Lactococcus lactis is capable of improving the riboflavin status in deficient rats

Lactococcus lactis is a commonly used starter strain that can be converted from a vitamin B2 consumer into a vitamin B2 'factory' by over-expressing its riboflavin biosynthesis genes. The present study was conducted to assess in a rat bioassay the response of riboflavin produced by GM or native lactic acid bacteria (LAB). The riboflavin-producing strains were able to eliminate most physiological manifestations of ariboflavinosis such as stunted growth, elevated erythrocyte glutathione reductase activation coefficient values and hepatomegalia that were observed using a riboflavin depletion–repletion model. Riboflavin status and growth rates were greatly improved when the depleted rats were fed with cultures of L. lactis that overproduced this vitamin whereas the native strain did not show the same effect. The present study is the first animal trial with food containing living bacteria that were engineered to overproduce riboflavin. These results pave the way for analysing the effect of similar riboflavin-overproducing LAB in human trials

Ability of Lactobacillus fermentum to overcome host α-galactosidase deficiency, as evidenced by reduction of hydrogen excretion in rats consuming soya α-galacto-oligosaccharides

<p>Abstract</p> <p>Background</p> <p>Soya and its derivatives represent nutritionally high quality food products whose major drawback is their high content of α-galacto-oligosaccharides. These are not digested in the small intestine due to the natural absence of tissular α-galactosidase in mammals. The passage of these carbohydrates to the large intestine makes them available for fermentation by gas-producing bacteria leading to intestinal flatulence. The aim of the work reported here was to assess the ability of α-galactosidase-producing lactobacilli to improve the digestibility of α-galacto-oligosaccharides <it>in situ</it>.</p> <p>Results</p> <p>Gnotobiotic rats were orally fed with soy milk and placed in respiratory chambers designed to monitor fermentative gas excretion. The validity of the animal model was first checked using gnotobiotic rats monoassociated with a <it>Clostridium butyricum </it>hydrogen (H₂)-producing strain. Ingestion of native soy milk by these rats caused significant H₂emission while ingestion of α-galacto-oligosaccharide-free soy milk did not, thus validating the experimental system. When native soy milk was fermented using the α-galactosidase-producing <it>Lactobacillus fermentum </it>CRL722 strain, the resulting product failed to induce H₂emission in rats thus validating the bacterial model. When <it>L. fermentum </it>CRL722 was coadministered with native soy milk, a significant reduction (50 %, <it>P </it>= 0.019) in H₂emission was observed, showing that α-galactosidase from <it>L. fermentum </it>CRL722 remained active <it>in situ</it>, in the gastrointestinal tract of rats monoassociated with <it>C. butyricum</it>. In human-microbiota associated rats, <it>L. fermentum </it>CRL722 also induced a significant reduction of H₂emission (70 %, <it>P </it>= 0.004).</p> <p>Conclusion</p> <p>These results strongly suggest that <it>L. fermentum </it>α-galactosidase is able to partially alleviate α-galactosidase deficiency in rats. This offers interesting perspectives in various applications in which lactic acid bacteria could be used as a vector for delivery of digestive enzymes in man and animals.</p

B Group Vitamins - Current Uses and Perspectives

B-group vitamins are involved in numerous metabolic reactions and their widespread deficiency can cause a large series of health problems. The aim of this book is to provide an update on the current use and perspectives of B-group vitamins. Novel methods to detect folates in pregnant women, the use and role of folate dentistry, the use of genotype notification to modify food intake behavior, thiamin metabolism in Archaea and its role in plants and in crop improvement, the use of riboflavin in blood safety and niacin in metabolic stress and resistance in dairy cows are some of the subjects that are described in this multitopic book written by authors from seven different countries

Physicochemical and microbiological evaluation of corrientes artisanal cheese during ripening Avaliação físico-química e microbiológica de queijo artesanal corrientes durante a maturação

The aim of this study was to evaluate some physical and chemical parameters (total solids, pH, acidity, fat, acid degree value of fat, salt, protein and nitrogen fractions) and their effects on the beneficial (lactic acid bacteria: LAB) and undesirable microbial populations (coliforms, Escherichia coli, Staphylococcus aureus, moulds, and yeast) during ripening of Artisanal Corrientes Cheese, an Argentinian cow's milk variety, to determine whether a longer ripening period than usual improve its hygienic-sanitary quality. The protein content was much higher than that of other cow's milk cheeses with similar values of fat. The larger peptides showed values three times higher in the 30 day-old cheese than those obtained in the beginning of the process. Staphylococcus aureus and Escherichia coli were detected (3.04 ± 1.48 log10 cfu/g of cheese, 2.21 ± 0.84 log10 MPN/g of cheese) even at 15 and 30 days of ripening, respectively. The distribution of three hundred LAB strains classified to the genus level (lactococci:lactobacilli:leuconostocs) was maintained during the ripening period. The high number of LAB in rennet may have contributed to the fermentation as a natural whey starter, unknown source of LAB for this specific cheese so far. The physicochemical changes that occur during ripening were not big enough to inhibit the growth of undesirable microorganisms.<br>O objetivo deste trabalho foi avaliar alguns parâmetros físicos e químicos (sólidos totais, pH, acidez, gordura, grau de acidez da gordura, sal, proteínas e frações de nitrogênio) e seus efeitos sobre as populações microbianas benéficas (bactérias lácticas: LAB) e indesejáveis (coliformes, Escherichia coli, Staphylococcus aureus, fungos e leveduras) durante a maturação do Queijo Artesanal de Corrientes, uma variedade argentina do leite cru da vaca, para determinar se um tempo de maturação mais longo do que o atual melhora as condições higiênico-sanitárias do queijo. O teor de proteína foi muito maior que de outros queijos o leite de vaca com valores semelhantes de gordura. Os péptidos maiores apresentaram valores, no queijo de 30 dias, três vezes mais altos que os do início do processo. Staphylococcus aureus e Escherichia coli foram detectadas (3.04 ± 1.48 log10 ufc/g de queijo, 2.21 ± 0.84 log10 NMP/g de queijo) ainda aos 15 e 30 dias de maturação, respectivamente. A distribuição das trezentas estirpes de LAB classificadas ao gênero (lactococci:lactobacilli:leuconostocs), foi mantida durante toda a maturação. O número elevado de LAB em coalho pode ter contribuído na fermentação como um soro-fermento natural, fonte desconhecida de LAB para este queijo específico até agora. As mudanças físico-químicas que ocorreram durante a maturação não geram condições fortemente inibidoras para o crescimento de micro-organismos indesejáveis

Characterization of the melA Locus for α-Galactosidase in Lactobacillus plantarum

Alpha-galactosides are abundant sugars in legumes such as soy. Because of the lack of α-galactosidase (α-Gal) in the digestive tract, humans are unable to digest these sugars, which consequently induce flatulence. To develop the consumption of the otherwise highly nutritional soy products, the use of exogenous α-Gal is promising. In this framework, we characterized the melA gene for α-Gal in Lactobacillus plantarum. The melA gene encodes a cytoplasmic 84-kDa protein whose enzymatically active form occurs as oligomers. The melA gene was cloned and expressed in Escherichia coli, yielding an active α-Gal. We show that melA is transcribed from its own promoter, yielding a monocistronic mRNA, and that it is regulated at the transcriptional level, i.e., it is induced by melibiose but is not totally repressed by glucose. Posttranscriptional regulation by the carbon source could also occur. Upstream of melA, a putative galactoside transporter, designated RafP, was identified that shows high homology to LacS, the unique transporter for both α- and β-galactosides in Streptococcus thermophilus. rafP is also expressed as a monocistronic mRNA. Downstream of melA, the lacL and lacM genes were identified that encode a heterodimeric β-galactosidase. A putative galM gene identified in the same cluster suggests the presence of a galactose operon. These results indicate that the genes involved in galactoside catabolism are clustered in L. plantarum ATCC 8014. This first genetic characterization of melA and of its putative associated transporter, rafP, in a lactobacillus opens doors to various applications both in the manufacture of soy-derived products and in probiotic and nutraceutical issues