Abstract Salmonella enterica serovar Heidelberg (SH), often isolated from broiler chicken samples, damages the entire production chain due to its high resistance in the environment. The search for sustainable disinfectant agents has intensified, focusing on the action of essential oils. This work's objective was to evaluate the in vitro, effect of Thymus vulgaris essential oil (TEO) and thymol in SH isolated from broilers, and the cytotoxicity in animal cells. Four different concentrations of TEO (0.1%, 0.2%, 0.4%, and 0.8%, (v/v)) were used against five SH isolates obtained from broilers and ATCC 8326. Thymol was evaluated at the concentrations of 0.023%, 0.047%, 0.071%, and 0.094% (v/v). In vitro antibacterial assays were performed by quantifying viable planktonic cells in the broth microdilution test. The MTT technique was used to assess the cytotoxicity in IEC-6 intestinal cells and NCTC fibroblasts. IC50 was assessed testing the concentrations of 0.0625%, 0.125%, 0.25%, and 0.5% of TEO and thymol in 24 hours. The bacterial activity was observed from the 0.2% concentration of TEO since no colony-forming units were observed. Thymol in the concentration of 0.094% controlled 83.33% of the bacteria. TEO presented an IC50 of 0.14% and 1.22%, while the IC50 for thymol was 0.068% and 0.001% for the IEC-6 and NCTC cells, respectively. On the other hand, TEO showed low cytotoxicity in fibroblasts and a potential action capacity to eliminate SH strains in vitro.

Resumo O objetivo deste trabalho foi avaliar a eficiência do processo de estabilização de dejetos suínos em lagoas de estabilização quanto à presença e à resistência a antibióticos de bactérias patogênicas. O estudo foi realizado em dois ensaios, em dez granjas de suínos localizadas no município de Presidente Castello Branco, no estado de Santa Catarina, Brasil. No primeiro ensaio, investigou-se a eficiência na redução de Escherichia coli (EC), coliformes não E. coli e Salmonella sp., bem como a resistência de isolados a antimicrobianos sob condições de manejo recomendadas. A amostragem foi realizada em três níveis de profundidade e dois tempos. No segundo ensaio, avaliou-se a concentração de coliformes totais e fecais (EC) em condições de manejo a campo, no momento da distribuição do dejeto na lavoura. A profundidade de amostragem não influencia a concentração de EC e Salmonella sp., e as bactérias isoladas são multirresistentes aos antibióticos avaliados. O tempo de retenção hidráulica é determinante na redução dos níveis populacionais dos agentes indicadores. Os resultados obtidos são indicativos de que o manejo dos dejetos suínos deve ser realizado de acordo com as normas sanitárias, para minimizar o risco de propagação e a resistência antimicrobiana de microrganismos patogênicos.

Abstract The objective of this work was to evaluate the efficiency of the stabilization process of swine manure in storage ponds regarding the presence and antibiotic resistance of pathogenic bacteria. The study was carried out in two trials in ten swine farms located in the municipality of Presidente Castello Branco, in the state of Santa Catarina, Brazil. In the first trial, the efficiency in reducing Escherichia coli (EC), non-E. coli coliforms, and Salmonella sp., as well as the resistance of isolates to antimicrobials, was investigated under recommended handling conditions. Sampling was done at three depths and two times. In the second trial, the concentration of total and fecal coliforms (EC) was evaluated under field handling conditions, when the manure was distributed on the field. Sampling depth does not influence the concentration of EC and Salmonella sp., and isolated bacteria are multi resistant to the evaluated antibiotics. Hydraulic retention time is determinant in reducing the population levels of the indicator agents. The obtained results are indicative that swine manure handling must be carried out according to sanitary standards, in order to minimize the propagation risk and antimicrobial resistance of pathogenic microorganisms.

RESUMO: Os biofilmes são responsáveis pela maior parte da interferência causada pelos micro-organismos no processamento de alimentos. O objetivo deste estudo foi avaliar a atividade anti-biofilme do óleo essencial de canela (Cinnamomum zeylanicum) e do composto majoritário eugenol. As concentrações utilizadas de óleo essencial foram de 0,0% (controle), 0,12%; 0,48%; 0,96% e 1,92%; a concentração de eugenol foi de 0,76%. As concentrações foram determinadas a partir de outros estudos publicados. Determinou-se o número de células viáveis e quantificou-se a biomassa bacteriana. O tratamento anti-biofilme foi eficaz na prevenção e formação de biofilmes. A concentração de 1,92% foi satisfatória, com redução de 5,91log CFUcm-2 de células viáveis em biofilme de Escherichia coli e redução de 5,17log CFU cm-2 de Staphylococcus aureus. A biomassa de ambas bactérias foi reduzida significativamente (P<0,05), entretanto, o tratamento sanitizante não foi eficaz na redução da biomassa. Diante dos resultados, o óleo essencial de canela e eugenol podem ser alternativas promissoras no controle de biofilmes.

ABSTRACT: Biofilms are responsible for most of the interference caused by microorganisms in food processing. The aim of this study was to evaluate the cinnamon (Cinnamomum zeylanicum) essential oil and eugenol sanitizer and anti-biofilm activity against biofilms. Concentrations used of essential oil were 0.0% (control) 0.12%; 0.48%; 0.96% and 1.92%; the amount of eugenol was 0.76%. Concentrations were determined from other published studies. Number of viable cells and quantification the bacterial biomass were determined. Anti-biofilm treatment was effective in preventing the formation of biofilms. The 1.92% concentration was the most satisfactorily with Escherichia coli reduction of 5.91log CFUcm-2 and Staphylococcus aureus reduction of 5.17log CFUcm-2 (P<0.05) biomass of the two bacteria. Sanitizing treatment was not effective in reducing biomass. Seen this, the cinnamon and eugenol essential oil may be promising alternatives for controlling biofilms.

Abstract Ricotta cheese has low fat and salt contents and a high quantity of proteins. The diversity of the nutrients and the high water content are factors that favor the development of microorganisms in this product. In this context, the aim of this study was to evaluate the microbiological quality of ricotta commercialized in the western region of Santa Catarina State, Brazil. Thirty samples, comprising 10 different brands of ricotta, were collected and sent to the Food Microbiology Laboratory at the Instituto Federal Catarinense (IFC), Campus Concórdia for microbiological analysis to determine the presence of Salmonella sp., Listeria sp., coagulase-positive Staphylococcus and thermotolerant coliforms. Of the 30 samples, the results for 33.3% were not within the parameters established by current legislation, that is, they were not fit for human consumption. This high percentage was due to contamination by thermotolerant coliforms, with 10 samples containing this group of microorganisms. One sample was contaminated with Listeria grayi, and for the other microorganisms investigated, (Salmonella sp. and coagulase-positive Staphylococcus) the results were satisfactory. This study characterizes the hygiene-sanitary conditions of ricotta commercialized in the western region of Santa Catarina State, highlighting the need for greater care during the production of this product.

This study demonstrates the possibility of using sanitizing detergents based on natural products for the elimination and/or reduction of Aeromonas hydrophila biofilm formed on stainless steel surfaces. The goal of this work was to determine the reduction effect of sanitizing detergents containing essential oils of Thymus vulgaris (thyme) and Cymbopogon citratus (lemongrass) on biofilm formed by A. hydrophila on AISI 304 stainless steel coupons, using UHT skimmed milk as substratum. There was adhesion and biofilm formation by A. hydrophila at 28 ºC, presenting 7.60 log cfu.cm-2 after the fourth day of cultivation. There was no significant difference between the lemongrass treatment and that of the thyme oil (p < 0.05). However, both treatments significantly reduced the biofilm, differing significantly from the NaOH control (p > 0.05). The treatment with lemongrass solution reduced the biofilm by 4.51 log cfu cm-2 at 25 ºC. The thyme detergent also reduced the number of cfu cm-2 by 3.84 log cycles at 25 ºC. The use of the lemongrass and thyme solutions efficiently reduced the A. hydrophila biofilm.

Diversos óleos essenciais de plantas condimentares e medicinais possuem atividade antimicrobiana comprovada, sendo de grande interesse para a indústria de alimentos. Dessa forma, as Concentrações Mínimas Inibitórias (CMI) desses óleos para diversas bactérias devem ser determinadas. As CMI variam de acordo com o óleo utilizado, dos compostos majoritários e da fisiologia da bactéria em estudo. Na presente pesquisa, os óleos essenciais das plantas Thymus vulgaris (tomilho), Cymbopogon citratus (capim-limão) e Laurus nobilis (louro) foram quantificados quimicamente e determinou-se a CMI sobre as bactérias Staphylococcus aureus ATCC 25923, Escherichia. coli ATCC 25922, Listeria monocytogenes ATCC 19117, Salmonella entérica Enteritidis S64 e Pseudomonas aeruginosa ATCC 27853. O óleo essencial de C. citratus demonstrou atividade bacteriana em todas as concentrações testadas e sobre todas as bactérias, sendo seus constituintes majoritários o geranial e neral. O constituinte majoritário de T. vulgaris foi 1,8 cineol e do óleo de L. nobilis, que apresentou menor atividade antibacteriana, foi o linalool, seguido pelo 1,8 cineol. As bactérias Gram-negativas demostraram maior resistência perante o uso dos óleos essenciais testados neste estudo, E. coli foi a menos sensível, sendo inibida apenas pelos óleos de C. citratus e L. nobilis.

Several essential oils of condiment and medicinal plants possess proven antimicrobial activity and are of important interest for the food industry. Therefore, the Minimum Inhibitory Concentrations (MIC) of those oils should be determined for various bacteria. MIC varies according to the oil used, the major compounds, and the physiology of the bacterium under study. In the present study, the essential oils of the plants Thymus vulgaris (time), Cymbopogon citratus (lemongrass) and Laurus nobilis (bay) were chemically quantified, and the MIC was determined on the bacteria Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Listeria monocytogenes ATCC 19117, Salmonella enterica Enteritidis S64, and Pseudomonas aeruginosa ATCC 27853. The essential oil of C. citratus demonstrated bacterial activity at all concentrations tested and against all of the bacteria tested. The majority of essential oil compounds were geranial and neral. The major constituent of T. vulgaris was 1.8-cineol and of L. nobilis was linalool, which presented lower antibacterial activity, followed by 1.8-cineol. The Gram-negative bacteria demonstrated higher resistance to the use of the essential oils tested in this study. E. coli was the least sensitive and was inhibited only by the oils of C. citratus and L. nobilis.