Biochemical characterization and low-resolution SAXS shape of a novel GH11 exo-1,4-β-xylanase identified in a microbial consortium

Biotechnologies that aim to produce renewable fuels, chemicals, and bioproducts from residual ligno(hemi)cellulosic biomass mostly rely on enzymatic depolymerization of plant cell walls (PCW). This process requires an arsenal of diverse enzymes, including xylanases, which synergistically act on the hemicellulose, reducing the long and complex xylan chains to oligomers and simple sugars. Thus, xylanases play a crucial role in PCW depolymerization. Until recently, the largest xylanase family, glycoside hydrolase family 11 (GH11) has been exclusively represented by endo-catalytic β-1,4- and β-1,3-xylanases. Analysis of a metatranscriptome library from a microbial lignocellulose community resulted in the identification of an unusual exo-acting GH11 β-1,4-xylanase (MetXyn11). Detailed characterization has been performed on recombinant MetXyn11 including determination of its low-resolution small angle Xray scattering (SAXS) molecular envelope in solution. Our results reveal that MetXyn11 is a monomeric globular enzyme that liberates xylobiose from heteroxylans as the only product. MetXyn11 has an optimal activity in a pH range from 6 to 9 and an optimal temperature of 50 oC. The enzyme maintained above 65% of its original activity in the pH range 5 to 6 after being incubated for 72 h at 50 oC. Addition of the enzyme to a commercial enzymatic cocktail (CelicCtec3) promoted a significant increase of enzymatic hydrolysis yields of hydrothermally pretreated sugarcane bagasse (16% after 24 h of hydrolysis)

Factors associated to breastfeeding cessation before 6 months

O objetivo da pesquisa foi identificar os fatores associados ao abandono do aleitamento materno (AM) e do aleitamento materno completo (AMC). Foram acompanhadas 248 mães que fizeram visita pós-parto. Os dados foram coletados mediante entrevista pessoal durante o primeiro mês pós-parto e, pelo telefone, aos quatro e seis meses seguintes. A análise se realizou mediante a Regressão de Cox. Os resultados mostram associação entre o abandono da AMC e do AM com o fato de não se ter amamentado anteriormente, com AM anterior ≤4 meses, e, com pior avaliação da experiência anterior. O menor nível de estudos se relaciona com maior abandono do AM e das chupetas, ou suplementos no hospital com o abandono da AMC. A educação pré-natal é fator protetor para o AMC e o AM. Conclui-se que o apoio ao AM deveria intensificar-se nas mães: sem experiência anterior, com experiência negativa, e, com pior acesso à informação; também deveria ser controlado o uso da chupeta e dos suplementos de leite artificial (LA) não indicados.El objetivo de la investigación fue identificar los factores asociados al abandono de la lactancia materna (LM) y de la lactancia materna completa (LMC). Fueron acompañadas 248 madres que acudieron a la visita posparto. Los datos fueron recolectados mediante entrevista personal durante el primer mes posparto y por teléfono a los cuatro y seis meses siguientes. El análisis se realizó mediante la Regresión de Cox. Los resultados muestran una asociación con el abandono de la LMC y de la LM con no haber amamantado anteriormente, con LM anterior ≤4 meses, y, con una peor valoración de la experiencia anterior. El menor nivel de estudios se relaciona con un mayor abandono de la LM y los chupetes o suplementos en el hospital con el abandono de la LMC. La educación prenatal es un factor protector para la LMC y la LM. Se concluye que el apoyo a la LM debería intensificarse las madres: sin experiencia anterior, con experiencia negativa, y, con peor acceso a la información; también debería controlarse el uso de chupetes y suplementos de leche artificial (LA) no indicados.This research aimed to identify the determinants of full breastfeeding (FBF) and any breastfeeding (ABF) cessation before 6 months, through a six-month follow-up of 248 mothers going a postpartum visit. Data were collected by personal interview during the first month and telephone interviews at four and six months postpartum. Cox’s proportional hazards model was used. Not having previous ABF experience, previous ABF duration ≤4 months and worse evaluation of previous experience were associated with cessation of ABF and FBF. Lower educational level was associated with cessation of ABF and the use of pacifiers or occasional breast-milk substitutes with cessation of FBF. Attending childbirth education was a protective factor against early FBF or ABF cessation. Activities supporting breastfeeding should be intensified for mothers with poorer access to information and with negative or without ABF previous experience. The use of pacifiers and not-medically indicated breast milk substitutes should be controlled