The effect of two fermented milks （FMI, FM2） with lactic acid bacteria and Bifidobacteria on the intestine mucosa was studied. BALB/c mice were divided in groups of non-sensitized or sensitized by oral route to cow...The effect of two fermented milks （FMI, FM2） with lactic acid bacteria and Bifidobacteria on the intestine mucosa was studied. BALB/c mice were divided in groups of non-sensitized or sensitized by oral route to cow＇s milk or colonized by FM1 [10^7 cfu/mL ofBifidobacterium longum （Bfl） and 10^8 cfu/mL of Streptococcus thermophillus （Stl）] and sensitized by oral route to cow＇s milk or colonized by FM2 [10^7 cfu/mL of Bfl and 10^7 cfu/mL ofLactobacillusplantarum （LbO）] and sensitized to cow＇s milk. Blood was sampled and the amount of anti-β-Lactoglobulin （β-Lg） IgG was measured. Mice were sacrificed, fragments of their intestines were isolated to inspect the structural changes of intestinal mucosa. A significant anti-β-Lg response was elicited by oral sensitization in positive control compared to other groups. Inspection of villi structural changes reveal signs of inflammation in challenged group compared with FM1 and FM2 groups, which conserved long villi characteristic of negative controls. The colonization of intestines by BfI-StI and BfI-LbO, and the evaluation of the residual antigenicity of β-Lg in mice sensitized to bovine milk by oral route followed by histological studies, revealed that FM1 and FM2 play protective role and reduce the histological lesions typical of bovine milk allergy.展开更多
The enzyme β-galactosidase （lactase; EC 3.2.1.23） is a commercially important enzyme due to its various applications in dairy and food industries, which are based on the β-galactosidase-catalysed hydrolysis of lac...The enzyme β-galactosidase （lactase; EC 3.2.1.23） is a commercially important enzyme due to its various applications in dairy and food industries, which are based on the β-galactosidase-catalysed hydrolysis of lactose into glucose and galactose. The objectives of this work were to identify novel and attractive sources of this industrially relevant enzyme, and to study the effect of selected growth parameters （carbon source, lactose concentration, nitrogen source, peptone concentration, initial pH and temperature） on the formation of β-galactosidase. Based on a screening of isolates from Tha Pai hot spring, Mae Hong Son Province, Thailand, strain BI.1 was selected for further studies. Strain BI.1 is a Gram-positive, rod-shaped, catalase-positive bacterium that forms endospores. Based on the sequence of the 16S rDNA determined, this isolate is most closely related to Anoxybacillus sp. and Bacillus sp., and hence the strain is designated as Bacillus sp. B 1. I.β-Galactosidase was produced by this strain with lactose and peptone as carbon and nitrogen sources, respectively. Optimal enzyme production occurred at an initial culture pH of 8.5 and at 45 ℃. Under these optimum culture conditions, maximal volumetric and specific β-galactosidase activity of 0.478 U mL^-1 and 0.338 U mg^-1 protein, respectively, were obtained after 13 h of cultivation in a medium contain 2.5% lactose, 2.0% peptone, 0.3% K2HPO4, 0.1% KH2PO4 and 0.05% MgSOa·7H2O.展开更多
文摘The effect of two fermented milks （FMI, FM2） with lactic acid bacteria and Bifidobacteria on the intestine mucosa was studied. BALB/c mice were divided in groups of non-sensitized or sensitized by oral route to cow＇s milk or colonized by FM1 [10^7 cfu/mL ofBifidobacterium longum （Bfl） and 10^8 cfu/mL of Streptococcus thermophillus （Stl）] and sensitized by oral route to cow＇s milk or colonized by FM2 [10^7 cfu/mL of Bfl and 10^7 cfu/mL ofLactobacillusplantarum （LbO）] and sensitized to cow＇s milk. Blood was sampled and the amount of anti-β-Lactoglobulin （β-Lg） IgG was measured. Mice were sacrificed, fragments of their intestines were isolated to inspect the structural changes of intestinal mucosa. A significant anti-β-Lg response was elicited by oral sensitization in positive control compared to other groups. Inspection of villi structural changes reveal signs of inflammation in challenged group compared with FM1 and FM2 groups, which conserved long villi characteristic of negative controls. The colonization of intestines by BfI-StI and BfI-LbO, and the evaluation of the residual antigenicity of β-Lg in mice sensitized to bovine milk by oral route followed by histological studies, revealed that FM1 and FM2 play protective role and reduce the histological lesions typical of bovine milk allergy.
文摘The enzyme β-galactosidase （lactase; EC 3.2.1.23） is a commercially important enzyme due to its various applications in dairy and food industries, which are based on the β-galactosidase-catalysed hydrolysis of lactose into glucose and galactose. The objectives of this work were to identify novel and attractive sources of this industrially relevant enzyme, and to study the effect of selected growth parameters （carbon source, lactose concentration, nitrogen source, peptone concentration, initial pH and temperature） on the formation of β-galactosidase. Based on a screening of isolates from Tha Pai hot spring, Mae Hong Son Province, Thailand, strain BI.1 was selected for further studies. Strain BI.1 is a Gram-positive, rod-shaped, catalase-positive bacterium that forms endospores. Based on the sequence of the 16S rDNA determined, this isolate is most closely related to Anoxybacillus sp. and Bacillus sp., and hence the strain is designated as Bacillus sp. B 1. I.β-Galactosidase was produced by this strain with lactose and peptone as carbon and nitrogen sources, respectively. Optimal enzyme production occurred at an initial culture pH of 8.5 and at 45 ℃. Under these optimum culture conditions, maximal volumetric and specific β-galactosidase activity of 0.478 U mL^-1 and 0.338 U mg^-1 protein, respectively, were obtained after 13 h of cultivation in a medium contain 2.5% lactose, 2.0% peptone, 0.3% K2HPO4, 0.1% KH2PO4 and 0.05% MgSOa·7H2O.
