Comparative protein composition analysis of goat milk produced by the Alpine and Saanen breeds in northeastern Brazil and related antibacterial activities.

The protein composition of goat milk differs between goat breeds and could present regional trends. The aim of this study was to comparatively analyze the protein composition of goat milk produced by the Alpine and Saanen breeds in northeastern Brazil and to evaluate the antibacterial activity of its protein fractions. SDS-PAGE, 2-DE electrophoresis and RP-HPLC analyses revealed the absence of αs1-casein in the milk of both breeds and no differences between the αs2-casein, ß-casein, ß-lactoglobulin and α-lactalbumin profiles. The amounts of soluble proteins and ß-casein hydrolysis residues were higher in Saanen milk. Only the protein fraction containing the largest amounts of casein (F60-90%) inhibited bacterial growth, with MIC values between 50 and 100 mg/mL. This study describe for the first time three important points about the goat milk protein of two Brazilian goat breeders: absence of α-s1 casein in the protein profile, differences between the milk protein composition produced by goats of Alpine and Saanen breeders and antibacterial activity of unbroken proteins (casein-rich fraction) present in these milk.

α-Lactoalbúmina como ingrediente de fórmulas infantiles

La α-lactoalbúmina es la principal proteína del lactosuero en la leche materna, alcanzando una concentración de 2,44 g/L en la leche madura. Su principal función es la síntesis de lactosa a partir de glucosa y galactosa en la glándula mamaria, aunque posee además otros efectos beneficiosos sobre la salud del lactante debido a su elevada proporción de aminoácidos esenciales (triptófano y cisteína). Según diversos estudios parece influir positivamente en la absorción de hierro en el intestino del niño, y en experimentos in vitro, unida al ácido oleico (complejo HAMLET), es efectiva frente a tumores celulares como el papiloma humano. El complejo HAMLET también presenta un claro efecto antimicrobiano frente a Streptococcus pneumoniae, Haemophilus influenzae, cepas enteropatógenas de Escherichia coli y Salmonella thypimurium, sin embargo no se ha demostrado que durante la digestión de la leche materna se forme dicho complejo en el tracto digestivo del lactante. El desarrollo de fórmulas infantiles destinadas a la alimentación del niño durante el primer año de vida ha mejorado considerablemente en las últimas décadas intentando no sólo adecuar la concentración de nutrientes a los requerimientos del lactante, sino también adicionando compuestos bioactivos de diferente naturaleza, como la α-lactoalbúmina, con el objetivo de alcanzar los efectos funcionales que se producen en los niños alimentados con leche materna.

α-Lactalbumin as an ingredient of infant formula. α-lactalbumin is the main whey protein in human milk rising 2,44 g/L in mature milk. It has a key function in the synthesis of lactose from glucose and galactose in the mammary gland although this compound has also other beneficial effects on the infant health due to the high proportion of essential aminoacids (tryptophan and cysteine). It seems also to increase iron absorption in the digestive track, and in in vitro experiments, linked to oleic acid (HAMLET complex), has shown anticarcinogenic effects against cellular tumor such as human papilloma. In addition, this complex has been reported to exhibit antimicrobial properties against Streptococcus pneumoniae,Haemophilus influenzae, enteropathogenic strains of Escherichia coli and Salmonella thypimurium. However, the in vivo synthesis of HAMLET complex during milk digestion has not been proved yet. Infant formula have been improved considerably during the last decades not only adapting nutrient concentrations to infants requirements but also by the addition of new bioactive ingredients such as α-lactalbumin, to have the same functional effect as in breast fed babies.

[Alpha-Lactalbumin as an ingredient of infant formula]. / Alpha-Lactoalbúmina como ingrediente de fórmulas infantiles.

Alpha-Lactalbumin is the main whey protein in human milk rising 2,44 g/L in mature milk. It has a key function in the synthesis of lactose from glucose and galactose in the mammary gland although this compound has also other beneficial effects on the infant health due to the high proportion of essential aminoacids (tryptophan and cysteine). It seems also to increase iron absorption in the digestive track, and in in vitro experiments, linked to oleic acid (HAMLET complex), has shown anticarcinogenic effects against cellular tumor such as human papilloma. In addition, this complex has been reported to exhibit antimicrobial properties against Streptococcus pneumoniae, Haemophilus influenzae, enteropathogenic strains of Escherichia coli and Salmonella thypimurium. However, the in vivo synthesis of HAMLET complex during milk digestion has not been proved yet. Infant formula have been improved considerably during the last decades not only adapting nutrient concentrations to infants requirements but also by the addition of new bioactive ingredients such as alpha-lactalbumin, to have the same functional effect as in breast fed babies.

Lactoferrin and free secretory component of human milk inhibit the adhesion of enteropathogenic Escherichia coli to HeLa cells.

BACKGROUND: Diarrhoea caused by Escherichia coli is an important cause of infant morbidity and mortality in developing countries. Enteropathogenic Escherichia coli (EPEC) is considered one of the major causes of diarrhoea in children living in developing countries. The ability of diarrhoeagenic strains of E. coli to adhere to and colonize the intestine is the first step towards developing the disease. EPEC strains adhere to enterocytes and HeLa cells in a characteristic pattern known as localized adherence. Many epidemiological studies of diarrhoea have shown that breast-feeding protects infants from intestinal infections. Both immunoglobulin and non-immunoglobulin elements of human milk are thought to contribute to the protection from diarrhoeal agents. RESULTS: The effects of human milk and its protein components on the localized adherence of EPEC were investigated. Non-immunoglobulin components of human milk responsible for the inhibition of EPEC adhesion to HeLa cells were isolated by chromatographic fractionation of human whey proteins. Besides secretory immunoglobulin A, which has been previously reported to affect the adhesion of EPEC, free secretory component (fSC) and lactoferrin (Lf) were isolated. Even in concentrations lower than those usually found in whole milk, fSC and Lf were able to inhibit the adhesion of EPEC. alpha-lactalbumin was also isolated, but showed no activity on EPEC adhesion. CONCLUSIONS: This study demonstrated that the immunoglobulin fraction, the free secretory component and lactoferrin of human milk inhibit EPEC adhesion to HeLa cells. These results indicate that fSC and Lf may be important non-specific defence factors against EPEC infections.

Human milk fractions inhibit the adherence of diffusely adherent Escherichia coli (DAEC) and enteroaggregative E. coli (EAEC) to HeLa cells.

Binding to a specific receptor is an essential step for most enteropathogens to initiate an intestinal infection. We analyzed the inhibitory effect of human milk and its protein components on adhesion of two diarrheagenic Escherichia coli strains, diffusely adherent E. coli (DAEC) and enteroaggregative E. coli (EAEC), to HeLa cells. Defatted milk, whey proteins, immunoglobulin and non-immunoglobulin fractions, in concentrations lower than usually found in whole milk, inhibited both DAEC and EAEC adhesion, indicating that human milk components may contribute to the defense of the infants against enteropathogens.