Occurrence and diversity of free-living protozoa on butterhead lettuce.

&lt;p&gt;The occurrence and diversity of free-living protozoa (FLP) on butterhead lettuce (Lactuca sativa L.) was investigated using four different sampling techniques (washing, swabbing, homogenization, and excising). FLP were recovered from all leaf samples (n=64), and cultures were FLP-positive after 1 week. Identification of FLP was performed by light microscopy and sequencing of denaturing gradient gel electrophoresis (DGGE)-separated 18S rRNA gene fragments. Bodo saltans, Spumella (-like) spp. and Cercozoa were the most common heterotrophic nanoflagellates. Amoebae belonged mainly to the Vannellida and Tubulinida. Colpoda steinii and Cyclidium glaucoma were the most common ciliates. The total number of FLP on middle leaves estimated by the Most Probable Number method ranged from 9.3 × 10(2)MPN/g to 2.4 × 10(5)MPN/g leaf, with flagellates (92 MPN/g to 2.4 ×10(5)MPN/g) being more abundant than amoebae (&lt;3 MPN/g to 9.3 × 10(3)MPN/g) and ciliates (&lt;3 MPN/g to 9.3 × 10(2)MPN/g). Washing or rinsing leaves followed by spin-drying in a household salad spinner reduced the protozoan number with maximum one log unit. Our survey shows that FLP on lettuce leaves are a common and diverse but largely unexplored group of microorganisms.&lt;/p&gt;</p

Sampling strategy, occurrence and diversity of free-living protozoa in domestic refrigerators.

&lt;p&gt;&lt;b&gt;AIMS: &lt;/b&gt;Evaluation of a sampling method to recover free-living protozoa (FLP) from plastic surfaces. Application of the method on different areas inside domestic refrigerators.&lt;/p&gt;&lt;p&gt;&lt;b&gt;METHODS AND RESULTS: &lt;/b&gt;Plastic coupons seeded with representatives of FLP were swabbed with cotton wools. The recovery efficiency was the highest for Chilomonas paramecium, followed by Tetrahymena pyriformis and the lowest for Acanthamoeba polyphaga. From 43 refrigerators, 19 and 26 were considered FLP positive when sample cultures were incubated at 7°C and 20°C, respectively. The number of FLP-positive cultures was the highest in samples taken from vegetable trays followed by discharge gutters, whereas interior walls were rarely FLP positive. Higher numbers of taxa were observed in enrichment cultures incubated at 20°C instead of 7°C. The combination of microscopy and denaturing gradient gel electrophoresis revealed that discharge gutters occasionally were contaminated with a persistent protozoan population of flagellates (Cercozoa) and amoebae (Tubulinea). The FLP-positive status of refrigerator surfaces was correlated with a high aerobic plate count.&lt;/p&gt;&lt;p&gt;&lt;b&gt;CONCLUSIONS: &lt;/b&gt;The cotton wool sampling method is useful to sample FLP from plastic surfaces. FLP are part of the microbial communities in domestic refrigerators.&lt;/p&gt;&lt;p&gt;&lt;b&gt;SIGNIFICANCE AND IMPACT OF THE STUDY: &lt;/b&gt;Knowledge on the occurrence of FLP in food-related indoor environments is scarce. For the first time, a high protozoan diversity in domestic refrigerators is described.&lt;/p&gt;</p

Bacillus cereus in Brazilian Ultra High Temperature milk Bacillus cereus em leite UHT brasileiro

Brazilian Ultra High Temperature (UHT) milk consumption has increased during the last decade from 187 to 4,200 million liters. In the continuous UHT process, milk is submitted for 2-4 s to 130-150ºC, in a continuous flow system with immediate refrigeration and aseptical packing in hermetic packages. This research had the purpose to verify the incidence of B. cereus species from the B. cereus group, in UHT milk. In 1998 high indexes of these organisms were reported, reaching 34.14% of the analyzed samples. Beyond this fact, there was the need to establish methods and processes adjusted for correct identification of B. cereus. Thus, commercial sterility tests of 6,500 UHT milk packages were investigated in two assays, after ten days incubation at 37ºC and 7ºC to germinate all possible spores and/or to recuperate injured vegetative cells followed by pH measurement. Samples (1,300 packages each) from five Brazilian UHT plants of whole UHT milk processed by direct steam injection, packaged in carton were investigated for the presence of Bacillus cereus through phenotypic and genetic (PCR) tests. Values of pH were different for the samples, ranging between 6.57 and 6.73. After storage of the samples, only four packages with pH measurement below the lower limit of 6.5 were found and analyzed for the presence of B. cereus. This organism was not detected in any of the samples indicating that the five Brazilian UHT milk processors control pathogenic microorganisms and it can be said that the consumption of UHT milk does not present safety problems to consumers. Fourier Transform Infrared Spectroscopy (FTIR) and PCR tests were efficient and must be adopted to confirm the biochemical series for B. cereus.<br>O consumo de leite ultra-alta temperatura (UHT) brasileiro aumentou, durante a última década, de 187 milhões de litros para 4,200 milhões de litros. No processo contínuo de leite UHT o leite é submetido por 2-4 seg a 130-150ºC, em sistemas de escoamento contínuo com refrigeração imediata e envase asséptico em embalagens herméticas. Esta pesquisa teve a finalidade de verificar a incidência da espécie B. cereus, em leite UHT. Em 1998, foi reportado alto índice destes organismos neste produto atingindo 34,14% das amostras analisadas. Além deste fato, existia a necessidade de se estabelece métodos e processos adequados para correta identificação de B. cereus. Assim, a esterilidade comercial de 6.500 embalagens de leite UHT foi estudada, em dois ensaios, após incubação das amostras a 37ºC e 7ºC por dez dias para germinar todos os possíveis esporos e/ou recuperar células vegetativas injuriadas. Após a incubação, foi realizada a medida de pH. Neste sentido, hum mil e trezentas amostras de cada uma de cinco plantas Brasileiras de processo UHT, que operam com injeção direta de vapor produzindo leite integral em embalagens cartonadas, foram investigadas em relação à presença de Bacillus cereus, através de ensaios fenotípicos e genéticos (PCR). Os valores de pH foram diferentes para as amostras analisadas oscilando entre 6,57 e 6,73. Após a estocagem das amostras, somente quatro embalagens suspeitas, com medida de pH abaixo de 6,5 foram analisadas na procura por B. cereus. Não foi detectado B. cereus em nenhuma amostra indicando que o leite integral UHT Brasileiro, das cinco plantas processadoras, não apresenta o microrganismo patogênico. Somente microrganismos deteriorantes foram isolados indicando que dentro do espaço amostral, o leite UHT analisado não representa riscos e problemas de saúde aos consumidores. A Espectroscopia Infravermelha por Transformada de Fourier (FTIR) e a Reação em cadeia da polimerase (PCR) foram consideradas eficientes e devem ser adotadas para confirmar a série bioquímica de B. cereus