, RU02 5 Molecular Proteolyses time, 72.9–29.0 29.0–14.6 8.0–4.1 4.1–1.6 Enzymatic hydrolysate IIIEnzymolisis – 18 hSuperose 12 (1, 6 x 50 cm)Eluent – 0.2 MNaCl+azideElution rate – 2.0 mL/minUV detector (280 nm)At the x-axes – molecularweight, kDaAt the y-axes – opticaldensity at 280 nm, RU0 2 4 6 8ThreonineValineMethionineIsoleucineLeucinePhenylalanineLysineTryptophanMicrobial protein Reference protein0510152025300 2 4 6 8 10 12 14Reducing substances, NH2,free amino acids, %Enzymolisis time, h1 – reducing substances, % 2 – amino nitrogen, %3 – free amino acids, %132010203040502 5 18Molecular weight distributionof peptide fractions, %Proteolyses time, h72.9–29.0 29.0–14.6 14.6–8.08.0–4.1 4.1–1.6 менее 1.6 кДаunitsper gbiomassof a complexproteinasesprotease per gless 1.6 kDa274Serba Е.М. et al. Foods and Raw Materials, 2020, vol. 8, no. 2, pp. 268–276valuable components. The yeast increased the amountof proteins, while the fungus raised the content ofessential amino acids. The fungus also increased theamount of intracellular enzymes, which are used duringenzymolisis. As a result of the mutual fortification, thetotal amino acid content increased by 1.5 times due tothe higher protein content in the yeast. In addition, thebiological value of the proteins in the new biomass mixproved to be higher than that in the traditional yeastbiomass. This fact means that the ingredients obtainedfrom the biomass mix could contribute to a wider rangeof functional properties.The comparative analysis showed the high biologicalvalue of the protein in the yeast and fungal biomassmix. The total content of essential amino acids was1.2 times higher than in the reference protein. Thebiomass appeared to contain two limiting amino acids– phenylalanine and methionine. Their amino acidscore accounted for 70% and 55% of their content inthe reference protein, respectively. Tryptophan, lysine,threonine, and leucine demonstrated the highest score.A significant amount of tryptophan, typical for fungalbiomass, might add extra functional properties toingredients obtained from their peptides and aminoacids. Tryptophan is known as an immunologicallyactive amino acid. It is a dipeptide with a wide rangeof immunomodulatory effects [32, 33]. Tryptophancontainingdrugs have an antidepressant effect andstimulate the production of vitamin B3 (niacin). Inaddition, tryptophan hydroxylation produces serotonin,an important brain neurotransmitter [34].The biomass mix fortified with essential amino acidsof proteins obtained from the S. cerevisiae yeast strainand the A. oryzae fungus could be used as a commercialsubstrate. It was found capable of facilitating theproduction of new biologically active peptide and aminoacid additives with a wide range of functional properties.We developed a new algorithm for biocatalyticpolymer conversion in the new microbial biomassmix. The algorithm made it possible to obtain easilydigestible peptide and amino acid ingredients usingfungal intracellular enzymes, as well as β-glucanaseand proteolytic enzymatic preparations. The conditionsof enzymatic hydrolysis proved to affect the fractionalcomposition of the enzymatic hydrolysates. A fivehourhydrolysis lowered the amount of peptides in therange over 29.0 kDa by 2.1 times, and 18-h hydrolysis –by 10.7 times. Intracellular proteinases and peptidasesare known to catalyze the decomposition of proteins.As a result, the enzymatic system with proteinases andpeptidases could provide food and feed ingredients thatcontained 75.3% of low-molecular-weight peptides andup to 50% of free amino acids that are responsible forbiologically active factors with functional properties.The low-molecular-weight peptides, free aminoacids, and essential amino acids are involved intovarious biological processes. They improved thedigestibility of the enzymatic hydrolysates obtainedfrom the microbial biomass mix, which can be used aspeptide and amino acid components of functional foodand feed products.CONTRIBUTIONAuthors are equally related to the writing of themanuscript and are equally responsible for plagiarism.CONFLICT OF INTERESTThe authors declare that there is no conflict ofinterests related to the publication of this article.