RESUMO
The effects of water activity (aw), pH, and temperature on transglycosylation activity of α-L-fucosidase from Thermotoga maritima in the synthesis of fucosylated oligosaccharides were evaluated using different water-organic cosolvent reaction systems. The optimum conditions of transglycosylation reaction were the pH range between 7 and 10 and temperature 90-95 °C. The addition of organic cosolvent decreased α-L-fucosidase transglycosylation activity in the following order: acetone > dimethyl sulfoxide (DMSO) > acetonitrile (0.51 > 0.42 > 0.18 mM/h). However, the presence of DMSO and acetone enhanced enzyme-catalyzed transglycosylation over hydrolysis as demonstrated by the obtained transglycosylation/hydrolysis rate (rT/H) values of 1.21 and 1.43, respectively. The lowest rT/H was calculated for acetonitrile (0.59), though all cosolvents tested improved the transglycosylation rate in comparison to a control assay (0.39). Overall, the study allowed the production of fucosylated oligosaccharides in water-organic cosolvent reaction media using α-L-fucosidase from T. maritima as biocatalyst.
Assuntos
Proteínas de Bactérias/química , Fucose/química , Oligossacarídeos/síntese química , Thermotoga maritima/enzimologia , alfa-L-Fucosidase/química , Solventes/química , Água/químicaRESUMO
Fucosylated oligosaccharides present in human milk perform various biological functions that benefit infants' health. These compounds can be also obtained by enzymatic synthesis. In this work, the effect of the immobilization of α-L-fucosidase from Thermotoga maritima on the synthesis of fucosylated oligosaccharides was studied, using lactose and 4-nitrophenyl-α-L-fucopyranoside (pNP-Fuc) as acceptor and donor substrates, respectively, and Eupergit® CM as an immobilization support. The enzyme was immobilized with 90% efficiency at pH 8 and ionic strength of 1.5 M. Immobilization decreased enzyme affinity for the donor substrate as shown by a 1.5-times higher KM value and a 22-times decrease of the kcat/KM ratio in comparison to the unbound enzyme. In contrast, no effect was observed on the synthesis/hydrolysis ratio (rs/rh) when α-L-fucosidase was immobilized. Also, the effect of initial concentration of substrates was studied. An increase of the acceptor concentration improved the yields of fucosylated oligosaccharides regardless enzyme immobilization. The synthesis yields of 38.9 and 40.6% were obtained using Eupergit® CM-bound or unbound enzyme, respectively, and 3.5 mM pNP-Fuc and 146 mM lactose. In conclusion, α-L-fucosidase from Thermotoga maritima was efficiently immobilized on Eupergit® CM support without affecting the synthesis of fucosylated oligosaccharides.
Assuntos
Thermotoga maritima , alfa-L-Fucosidase , Fucose , Oligossacarídeos , Especificidade por Substrato , Thermotoga , Thermotoga maritima/metabolismo , alfa-L-Fucosidase/metabolismoRESUMO
Malnutrition is commonly associated with immunological deregulation, increasing the risk of infectious illness and death. The objective of this work was to determine the in vitro effects of heat-killed Lactobacillus casei IMAU60214 on monocyte-derived macrophages (MDMs) from well-nourished healthy children, well-nourished infected children and malnourished infected children, which was evaluated by an oxygen-dependent microbicidal mechanism assay of luminol-increase chemiluminescence and the secretion of tumor necrosis factor (TNF-α), interleukin (IL-1ß), IL-6 and IL-10, as well as phagocytosis using zymosan and as its antibacterial activity against Salmonella typhimurium, Escherichia coli and Staphylococcus aureus. We found that reactive oxygen species (ROS), secretion cytokines (TNFα, IL-1ß, IL-6 and IL-10 levels), phagocytosis and bactericidal capacity increased in all groups after pre-treatment with heat-killed L. casei IMAU60214 at a ratio of 500:1 (bacteria:MDM) over 24 h compared with MDM cells without pre-treatment. The results could indicate that heat-killed L. casei IMAU60214 is a potential candidate for regulating the immune function of macrophages.
Assuntos
Citocinas/imunologia , Transtornos da Nutrição do Lactente/imunologia , Lacticaseibacillus casei/imunologia , Macrófagos/imunologia , Probióticos/farmacologia , Técnicas Bacteriológicas , Atividade Bactericida do Sangue/imunologia , Citocinas/sangue , Feminino , Temperatura Alta , Humanos , Lactente , Transtornos da Nutrição do Lactente/sangue , Transtornos da Nutrição do Lactente/microbiologia , Interleucina-10/sangue , Interleucina-10/imunologia , Interleucina-1beta/sangue , Interleucina-1beta/imunologia , Interleucina-6/sangue , Interleucina-6/imunologia , Macrófagos/microbiologia , Masculino , Fagocitose/imunologia , Fator de Necrose Tumoral alfa/sangue , Fator de Necrose Tumoral alfa/imunologiaRESUMO
Since the high incidence of aflatoxin M1 (AFM1) in milk and dairy products poses a serious risk to human health, this work aimed to investigate the complex formation between bovine α-lactalbumin (α-La) and AFM1 using different spectroscopic methods coupled with molecular docking studies. Fluorescence spectroscopy measurements demonstrated the AFM1 addition considerably reduced the α-La fluorescence intensity through a static quenching mechanism. The results indicated on the endothermic character of the reaction, and the hydrophobic interaction played a major role in the binding between AFM1 and α-La. The binding site stoichiometric value (nâ¯=â¯1.32) and a binding constant of 2.12â¯×â¯103â¯M-1 were calculated according to the Stern-Volmer equation. The thermodynamic parameters ΔH, ΔS and ΔGb were determined at 93.58â¯kJâ¯mol-1, 0.378â¯kJâ¯mol-1â¯K-1 and -19.17⯱â¯0.96â¯kJâ¯mol-1, respectively. In addition, far-UV circular dichroism studies revealed alterations in the α-La secondary structures when the α-La-AFM1 complex was formed. An increased content of the α-helix structures (from 35 to 40%) and the ß-sheets (from 16 to 19%) were observed. Furthermore, protein-ligand docking modelling demonstrated AFM1 could bind to the hydrophobic regions of α-La protein. Overall, the gathered results confirmed the α-La-AFM1 complex formation.
Assuntos
Aflatoxina M1/química , Contaminação de Alimentos/análise , Lactalbumina/química , Animais , Sítios de Ligação , Bovinos , Humanos , Interações Hidrofóbicas e Hidrofílicas , Ligantes , Leite/química , Simulação de Acoplamento Molecular , Estrutura Secundária de Proteína , Soroalbumina Bovina/química , TermodinâmicaRESUMO
Most Lactobacillus species have beneficial immunological ("immunoprobiotic") effects in the host. However, it is unclear how probiotic bacteria regulate immune responses. The present study investigated the effects of heat-killed Lactobacillus casei IMAU60214 on the activity of human monocyte-derived macrophages (MDMs). Human MDMs were treated with heat-killed L. casei at a ratio (bacteria/MDM) of 50:1, 100:1, 250:1, and 500:1, and then evaluated for the following: NO production, by Griess reaction; phagocytosis of FITC-labeled Staphylococcus aureus particles; cytokine secretion profile (tumor necrosis factor (TNF)-α, interleukin (IL)-1ß, IL-6, IL-12p70, IL-10, and transforming growth factor (TGF)-ß) by ELISA; and costimulatory molecule (CD80 and CD86) surface expression, by flow cytometry. Heat-killed L. casei IMAU60214 enhanced phagocytosis, NO production, cytokine release, and surface expression of CD80 and CD86 in a dose-dependent manner. All products were previously suppressed by pretreatment with a Toll-like receptor 2 (TLR2)-neutralizing antibody. Overall, our findings suggest that this probiotic strain promotes an M1-like pro-inflammatory phenotype through the TLR2 signaling pathway. These effects on macrophage phenotype help explain the probiotic efficacy of Lactobacillus and provide important information for the selection of therapeutic targets and treatments compatible with the immunological characteristics of this probiotic strain.
RESUMO
Fucosyl-oligosaccharides are natural prebiotics that promote the growth of probiotics in human gut and stimulate the innate immune system. In this work, the release of α-lfucosidase by Lactobacillus rhamnosus GG, and the use of this enzyme for the synthesis of fucosyl-oligosaccharides were investigated. Since α-lfucosidase is a membrane-bound enzyme, its release from the cells was induced by addition of 4-nitrophenyl-α-l-fucopyranoside (pNP-Fuc). Enzyme activity associated with the cell was recovered at 78% of its total activity. Fucosyl-oligosaccharides where synthesized using α-l-fucosidase extract and pNP-Fuc as donor substrate, and D-lactose or D-lactulose as acceptor substrates, reaching a yield up to 25%. Fucosyllactose was obtained as a reaction product with D-lactose, and its composition was confirmed by mass spectrometry (MALDI-TOF MS). It is possible that the fucosyl-oligosaccharide synthesized in this study has biological functions similar to human milk oligosaccharides.
Assuntos
Lacticaseibacillus rhamnosus/enzimologia , Oligossacarídeos/biossíntese , alfa-L-Fucosidase/isolamento & purificação , Proteínas de Bactérias/isolamento & purificação , Proteínas de Bactérias/metabolismo , Parede Celular/enzimologia , Cromatografia Líquida de Alta Pressão , Glicosídeos/química , Humanos , Espectrometria de Massas , Oligossacarídeos/química , Prebióticos , Especificidade por Substrato , alfa-L-Fucosidase/metabolismoRESUMO
The aim of this research was to determine the physicochemical properties, microbial counts and aflatoxin M1 (AFM1) levels of thermoultrasonicated, pasteurized and untreated milk (control) at days 1, 7 and 14 of storage. Thermoultrasound treatment was performed at a rate of 20â¯kHz for 10 or 15â¯min and 95% amplitude on homogenized and non-homogenized milk samples. Results showed that most physicochemical parameters were within the Mexican norms established for milk. Ultrasound treatment for 15â¯min reduced solids precipitation (pâ¯<â¯0.05) in unhomogenized milk during storage as compared to the pasteurized milk. All samples complied with aerobic mesophilic counts limits set by the Mexican norm except the control and the homogenized milk sample which was thermoultrasonicated for 10â¯min. Enterobacteriaceae counts of pasteurized and 15â¯min-thermoultrasound homogenized milks complied with the norm. The lowest levels of AFM1 were found in the 10â¯min-thermoultrasound unhomogenized milk (0.15⯱â¯0.05â¯pgâ¯AFMâ 1E/mL) one day after storage. Thermoultrasound did not affect the color of samples but homogenized milk treated for 10â¯min exhibited less total color difference. A high phenolic content was found in thermoultrasound and pasteurized milks on day 1. Thermoultrasound could be an alternative to milk pasteurization that preserves the physicochemical and microbiological quality of milk while reducing AFM1 levels.
Assuntos
Aflatoxina M1/análise , Enterobacteriaceae/isolamento & purificação , Microbiologia de Alimentos , Armazenamento de Alimentos , Leite/química , Leite/microbiologia , Pasteurização/métodos , Sonicação/métodos , Animais , Antioxidantes/farmacologia , Bovinos , Contagem de Colônia Microbiana , Cor , Sequestradores de Radicais Livres/farmacologia , México , Fenóis/análiseRESUMO
The influence of CaCl2 and NaCl in the hydrolytic activity and the influence of CaCl2 in the synthesis of fucosylated oligosaccharides using α-L-fucosidase from Thermotoga maritima were evaluated. The hydrolytic activity of α-L-fucosidase from Thermotoga maritima displayed a maximum increase of 67% in the presence of 0.8 M NaCl with water activity (aw) of 0.9672 and of 138% in the presence of 1.1 M CaCl2 (aw 0.9581). In addition, the hydrolytic activity was higher when using CaCl2 compared to NaCl at aw of 0.8956, 0.9581 and 0.9672. On the other hand, the effect of CaCl2 in the synthesis of fucosylated oligosaccharides using 4-nitrophenyl-fucose as donor substrate and lactose as acceptor was studied. In these reactions, the presence of 1.1 M CaCl2 favored the rate of transfucosylation, and improved the yield of synthesis duplicating and triplicating it with lactose concentrations of 58 and 146 mM, respectively. CaCl2 did not significatively affect hydrolysis rate in these reactions. The combination of the activating effect of CaCl2, the decrement in aw and lactose concentration had a synergistic effect favoring the synthesis of fucosylated oligosaccharides.
Assuntos
Proteínas de Bactérias/metabolismo , Oligossacarídeos/biossíntese , Thermotoga maritima/enzimologia , alfa-L-Fucosidase/metabolismo , Cálcio/metabolismo , Fucose/análogos & derivados , Sódio/metabolismoRESUMO
Fucosylated oligosaccharides, such as 2'-fucosyllactose in human milk, have important biological functions such as prebiotics and preventing infection. In this work, the effect of an acceptor substrate (lactose) and the donor substrate 4-nitrophenyl-α-L-fucopyranoside (pNP-Fuc) on the synthesis of a fucosylated trisaccharide was studied in a transglycosylation reaction using α-L-fucosidase from Thermotoga maritima. Conducting a matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), it was demonstrated that synthesized oligosaccharide corresponded to a fucosylated trisaccharide, and high-performance liquid chromatography (HPLC) of the hydrolyzed compound confirmed it was fucosyllactose. As the concentration of the acceptor substrate increased, the concentration and synthesis rate of the fucosylated trisaccharide also increased, and the highest concentration obtained was 0.883 mM (25.2% yield) when using the higher initial lactose concentration (584 mM). Furthermore, the lower donor/acceptor ratio had the highest synthesis, so at the molar ratio of 0.001, a concentration of 0.286 mM was obtained (32.5% yield).
Assuntos
Fucose/biossíntese , Thermotoga maritima/enzimologia , Trissacarídeos/metabolismo , alfa-L-Fucosidase/metabolismo , Cromatografia Líquida de Alta Pressão , Fucose/metabolismo , Glicosilação , Lactose/metabolismo , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Especificidade por SubstratoRESUMO
There is a great variety of fermented milks containing lactic acid bacteria that present health-promoting properties. Milk proteins are hydrolyzed by the proteolytic system of these microorganisms producing peptides which may also perform other functions in vivo. These peptides are encrypted within the primary structure of proteins and can be released through food processing, either by milk fermentation or enzymatic hydrolysis during gastrointestinal transit. They perform different activities, since they act in the cardiovascular, digestive, endocrine, immune and nervous systems. Bioactive peptides that have an antihypertensive, antithrombotic, antioxidant and hypocholesterolemic effect on the cardiovascular system can reduce the risk factors for chronic disease manifestation and help improve human health. Most studied bioactive peptides are those which exert an antihypertensive effect by inhibiting the angiotensin-converting enzyme (ACE). Recently, the study of these peptides has focused on the implementation of tests to prove that they have an effect on health. This paper focuses on the production of ACEinhibitory antihypertensive peptides from fermented milks, its history, production and in vivo tests on rats and humans, on which its hypotensive effect has been shown.
Assuntos
Produtos Fermentados do Leite , Hipertensão/dietoterapia , Inibidores da Enzima Conversora de Angiotensina/isolamento & purificação , Animais , Bifidobacterium/enzimologia , Bovinos , Produtos Fermentados do Leite/enzimologia , Produtos Fermentados do Leite/microbiologia , Humanos , Lactobacillus/enzimologia , Lactococcus/enzimologia , Proteínas do Leite/metabolismo , Peptídeos/farmacocinética , Peptídeos/farmacologia , Ratos , Streptococcus/enzimologiaRESUMO
BACKGROUND: Probiotics and prebiotics are among the most important functional food ingredients worldwide. The proven benefits of such ingredients to human health have encouraged the development of functional foods containing both probiotics and prebiotics. In this work, the production of antimicrobial compounds coupled to the uptake of commercial prebiotics by probiotic bacteria was investigated. RESULTS: The probiotic bacteria studied were able to take up commercial prebiotic carbohydrates to the same or higher extent than that observed for lactose (control carbohydrate). The growth of probiotic bacteria was coupled to the production of antimicrobials such as short-chain fatty acids (SCFA), H2 O2 and bacteriocins. A higher production of antimicrobial compounds was recorded with Oligomate 55® compared with Regulact® and Frutafit® (3-5 and 10-115 times higher SCFA and H2 O2 production, respectively). The probiotic bacteria grown with Oligomate 55® also produced bacteriocins and other non-identified antimicrobial compounds. The antimicrobials produced by the probiotic bacteria inhibited up to 50% the growth of model pathogens such as Escherichia coli, Listeria innocua and Micrococcus luteus compared with control cultures. CONCLUSIONS: The results here obtained are useful for the adequate selection of probiotic/prebiotics pairs and therefore in the development of efficient functional foods.
Assuntos
Anti-Infecciosos/farmacologia , Bacteriocinas/biossíntese , Ácidos Graxos Voláteis/biossíntese , Peróxido de Hidrogênio/metabolismo , Lactobacillus/metabolismo , Prebióticos , Probióticos/metabolismo , Antibiose , Bacteriocinas/farmacologia , Comércio , Carboidratos da Dieta/metabolismo , Escherichia coli/efeitos dos fármacos , Ácidos Graxos Voláteis/farmacologia , Humanos , Peróxido de Hidrogênio/farmacologia , Listeria/efeitos dos fármacos , Micrococcus/efeitos dos fármacos , SimbióticosRESUMO
There is a great variety of fermented milks containing lactic acid bacteria that present health-promoting properties. Milk proteins are hydrolyzed by the proteolytic system of these microorganisms producing peptides which may also perform other functions in vivo. These peptides are encrypted within the primary structure of proteins and can be released through food processing, either by milk fermentation or enzymatic hydrolysis during gastrointestinal transit. They perform different activities, since they act in the cardiovascular, digestive, endocrine, immune and nervous systems. Bioactive peptides that have an antihypertensive, antithrombotic, antioxidant and hypocholesterolemic effect on the cardiovascular system can reduce the risk factors for chronic disease manifestation and help improve human health. Most studied bioactive peptides are those which exert an antihypertensive effect by inhibiting the angiotensin-converting enzyme (ACE). Recently, the study of these peptides has focused on the implementation of tests to prove that they have an effect on health. This paper focuses on the production of ACEinhibitory antihypertensive peptides from fermented milks, its history, production and in vivo tests on rats and humans, on which its hypotensive effect has been shown.
Assuntos
Produtos Fermentados do Leite , Hipertensão/dietoterapia , Inibidores da Enzima Conversora de Angiotensina/isolamento & purificação , Animais , Bifidobacterium/enzimologia , Bovinos , Produtos Fermentados do Leite/enzimologia , Produtos Fermentados do Leite/microbiologia , Humanos , Lactobacillus/enzimologia , Lactococcus/enzimologia , Proteínas do Leite/metabolismo , Peptídeos/farmacocinética , Peptídeos/farmacologia , Ratos , Streptococcus/enzimologiaRESUMO
Native beta-lactoglobulin binds and increases the activity of Kluyveromyces lactis beta-galactosidase. Construction of a three-dimensional (3D) model of beta-lactoglobulin showed that lysine residues 15, 47, 69, and 138 are the most exposed ones, thus the ones more likely to interact with beta-galactosidase. Molecular docking estimated the interaction energies of amino acid residues with either lactose or succinic anhydride, showing that Lys(138) is the most likely to react with both. Affinity chromatography demonstrated that succinylated beta-lactoglobulin diminished its ability to bind to the enzyme. Furthermore, when activity was measured in the presence of succinylated beta-lactoglobulin, its activating effect was lost. Since succinylation specifically blocks Lys epsilon-amino groups, their loss very likely causes the disappearance of the activating effect. Results show that the activating effect of beta-lactoglobulin on beta-galactosidase activity is due to the interaction between both proteins and that this interaction is very likely to occur through the Lys epsilon-amino groups of beta-lactoglobulin.
Assuntos
Ativação Enzimática/efeitos dos fármacos , Kluyveromyces/enzimologia , Lactoglobulinas/química , Lactoglobulinas/farmacologia , Lisina/química , beta-Galactosidase/metabolismo , Sítios de Ligação , Lactoglobulinas/metabolismo , Lisina/metabolismo , Modelos Moleculares , TermodinâmicaRESUMO
The present study evaluated the influence of water activity and lactose concentration on the synthesis of galactooligosaccharides (GOS), by means of a hyperthermophilic beta-glycosidase in an organic system. The production of GOS gradually grew as water activity increased in the reaction system; later, their synthesis decreased as water activity increased. The authors used the response surface methodology to study how different water activities and different concentrations of lactose influenced the synthesis of GOS and their length. In every case, the variable that proved to have the greatest effect on GOS synthesis was water activity. Maximum GOS3 synthesis was reached at a water activity interval of 0.44-0.57, with lactose concentrations of 0.06%-0.1%, while GOS4 and GOS5 maxima were reached at water activity intervals of 0.47-0.57 and 0.49-0.60, respectively. The research showed that higher water activity was required to synthesize GOS of greater length. Synthesis of GOS would then depend on the flexibility of the enzyme, which in turn would depend on water activity of the reaction system. This hypothesis was supported by experiments in which the reaction temperature was modified in order to change the flexibility of the enzyme, thus leading to longer GOS.
Assuntos
Acetona/química , Galactose/biossíntese , Glicosídeo Hidrolases/metabolismo , Oligossacarídeos/biossíntese , Água/química , Catálise , Galactose/química , Glucose/química , Glucose/metabolismo , Glicosídeo Hidrolases/química , Temperatura Alta , Cinética , Lactose/química , Lactose/metabolismo , Oligossacarídeos/química , Compostos Orgânicos/química , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Solventes/química , TemperaturaRESUMO
The secondary structure of Kluyveromyces lactis beta-galactosidase was determined by circular dichroism. It is mainly a beta-type protein, having 22% beta-turns, 14% parallel beta-sheet, 25% antiparallel beta-sheet, 34% unordered structure, and only 5% alpha-helix. The structure-activity relationship as a function of the pH was also studied. The pH conditions leading to the highest secondary structure content (100% ellipticity) of the enzyme was found at pH 7.0; at pH 6.5-7.0, the percent ellipticity decreased slightly, suggesting little structural change, but the activity decreased significantly, probably because of variations in critical residues. On the other hand, at pH's above 7.0, a more noticeable change in ellipticity was observed due to structural changes; the CD analysis showed a small increase in the helical content toward higher pH, whereas the maximum activity was found at pH 7.5, meaning that the changes produced in the secondary structure at this pH favored the interaction between the enzyme and the substrate.
Assuntos
Kluyveromyces/enzimologia , beta-Galactosidase/química , Cromatografia em Gel , Dicroísmo Circular , Eletroforese em Gel de Poliacrilamida , Proteínas Fúngicas/biossíntese , Proteínas Fúngicas/química , Concentração de Íons de Hidrogênio , Lactase/química , Lactase/isolamento & purificação , Conformação Proteica , Relação Estrutura-AtividadeRESUMO
The activities of some enzymes belonging to the Leloir pathway, phosphoglucomutase, UDP-glucose pyrophosphorylase, UDP-galactose 4-epimerase and galactose 1-P uridyl transferase, were studied in a wild ropy, a non-ropy and an overproducing mutant ropy strain of Streptococcus thermophilus. These activities were assayed over successive culture transfers along with exocellular polysaccharide (EPS) production. The overproducing mutant ropy strain showed increments in polysaccharide production over successive culture transfers, as opposed to reductions in production by the wild ropy strain. The observed variations among strains in the enzyme activities that were analysed in relation to EPS production suggest their involvement in the synthesis of sugar-nucleotide EPS precursors.
Assuntos
Fosfoglucomutase/genética , Fosfoglucomutase/metabolismo , Polissacarídeos Bacterianos/biossíntese , Streptococcus/enzimologia , Streptococcus/genética , Regulação Bacteriana da Expressão Gênica , Regulação Enzimológica da Expressão Gênica , Mutação/fisiologia , Fenótipo , UDPglucose 4-Epimerase/genética , UDPglucose 4-Epimerase/metabolismo , UTP-Glucose-1-Fosfato Uridililtransferase/genética , UTP-Glucose-1-Fosfato Uridililtransferase/metabolismo , UTP-Hexose-1-Fosfato Uridililtransferase/genética , UTP-Hexose-1-Fosfato Uridililtransferase/metabolismoRESUMO
Las fuentes comerciales de ß-galactosidasa (lactasas) microbianas incluyen a las especies de levaduras Kluyveromyces marxianus, Kluyveromyces lactis y Candida kefyr, las cuales son utilizadas en la hidrólisis de la lactosa en leche por tener un pH óptimo adecuado para este propósito. Por otra parte, las lactasas obtenidas de los hongos Aspergillus niger y Aspergillus oryzae tiene un pH óptimo ácido por lo cual más bien se utilizan en la hidrólisis de lactosa en suero para obtener los jarabes dulces de suero que se utilizan como materia prima en la industria de alimentos. El problema de enzimas de origen microbiano, no sólo para el consumo de leche de personas sanas con mala digestión de lactosa sino para la elaboración de dietas especiales para enfermos, anciano y bebés intolerantes a lactosa por deficiencia secundaria, etc. En la mayoría de los casos de hidrólisis de la lactosa en lehe se utiliza la enzima libre, pero también ha habido importantes desarrollos de catalizadores de lactasas inmovilizadas, los cuales han tenido particular impacto en el aprovechamiento del suero de leche
Assuntos
Humanos , beta-Galactosidase/uso terapêutico , Hidrólise , Lactose , Intolerância à Lactose/dietoterapia , LevedurasRESUMO
De la fermentación de suero de leche entera se obtuvo un producto consistente en una mezcla de biomasa de Kluyveromyces fragilis y proteínas coaguladas del suero. El producto tuvo una composición similar a la de productos lavados de que se informa en la literatura, con un alto contenido de proteína cruda y un bajo contenido de cenizas. Asimismo, acusó tambiém un alto contenido de aminoácidos azufrados y de triptofano, los que usualmente son limitantes en al biomasa de levadura. El contenido de lisina fue inexplicablemente más bajo de lo esperado resusltando ser el aminoácido limitante. La calificación química de la protéina fue 91%. Del producto de biomasa com proteínas de suero se obtuvo un concentrado proteínico con un rendimento de 80%. El contenido de proteína del aislado fue de 75% y el contenido de ácidos nucleícos se redujó en 90.8%. Los restos de pared celular también se redujeron considerablemente