Optimization of a propidium monoazide-qPCR method for Escherichia coli quantification in raw seafood.

The present study compared different concentrations of propidium monoazide (PMA), time of exposure to light and different light intensities to determine the optimal conditions for the quantification of viable Escherichia coli in cell suspension and in food matrix. The influence of cell density and the effectiveness of PMA in viable but non-culturable (VBNC) E. coli cells were evaluated and also applied in food matrix. For that purpose, different concentrations of PMA (20 µM, 40 µM, 50 µM, 60 µM and 80 µM) under different times of exposure (5 min, 10 min, 15 min, 20 min and 30 min) to lights of different intensities (500 W and 650 W) were evaluated. After determining the optimal conditions, the PMA-qPCR methods were applied to different compositions of live and heat-killed E. coli suspensions (v:v; 0:1; 1:0; 1:1) in concentrations ranging from 3 Log to 7 Log CFU/mL. The same dilutions were prepared with E. coli in VBNC state and applied in food matrix. The results obtained from qPCR, PMA-qPCR and plate counts were compared. The results suggested that a PMA treatment of 50 µM PMA for 15 min under 650 W light intensity was optimal under our conditions. For E. coli cell suspensions, the amplification of heat-killed cells was inhibited greatly by PMA when concentrations were ≤ 5 Log CFU/mL. For the samples of oyster inoculated with heat-killed cells, E. coli was not detected by PMA-qPCR in concentrations ≤4 Log CFU/g. Regarding the results with VBNC state, we considered the PMA-qPCR method to be applicable for enumerating E. coli VBNC cells in oyster samples. Based on our findings, we further recommend the use of PMA-qPCR with the aim of reducing the amplification of dead cells for improving its performance, since false-positives could still occur depending on the level of E. coli in the sample. The application of the PMA-qPCR for quantification of bacteria, compared to the use of culture-dependent methods, is quite promising. However, further studies are recommended, especially using different food matrices.

Evaluation of the interaction between microencapsulated Bifidobacterium BB-12 added in goat's milk Frozen Yogurt and Escherichia coli in the large intestine.

Goat milk and goat milk and inulin were used as encapsulating agents of Bifidobacterium BB-12 and applied in Frozen Yogurt (GF2 and GF3, respectively) in order to evaluate the antagonistic effect against Escherichia coli. GF1 is a control containing only Escherichia coli. Simulation of gastrointestinal digestion occurred sequentially. Quantification of Bifidobacterium BB-12 was performed using plate counting while E. coli count was compared with quantification by qPCR with viable and nonviable cell differentiation. The Bifidobacterium BB-12 count was <1.0, 9.23 and 9.11 log CFU g-1 for GF1, GF2 and GF3, respectively. In the ascending colon, all samples showed E. coli counts of approximately 5 log CFU g-1 by plate counting and by qPCR. Throughout the transverse (24 h) and descending colon (48 h) samples GF2 and GF3 showed decrease in E. coli number. GF3 showed higher decrease of E. coli in the descending colon because of inulin bifidogenic characteristic. The production of organic acids by bifidobacteria was directly related to the decrease in the E. coli count. In plate counts, E. coli was not detected for the GF3 sample in the descending colon. However, when quantified by qPCR the sample presented amplification that corresponded to 3 log CFU g-1. In this way, it was possible to observe the phenomenon of the viable but not-culturable cells of E. coli. Finally, it is recommended the microcapsule produced with goat milk and the inulin for application in goat milk products, due to the better antagonist effect against E. coli.

Isolation and Identification of a Potential Amylolytic Probiotic Bacterium from the Gut of Jundiá Catfish, Rhamdia quelen

ABSTRACT This study aimed to isolate a potential probiotic amylolytic strain from the gut of jundiá catfish to improve carbohydrate digestibility in fish. Two of 31 strains isolated from the foregut of Rhamdia quelen were able to grow on starch-agar medium and were considered amylolytic. The strain that presented higher amylolytic potential, based on a qualitative amylase assay, was chosen. The strain was phenotypically characterized and analysed to determine bile and pH tolerance and extracellular quantitative amylase activity. The probiotic candidate, identified as Aeromonas veronii, showed the ability to survive stresses from a range of pH and bile salt conditions and secreted an interesting enzymatic profile, which may exhibit a synergistic effect when combined with the enzymes secreted by the jundiá catfish, improving carbohydrate digestion in the host. The results demonstrated the potential of A. veronii to improve the digestion process in jundiá by providing exogenous enzymes for the breakdown and absorption of nutrients.

Esponjas utilizadas em cozinha hoteleira: contaminação e métodos de desinfecção / Sponges used in hotel cooking: contamination and disinfection methods

Um dos mais relevantes problemas em uma Unidade de Alimentação e Nutrição (UAN), referente a surtos alimentares, é a contaminação cruzada. Desta forma, acredita- -se que a esponja de cozinha seja um possível vetor da contaminação microbiológica em alimentos. De fato não existem padrões de tempo de uso para esponjas e este pode ser um problema, pois estas são acondicionadas à temperatura ambiente em meio umedecido rico em matéria orgânica. Além de se conhecer o nível de contaminação microbiológica, é também necessário descobrir qual o melhor método de higienização, a fim de se manter a segurança microbiológica do local, prevenindo assim a contaminação cruzada e consequentemente a ocorrência de um surto de doença transmitido por alimentos. Foram utilizadas esponjas com 24 a 48 horas de uso regular na cozinha de uma UAN hoteleira, estas foram submetidas à contagem microbiológica e aos métodos de desinfecção: imersão em solução de hipoclorito por 15 minutos e em água fervente por 5 minutos. A carga microbiana das esponjas sem higienização analisadas foi de 4,29x105 UFC/cm² (± 1,2x105 UFC/cm²), das tratadas com hipoclorito foi 5,64x103 UFC/cm² (± 1,63x10³ UFC/cm²) e das submetidas à fervura foi 1,1x10-1 UFC/cm² (± 1,26x10-2 UFC/cm²). Diante destas análises é possível afirmar que a esponja é sim um vetor em potencial de contaminação microbiológica e que a imersão em água fervente é o processo de desinfecção mais eficiente, entre os avaliados neste estudo, para reduzir a carga microbiológica de esponjas de cozinha.

Avaliação do sistema Petrifilm™ HS na contagem de coliformes em leite pasteurizado / Evaluation of the Petrifilm™ HS system for counting coliforms in pasteurized milk

Os métodos microbiológicos alternativos apresentam vantagens sobre os ensaios convencionais, no entanto é preciso confirmar sua eficácia. O presente trabalho avaliou o sistema Petrifilm™ HS com o sistema Petrifilm™ EC, em comparação com a metodologia convencional na contagem de coliformes a 35 ºC em leite pasteurizado. Altas correlações foram encontradas entre as metodologias utilizadas para efetuar a contagem de coliformes a 35 ºC. O sistema Petrifilm™ HS para contagem de coliformes a 35 ºCem leite pasteurizado mostrou resultados satisfatórios...

Occurrence of potentially pathogenic Vibrio in oysters (Crassostrea gigas) and waters from bivalve mollusk cultivations in the South Bay of Santa Catarina.

INTRODUCTION: This research aimed to identify and quantify potentially pathogenic Vibrio from different cultivations of bivalve shellfish in the State of Santa Catarina, Brazil, and water regions in the South Bay, as well as correlate the incidence of these microorganisms with the physicochemical parameters of marine waters. METHODS: Between October 2008 and March 2009, 60 oyster and seawater samples were collected from six regions of bivalve mollusk cultivation, and these samples were submitted for Vibrio counts. RESULTS: Twenty-nine (48.3%) oyster samples were revealed to be contaminated with one or more Vibrio species. The Vibrio parahaemolyticus and Vibrio vulnificus counts in the samples ranged from < 0.5 log10 Most Probable Number (MPN) g(-1) to 2.3 log10 MPN g(-1) oyster and from < 0.5 log10 MPN g(-1) to 2.1 log10 MPN g(-1) oyster, respectively. Of the 60 seawater samples analyzed, 44 (73.3%) showed signs of contamination with one or more vibrio species. The counts of V. parahaemolyticus and V. vulnificus in the samples ranged from < 0.3 log10 MPN·100mL(-1) to 1.7 log10MPN·100mL(-1) seawater and from < 0.3 log10 MPN·100mL(-1) to 2.0 log10 MPN·100mL(-1) seawater, respectively. A positive correlation between V. vulnificus counts and the seawater temperature as well as a negative correlation between the V. parahaemolyticus counts and salinity were observed. CONCLUSIONS: The results suggest the need to implement strategies to prevent vibrio diseases from being transmitted by the consumption of contaminated bivalve shellfish.

Occurrence of potentially pathogenic Vibrio in oysters (Crassostrea gigas) and waters from bivalve mollusk cultivations in the South Bay of Santa Catarina

Introduction This research aimed to identify and quantify potentially pathogenic Vibrio from different cultivations of bivalve shellfish in the State of Santa Catarina, Brazil, and water regions in the South Bay, as well as correlate the incidence of these microorganisms with the physicochemical parameters of marine waters. Methods Between October 2008 and March 2009, 60 oyster and seawater samples were collected from six regions of bivalve mollusk cultivation, and these samples were submitted for Vibrio counts. Results Twenty-nine (48.3%) oyster samples were revealed to be contaminated with one or more Vibrio species. The Vibrio parahaemolyticus and Vibrio vulnificus counts in the samples ranged from < 0.5 log10 Most Probable Number (MPN) g–1 to 2.3 log10 MPN g–1 oyster and from < 0.5 log10 MPN g–1 to 2.1 log10 MPN g–1 oyster, respectively. Of the 60 seawater samples analyzed, 44 (73.3%) showed signs of contamination with one or more vibrio species. The counts of V. parahaemolyticus and V. vulnificus in the samples ranged from < 0.3 log10 MPN·100mL–1 to 1.7 log10MPN·100mL–1 seawater and from < 0.3 log10 MPN·100mL–1 to 2.0 log10 MPN·100mL–1 seawater, respectively. A positive correlation between V. vulnificus counts and the seawater temperature as well as a negative correlation between the V. parahaemolyticus counts and salinity were observed. Conclusions The results suggest the need to implement strategies to prevent vibrio diseases from being transmitted by the consumption of contaminated bivalve shellfish. .

Evaluation of the PetrifilmTM EB and TEMPO® EB systems with ISO 21528-2:2004 method for the count of Enterobacteriaceae in milk

The development of alternative microbiological techniques is driven by the necessity to meet the current needs to deliver rapid results in the manufacturing process of foods, but it is important that these methods be evaluated for each application. The objective of the present study was to assess the PetrifilmTM EB and the TEMPO® EB systems with ISO 21528-2:2004 for the count of Enterobacteriaceae in pasteurized and UHT milk samples. We analyzed the microflora of 141 pasteurized milk samples, 15 samples of artificially contaminated pasteurized milk and 15 samples of artificially contaminated UHT milk. Investigation of the method PetrifilmTM EB and ISO 21528:2 regression analysis showed a high correlation in the samples, r = 0.90 for the microflora of pasteurized milk, r = 0.98 for artificially contaminated pasteurized milk and r = 0.99 for the artificially contaminated UHT milk. In evaluating the system TEMPO EB ® method and ISO 21528:2 correlation was also significant in the analyzed samples, with r = 0.86 for the microflora of pasteurized milk, r = 0.96 for artificially contaminated pasteurized milk and r = 0.99 for artificially contaminated UHT milk. No statistically significant differences were observed between the three methods conducted to analyze artificially contaminated pasteurized and UHT milk at three inoculum levels. In conclusion, the PetrifilmTM EB system and the TEMPO® EB system may be an alternative to the ISO 21528-2:2004 for the Enterobacteriaceae assay for milk as because of the ease-of-operation and the time reduction achieved for conducting the microbiological assay using these systems.

Métodos alternativos para contagem de micro-organismos em carcaças suínas / Alternative methods for the enumeration of microorganisms in swine carcasses

Micro-organismos estão presentes em toda a cadeia de processamento da carne, desde a matéria-prima até o produto final e compete aos programas de qualidade industrial verificar se existe contaminação na matéria-prima e nos produtos finais para, dessa forma, garantir um produto seguro ao consumidor. Para tanto, faz-se necessário utilizar metodologias alternativas à convencional na rotina diagnóstica dos laboratórios para obtenção de resultados confiáveis e em menor tempo possível. Com objetivo de verificar e comparar a correlação e o tempo de processamento, da metodologia convencional com as metodologias alternativas do sistema PetrifilmTM (3M) e sistema TEMPO® (bioMeriéux), foi realizada contagem de micro-organismos mesófilos, de enterobactérias e de Escherichia coli. As amostras foram coletadas da superfície de carcaças suínas em um abatedouro com Inspeção Federal no Estado de Santa Catarina, Brasil. A contagem de micro-organismos mesófilos, de enterobactérias e Escherichia coli foi feita por meio de ensaios realizados com os métodos alternativos TEMPO®, Petrifilm™ e o método convencional de contagem de micro-organismos em placas. Após análise estatística, o coeficiente de correlação de Pearson (r) demonstrou fortes correlações, acima de 0.70 entre as metodologias utilizadas para a contagem de enterobactérias e micro-organismos mesófilos, porém demonstrou moderada correlação, entre 0.30 a 0.70, para o diagnóstico de Escherichia coli. O uso dos métodos alternativos testados em substituição à metodologia convencional pode ser utilizado para diagnóstico de Escherichia coli, enterobactérias e micro-organismos mesófilos, por haver concordância entre os resultados encontrados, acrescido da rapidez dessas metodologias com benefício direto para a indústria de carne suína.

Micro-organisms are present throughout the meat processing chain, from raw materials until finished product. Industrial quality programs check for contamination in raw materials and final products to ensure the safety of consumer products; for this reason, the use of alternative methods instead of the conventional methods used in routine diagnostic laboratories is necessary to obtain reliable results in the shortest time possible. Samples of pig carcasses were collected in a slaughterhouse with Federal Inspection in the State of Santa Catarina, Brazil. Mesophilic micro-organisms, Enterobacteriaceae and Escherichia coli were evaluated and tests performed by alternative methods, TEMPO®, Petrifilm™, and the conventional method of counting micro-organisms in Petri dishes. After statistical analysis, the Pearson correlation coefficient (r) showed a strong correlation up to 0.70 between the methodologies used for the enumeration of Enterobacteriaceae and mesophilic micro-organisms, show a moderate correlation between 0.30 to 0.70, for the diagnosis of Escherichia coli. The use of alternative methods to replace the conventional method can be recommended for diagnosis of Escherichiacoli, Enterobacteriaceae and mesophilic micro-organisms, because there was consistency between the results and the speed was increased by the alternative methodologies benefiting the pork industry.

Evaluation of the Petrifilm™ EB and TEMPO(®) EB systems with ISO 21528-2:2004 method for the count of Enterobacteriaceae in milk.

The development of alternative microbiological techniques is driven by the necessity to meet the current needs to deliver rapid results in the manufacturing process of foods, but it is important that these methods be evaluated for each application. The objective of the present study was to assess the Petrifilm™ EB and the TEMPO(®) EB systems with ISO 21528-2:2004 for the count of Enterobacteriaceae in pasteurized and UHT milk samples. We analyzed the microflora of 141 pasteurized milk samples, 15 samples of artificially contaminated pasteurized milk and 15 samples of artificially contaminated UHT milk. Investigation of the method Petrifilm™ EB and ISO 21528:2 regression analysis showed a high correlation in the samples, r = 0.90 for the microflora of pasteurized milk, r = 0.98 for artificially contaminated pasteurized milk and r = 0.99 for the artificially contaminated UHT milk. In evaluating the system TEMPO EB ® method and ISO 21528:2 correlation was also significant in the analyzed samples, with r = 0.86 for the microflora of pasteurized milk, r = 0.96 for artificially contaminated pasteurized milk and r = 0.99 for artificially contaminated UHT milk. No statistically significant differences were observed between the three methods conducted to analyze artificially contaminated pasteurized and UHT milk at three inoculum levels. In conclusion, the Petrifilm™ EB system and the TEMPO(®) EB system may be an alternative to the ISO 21528-2:2004 for the Enterobacteriaceae assay for milk as because of the ease-of-operation and the time reduction achieved for conducting the microbiological assay using these systems.

Composição química e atividade antibacteriana dos óleos essenciais de Cymbopogon winterianus (citronela), Eucalyptus paniculata (eucalipto) e Lavandula angustifolia (lavanda) / Chemical composition and antibacterial activity of essential oils from Cymbopogon winterianus (citronella), Eucalyptus paniculata (eucalyptus) and Lavandula angustifolia (lavender)

Neste estudo, foi determinada a composição química de óleos essenciais obtidos de três espécies de plantas medicinais cultivadas na região Sul do Brasil: Cymbopogon winterianus (citronela), Eucalyptus paniculata (eucalipto) e Lavandula angustifolia (lavanda), e as atividades antimicrobianas foram avaliadas frente a 11 espécies de bactérias, incluindo-se espécies de importância em alimentos e em saúde pública. A composição dos óleos essenciais, obtidos por destilação a vapor, foi determinada por CG/DIC e CG/EM; a atividade antimicrobiana foi detectada pela técnica de difusão em disco; a CMI e a CMB foram determinadas pela metodologia de microdiluição. Os óleos essenciais de lavanda e citronela apresentaram monoterpenos oxigenados como componentes majoritários e, no óleo essencial de eucalipto, os monoterpenos hidrocarbonados foram os principais constituintes. O óleo essencial de citronela foi o mais ativo contra a maioria das bactérias testadas, com valores de CMI e CMB, respectivamente, de 0,075 e 0,31mg/mL para Yersinia enterocolitica. O óleo essencial de lavanda destacou-se pela atividade inibitória contra Escherichia coli e Salmonella Typhimurium, e o óleo de eucalipto foi ativo contra Pseudomonas aeruginosa. Este estudo demonstra que os óleos essenciais avaliados apresentam potencial para aplicação como agentes antimicrobianos naturais.

Depuration of Oysters (Crassostrea gigas) contaminated with Vibrio parahaemolyticus and Vibrio vulnificus with UV light and chlorinated seawater.

The efficacy of depuration using UV light and chlorinated seawater for decontaminating Vibrio parahaemolyticus and Vibrio vulnificus from oysters was investigated. Oysters were contaminated with a five-strain cocktail of V. parahaemolyticus or V. vulnificus to levels of 10(4) to 10(5) CFU ml(-1) for bioaccumulation. The depuration was conducted in a closed system in which 350 liters of seawater was recirculated at a rate of 7 liters/min for 48 h at room temperature. Counts of V. parahaemolyticus or V. vulnificus were determined at 0, 6, 18, 24, and 48 h. Three treatments were conducted: T1, control treatment; T2, UV treatment; and T3, UV plus chlorine treatment. After 48 h of depuration of V. parahaemolyticus, T3 reduced the count by 3.1 log most probable number (MPN) g(-1) and T2 reduced the count by 2.4 log MPN g(-1), while T1 reduced the count by only 2.0 log MPN g(-1). After 48 h of depuration of V. vulnificus, T2 and T3 were efficient, reducing the counts by 2.5 and 2.4 log MPN g(-1), respectively, while T1 reduced the count by only 1.4 log MPN g(-1). The UV light plus chlorine treatment was more efficient for controlling V. parahaemolyticus in oysters. Both UV light and UV light plus chlorine were efficient for V. vulnificus. The present study is the first report showing the efficacy of depuration systems for decontaminating V. parahaemolyticus and V. vulnificus in oysters cultivated on the Brazilian coast. This study provides information on processes that can contribute to controlling and preventing such microorganisms in oysters and could be used for effective postharvest treatment by restaurants and small producers of oysters on the coast of Brazil.

Chemical composition and antimicrobial activity of essential oils from selected herbs cultivated in the South of Brazil against food spoilage and foodborne pathogens / Composição química e atividade antimicrobiana de óleos essenciais de plantas selecionadas cultivadas no Sul do Brasil contra micro-organismos patogênicos e deteriorantes de alimentos

The chemical composition of 10 selected plant essential oils obtained by steam distillation was determined by GC and GC/MS. The antimicrobial activity of the essential oils was screened against 12 important food-related bacterial strains by agar disc-diffusion assay. MIC and MBC were determined for the essential oils that presented the highest activity in the agar disc-diffusion test. The most active essential oils against the tested bacteria were, in descending order, lemongrass (Cymbopogon flexuosus), basil (Ocimum basilicum), oregano (Origanum vulgare), cinnamon leaf (Cinnamomum zeylanicum), and laurel (Laurus nobilis). Except for S. Typhimurium, the tested bateria were inhibited at MIC values lower or equal to 0.62mg mL-1 by lemongrass (Cymbopogon flexuosus) essential oil. Yersinia enterocolitica presented the highest sensitivity to all essential oils tested (CMI≤0.62mg mL-1). There was a significant correlation (P<0.05) between oxygenated monoterpenes levels in the essential oils and MIC and MBC values against Escherichia coli. Results showed that the evaluated essential oils present high potential as natural preservatives.

A composição química de 10 óleos essenciais obtidos por destilação a vapor foi determinada por CG/DIC e CG/EM. A atividade antimicrobiana dos óleos essenciais foi detectada através do método de difusão em ágar frente a 12 espécies de bactérias de importância em alimentos. As CMI e CMB foram determinadas para os óleos essenciais que na difusão em ágar evidenciaram maior atividade. Os óleos essenciais que apresentaram maior atividade contra as bactérias testadas foram, em ordem decrescente, os de capim-limão (Cymbopogon flexuosus), manjericão (Ocimum basilicum), orégano (Origanum vulgare), folha de canela (Cinnamomum zeylanicum) e louro (Laurus nobilis). Com exceção de S. Typhimurium, o óleo essencial de capim limão (Cymbopogon flexuosus) apresentou valores de CMI e CMB iguais ou inferiores a 0,62mg mL-1 contra os micro-organismos testados. Yersinia enterocolitica foi o patógeno mais sensível frente a todos os óleos essenciais avaliados (CMI≤0,62mg mL-1). Foi detectada correlação significativa (P<0,05) entre os níveis de monoterpenos oxigenados dos óleos essenciais e os valores de CMI e CMB contra Escherichia coli. Os resultados demonstram que os óleos essenciais avaliados apresentam grande potencial como agentes antimicrobianos naturais para alimentos.

Microbiological quality of pre-cooked seafood marketed in Santa Catarina Island, Brazil / Qualidade microbiológica de frutos do mar pré-cozidos comercializados na Ilha de Santa Catarina, Brasil

The present study assessed the microbiological quality of pre-cooked and refrigera ted sea food marketed in Santa Catarina Island, Brazil. Forty-eight samples of crabs, mussels, shrimp and clams were purchase dat fish markets in Santa Catarina Island from June to September 2008. Microbiological analysis were conducted for total counts of psychrotrophic, coliforms at 45 °C, Enterococcus spp., Escherichia coli, coagulase-positive staphylococci and Salmonella spp. detecting. All of analyzed samples showed absenceof Salmonella spp. in 25g. Two (4.2 per cent) samples exceeded the counting limits of coliforms at 45 °C (one ofmussel and one of crab meat), and nine (18.75 per cent) samples (five of clams and four of crab meat) exceeded the limits for coagulase-positive staphylococci. The psychrotrophic counts were high in all products analyzed. Positive correlations were found between coliforms counting at 45 °C and Escherichia coli, but no correlation was found between Enterococcus spp. and coliforms at 45 °C or Escherichia coli. This study evidenced that about 20 per cent of the samples were not comply with the sanitary standards established by the Brazilian legislation.

Atividade antimicrobiana de Lactobacillus reuteri contra bactérias de interesse alimentar / Antimicrobial activity of Lactobacillus reuteri against bacteria of nourishment concern

Lactobacillus reuteri é uma espécie heterofermentativa que reside nos tratos gastrointestinal (GI), vaginale oral do homem e de outros animais de sangue quente. A ação probiótica de L. reuteri é atribuída a sua capacidade de exercer um efeito inibitório sobre micro-organismos patogênicos pela combinação de diversos mecanismos, incluindo-se a produção de ácido lático, peróxido de hidrogênio e produção de bacteriocinas. A reuterina é um composto neutro, de baixo peso molecular, solúvel em água, ativa em uma larga faixa de pH e resistente a ação de enzimas proteolíticas e lipolíticas. Neste estudo foi avaliado o efeito inibitório de L. reuteri sobre bactérias patogênicas ou deteriorantes de alimentos. L. reuteri apresentou capacidadede inibir o crescimento de Aeromonas hydrophila, Bacillus cereus, Enterobacter aerogenes, Proteus vulgaris, Pseudomonas aeruginosa, Salmonella tiphymurium, Staphylococcus aureus e Vibrio cholerae. Sugere-se que o antimicrobiano produzido pelo L. reuteri seja a reuterina.

Lactobacillus reuteri is a heterofermentative species that lives in the gastrointestinal (GI), vaginal and oraltracts of humans and other warm-blooded animals. The action of probiotic L. reuteri is derived from itsability to exert an inhibitory effect on pathogens, combining several mechanisms, including the productionof lactic acid, hydrogen peroxide and bacteriocin production. The reuterin is a neutral compound of lowmolecular weight, water soluble, active in a wide pH range, and resistant to proteolytic and lipolytic enzymes.This study evaluated the inhibitory effect of L. reuteri on pathogenic bacteria or food deterioration. L. reuterishowed ability to inhibit the growth of Aeromonas hydrophila, Bacillus cereus, Enterobacter aerogenes, Proteusvulgaris, Pseudomonas aeruginosa, Salmonella tiphymurium, Staphylococcus aureus and Vibrio cholerae. Itis suggested that the antibiotic produced by L. reuteri is the reuterin.Key words. reuterin, L. reuteri, antimicrobial activity.

Atividade antimicrobiana de Lactobacillus reuteri contra bactérias de interesse alimentar / Antimicrobial activity of Lactobacillus reuteri against bacteria of nourishment concern

Lactobacillus reuteri é uma espécie heterofermentativa que reside nos tratos gastrointestinal (GI), vaginale oral do homem e de outros animais de sangue quente. A ação probiótica de L. reuteri é atribuída a sua capacidade de exercer um efeito inibitório sobre micro-organismos patogênicos pela combinação de diversos mecanismos, incluindo-se a produção de ácido lático, peróxido de hidrogênio e produção de bacteriocinas. A reuterina é um composto neutro, de baixo peso molecular, solúvel em água, ativa em uma larga faixa de pH e resistente a ação de enzimas proteolíticas e lipolíticas. Neste estudo foi avaliado o efeito inibitório de L. reuteri sobre bactérias patogênicas ou deteriorantes de alimentos. L. reuteri apresentou capacidadede inibir o crescimento de Aeromonas hydrophila, Bacillus cereus, Enterobacter aerogenes, Proteus vulgaris, Pseudomonas aeruginosa, Salmonella tiphymurium, Staphylococcus aureus e Vibrio cholerae. Sugere-se que o antimicrobiano produzido pelo L. reuteri seja a reuterina.

Lactobacillus reuteri is a heterofermentative species that lives in the gastrointestinal (GI), vaginal and oraltracts of humans and other warm-blooded animals. The action of probiotic L. reuteri is derived from itsability to exert an inhibitory effect on pathogens, combining several mechanisms, including the productionof lactic acid, hydrogen peroxide and bacteriocin production. The reuterin is a neutral compound of lowmolecular weight, water soluble, active in a wide pH range, and resistant to proteolytic and lipolytic enzymes.This study evaluated the inhibitory effect of L. reuteri on pathogenic bacteria or food deterioration. L. reuterishowed ability to inhibit the growth of Aeromonas hydrophila, Bacillus cereus, Enterobacter aerogenes, Proteusvulgaris, Pseudomonas aeruginosa, Salmonella tiphymurium, Staphylococcus aureus and Vibrio cholerae. Itis suggested that the antibiotic produced by L. reuteri is the reuterin.Key words. reuterin, L. reuteri, antimicrobial activity.

Microrganismos indicadores de qualidade higiênico-sanitária em ostras(Crassostrea gigas) e águas salinas de fazendas marinhas localizadas na Baía Sul da Ilha de Santa Catarina, Brasil / Hygienic sanitary indicator microorganisms in oysters (Crassostrea gigas) and saline waters from sea farms in the Baía Sul of the Santa Catarina’s Island, Brazil

Esta investigação teve como objetivo efetuar o monitoramento da qualidade higiênico-sanitária em ostras (Crassostrea gigas) e águas salinas de fazendas marinhas da Baía Sul da Ilha de Santa Catarina, por meio de microrganismos indicadores, durante o período de um ano. As amostras de ostras e águas salinas foram submetidas a ensaios microbiológicos para enumeração de coliformes a 35°C, coliformes a 45°C e Escherichia coli. Foram avaliados os parâmetros físico químicos de temperatura, salinidade, turbidez e pH nas águas e pH nas ostras. Foram observadas correlações positivas entre as contagens de coliformes a 35°C, coliformes a 45°C e E. coli nas amostras de águas salinas e de carne das ostras; e diferenças estatisticas significativas foram verificadas entre as contagens de coliformes a 45°C nas amostras de águas salina provenientes da região E. Os parâmetros físico-químicos apresentaram pouca ou nenhuma correlação estatística com as contagens bacteriológicas. Considerando-se a Baía Sul em toda sua extensão, observou se a influência do índice pluviométrico sobre as contagens bacteriológicas obtidas nas águas e nas ostras. As contagens de coliformes a 45°C observadas nas águas salinas estavam de acordo com os parâmetros descritos na legislação brasileira, contudo, ressalta-se a importância da implantação de saneamento básico em regiões de cultivo de moluscos bivalves, assim como o constante monitoramento bacteriológico de indicadores de qualidade nas águas e nos moluscos.

This investigation was conducted for one year in order to monitor the hygienic sanitary conditions of oysters(Crassostrea gigas) and saline waters from sea farms at the South Bay of Santa Catarina Island, by means ofmicroorganism indicators. Oysters and saline waters samples were assayed by bacteria counting techniquefor coliforms at 35°C, coliforms at 45°C and Escherichia coli. Physical and chemical parameters were assessedin water samples (pH, salinity, turbidity and temperature) and oyster samples (pH). Positive correlations oncoliform counts at 35°C and at 45°C, and E. coli were observed within saline waters and samples of oyster meat.Statistically significant differences on coliforms counting at 45ºC were observed among saline water samplescollected from the region E. Physical-chemical parameters showed somewhat no statistical correlation with microorganism counting. Nonetheless, the influence of rainfall indices in the Great Florianopolis region over the bacteriological counting in saline waters and oysters could be observed. The coliforms counting at 45°C in saline water samples complied with the parameters established by the Brazilian legislation, although the basicsanitation at bivalve shellfish growing sites and a regular bacteriological quality monitoring by using specificindicators are demanded for the culturing water and for growing oysters.