Design of a Forest Fire Early Alert System through a Deep 3D-CNN Structure and a WRF-CNN Bias Correction.

Throughout the years, wildfires have negatively impacted ecological systems and urban areas. Hence, reinforcing territorial risk management strategies against wildfires is essential. In this study, we built an early alert system (EAS) with two different Machine Learning (ML) techniques to calculate the meteorological conditions of two Colombian areas: (i) A 3D convolutional neural net capable of learning from satellite data and (ii) a convolutional network to bias-correct the Weather Research and Forecasting (WRF) model output. The results were used to quantify the daily Fire Weather Index and were coupled with the outcomes from a land cover analysis conducted through a Naïve-Bayes classifier to estimate the probability of wildfire occurrence. These results, combined with an assessment of global vulnerability in both locations, allow the construction of daily risk maps in both areas. On the other hand, a set of short-term preventive and corrective measures were suggested to public authorities to implement, after an early alert prediction of a possible future wildfire. Finally, Soil Management Practices are proposed to tackle the medium- and long-term causes of wildfire development, with the aim of reducing vulnerability and promoting soil protection. In conclusion, this paper creates an EAS for wildfires, based on novel ML techniques and risk maps.

Construcción de identidad en jóvenes infractores de ley, reflexiones a partir de dos décadas de investigaciones en el sur de Chile / Identity construction in young law offenders, reflections from two decades of research in southern Chile

En este artículo, en la modalidad de ensayo, se analiza la construcción de identidad en jóvenes infractores de ley a partir del resultado de un conjunto de investigaciones realizadas con población infanto-juvenil urbana, que vive en condiciones de pobreza en regiones del sur de Chile. Estas investigaciones desarrolladas durante más de dos décadas, primero de tipo cualitativo y luego cuantitativo, permiten identificar particularidades en el proceso de construcción de identidad, que hacen posible plantear una identidad delictiva conformada en un proceso de larga data en niños y adolescentes que viven la experiencia de desadaptación social, apreciándose diferentes trayectorias persistentes en el tiempo. En adolescentes que construyen una identidad que valida la delincuencia como forma de vida, si bien se identifican factores de riesgos en diversos planos, similares a los que la literatura destaca, en la realidad estudiada aparecen importantes condiciones contextuales (dinámica familiar, condiciones barriales, experiencias escolares y con programas de intervención, etc.) que desempeñan un papel de relevancia que valida y refuerza esa identidad.

Cumplimiento de derechos infantiles en Chile: evaluación de profesionales de programas públicos / The fulfilment of children's rights in Chile: Evaluation of public program staff / Conformidade com os direitos da criança no Chile: Avaliação de profissionais de programas públicos

Resumen (analítico) Ante la escasez de evidencia, el objetivo general de este estudio fue describir y aplicar un instrumento propuesto para medir los derechos infantiles en Chile, desde el ejercicio cotidiano de operadores sociales que trabajan con infancia y adolescencia en centros educacionales, de salud, justicia o de desarrollo psicosocial. La muestra estuvo compuesta por 407 participantes (profesores, psicólogos, entre otros). El instrumento considera los cuatro principios fundamentales de la Convención de Derechos del Niño: no discriminación, interés superior, derecho a la vida, desarrollo, supervivencia y participación. Los resultados preliminares sugieren que existen diferencias estadísticamente significativas en el grado de cumplimiento de los derechos según el ámbito de desempeño. Se discute la consistencia in-terna del instrumento y su adaptación según ámbito, población atendida y aplicación en población infantil general y específica.

Abstract (analytical) Given the lack of evidence in this area, the general objective of this study was to describe and apply an instrument designed to measure children's rights in Chile based on the day to day practices of social operators who work with children and adolescents, in educational, health, justice and psychosocial development centers. The sample consisted of 407 participants (including teachers and psychologists). The instrument takes into account the four fundamental principles of the Convention on the Rights of the Child: non-discrimination; the best interest of the child; the right to life, development and survival; and the right to be heard. The preliminary results suggest that there are statistically significant differences in the degree of fulfillment of rights in relation to each fundamental principle. The internal consistency of the instrument, its adaptation to measure the fulfillment of each principle and the population that receive assistance are discussed, as well as application of the instrument with general and specific child populations.

Resumo (analítico) Dada a falta de evidências, o objetivo geral deste estudo foi descrever e aplicar um instrumento proposto para medir os direitos da criança no Chile, a partir da prática diária de operadores sociais que trabalham com crianças e adolescentes, em centros educacionais, de saúde, justiça ou desenvolvimento psicossocial. A amostra foi composta por 407 participantes (professores, psicólogos, entre outros). O instrumento considera os quatro princípios fundamentais da Convenção sobre os Direitos da Criança: Não discriminação; Interesse superior; Direito à vida, à sobrevivência e ao desenvolvimento; Participação. Os resultados preliminares sugerem que existem diferenças estatisticamente significativas no grau de cumprimento dos direitos de acordo com o âmbito de desempenho. Além disso, o trabalho discute a consistência interna do instrumento e sua adaptação segundo o campo, população atendida e aplicação em população infantil geral e específica.

Caracterización psicosocial y criminológica de adolescentes chilenos con prácticas abusivas sexuales / Psychosocial and criminological characterization of Chilean adolescents with sexually abusive behavior / Caracterização psicossocial e criminológica de adolescentes chilenos com comportamentos sexuais abusivos

Resumen (analítico) El objetivo de este estudio fue caracterizar las variables psicosociales y criminológicas asociadas a los adolescentes que desarrollan prácticas abusivas sexuales (PAS), en función de la edad de las víctimas. Mediante un diseño no experimental y transversal, con características descriptivas y correlacionales, se analizan antecedentes psicosociales y criminológicos de 232 adolescentes varones que han realizado PAS. Los resultados indican diferencias estadísticas significativas entre los adolescentes que cometen PAS contra víctimas menores, en contraste con quienes abusan de víctimas pares, tanto en las variables psicosociales (trayectoria escolar e historial de victimizaciones) como en las variables criminológicas (contexto de la práctica abusiva sexual y relación adolescente-víctima). Finalmente, se discuten los resultados en relación con la evidencia internacional y las implicaciones de la generación de conocimientos sobre la temática.

Abstract (analytical) The aim of this study is to characterize the psychosocial and criminological variables associated with adolescents who develop sexually abusive behavior, depending on the age of the victims. Psychosocial and criminological data were collected from 232 male adolescents who have demonstrated sexually abusive behavior. This data was analyzed using a non-experimental, cross-sectional design with descriptive and correlational characteristics. The results indicate statistically significant differences between adolescents who offended against a child victim versus adolescents who offended against a peer-aged victim, both in psychosocial variables (school history and history of victimization) and criminological variables (context of sexually abusive behavior and adolescent-victim relationship). The results are discussed in relation to international evidence and the implications of generating knowledge in this area.

Resumo (analítico) O objetivo deste estudo foi caracterizar as variáveis psicossociais e criminológicas associadas a adolescentes que desenvolvem comportamentos sexuais abusivos, dependendo da idade das vítimas. A partir de um delineamento transversal não experimental com características descritivas e correlacionais, foi analisado o histórico psicossocial e criminológico de 232 adolescentes do sexo masculino que praticaram comportamento sexual abusivo. Os resultados indicam diferenças estatísticas significativas entre os adolescentes que cometem abuso sexual contra menores e os que cometem contra vítimas de idade semelhante, tanto em variáveis psicossociais (histórico escolar e histórico de vitimizações) quanto em variáveis criminológicas (contexto de comportamento sexual abusivo e relacionamento adolescente-vítima). Por fim, os resultados são discutidos em relação às evidências internacionais e as implicações da geração de conhecimentos na área.

The effect of sewage sludge containing microplastics on growth and fruit development of tomato plants.

Microplastics (MPs) are becoming an environmental growing concern, being the sewage sludge applied to agriculture fields one of the most important inputs to the environment. To date, there is no standardized protocol for their extraction and changes in vegetative growth and fruit maturation on cultivated plants induced by sludge containing MPs have not been studied yet. Sewage sludge from three different wastewater treatment plants located in Murcia, Spain, were studied. First, the microplastic concentration was estimated and, then, the effects of the sewage sludge in the development of tomato plants and fruit production was analyzed. The measured parameters in tomato plants were both, biomass and length, for shoot and root part, as well as, stem diameter and tomato production. The present work has developed and validated a protocol for the extraction and quantification of MPs comprising several shapes, materials and sizes from samples of sewage sludges, which offers a good compromise for the extraction of different types of microplastic. The protocol used for MPs extraction had a recovery efficiency of 80 ± 3% (mean ± SE) and used bicarbonate, to maximize MPs extraction. The mean abundance of MPs in the studied sewage sludge samples was 30,940 ± 8589 particles kg-1 dry weight. Soils with sludge containing MPs fostered the growth of tomato plants, while delaying and diminished fruit production. However, other factors or their interactions with MPs could have influenced the outcomes. Further studies are necessary to corroborate these findings and explain the mechanisms of possible effects of MPs on plants.

Desistimiento delictual en mujeres chilenas que han estado privadas de libertad / Criminal desistance in Chilean women who have been deprived of liberty / Criminal desistance in Chilean women who have been deprived of liberty / Desistência criminal em mulheres chilenas que têm ficadoprivadas de liberdade

Resumen Diversas investigaciones han estudiado el fenómeno del desistimiento delictual en mujeres, evidenciando factores característicos para esta población. El objetivo de este estudio fue explorar un modelo predictivo del desistimiento delictual femenino, a partir de factores psicosociales, autoeficacia, apoyo social percibido y etapa de motivación al cambio. Se trabajó con un grupo de 50 mujeres que habían sido condenadas a penas privativas de libertad en Santiago, Chile. Todas participaron de entrevistas semiestructuradas y dieron respuesta a cuestionarios de autoinforme, creando una base de datos de caracterización del proceso delictual, identificando factores específicos que permitieron crear un índice de desistimiento femenino. Mediante regresión lineal múltiple se buscó determinar las variables predictoras, encontrándose dos perfiles con diferentes probabilidades de desistir en el delito; asimismo, las etapas de acción y mantenimiento explican un 25.4% el desistimiento, mostrando la relevancia de la voluntad y la capacidad de agencia en el proceso de cambio de las mujeres que han infringido la ley. Esto permite proponer la incorporación del enfoque motivacional en las intervenciones con mujeres que han estado recluidas y seguir profundizando en los perfiles encontrados.

Abstract Diverse investigations have studied the phenomenon of criminal desistance in women, evincing characteristic factors for this population. The objective of this study was to explore a predictive model of the female criminal desistance from psychosocial factors, self-efficacy, perceived social support and stage of motivation to change. One worked with a group of 50 women who had been sentenced to deprivation of liberty punishments in Santiago, Chile. All of them participated in semi-structured interviews and gave answer to self-report questionnaires, creating a database of characterization of the criminal process, identifying specific factors that permitted create a female desistance index. By means of multiple linear regression the aim was to determine the predictor variables, finding two profiles with different probabilities of desistance from the crime; likewise, the stages of action and maintenance explain a 25.4% of the desistance, showing the relevance of the will and the capacity of agency in the change process of the women who have infringed the law. This permits to propose the incorporation of the motivational approach in the interventions with women who have been detained and to further deepen in the found profiles.

Abstract Diverse investigations have studied the phenomenon of criminal desistance in women, evincing characteristic factors for this population. The objective of this study was to explore a predictive model of the female criminal desistance from the psychosocial factors, self-efficacy, perceived social support and stage of motivation to change. Work was done with a group of 50 women who had been sentenced to deprivation of liberty punishments in Santiago, Chile. All of them participated in semi-structured interviews and gave an answer to self-report questionnaires, creating a database of characterization of the criminal process, identifying specific factors that permitted create a female desistance index. By means of multiple linear regression the aim was to determine the predictor variables, finding two profiles with different probabilities of desistance from the crime; likewise, the stages of action and maintenance explain a 25.4% of the desistance, showing the relevance of the will and the capacity of agency in the change process of the women who have infringed the law. This permits to propose the incorporation of the motivational approach in the interventions with women who have been detained and to further deepen in the found profiles.

Resumo Diversas investigações têm estudado o fenómeno da desistência do crime em mulheres, evidenciando fatores característicos para esta população. O objetivo deste estudo foi explorar um modelo preditivo da desistência criminal feminina, a partir de fatores psicossociais, autoeficácia, apoio social percebido e etapa de motivação à mudança. Trabalhou-se com um grupo de 50 mulheres que têm sido condenadas a penas privativas de liberdade em Santiago, Chile. Todas participaram de entrevistas semiestruturadas e deram resposta a questionários de auto-relatório, criando uma base de dados de caracterização do processo delitivo, identificando fatores específicos que permitiram criar um índice de desistência criminal feminina. Através de regressão linear múltipla buscou-se determinar as variáveis preditoras, encontrando-se dois perfis com diferentes probabilidades de desistir no crime; do mesmo modo, as etapas de ação e manutenção explicam um 25.4% a desistência, mostrando a relevância da vontade e a capacidade de agência no proceso de mudança das mulheres que têm infringido a lei. Isto permite propor a incorporação do enfoque motivacional nas intervenções com mulheres que têm ficado recluídas e seguir aprofundando nos perfis encontrados.

Identidad étnica y conductas sociales en adolescentes indígenas mapuche sancionados por la Ley de Responsabilidad Penal Adolescente en regiones del sur de Chile / Ethnic Identity and Social Behaviors in Indigenous Juvenile Offenders Sentenced by the Law in the South of Chile

RESUMEN Se analiza la relación entre identidad étnica y conductas sociales en 60 adolescentes indígenas infractores de ley autoidentificados como mapuche. La identidad étnica se obtiene con la Escala IEM; conductas sociales, con CACSA; delitos autorreportados, con EDA y judicializados, con Ficha FER-R. El objetivo fue evaluar la asociación entre grado de desarrollo de identidad étnica con presencia de conductas antisociales y prosociales. Los resultados indican que a mayor desarrollo de identidad étnica menor presencia de conductas antisociales, no observándose relación entre identidad étnica y conductas prosociales. Se discute la relevancia de la identidad étnica como factor protector específico en adolescentes infractores mapuche y en adolescentes de otros pueblos indígenas en general, convirtiéndose en posible foco de intervención para desestimar estas conductas.

ABSTRACT We examined the relationship between ethnic identity and social behaviors in 60 indigenous juvenile offenders self-identified as mapuche. Ethnic identity is obtained with IEM scale, social behaviors with CACSA, self-reported and sentenced offenses with EDA and FER-R. The objective was to evaluate the association between the degree of ethnic identity development with presence of antisocial and prosocial behavior. The results indicate that ethnic identity development was related to lesser presence of antisocial behaviors, though no relationship between ethnic identity and prosocial behaviors. The possible relevance of ethnic identity as a protective factor in mapuche youth offenders in specific and in general to adolescents of other indigenous people, becoming a possible focus of intervention to dismiss these behaviors is discussed.

Instrumentos para la valoración del riesgo de violencia sexual en ofensores sexuales adolescentes: evidencias de validez en países de América Latina / Instruments for the appreciation of the sexual violence risk in adolescent sexual offenders: validity evidences in Latin American countries / Instrumentos para o valoração do risco da violência sexual em ofensores sexuais adolescentes: evidências da validez nos países de América Latina

Este artículo de revisión tiene por objeto conocer la evidencia de validez disponible, en América Latina, de los principales instrumentos en el ámbito internacional para la valoración del riesgo de reincidencia sexual en ofensores sexuales adolescentes. Para ello se realizó una revisión bibliográfica descriptiva, en la que se utilizaron palabras claves afines con la materia analizada, a través de las bases de datos ISI Web of Science y Scopus y del metabuscador Google Scholar. Los resultados destacan como países principales en la creación de este tipo de herramientas a Canadá y Estados Unidos, con herramientas como J-SOAP-II, ERASOR 2.0, JSORRAT-II, JRAT, MEGA y DASH-13. Asimismo, se constata escasez de investigaciones que exploren las propiedades psicométricas de estos instrumentos en Latinoamérica, y carencia de indicios en torno a la construcción de instrumentos de valoración del riesgo de violencia sexual dentro de dicha zona geográfica. Se discuten las implicancias de estos efectos para la evaluación e intervención en ofensores sexuales adolescentes, y se reconocen las dificultades relativas a la sobreutilización del procedimiento de juicio clínico en la valoración del riesgo y/o el uso de herramientas carentes de evidencias de validez para esta población

The objective of this review article consist of getting to know the validity evidence available in Latin America of the main instruments existing in the international sphere for the appreciation of the sexual recidivism risk in adolescent sexual offenders. For this purpose, a descriptive bibliographical review was carried out where similar or associated key words were used with the matter being analyzed, through the ISI Web of Science and Scopus databases and the Google Scholar metasearch. The results point at Canada and the United States as the major countries in the creation of this type of mechanisms, with tools such as J-SOAP-II, ERASOR 2.0, JSORRAT-II, J-RAT, MEGA and DASH-13. Likewise, a scarcity of researches serving to explore the psychometric properties of these instruments in Latin America and the lack of signs around the construction of those serving for the assessment of sexual violence within this geographical zone. The implications of these effects for evaluation and intervention in adolescent sexual offenders are discussed and the difficulties relating to the overutilization of clinical judgment in risk assessment and/or the use of tools deprived of validity for this population are duly acknowledged

Este artigo de revisão pretende conhecer a evidência da validez disponível, em América Latina, dos instrumentos principais no âmbito internacional para a valoração do risco de reincidência sexual em ofensores sexuais adolescentes. Para isso uma revisão bibliográfica descritiva foi feita, e palavras chaves compatíveis com a matéria analisada foram usadas, através dos bancos de dados ISI Web of Science e Scopus e do metabuscador Google Scholar. Os resultados destacam, como países principais na criação deste tipo de mecanismos, a Canadá e Estados Unidos, com ferramentas como J-SOAP-II, ERASOR 2.0, JSORRAT-II, J-RAT, MEGA e DASH-13. Também, constatase a falta de pesquisas que exploram as propriedades psicométricas destes instrumentos em América Latina, e a carência de indício em torno da construção daqueles de valoração do risco da violência sexual dentro desta zona geográfica. Discutem-se as implicâncias destes efeitos para a avaliação e a intervenção em ofensores sexuais adolescentes, e as dificuldades relativas ao uso excessivo do procedimento julgamento clínico reconhecido na valoração do risco e/ou o uso de ferramentas carentes das certezas da validez para esta população

Validez y confiabilidad de una prueba para evaluar comportamientos lingüísticos en población con discapacidad cognitiva / Validity and reliability of a test to assess linguistic behaviour in population with cognitive disabilities

El lenguaje se constituye en una variable importante en el desarrollo de la habilidad comunicativa de todo ser humano; su desarrollo depende, entre otros aspectos, de las oportunidades dadas por el contexto. Dentro de estas oportunidades, se encuentran los servicios de fonoaudiología, en donde los procesos de intervención se derivan de una evaluación. Dicho proceso evaluativo en la población con discapacidad cognitiva presenta limitaciones por la falta de pruebas objetivas, válidas y confiables que permitan determinar las características de su situación comunicativa. El objetivo de esta investigación fue establecer la validez (de contenido y constructo) y la confiabilidad de una prueba para evaluar comportamientos lingüísticos en población con discapacidad cognitiva de la ciudad de Medellín. Para ello se utilizó un método analítico inferencial relacionado con la validación de instrumentos de medición; la validez de contenido se realizó por juicio de expertos; participaron 13 fonoaudiólogos con experiencia en la atención a la población objeto, quienes evaluaron la prueba bajo los criterios de pertinencia y suficiencia. Para establecer la validez de constructo confirmatorio se utilizó el análisis factorial y se determinó la confiabilidad del instrumento a partir de la consistencia interna de constructo y la prueba test-retest; participaron 75 usuarios. Los resultados del presente estudio avalan la consistencia interna y la estabilidad de la prueba, su validez de contenido y de constructo (AU)

Language is an important variable in the development of the communication skill of every human being; their development depends among other things of the opportunities given by the context. Among these opportunities are the services of phonoaudiology, where the intervention processes are derived from an assessment. This evaluative process in people with cognitive disabilities presents limitations due to the lack of objective, valid and reliable evidence for our context, that allow us to determine the characteristics of their communicative situation. The goal of this research was to establish the validity (in content and construct terms) and the reliability of a test to assess linguistic behaviours in people with cognitive disabilities in the city of Medellin. For this purpose an analytical inferential method was used, related to the validation of measuring instruments: content validity was performed by expert judgment, in which 13 phonoaudiologists participated with experience in care of target population, who assessed the test under the criteria of relevance and adequacy. To establish the validity of confirmatory construct, a factorial analysis was used and the instrument's reliability was determined from the internal consistency of the construct and the test - re test method, applied in 75 users. The results of this study show the internal consistency and stability of the test, as well as content and construct validity (AU)

Biogenic amines in Zamorano cheese: factors involved in their accumulation.

BACKGROUND: Ripened cheese is among fermented food the most often associated with food poisoning from biogenic amines. The influence of ripening time, heat treatment of milk and the effect of using milk from a different ewe breed on the biogenic amine (BA) content of Zamorano cheese was studied by high-performance liquid chromatography. Physicochemical, proteolytic and microbiological parameters were also studied. RESULTS: BA content increased significantly during ripening and their final values were around 400 mg kg(-1). Cheeses elaborated with raw milk duplicated the concentration of BA relative to those elaborated with pasteurized milk (72 °C for 20 s). The average levels of putrescine, spermine and tyramine were higher in cheeses made with a greater proportion of milk from Churra breed. Significant differences in microbial counts and nitrogen soluble in 5% phosphotungstic acid were observed between the different batches. CONCLUSION: Ripening time and heat treatment applied to milk were the factors that exercised the greatest influence upon the concentration of BA in Zamorano cheese.

Compositional and biochemical changes in Genestoso cheese, a Spanish raw cow's milk variety, during ripening.

BACKGROUND: Physicochemical characteristics, proteolysis and lipolysis were studied throughout the ripening of eight batches of a traditional Spanish variety made from raw cow's milk, in order to establish a basis for its industrial production. RESULTS: The main compositional characteristics of this cheese after 60 days of ripening were its high proportion of total solids (TS; 752 g kg⁻¹ of cheese), an average content of protein (452.8 g kg⁻¹ TS) and fat (475.1 g kg⁻¹ TS) and the presence of residual lactose (12.5 g kg⁻¹ TS). Its pH value (4.04) was extremely low. Phosphorus (5.13 g kg⁻¹ TS) and sodium (8.29 g kg⁻¹ TS) were the most abundant mineral elements in cheese, whereas calcium levels (1.92 g kg⁻¹ TS) were very low. Proteolysis extension and depth were very low, which resulted in almost zero degradation of αs1- and ß-casein. Fat acidity increased during ripening, reaching final values of 50.1 mg KOH kg⁻¹ of fat. The main free fatty acid was C16:0, followed by C18:1 and C14:0. CONCLUSION: These results suggest that this variety undergoes a limited proteolysis and moderate lipolysis during ripening. The low pH, low calcium content and limited proteolysis led to a crumbly texture in this cheese variety.

Detección y descripción de rasgos psicopáticos en adolescentes utilizando el MACI / Screening and describing psychopathic traits in adolescents using the MACI

Este estudio reporta las características psicométricas de las dos escalas de Psicopatía del MACI y evalúa su utilidad para pesquisar y describir a adolescentes con alta psicopatía. Cuatro grupos representantes del continuo adaptación-desadaptación social respondieron el MACI y un autorreporte de comportamiento social adolescente. El análisis factorial de las escalas determinó estructuras de dos y tres factores, respectivamente, que son respaldadas por los modelos de psicopatía de Hare y de Cookie y Michie. Un algoritmo desarrollado con las puntuaciones de estas escalas identificó y permitió caracterizar un grupo de 49 jóvenes (11.2 % de la muestra) con alta psicopatía. Se discuten las características psicométricas y la utilidad de estas escalas para identificar a adolescentes con perfiles psicopáticos.

This study reports psychometric characteristics for two Psychopathy scales developed with the MACI and assess their utility for screening and describing high psychopathic adolescents. Four groups representing the social adjustment and maladjustment continue answered the MACI and a self report about adolescent social behaviour. A factorial analysis of the psychopathy scales determined structures formed by two and three factors which are supported by the models of psychopathy presented by Hare and by Cookie and Michie. An algorithm developed with these scales-scores identified and allowed to characterize a group of 49 adolescents (11.2 % of the sample) with high psychopathy. Psychometric characteristics and the utility of these two scales for identifying adolescents with psychopathic profiles are discussed.

Enzymatic activity of lactic acid bacteria (with antimicrobial properties) isolated from a traditional Spanish cheese.

Twenty-four strains of lactic acid bacteria (LAB) isolated from a traditional Spanish cheese (Genestoso cheese) were evaluated for their enzymatic activities (acidifying and proteolytic abilities and carboxypeptidase, aminopeptidase, dipeptidase, caseinolytic and esterase activities), in order to select indigenous strains of technical interest for the manufacture of cheese. These strains were selected on the basis of their antimicrobial activity relative to five reference strains and were identified as Lactococcus lactis subsp. lactis (thirteen strains), Leuconostoc mesenteroides (two strains), Leuconostoc pseudomesenteroides (one strain), Lactobacillus paracasei (two strains), Lactobacillus plantarum (one strain) and Enterococcus faecalis (five strains). Lactococcus strains were those that showed the greatest degree of acidifying and proteolytic activity. The cell-free extracts (CFE) of L. paracasei exhibited the highest level of aminopeptidase activity. The highest level of caseinolytic activity was shown by the CFE of one strain of L. lactis. High values were also obtained with the CFE of Lactobacillus and of several Leuconostoc. The highest level of dipeptidase activity was found amongst the strains of L. lactis. Carboxypeptidase activity was generally very low or undetectable for the majority of strains. The greatest degree of esterolytic activity was detected for Enterococcus.

Modifications in membrane fatty acid composition of Salmonella typhimurium in response to growth conditions and their effect on heat resistance.

The effects of growth temperature (in the range 10-45 degrees C) and acidification up to pH 4.5 of the culture medium (Brain Heart Infusion, BHI) with different organic acids (acetic, citric and lactic) and hydrochloric acid on membrane fatty acid composition and heat resistance of Salmonella typhimurium CECT 443 were studied. The heat resistance was maximal in cells grown at 45 degrees C (cells grown in non-acidified BHI showed a D58-value of 0.90 min) and decreased with decreasing growth temperature up to 10 degrees C (D58-value of 0.09 min). The growth of cells in acidified media caused an increase in their heat resistance. In general, acid adapted cells showed D-values of between 1.5 and 2 times higher than the corresponding for non-acid adapted control cells. This cross-protection response, which has important implications in food processing, was not dependent on the pH value and the acid used to acidify the growth medium. A membrane adaptation corresponding to an increase in the unsaturated to saturated fatty acids ratio (UFA/SFA) and membrane fluidity was observed at low growth temperature. Moreover, the acidification of the growth medium caused a decrease in UFA/SFA ratio and in the C18:1 relative concentration, and an increase in cyclopropane fatty acids (CFA) content mainly due to the increase in cyc19 relative concentration. Thus, acid adapted cells showed CFA levels 1.5 times higher than non-acid adapted control cells. A significant proportion of unsaturated fatty acids were converted to their cyclopropane derivatives during acid adaptation. These changes in membrane fatty acid composition result in cells with decreased membrane fluidity. A clear relation between membrane fatty acid composition and heat resistance was observed. In general, D-values were maximum for cells with low UFA/SFA ratio, and, consequently, with low membrane fluidity. Moreover, CFA formation played a major role in protecting acid adapted cells from heat inactivation. However, changes observed in membrane fatty acid composition are not enough to explain the great thermotolerance of cells grown at 45 degrees C. Thus, other mechanisms, such as the synthesis of Heat Shock Proteins, could be responsible for this increase in the bacterial heat resistance.