1,988,759 research outputs found
Comparison of methods for the microbiological identification and profiling of cronobacter species from ingredients used in the preparation of infant formula
Full text linkCronobacter spp. (formerly Enterobacter sakazakii) can be isolated from a wide range of foods and environments, and its association with neonatal infections has drawn considerable attention from regulatory authorities. The principle route of neonatal infection has been identified as the ingestion of contaminated infant formula. A number of methods have been developed to identify Cronobacter spp., however these were before the most recent (2012 ) taxonomic revision of the genus into seven species. In this study, phenotyping, protein profiling and molecular methods were used to identify Cronobacter strains which had been recently isolated from ingredients used in the preparation of infant formula. Pulsed field gel electrophoresis revealed that different Cronobacter strains had been recovered from the same food products. All isolates were identified as C sakazakii according to four genus specific PCR-probes and protein profiling using MALDI-TOF analysis. However, 16S rDNA sequence analyses and fusA allele sequencing gave more accurate identification: four strains were C sakazakii, one strain was C malonaticus and the remaining strain was C universalis. Multilocus sequence typing showed the strains were different sequence types. These results demonstrate the presence of different Cronobacter species in food ingredients used in the preparation of infant formula, and also the need for molecular identification and profiling methods to be revised according to taxonomic revisions
Interação in vitro e in vivo entre fungo micorrízico arbuscular, trichoderma spp. e fusarium spp.
Full text linkTCC (graduação em Agronomia) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias, 2010Fungos micorrízicos arbusculares (FMA) e Trichoderma spp. são constantemente sugeridos como potenciais agentes de controle biológico, principalmente contra fungos patogênicos do gênero Fusarium spp., agente causal de doenças em plantas de importância agrícola. Vários experimentos in vitro e in vivo têm sido realizados para analisar a interação entre o FMA, Trichoderma spp. e fungo patogênico, mas devido à presença de resultados contraditórios ainda não há certeza quanto ao efeito desta interação. O trabalho teve por objetivo avaliar a interação entre um fungo micorrízico arbuscular, Trichoderma spp. e Fusarium spp. e os efeitos sobre o crescimento e desenvolvimento dos fungos em condições in vitro e in vivo. Dois experimentos in vitro analisaram a interação de diferentes espécies de Fusarium spp. e Trichoderma spp. cultivados conjuntamente em meio de cultura Arroz-Agar e CZID-Agar. Um experimento in vitro, utilizando placas de petri descartáveis contendo dois ou três compartimentos, analisou o desenvolvimento de Glomus intraradices, Trichoderma atroviride e Fusarium culmorum ou Fusarium graminearum quando cultivados conjuntamente. Um experimento in vivo (Triticum aestivum L.) analisou o crescimento das plantas e inoculação fúngica quando cultivados com Glomus intraradices, Trichoderma atroviride e Fusarium culmorum. Nestes dois últimos experimentos também foi realizado a análise das enzimas micorrízicas fosfatase ácida e ?-glucosidase. Os fungos Trichoderma spp. e Fusarium spp. apresentaram crescimento diferenciado nos dois meios de cultura e Trichoderma spp. inibiu o desenvolvimento somente da espécie menos agressiva de Fusarium spp. O crescimento in vitro de Trichoderma spp. foi estimulado na presença de FMA e Fusarium spp. foi inibido. As plantas inoculadas com os três fungos apresentaram maior peso de matéria fresca da parte aérea e da raiz e maior colonização fúngica. Maior atividade de fosfatase ácida foi verificada no tratamento micorriza e fusarium, indicando maior atividade da micorriza devido a presença do patógeno. No tratamento com os três fungos essa atividade foi similar ao controle, o que indica a ação inibitória de Trichoderma spp. sobre a atividade do FMA
Phylogeny, phylogeography and movement of Kirramyces spp. associated with leaf blight diseases of plantation eucalypts
Full text linkWhen this study commenced in early 2004, only five Phaeophleospora species. had been reported from eucalypts of which only two; P. destructans (STE-U 1336) and P. epicoccoides (STE-U 1346) had been sequenced. In a former study, Phaeophleospora species emerged in two separate clades suggesting that Phaeophelospora is polyphyletic. The appearance and severity of lesions on eucalypt leaves are generally used to recognise the species of Phaeophleospora responsible for disease. However, depending on host and climate, the symptoms associated with infection by P. epicoccoides, P. eucalypti and P. destructans can be almost identical and incorrect diagnosis is a common problem. Thus, Phaeophleospora species were compared based on DNA sequences and multi gene genealogies were constructed. In addition species- specific primers were designed and tested on leaf material.
Many isolates of Phaeophleospora spp. were collected and sequenced, and all Phaeophleospora spp. from eucalypts were shown to cluster together and are closely related to the most important leaf pathogens associated with eucalypts namely Colletogloeopsis zuluensis, Mycosphaerella cryptica and M. nubilosa. In contrast, these fungi are distantly related to the type specimen of the genus Phaeophleospora, P. eugeniae. Furthermore, all DNA sequences of isolates of P. destructans examined in this thesis, including the ex-type culture, were identical but different to one previously lodged in GenBank.
This phylogenetic separation led to a morphological study of the species assigned to Phaeophleospora and compared the species from eucalypts with P. eugeniae the type specimen of Phaeophleospora. The phylogenetic and morphological studies show that P. eugeniae is well separated from Phaeophleospora spp. occurring on eucalypts and led to the resurrection of the previous generic name, Kirramyces for Phaeophleospora spp. occurring on eucalypts. Furthermore, phylogenetic analysis and morphological observation of Kirramyces spp. and Colletogloeopsis spp. occurring on eucalypts showed considerable overlap between these two genera. Therefore, Colletogloeopsis was reduced to synonymy with Kirramyces. Consequently, the genus Kirramyces was expanded from five to 14 species, and included the description of two new species, K. angophorae and K. corymbiae. In order to assist with their identification a key based on morphology of conidia for Kirramyces species was developed.
Kirramyces destructans is a devastating pathogen originally described from Indonesia in 1996 and has since been found throughout Asia where all common tropical and subtropical plantation eucalypt species and hybrids are susceptible. K. destructans is considered a major biosecurity threat in Australia, both to native eucalypt forests and the tropical plantation industry. Prior to the current study, there had been no investigation into the origin and movement of this important pathogen. Thus, five gene regions and six microsatellite loci were sequenced for 43 representative isolates of K. destructans from a range of geographical locations and hosts. Two microsatellite markers detected very low nucleotide polymorphism (three haplotypes for each loci); five other gene regions, including four microsatellite region were uniform. This low level of genetic diversity provides strong evidence that K. destructans was introduced into Indonesia as a founder population and that it has subsequently been spread throughout Asia via human-mediated movement of germplasm. Timor and Northern Australia were considered to be a possible source of origin of this fungus, but the high susceptibility of native E. urophylla to K. destructans in Timor indicates that the pathogen is unlikely to be endemic to Timor.
The current distribution of Kirramyces eucalypti is New South Wales, Queensland, Victoria, Tasmania and New Zealand (North Island). The main host of this pathogen is E. nitens which is native to Victoria and New South Wales. Kirramyces eucalypti has not been found in South Africa, yet it causes a severe disease on eucalypt hybrids originating from South Africa growing in New South Wales indicating movement to these hybrids from either native eucalypts or nearby plantations. As such, K. eucalypti poses a threat for the plantation industry in sub-tropical and tropical Australia. The phylogeography of K. eucalypti in Australia and New Zealand was studied by sequencing three gene regions and one microsatellite locus of fifty-seven representative isolates of K. eucalypti from Queensland, New South Wales, Victoria, Tasmania and New Zealand. The highest genetic variation was found among isolates from NSW suggesting that K. eucalypti originates from NSW. Isolates in New Zealand appear to have been introduced from NSW. Isolates from Queensland were consistently different to those from other regions and may in fact represent a cryptic species or a hybrid.
During monitoring of eucalypt taxa trials in far North Queensland, infected leaves resembling symptoms typical of K. destructans were collected and examined. Phylogenetic data based on three gene regions and some morphological characteristics revealed a new taxon described in this study as K. viscidus. Kirramyces viscidus was also shown to be closely related to the devastating pathogen K. destructans. Kirramyces viscidus had been found to cause extensive damage to eucalypt hybrids originating from South America, and less damage to E. grandis from Australia, indicating that this pathogen is probably endemic to Australia. Kirramyces viscidus has the potential to seriously damage tropical eucalypt plantations, especially if clonal and planted off-site.
In conclusion, this study resurrected genus Kirramyces for the Phaeophleospora and Coletoglloeopsis spp. occurring on eucalypts. It also studied the phylogeography and gene flow of the two most important Kirramyces species, K. destructans and K. eucalypti and describes three new Kirramcyes spp. found on eucalypts in Australia. Very recently, K. destructans has been discovered in Northern Australia. This raises a whole series of new issues as there are now several pathogens, K. eucalypti, K. viscidus and K. destructans present in Australia that known to cause serious damage on plantation eucalypts. Recent investigations have also revealed several undescribed Kirramyces spp. in Northern Australia. Their impact, distribution, movement and potential for hybridization now need to be examined
Genotyping of Cryptosporidium spp. isolated from human stool samples in Switzerland
Full text linkIn a study to estimate the frequency of Cryptosporidium infections in Switzerland, stool samples from patients found to be positive for Cryptosporidium spp. by modified Ziehl-Neelson staining and fluorescence microscopy were used for genotyping experiments. With 9 of 12 samples, DNA extraction and subsequent genotyping was successful. All Cryptosporidium-isolates belonged to the bovine genotype. In one stool sample, two strains of Cryptosporidium were demonstrated, suggesting a mixed infection. In comparison with reference strains from calves, one of the isolates showed a full sequence identity and the other a similarity of 97.5%. The fact that only bovine genotypes were detected suggests, that cryptosporidiosis must primarily be considered as a zoonotic disease in Switzerland. This is in contrast to other countries, where the human genotype of C. parvum was shown to dominate the epidemiological situation. The results of our study are supported by the previous finding, that two of the analysed strains originated from patients who used to consume raw milk or raw cream, a known risk factor for cryptosporidiosis
Detecção e avaliação in vitro do crescimento de Trichoderma spp. isolados de composto frente à fitopatógenos
Full text linkDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Agrárias, Programa de Pós-Graduação em Agroecossistemas, Florianópolis, 2009A compostagem é um processo que garante o retorno da matéria orgânica e nutrientes ao solo. Estudos apontam o composto como um meio naturalmente supressivo a patógenos de plantas, o que pode estar relacionado com a presença de Trichoderma spp. no meio. Os objetivos do presente trabalho foram: comparar três métodos de isolamento de Trichoderma spp. do composto; compreender a colonização do composto com uma semana, um e dois anos de maturação comparado com o solo de áreas adjacentes ao pátio de compostagem; e verificar características úteis de Trichoderma spp. para a utilização no controle biológico de fitopatógenos. Método de iscas; diluição em série de soluções do solo e plaqueamento direto de fragmentos de composto, foram os métodos utilizados para o isolamento de Trichoderma spp. O método de plaqueamento direto foi considerado o mais viável para verificar a presença de Trichoderma spp. Esse método foi utilizado para selecionar oito isolados de Trichoderma spp.; três do composto de um ano (N1, N2 e N3), três do composto de dois anos (M1, M2 e M3), e dois do solo da mata adjacente ao pátio (S2 e S3). Os isolados M1 e M2 foram identificados, respectivamente, como Trichoderma asperellum e Hypocrea lixii. Todos os isolados foram comparados com Trichoderma asperellum de formulação comercial (TC) quanto ao crescimento micelial, esporulação em BDA (batata-dextrose-ágar) e confrontados com Sclerotinia sclerotiorum. Em seguida, apenas um dos isolados (M2) do composto de dois anos e o TC foram confrontados com S. sclerotiorum, Rhizoctonia sp. e Fusarium solani. O crescimento micelial entre isolados do composto e do solo foram semelhantes. Isolados do composto de um ano apresentaram a maior esporulação. Isolados do composto de dois anos competiram melhor frente aos patógenos, por espaço e nutrientes, um dos possíveis mecanismos para a supressividade natural do composto
Estudo de caso: Ocorrência de contaminação por Salmonella spp. em uma fábrica de ração de aves
Full text linkTCC (graduação) - Universidade Federal de Santa Catarina. Centro de Ciências Agrárias. Curso de Zootecnia.A Salmonella pode estar presente em toda a cadeia produtiva, desde a produção de alimentos destinados à alimentação animal, durante a criação dos animais nas granjas até o processo final de abate e distribuição do produto ao consumidor. Diante disso, o presente trabalho teve como objetivo avaliar a ocorrência de contaminação por Salmonella spp. em amostras de ambiente e produtos finais de uma fábrica de ração para aves. Foram utilizados dados de análises microbiológicas para detecção de Salmonella spp. em swabs de superfície das áreas limpa e suja de uma fábrica de ração, caminhões de transporte de matérias primas e expedição de rações, bem como análise microbiológica de produtos acabados destinados a alimentação animal. As análises referem-se ao período de janeiro de 2013 a agosto de 2014. Em 2013 no total foram realizadas análises de swab de superfície em 580 amostras da área suja, 1071 da área limpa e 322 dos caminhões de expedição. Nas rações expedidas foi realizada análise microbiológica de 2456 amostras. Em 2014 foram realizadas análises de swab de superfície em 190 amostras da área suja, 558 da área limpa, 205 dos caminhões de expedição e análise microbiológica de 1164 amostras de rações expedidas. Para cada análise realizada foram apresentados resultados de ausência (A) ou presença (P) de Salmonella spp. nas amostras. A ocorrência de Salmonella spp. na fábrica de ração foi avaliada por frequência utilizando o pacote Microsoft Office Excel. Os resultados indicaram que em 2013, foi constatada contaminação por Salmonella spp. nos seguintes equipamentos e locais da área suja da fábrica: silos, moegas, armazém de ingredientes, balança, moinhos e tombador, e em 2014, na área externa do telhado, caixas de ingredientes, silos, tombador, moegas, botas dos operadores e armazém de ingredientes. Dos equipamentos da área limpa foi detectada contaminação nos silos de expedição, triturador, prensa e resfriador. Já em 2014 além dos equipamentos descritos anteriormente, foi constatada também a ocorrência no transportador horizontal. Com relação aos locais da área limpa, em 2013 a Salmonella spp. estava presente em amostras de resíduos e utensílios de limpeza, piso do resfriador, piso da prensa, caixas de rações e caminhões de expedição das rações. Em 2014 estava presente na entrada de ar do resfriador, piso do resfriador, piso da prensa, caixas de rações, piso e teto da área de depósito das caixas, piso da área de expedição, pedilúvio, tubulações e caminhões de expedição de rações. As rações expedidas não apresentaram contaminação por Salmonella spp. A fábrica de ração apresentou contaminação por Salmonella spp. em diferentes locais da área suja e limpa e expedição das rações, todavia não foi encontrada contaminação nas amostras de rações expedidas nos dois anos. Os pontos de controle da contaminação identificados na fábrica foram: as caixas de transporte de ingredientes, as botas dos operadores, a área externa do telhado da área suja da fábrica, o piso da prensa, o resfriador e a área de expedição das rações. A ocorrência de Salmonella spp. na fábrica de ração pode estar associada às falhas apresentadas pela empresa no plano de ação
Mycosphaerella spp. on Eucalyptus in Asia: new species, new hosts and new records.
Full text linkLeaf spots caused by Mycosphaerella spp. are of increasing concern in eucalypt plantations around the world, but few species have been reported infecting eucalypts in Asia. From leaf material collected in China, Vietnam and Indonesia, we describe three new Mycosphaerella spp.; M. vietnamiensis, M. obscuris and M. yunnanensis. Mycosphaerella crystallina, previously known only from South Africa, and M. stramenticola, previously reported from Eucalyptus leaf litter in Brazil, are new records. Mycosphaerella citri, an important pathogen of citrus, was found infecting Eucalyptus. Mycosphaerella marksii and M. suttoniae, which have been previously reported in Asia, were regularly encountered. Pseudocercospora spp. were also common throughout the region. This study highlights the potential biodiversity of Mycosphaerella spp. on eucalypts in South-East Asia
Isolation and Characterization of Klebsiella spp. and Staphylococcus aureus from Engorged Adult Females of Rhipicephalus spp.
No full textTo mention the role of ticks in transmission of Klebsiella spp. and Staphylococcus aureus, sixty seven engorged adult females of the type which called hard ticks (Rhipicephalus spp.) were collected from cattle and sheep randomly from diverse regions of Baghdad city through the period November 2015 till March 2016. Blood swabs from ticks were subjected to the culture media to determine the percentages of Klebsiella spp. and Staphylococcus aureus. Results showed that out of 67 samples, 13 (14.40%) samples were positive for Klebsiella spp., 16 (23.88%) samples were positive for Staphylococcus aureus and 8 samples were positive for both bacteria. This study revealed that hard ticks (Rhipicephalus spp.) is a good source for bacterial infection by Klebsiella spp. and Staphylococcus aureus
Presence of Salmonella spp., Campylobacter spp., and Listeria spp. in Different Animal Species Raw Milk in Diyarbakır Province
Full text linkContamination of raw or unpasteurized milk with zoonotic pathogens can seriously affect public health. In this study, milk samples were collected from sheep/goat and bovine farms in Diyarbakır province engaged in home breeding to investigate the prevalence of pathogens in raw milk. A total of 253 raw milk samples from bulk milk tanks belonging to 58 cows, 72 buffaloes, 48 sheep, and 75 goats were analyzed by conventional and molecular methods. All milk samples were negative for Salmonella spp. through both methods. Campylobacter spp. could not be isolated, but the polymerase chain reaction analysis found that 26 (10.28%) of the milk samples were contaminated with Campylobacter spp. However, Campylobacter jejuni was not detected in any of the samples. The prevalence of Listeria spp. was 2.77%. Listeria spp. was detected in raw milk from cows, buffaloes, and goats, but not in milk from sheep. While Listeria monocytogenes was not detected in any of the milk samples analyzed, the isolated strains were defined as Listeria innocua, Listeria welshimeri, and Listeria grayi. It was concluded that compared to reports from other countries, the prevalence of pathogens was low. Still, raw milk consumption poses a potential risk to public health, more so, as some of the pathogenic bacteria can survive and multiply even at low temperatures
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