Desarrollo de un endulzante natural a base de yacón (Smallanthus sonchifolius) y su evaluación sensorial / Development of a natural sweetener based on yacon (Smallanthus sonchifolius) and its sensory evaluation

Fundamentos: El yacón se considera un producto prometedor que puede posicionarse en el mercado dealimentos funcionales, dado su valor nutricional representado principalmente por su alto contenido defructooligosacáridos. La obtención de un sirope de yacón agrega valor a esta materia prima, incentivando suproducción y consumo, no solo como endulzante de mesa, sino como materia prima para la industria e inclusocomo alimento funcional. El objetivo de este trabajo fue estandarizar las condiciones para la elaboración deun sirope de yacón, y mediante análisis sensorial realizar su descripción y valoración organoléptica.Métodos: Se definieron las condiciones para la obtención de sirope de yacón y se evaluó mediante pruebasdescriptivas y afectivas en un análisis sensorial con evaluadores semi entrenados.Resultados: Con un rendimiento de cerca del 10,0% a partir de yacón fresco, se obtuvo un sirope con 65°Brixy aspecto similar a la miel, en el que se destacaron aromas a miel, propóleos y caramelo. En las pruebasafectivas, utilizando una escala hedónica de cinco puntos, las mayores valoraciones fueron para los atributoscolor 4,8 ± 0,6 y textura 4,5 ± 0,7 y la menor para el sabor 3,2 ± 1,0.Conclusiones: Las características sensoriales y su aceptabilidad proyectan el sirope de yacón como un potencialalimento funcional comercializable. (AU)

Background: Yacon is considered a promising product that can be positioned in the functional food market,given its nutritional value represented mainly by its high FOS content. Obtaining a yacon syrup adds value tothis raw material, encouraging its production and consumption, not only as a table sweetener, but also as a rawmaterial for the industry. The objetive was to standardize the conditions for the elaboration of a yacon syrup,and through sensory analysis to carry out its description and organoleptic evaluation.Methods: The conditions for obtaining yacon syrup were defined. And it was evaluated through descriptiveand affective tests in a sensory analysis with semi-trained evaluators.Results: With a yield of close to 10.0% from fresh yacon, a syrup with 65°Brix and an appearance similar tohoney was obtained, in which aromas of honey, propolis and caramel stand out. In the affective tests, using afive-point hedonic scale, the highest evaluations were for the attributes color 4.8 ± 0.6 and texture 4.5 ± 0.7and the lowest for flavor 3.2 ± 1.0.Conclusions: The sensory characteristics and its acceptability project yacon syrup as a potentially marketable functional food. (AU)

Relationship between vitamin B12 levels and insulin resistance in postmenopausal women from Colombia Caribbean / Relação entre níveis de vitamina B12 e resistência à insulina em mulheres na pós-menopausa da Colômbia Caribe

Introduction: The high prevalence of low vitamin B12 serum levels has been recognized as a public health problem in Latin America; however, the current magnitude of this deficiency in Colombia is uncertain. Low levels of vitamin B12 can induce clinical and subclinical hematological and neurological disorders. Epidemiological studies have demonstrated a relationship between vitamin B12 deficiency and cardiovascular diseases (CVDs). However, the role of vitamin B12 in insulin resistance has been poorly studied. Objective: This study aimed to evaluate the relationship between vitamin B12 serum levels and biochemical and anthropometric markers related to CVDs and insulin resistance in postmenopausal women from Colombia Caribbean. Methods: Correlational, descriptive study. By convenience sampling, 182 postmenopausal women from the medical consultation service of a health institution were linked. Serum vitamin B12 levels, anthropometric variables (body mass index, abdominal perimeter), and biochemical variables (glycemia, insulin, lipid profile, HOMA IR) were evaluated. Results: The average value of the vitamin B12 serum level was 312.5 ± 122.5 pg/mL (230.6 ± 90.4 pmol/L); 46.7% of the women had less than adequate levels of 300 pg/mL (> 221 pmol/L), and 9. 9% were deficient, with levels of less than 200 pg/mL (148 pmol/L). The women with metabolic syndrome were 63.7%, and according to HOMA IR, 52.7 % had insulin resistance. A significant inverse relationship was shown between serum vitamin B12 levels with basal glycemic (P =0.002) and HOMA-IR (P =0.040). Conclusions: A significant inverse relationship between vitamin B12 levels and basal glycemia and HOMA-IR was observed. These findings highlight vitamin B12 deficiency in postmenopausal women and suggest nutritional supplementation.Keywords: Vitamin B12, Insulin resistance, Diet, Postmenopause, Cardiovascular diseases (AU).

Introdução: A alta prevalência de baixos níveis séricos de vitamina B12 foi reconhecida como um problema de saúde pública na América Latina, mas a magnitude atual dessa deficiência na Colômbia é incerta. Baixos níveis de vitamina B12 podem induzir distúrbios hematológicos e neurológicos clínicos e subclínicos. Na verdade, estudos epidemiológicos demonstram uma relação entre deficiência de vitamina B12 e doenças cardiovasculares (DCVs). No entanto, o papel da vitamina B12 na resistência à insulina tem sido pouco estudado. Objetivo: O objetivo deste estudo foi avaliar a relação entre os níveis séricos de vitamina B12 e marcadores bioquímicos e antropométricos relacionados com doenças cardiovasculares e resistência à insulina em mulheres pós-menopáusicas da Colômbia Caribe. Métodos: Estudo correlacional, descritivo. Por amostragem de conveniência, foram vinculadas 182 mulheres na pós-menopausa do serviço de consulta médica de uma instituição de saúde. Níveis séricos de vitamina B12, variáveis antropométricas (índice de massa corporal, perímetro abdominal) e variáveis bioquímicas (glicemia, insulina, perfil lipídico, HOMA IR) foram avaliadas. Resultados: O valor médio do nível sérico de vitamina B12 foi de 312,5 ± 122,5 pg/mL (230,6 ± 90,4 pmol/L); 46,7% das mulheres tinham níveis abaixo do adequado de 300 pg/mL (> 221 pmol/L), e 9,9% eram deficientes, com níveis abaixo de 200 pg/mL (148 pmol/L).As mulheres com síndrome metabólica foram 63,7% e, segundo o HOMA IR, 52,7% apresentavam resistência à insulina. Uma relação inversa significativa entre os níveis séricos de vitamina B12 com glicemia basal (P = 0,002) e HOMA-IR (P = 0,040) foi mostrada. Conclusões: Foi observada uma relação inversa significativa entre os níveis de vitamina B12 e glicemia basal e HOMA-IR. Esses achados destacam a deficiência de vitamina B12 em mulheres na pós-menopausa e sugerem suplementação nutricional (AU).

Evaluación sensorial de golosinas tipo goma hechos a base de verduras y edulcorante bajo en calorías / Sensory evaluation of gummy candies made from vegetables and low-calorie sweetener

Fundamentos: La Organización Mundial de la Salud (OMS) recomienda aumentar el consumo de frutas y hortalizas hasta 400 g diarios, principalmente en la población infantil. Recientes estudios han sugerido que la exposición a las propiedades sensoriales de las verduras puede aumentar la apetencia por estas. En este trabajo se evaluó mediante análisis sensorial el nivel de aceptación de golosinas tipo goma a base de verdurasendulzadas con xilitol, en una población de niños y jóvenes entre 7 a 14 años de edad. Métodos: se estandarizó la preparación de gomas de verduras con extracto de Zanahoria (Daucus carota), tomate (Lycopersicum esculentum) y pimentón verde (Capsicum annuum),utilizando el edulcorante bajo en calorías xilitol. El análisis sensorial consistió en una prueba afectiva de los atributos aspecto, color, olor, textura y sabor, mediante una escala hedónica grafica de cinco puntos; y una prueba de preferencia por ordenamiento para evaluar la aceptación global del producto. Los evaluadores no entrenados, fueron setenta estudiantes de una institución educativa.Resultados: Las gomas de zanahoria y tomate mostraron una aceptación superior al 80%, la aceptación global de las gomas mostró diferencias significativas entre los tres sabores(p < 0,000 Chi cuadrado). Los atributos olor y sabor obtuvieron las menores valoraciones, aunque superiores a 3,3 en la escala hedónica de cinco puntos, debido posiblemente a la presenciade aromas y sabores propios de las verduras. Conclusiones: La creación de golosinas tipo goma que incorporen sabores propios de las verduras, podría constituirse como una estrategia eficiente para promover la mejor aceptación y consumo de verduras por la población infantil. (AU)

Background: The World Health Organization (WHO) recommends increasing the consumption of fruit and vegetables up to 400 g daily, mainly in the child population. Recent studieshave suggested that exposure to the sensory properties of vegetables may increase appetite for them. In this study was evaluate by sensory analysis the level of acceptance of gumtype sweets based on vegetables, sweetened with xylitol, in a population of children and young people between 7 and 14years of age. Methods: the preparation of vegetable gums with extractof Carrot (Daucus carota), tomato (Lycopersicum esculentum) and green paprika (Capsicum annuum) was standardized, using the low calorie xylitol sweetener. Sensory analysisconsisted of an affective sensory test of the attributes appearance, color, odor, texture, and flavor using a five-pointgraphical hedonic scale; and a test of preference for ordering. The untrained evaluators were seventy students froman educational institution. Results: Carrot and tomato gums showed an acceptance higher than 80%, odor and flavor attributes obtained thelowest ratings, although higher than 3.3 on the five-point scale, possibly due to the presence of aromas and flavors typical of vegetables. The overall acceptability of the gums showedsignificant differences between the three flavors (p < 0.000 Chi square).Conclusions: The creation of gum-type sweets that incorporate flavors typical of vegetables, could constitute an efficient strategy to promote the best acceptance and consumption of vegetables by the child population. (AU)

Bifidobacterias como indicadoras de contaminación fecal en aguas tropicales

La contaminación fecal humana en el agua constituye un importante riesgo para la salud pública, sin embargo, los microorganismos indicadores comúnmente utilizados para detectar contaminación fecal no identifican su fuente específica. La detección de ciertas especies del género Bifidobacterium como B. adolescentis y B. dentium ha sido propuesta como un efectivo marcador de contaminación fecal humana, pero esto no ha sido evaluado en las condiciones ambientales tropicales. El objetivo de este trabajo fue determinar el perfil de bifidobacterias, en una muestra de agua de la Ciénaga de Mesolandia en el Caribe Colombiano y en 260 muestras fecales humanas y 94 de animales domésticos de un asentamiento humano periférico a la ciénaga. El ADN extraído de cada una de las muestras fue amplificado por PCR mediante el uso de cebadores específicos de género basados en la secuencia del gen 16S ARNr y separados por DGGE (Electroforesis en Gel con Gradiente Desnaturalizante). Las bandas obtenidas en DGGE, fueron extraídas del gel, re-amplificadas, secuenciadas y las secuencias comparadas con la base de datos del GenBank. El perfil de bifidobacterias en DGGE mostró la presencia de ocho especies de Bifidobacterias en la muestra de agua, las cuales también fueron identificadas en las heces humanas. B. adolescentis y B. dentium propuestas como marcadores de contaminación fecal humana, también fueron encontradas en animales domésticos. En este estudio bajo las condiciones ambientales y experimentales evaluadas no fue posible encontrar una especie de Bifidobacteria específica para ser utilizada como marcador de contaminación fecal humana en ambientes tropicales. Sin embargo, el método aplicado permitió una aproximación más cercana al origen de la contaminación fecal en relación con los métodos culturales tradicionales, ya que fue posible encontrar secuencias de ADN idénticas en el agua y en las muestras fecales.

Human fecal pollution in water constitute a serious risk to the public health, nevertheless the indicator microorganisms commonly used to detect the levels of fecal pollution does not identify the specific source. The detection of certain Bifidobacterium species as B. adolescentis and B. dentium have been proposed as an effective marker of human fecal contamination, but this has not yet been demonstrated in tropical environmental conditions. The aim of the present work was to determine the Bifidobacteria profile in one sample of water from the Mesolandia Swamp in the Colombian Caribbean and feces samples of 260 human and 94 domestic animals from a human settlement around the swamp. DNA from all the samples was amplified by PCR using specific specie primers based on the 16S rRNA gene sequence and separated by DGGE (Denaturing Gradient Gel Electrophoresis). DGGE bands were excised, reamplified, sequenced, and compared to GenBank database. Bifidobacterial DGGE profiles showed that eight species of Bifidobacterium that were found in the water sample, were also present in the human and animal feces. Bifidobacterium adolescentis and B. dentium described as potential human fecal pollution indicators were found in domestic animals. In this study under the environmental and experimental conditions evaluated was not possible to find a Bifidobacterium species as specific marker of human fecal contamination in tropical areas. However, the applied method in this study could be useful to detect fecal pollution in tropical waters allowing a nearest approximation to the origin of the fecal pollution compared with cultural traditional methods, since it was possible to find identical DNA sequences in the water and in the fecal samples.

Parasitismo intestinal en poblaciones con alto grado de vulnerabilidad del Caribe colombiano / Intestinal parasitism in populations with a high degree of vulnerability in the Colombian Caribbean

Introducción: Los parásitos intestinales tienen alto impacto en la salud de la población mundial y pueden constituir un factor más de riesgo en poblaciones en alto grado de vulnerabilidad por desplazamientos humanos a causa de la pobreza, violencia o catástrofes naturales. Objetivo: Evaluar el parasitismo intestinal en los habitantes de dos asentamientos humanos en alto grado de vulnerabilidad. Métodos: estudio descriptivo de corte transversal, en el que se analizaron 367 muestras fecales de los habitantes de dos asentamientos humanos en estado de vulnerabilidad del departamento del Atlántico-Colombia, durante los años 2015 y 2016. Se realizó examen directo de las heces en solución salina, lugol y concentración con el método formol-éter. Se estableció la frecuencia absoluta y relativa de los parásitos presentes y se compararon los resultados entre los dos lugares de muestreo. Resultados: el 91,28 por ciento de la población analizada tenía parásitos intestinales. Las helmintiasis presentaron una frecuencia del 52,32 por ciento. Los parásitos más frecuentes fueron Blastocystis sp. (49,05 por ciento) y Trichuris trichiura (44,96 por ciento). Conclusiones: La alta prevalencia de parásitos en las poblaciones vulnerables analizadas, plantea la necesidad de implementar estrategias para el control del parasitismo intestinal dentro de los planes de prevención y mitigación de riesgos(AU)

Introduction: Intestinal parasites have high impact in the health of the world population and can constitute another risk factor in populations with a high degree of vulnerability by human displacements because of poverty, violence or natural catastrophes. Objective: To evaluate intestinal parasitism in inhabitants of two populations with high degree of vulnerability. Methods: Cross sectional, descriptive study in which 367 stool samples were analyzed from the inhabitants of two populations with high vulnerability's degree, in Atlántico-Colombia department during the years 2015 and 2016. The parasitological analysis was performed by direct examination of the stool samples in saline, lugol and concentration solutions by the formalin-ether method. The absolute and relative frequencies of the parasites present were established and the results between the sampled places were compared. Results: 91.28 percent of the population was infected with intestinal parasites. Helminthiasis showed a frequency of 52.32 percent. The most frequents parasites were Blastocystis sp. (49.05 percent) and Trichuris trichiura (44.96 percent). Conclusions: The high prevalence of parasites in the analyzed populations with a high degree of vulnerability expresses the need of implementing strategies for the control of intestinal parasitism in the prevention and risk's mitigation planning(AU)

Relationship between Serum Vitamin D Levels and HDL Cholesterol in Postmenopausal Women from Colombian Caribbean.

BACKGROUND: Previous evidence suggests that metabolic disorders in postmenopausal women could be related with low serum vitamin D levels. For example, vitamin D deficiency has been associated with increased risk factors for cardiovascular disease (CVD), mainly those related with metabolic syndrome. OBJECTIVE: To assess the relationship between the serum vitamin D (25-OH-D) levels and the metabolic syndrome markers in postmenopausal women. METHODS: This descriptive and cross-sectional study was conducted in 183 postmenopausal women of four municipalities from Colombian Caribbean. The serum 25-OH-D levels and the anthropometric and biochemical markers were assessed and correlated with metabolic syndrome. RESULTS: The average value of serum vitamin D (25-OH-D) was 26.34 ± 9.08 ng/mL, and 69.95% of the women had vitamin D levels <30 ng/mL, of which 43.72% were with insufficiency (<30 to >20 ng/mL) and 26.23% with deficiency (<20 ng/mL). Of the evaluated women, the 81.42% seemed to have metabolic syndrome. Through the linear regression, one significant positive association was observed between the HDL cholesterol and the 25-OH-D levels (P=0.014). CONCLUSION: In the evaluated population in this study, vitamin D deficiency is related with low HDL cholesterol levels.

Estado de la 25-hidroxivitamina D sérica en niños sanos menores de 10 años del área metropolitana de Barranquilla / Serum 25-hydroxyvitamin D state in healthy children ten year minors old of Barranquilla metropolitan area

Resumen: Objetivo: Evaluar los niveles séricos de 25-hidroxivitamina D (25-OH-D) en niños sanos menores de 10 años del área metropolitana de Barranquilla (AMB). Material y métodos: Estudio descriptivo de corte transversal, que evaluó los niveles séricos de 25-OH-D en 360 niños del AMB en los años 2014-2015. Resultados: El valor promedio de 25-OH-D en la población estudiada fue 32.23±8.56 ng/mL; 46.38% de los niños tenía niveles de vitamina D considerados insuficientes (<30 ng/mL) y 3.05% mostro deficiencia (<20 ng/mL). Soledad y Puerto Colombia fueron los municipios con mayor población en esta condición. Conclusiones: Es necesario generar programas de suplementación nutricional y fomentar estilos de vida que permitan, de forma segura, mejorar los niveles de vitamina D en la población.

Abstract: Objetive: To evaluate the serum 25-hydroxyvitamin D (25-OH-D) levels in healthy children under 10 years of the Barranquilla metropolitan area. Materials and methods: A descriptive cross-sectional study in which serum levels of 25-OH-D were analyzed in 360 healthy children from 2014 to 2015. Results: The median value of 25-OH-D serum level was 32.23±8.56 ng/mL; 46.38% of children had vitamin D levels in the insufficient range (<30 ng/mL), while 3.05% were deficient (<20 ng/mL). Soledad and Puerto Colombia were the municipalities with more population in this condition. Conclusions: It is necessary to promote vitamin D supplement consumption and healthy lifestyles in order to safely improve levels of this micronutrient in the population.

[Serum 25-hydroxyvitamin D state in healthy children ten year minors old of Barranquilla metropolitan area]. / Estado de la 25-hidroxivitamina D sérica en niños sanos menores de 10 años del área metropolitana de Barranquilla.

OBJETIVE: To evaluate the serum 25-hydroxyvitamin D (25-OH-D) levels in healthy children under 10 years of the Barranquilla metropolitan area. MATERIALS AND METHODS: A descriptive cross-sectional study in which serum levels of 25-OH-D were analyzed in 360 healthy children from 2014 to 2015. RESULTS: The median value of 25-OH-D serum level was 32.23±8.56 ng/mL; 46.38% of children had vitamin D levels in the insufficient range (<30 ng/mL), while 3.05% were deficient (<20 ng/mL). Soledad and Puerto Colombia were the municipalities with more population in this condition. CONCLUSIONS: It is necessary to promote vitamin D supplement consumption and healthy lifestyles in order to safely improve levels of this micronutrient in the population.

OBJETIVO: Evaluar los niveles séricos de 25-hidroxivitamina D (25-OH-D) en niños sanos menores de 10 años del área metropolitana de Barranquilla (AMB). MATERIAL Y MÉTODOS: Estudio descriptivo de corte transversal, que evaluó los niveles séricos de 25-OH-D en 360 niños del AMB en los años 2014-2015. RESULTADOS: El valor promedio de 25-OH-D en la población estudiada fue 32.23±8.56 ng/mL; 46.38% de los niños tenía niveles de vitamina D considerados insuficientes (<30 ng/mL) y 3.05% mostro deficiencia (<20 ng/mL). Soledad y Puerto Colombia fueron los municipios con mayor población en esta condición. CONCLUSIONES: Es necesario generar programas de suplementación nutricional y fomentar estilos de vida que permitan, de forma segura, mejorar los niveles de vitamina D en la población.

La deficiencia de zinc: un problema global que afecta la salud y el desarrollo cognitivo / Zinc deficiency: a global problem that affect the health and cognitive development

La deficiencia de zinc afecta aproximadamente un tercio de la población mundial, principalmente en los países en vía de desarrollo, en las áreas rurales y en las comunidades más pobres, donde constituye un importante factor de riesgo asociado a enfermedad. En este trabajo se realiza una revisión de los avances científicos que han permitido conocer el papel fundamental del zinc en el control de la neurogénesis, el funcionamiento del cerebro y el desarrollo cognitivo. Con el fin de generar en los profesionales de salud, interés por la investigación de los efectos de la deficiencia de zinc en el desarrollo neurológico y cognitivo y su impacto negativo en el desarrollo cultural, social y económico de los pueblos(AU)

The zinc deficiency affects approximately a third of the world population, principally in the developing countries, the rural areas and in the poorest communities, where this micronutrient deficiency is one of the most prevalent risk factor for nutrientrelated diseases. This paper compiles scientific advances about the key role of the essential trace element zinc in the neurogenesis control, brain function and cognitive development. The aim of this work is to generate in health professionals, interest about the zinc deficiency effects in neuro-intellectual development and its negative impact in the cultural, economic and social development of the countries(AU)

Zinc deficiency: A global problem that affect the health and cognitive development.

The zinc deficiency affects approximately a third of the world population, principally in the developing countries, the rural areas and in the poorest communities, where this micronutrient deficiency is one of the most prevalent risk factor for nutrientrelated diseases. This paper compiles scientific advances about the key role of the essential trace element zinc in the neurogenesis control, brain function and cognitive development. The aim of this work is to generate in health professionals, interest about the zinc deficiency effects in neuro-intellectual development and its negative impact in the cultural, economic and social development of the countries.

Antígenos asociados a tumores y su potencial uso en el tratamiento del cáncer / Tumor associated antigens and its potential use in cancer therapy

De acuerdo con cifras de la Organización Mundial de la Salud (OMS) en su reporte mundial de cáncer 2008, la incidencia de esta enfermedad se duplicó en las últimas tres décadas del siglo XX, y a pesar de los importantes esfuerzos de la ciencia por combatir este flagelo y de la creación de nuevas estrategias terapéuticas, se calcula que para 2050 la mitad de la población estará en riesgo de desarrollar algún tipo de cáncer. El rápido desarrollo de la tecnología en las últimas décadas ha permitido dilucidar algunos de los mecanismos moleculares y de las interacciones de la célula tumoral con el sistema inmunológico, que conllevan finalmente al desarrollo o eliminación del tumor y en los que la estructura antigénica de este juega un papel fundamental. El descubrimiento de una gran variedad de antígenos asociados a tumores ha permitido el desarrollo de inmunoterapias que mediante el uso de anticuerpos monoclonales o de vacunas para inmunización activa se han convertido en una nueva estrategia con interesantes y alentadoras perspectivas en el tratamiento de esta enfermedad. En este artículo se describen las características básicas de algunos de estos antígenos, su influencia en el desarrollo tumoral y su actual aplicación en inmunoterapias, con el fin de generar en el lector interés y expectativas acerca de este promisorio futuro terapéutico contra el cáncer.

According to the World Health Organization data in the World Cancer Report 2008, the cancer incidence was duplicated in the last three decades of the 20th century and in spite of the important efforts of the science for attacking this scourge and of the creation of new therapeutic strategies, it is calculated that for the year 2050, the half of the population will be in risk of developing some cancer type. The rapid development of the technology in the last decades has allowed explaining some of the molecular mechanisms and the interactions of the tumor cell with the immune system, that finally produces the tumor development or elimination and on the tumor antigenic structure plays a fundamental role. The discovery of variety of tumors associated antigens has allowed the immunotherapy development with the use of monoclonal antibodies or vaccines for active immunization, these news strategies represent important trends in cancer treatment. In this paper there are described some of these antigens in its basic characteristics, influence in the tumor development and current application in immunotherapy, in order to generate in the reader expectations about this future cancer therapy.

Characterization of a novel Lactobacillus species closely related to Lactobacillus johnsonii using a combination of molecular and comparative genomics methods.

BACKGROUND: Comparative genomic hybridization (CGH) constitutes a powerful tool for identification and characterization of bacterial strains. In this study we have applied this technique for the characterization of a number of Lactobacillus strains isolated from the intestinal content of rats fed with a diet supplemented with sorbitol. RESULTS: Phylogenetic analysis based on 16S rRNA gene, recA, pheS, pyrG and tuf sequences identified five bacterial strains isolated from the intestinal content of rats as belonging to the recently described Lactobacillus taiwanensis species. DNA-DNA hybridization experiments confirmed that these five strains are distinct but closely related to Lactobacillus johnsonii and Lactobacillus gasseri. A whole genome DNA microarray designed for the probiotic L. johnsonii strain NCC533 was used for CGH analysis of L. johnsonii ATCC 33200T, L. johnsonii BL261, L. gasseri ATCC 33323T and L. taiwanensis BL263. In these experiments, the fluorescence ratio distributions obtained with L. taiwanensis and L. gasseri showed characteristic inter-species profiles. The percentage of conserved L. johnsonii NCC533 genes was about 83% in the L. johnsonii strains comparisons and decreased to 51% and 47% for L. taiwanensis and L. gasseri, respectively. These results confirmed the separate status of L. taiwanensis from L. johnsonii at the level of species, and also that L. taiwanensis is closer to L. johnsonii than L. gasseri is to L. johnsonii. CONCLUSION: Conventional taxonomic analyses and microarray-based CGH analysis have been used for the identification and characterization of the newly species L. taiwanensis. The microarray-based CGH technology has been shown as a remarkable tool for the identification and fine discrimination between phylogenetically close species, and additionally provided insight into the adaptation of the strain L. taiwanensis BL263 to its ecological niche.

Sorbitol production from lactose by engineered Lactobacillus casei deficient in sorbitol transport system and mannitol-1-phosphate dehydrogenase.

Sorbitol is a sugar alcohol largely used in the food industry as a low-calorie sweetener. We have previously described a sorbitol-producing Lactobacillus casei (strain BL232) in which the gutF gene, encoding a sorbitol-6-phosphate dehydrogenase, was expressed from the lactose operon. Here, a complete deletion of the ldh1 gene, encoding the main L-lactate dehydrogenase, was performed in strain BL232. In a resting cell system with glucose, the new strain, named BL251, accumulated sorbitol in the medium that was rapidly metabolized after glucose exhaustion. Reutilization of produced sorbitol was prevented by deleting the gutB gene of the phosphoenolpyruvate: sorbitol phosphotransferase system (PTS(Gut)) in BL251. These results showed that the PTS(Gut) did not mediate sorbitol excretion from the cells, but it was responsible for uptake and reutilization of the synthesized sorbitol. A further improvement in sorbitol production was achieved by inactivation of the mtlD gene, encoding a mannitol-1-phosphate dehydrogenase. The new strain BL300 (lac::gutF Deltaldh1 DeltagutB mtlD) showed an increase in sorbitol production whereas no mannitol synthesis was detected, avoiding thus a polyol mixture. This strain was able to convert lactose, the main sugar from milk, into sorbitol, either using a resting cell system or in growing cells under pH control. A conversion rate of 9.4% of lactose into sorbitol was obtained using an optimized fed-batch system and whey permeate, a waste product of the dairy industry, as substrate.

Regulation of Lactobacillus casei sorbitol utilization genes requires DNA-binding transcriptional activator GutR and the conserved protein GutM.

Sequence analysis of the five genes (gutRMCBA) downstream from the previously described sorbitol-6-phosphate dehydrogenase-encoding Lactobacillus casei gutF gene revealed that they constitute a sorbitol (glucitol) utilization operon. The gutRM genes encode putative regulators, while the gutCBA genes encode the EIIC, EIIBC, and EIIA proteins of a phosphoenolpyruvate-dependent sorbitol phosphotransferase system (PTS(Gut)). The gut operon is transcribed as a polycistronic gutFRMCBA messenger, the expression of which is induced by sorbitol and repressed by glucose. gutR encodes a transcriptional regulator with two PTS-regulated domains, a galactitol-specific EIIB-like domain (EIIB(Gat) domain) and a mannitol/fructose-specific EIIA-like domain (EIIA(Mtl) domain). Its inactivation abolished gut operon transcription and sorbitol uptake, indicating that it acts as a transcriptional activator. In contrast, cells carrying a gutB mutation expressed the gut operon constitutively, but they failed to transport sorbitol, indicating that EIIBC(Gut) negatively regulates GutR. A footprint analysis showed that GutR binds to a 35-bp sequence upstream from the gut promoter. A sequence comparison with the presumed promoter region of gut operons from various firmicutes revealed a GutR consensus motif that includes an inverted repeat. The regulation mechanism of the L. casei gut operon is therefore likely to be operative in other firmicutes. Finally, gutM codes for a conserved protein of unknown function present in all sequenced gut operons. A gutM mutant, the first constructed in a firmicute, showed drastically reduced gut operon expression and sorbitol uptake, indicating a regulatory role also for GutM.

Dietary supplementation with sorbitol results in selective enrichment of lactobacilli in rat intestine.

A potential prebiotic action has been ascribed to sorbitol, but in vivo evidence of this remains scarce. In the present work, the effect of sorbitol was compared to that of fructo-oligosaccharides (FOS) in a rat model. Microbiota changes, particularly in lactobacilli, were analyzed on fecal, colonic and cecal samples. Denaturing gradient gel electrophoresis (DGGE) analysis of 16S rRNA gene amplicons using universal primers showed that FOS and sorbitol diets exerted a strong influence upon gut microbiota patterns. When Lactobacillus group-specific primers were used, DGGE profiles revealed five DNA bands that belonged to Lactobacillus johnsonii, Lactobacillus sp. AD102, Lactobacillus intestinalis, Lactobacillus murinus and Lactobacillus reuteri. Although these species are present in all dietary groups, quantification by real-time PCR showed that sorbitol and FOS intake increased L. reuteri cell numbers, and sorbitol also contributed to maintaining the levels of Lactobacillus sp. AD102. Analysis of organic acid concentrations showed that sorbitol intake significantly increased colonic and cecal butyrate levels. Hence, sorbitol, which is widely used as a low-calorie sweetener, has the capacity, in our animal model, to modify gut microbiota activity in such a way as to possibly contribute to healthy colonic mucosa.