Bacteriophage induction versus vaginal homeostasis: Role of H2O2 in the selection of Lactobacillus defective prophages

Vaginal disorders associated with systemic chemotherapy arise by direct inhibition of the resident microbiota (dominated by lactobacilli) or, possibly, by induction of prophages harbored in their genomes, leading to cell lysis. In the present study, proficient Lactobacillus phages could not be isolated from vaginal exudates. However, lysogeny appeared to be widespread, although about half of the strains harbored prophage sequences that were not responsive to SOS activation. In other cases, prophage induction was achieved, but viable phages were not generated, despite the fact that the induced supernatants of some strains were bactericidal. In one case, this activity was accompanied by the production of a bacteriophage subsequently identified as a member of the family Siphoviridae (isometric capsid and long non-contractile tail). Most of the lactobacilli tested generated hydrogen peroxide, which acted as an inducer of the SOS response, suggesting that H2O2 selects for strains that harbor SOS-insensitive, defective prophages, which are thus unable to promote vaginal lactobacilli phage-induced lysis

Chemostat Production of Plantaricin C By Lactobacillus plantarum LL441

Plantaricin C, a bacteriocin synthesized by Lactobacillus plantarum LL441, was optimally produced in chemostats kept at pH 5.0, 30°C, 150 rpm, and a dilution rate of 0.05 h1 when glucose was used as carbon source and a dilution rate of 0.10 to 0.12 h1 when sucrose or fructose was used instead. Production was abolished at high dilution rates, i.e., when the cells grew rapidly in all carbon sourcesThis work was supported by grants ALI93-0873-CO2 and BIOT-CT96-0402 from the Comisión Interministerial de Ciencia y Tecnología of Spain and the BIOTECH Program of the European Union, respectively. F.S. was the recipient of a visitor's grant from the University of Oviedo.Peer reviewe

Resultados de una encuesta sobre el soporte nutricional perioperatorio en la cirugía pancreática y biliar en España

Introduction: a survey on peri-operative nutritional support in pancreatic and biliary surgery among Spanish hospitals in 2007 showed that few surgical groups followed the 2006 ESPEN guidelines. Ten years later we sent a questionnaire to check the current situation. Methods: a questionnaire with 21 items sent to 38 centers, related to fasting time before and after surgery, nutritional screening use and type, time and type of peri-operative nutritional support, and number of procedures. Results: thirty-four institutions responded. The median number of pancreatic resections (head/total) was 29.5 (95% CI: 23.0-35; range, 5-68) (total, 1002); of surgeries for biliary malignancies (non-pancreatic), 9.8 (95% CI: 7.3-12.4; range, 2-30); and of main biliary resections for benign conditions, 10.4 (95% CI: 7.6-13.3; range, 2-33). Before surgery, only 41.2% of the sites used nutritional support (&lt; 50% used any nutritional screening procedure). The mean duration of preoperative fasting for solid foods was 9.3 h (range, 6-24 h); it was 6.6 h for liquids (range, 2-12). Following pancreatic surgery, 29.4% tried to use early oral feeding, but 88.2% of the surveyed teams used some nutritional support; 26.5% of respondents used TPN in 100% of cases. Different percentages of TPN and EN were used in the other centers. In malignant biliary surgery, 22.6% used TPN always, and EN in 19.3% of cases. Conclusions: TPN is the commonest nutrition approach after pancreatic head surgery. Only 29.4% of the units used early oral feeding, and 32.3% used EN; 22.6% used TPN regularly after surgery for malignant biliary tumours. The 2006 ESPEN guideline recommendations are not regularly followed 12 years after their publication in our country.Introducción: realizamos una encuesta sobre soporte nutricional perioperatorio en cirugía pancreática y biliar en hospitales españoles en 2007, que mostró que pocos grupos quirúrgicos seguían las guías de ESPEN 2006. Diez años después enviamos un cuestionario para comprobar la situación actual. Métodos: treinta y ocho centros recibieron un cuestionario con 21 preguntas sobre tiempo de ayunas antes y después de la cirugía, cribado nutricional, duración y tipo de soporte nutricional perioperatorio, y número de procedimientos. Resultados: respondieron 34 grupos. La mediana de pancreatectomías (cabeza/total) fue de 29,5 (IC 95 %: 23,0-35; rango, 5-68) (total, 1002), la de cirugías biliares malignas de 9,8 (IC 95 %: 7,3-12,4; rango, 2-30) y la de resecciones biliares por patología benigna de 10,4 (IC 95 %: 7,6-13,3; rango, 2-33). Solo el 41,2 % de los grupos utilizaban soporte nutricional antes de la cirugía (< 50 % habian efectuado un cribado nutricional). El tiempo medio de ayuno preoperatorio para sólidos fue de 9,3 h (rango, 6-24 h), y de 6,6 h para líquidos (rango, 2-12). Tras la pancreatectomía, el 29,4 % habían intentado administrar una dieta oral precoz, pero el 88,2 % de los grupos usaron algún tipo de soporte nutricional y el 26,5 % usaron NP en el 100 % de los casos. Los demás grupos usaron diferentes porcentajes de NP y NE en sus casos. En la cirugía biliar maligna, el 22,6 % utilizaron NP siempre y NE en el 19,3 % de los casos. Conclusiones: la NP es el soporte nutricional más utilizado tras la cirugía de cabeza pancreática. Solo el 29,4 % de las unidades usan nutrición oral precoz y el 32,3 % emplean la NE tras este tipo de cirugía. El 22,6 % de las instituciones usan NP habitualmente tras la cirugía de tumores biliares malignos. Las guías ESPEN 2006 no se siguen de forma habitual en nuestro país tras más de 10 años desde su publicación

Mecanismos de acción de los probióticos

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Prophage induction in Lactococcus lactis by the bacteriocin Lactococcin 972

Lactococcin 972 (Lcn972) is a non-pore forming bacteriocin with a narrow spectrum of activity restricted to Lactococcus. Lcn972 inhibits the incorporation of cell wall precursors in the septum area, thereby inhibiting cell division. In this work, an additional inhibitory effect is described, namely, the induction of the lytic cycle of resident prophages in the lysogenic strain L. lactis IPLA 513. Lcn972 triggered the release of prophages in a concentration-dependent fashion. The extent of prophage induction was influenced by the physiological status of the cultures, being maximal at the early exponential growth phase. A microtiter based protocol was designed and the induction ability of several antimicrobials was compared. Prophages were activated by all cell wall biosynthesis inhibitors tested, although the levels of induction were lower than those obtained after activation of the SOS response. As far as we know, this is the first report of prophage induction by an antimicrobial peptide. Since Lcn972 is active against L. lactis strains currently used in commercial starters, promising applications for dairy fermentations are discussed. © 2008 Elsevier B.V. All rights reserved.This work has been funded by grants BIO2004-04312 and BIO2007-65061 from the Spanish Ministerio de Ciencia e Innovación and COF-0421 from FICYT (Gobierno Regional de Asturias).Peer Reviewe

A new contribution to the history of probiotics

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