Antibacterial efficacy of Enterococcus microencapsulated bacteriocin on Listeria monocytogenes, Listeria innocua and Listeria ivanovi

This study focused on the microencapsulation of enterocin from Enterococcus durans (E. durans MF5) in whey powder (WP) using a spray-drying technique followed by the evaluation of how complexation can preserve the enterocin structure and antimicrobial activity against foodborne pathogens. Crude enterocin samples (1 and 5%) were microencapsulated in 10% WP. The antimicrobial activity of unencapsulated (crude) enterocin and microencapsulated enterocin was tested against the target bacteria Salmonella Typhimurium, Escherichia coli, Listeria monocytogenes, Listeria innocua, and Listeria ivanovi. The microencapsulation yields were 31.66% and 34.16% for concentrations of 1 and 5% enterocin, respectively. There was no significant difference between these concentrations. Microencapsulated enterocin was efficient for up to 12 h of cocultivation with Listeria sp., and the concentration required to inhibit the growth of target bacteria presented values of 6400 AU/ mL (arbitrary unit). Microencapsulated enterocin demonstrated enhanced efficacy against Listeria species and E. coli when compared with crude enterocin (p < 0.05). Fourier transform-infrared spectroscopy and differential scanning calorimetry results confirmed the presence of enterocin in the microparticles. Scanning electron microscopy showed cell damage of the target bacteria. The results showed that complexation with WP preserved enterocin antimicrobial activity during spray-drying, indicating its potential use as a food preservative.This work was supported by Fundação Araucária/Governo do Paraná—Brazil, UTFPR-Londrina Campus and State University of Londrina-Paraná. The authors thank the “Central Analítica Multiusuário da UTFPR Campo Mourão (CAMulti-CM)¨ and “Laboratório Multiusuário da UTFPR Campus Londrina (LabMulti-LD)¨ for the analyses. Fernanda V. Leimann (process 039/2019) thanks to Fundação Araucária (CP 15/2017- Programa de Bolsas de Produtividade em Pesquisa e Desenvolvimento Tecnológico) and to CNPq (process number 421541/2018-0, Chamada Universal MCTIC/CNPq n.° 28/2018).info:eu-repo/semantics/publishedVersio

Identificação molecular de Aspergillus spp. isolados de grãos de café

Algumas espécies pertencentes ao gênero Aspergillus possuem potencial para produção de Ocratoxina A (OA), uma micotoxina de efeitos nefrotóxicos, imunossupressivos, teratogênicos e carcinogênicos. Com o objetivo de identificar as espécies de Aspergillus que contaminam o interior de grãos de café, foram coletadas amostras em diferentes estádios de maturação do produto, em 16 propriedades produtoras do norte do estado do Paraná. Um total de 108 isolados de Aspergillus spp. foram identificados ao nível de espécie, pelo sequenciamento dos espaços internos transcritos (ITS1-5,8S-ITS2) do DNA ribossomal (rDNA). Os resultados revelaram a presença de espécies potencialmente ocratoxigênicas em 82% das regiões analisadas, sendo dentre estas, Aspergillus niger a espécie mais freqüentemente detectada,seguida por A. ochraceus, e A. carbonarius. É relatada pela primeira vez a presença de A. carbonarius em frutos de café coletados na árvore.Some species belonging to the genus Aspergillus are potential producers of ochratoxin A (OA), a mycotoxin with nephrotoxic, immunosuppressive, teratogenic and carcinogenic effects. The aim of the present study was to identify the species of Aspergillus that contaminate the inside of coffee beans collected in the stage of maturation and drying, from 16 producing areas located in the northern region of the State of Paraná, in the South of Brazil. A total of 108 isolates of Aspergillus spp. was identified at the species level, by sequencing the internal transcribed spacer (ITS1-5.8S-ITS2) of ribosomal DNA (rDNA). The results revealed the presence of potentially ochratoxigenic species in 82% of the geographic regions studied, among which Aspergillus niger was the species most frequently detected, followed by A. ochraceus and A. carbonarius. The presence of A. carbonarius in immature coffee fruits harvested from trees is reported for the first time

Genome of Herbaspirillum seropedicae Strain SmR1, a Specialized Diazotrophic Endophyte of Tropical Grasses

The molecular mechanisms of plant recognition, colonization, and nutrient exchange between diazotrophic endophytes and plants are scarcely known. Herbaspirillum seropedicae is an endophytic bacterium capable of colonizing intercellular spaces of grasses such as rice and sugar cane. The genome of H. seropedicae strain SmR1 was sequenced and annotated by The Paraná State Genome Programme—GENOPAR. The genome is composed of a circular chromosome of 5,513,887 bp and contains a total of 4,804 genes. The genome sequence revealed that H. seropedicae is a highly versatile microorganism with capacity to metabolize a wide range of carbon and nitrogen sources and with possession of four distinct terminal oxidases. The genome contains a multitude of protein secretion systems, including type I, type II, type III, type V, and type VI secretion systems, and type IV pili, suggesting a high potential to interact with host plants. H. seropedicae is able to synthesize indole acetic acid as reflected by the four IAA biosynthetic pathways present. A gene coding for ACC deaminase, which may be involved in modulating the associated plant ethylene-signaling pathway, is also present. Genes for hemagglutinins/hemolysins/adhesins were found and may play a role in plant cell surface adhesion. These features may endow H. seropedicae with the ability to establish an endophytic life-style in a large number of plant species

Revisão: Aspectos gerais das bacteriocinas

Resumo Bacteriocinas são peptídeos antimicrobianos sintetizados nos ribossomos, tendo sido descrita uma grande diversidade de bacteriocinas, as quais diferem entre si quanto a composição de aminoácidos, biossíntese, transporte e modo de ação. Nos alimentos, as bacteriocinas podem ser encontradas naturalmente como produtos da microbiota normal ou introduzida (cultura starter ou probióticos). Devido às suas aplicabilidades frente a organismos patogênicos contaminantes em alimentos, vários estudos têm sido publicados, tornando o uso destes peptídeos uma alternativa aos conservantes químicos tradicionais. Considerando-se as propriedades das bacteriocinas e sua potencial aplicação como bioconservadores de alimentos e alternativa aos antibióticos, o presente estudo busca acercar-se de uma visão geral das bacteriocinas quanto aos aspectos históricos, sistemas de classificação, biossíntese e transporte, modo de ação, abordando também algumas de suas aplicações na indústria de alimentos

Hemólise produzida por Candida tropicalis isoladas de amostras clínicas Hemolysis produced by Candida tropicalis isolates from clinical samples

INTRODUÇÃO: Leveduras do gênero Candida são responsáveis pela maioria das infecções fúngicas em humanos. Candida tropicalis tem sido uma das mais comumente isoladas dentre as espécies não-albicans. O objetivo foi analisar a hemólise in vitro promovida por isolados clínicos de C. tropicalis provenientes de sangue e outras amostras clínicas de pacientes internados no Hospital Universitário da UEL, PR-Brasil. MÉTODOS: Foi avaliada a hemólise promovida por 28 isolados clínicos de C. tropicalis, sendo os isolados agrupados em classes de acordo com os níveis de hemólise. RESULTADOS: A maioria dos isolados de sangue apresentou hemólise fraca (+), enquanto as classes de hemólise forte (+++) e muito forte (++++) foram as predominantes nos isolados de outras amostras clínicas como urina, lesão de unha e secreção traqueal, embora não tenham sido detectadas diferenças estatísticas (p>0,05). CONCLUSÕES: Isolados de C. tropicalis, obtidos de diferentes amostras clínicas, apresentam capacidade de promover hemólise in vitro.<br>INTRODUCTION: Yeasts belonging to the genus Candida are responsible for the majority of fungal infections in humans. Candida tropicalis has been one of most commonly isolated non-albicans species. To analyze in vitro hemolysis promoted by clinical isolates of C. tropicalis obtained from blood and other clinical samples from hospitalized patients at the University Hospital of Londrina State University, Paraná, Brazil. METHODS: The hemolysis promoted by 28 clinical isolates of C. tropicalis was evaluated, and the isolates were grouped into classes according to the hemolysis levels. RESULTS: The majority of the blood isolates showed weak hemolysis (+), while the classes of strong hemolysis (+++) and very strong hemolysis (++++) predominated among isolates from other clinical samples such as urine, nail lesions and tracheal secretions. However, no statistical differences were detected (p> 0.05). CONCLUSIONS: Isolates of C. tropicalis obtained from different clinical samples showed a capacity to promote in vitro hemolysis