The bacterium Candidatus Liberibacter asiaticus (CLas) is associated with huanglongbing (HLB) in citrus in many countries. Despite the fact that many characteristics of the disease are known, the rate of multiplication of the bacterium within an infected tree is still poorly understood. To study this feature, we used the quantitative Real-Time polymerase chain reaction (Q-PCR) assay to follow and to quantify the multiplication of CLas in grafted infected young sweet orange plants. The rate of infection by grafting reached 100% at 120 days post-inoculation (dpi) showing that grafting could easily transmit CLas. A well-adjusted linear regression equation describing the bacterial growth in planta was obtained independently with measurements taken using repeated sampling in the same plant or different plants through the analysed period. The bacterial population, measured as copy number (CN) of the 16S rDNA target gene g −1 of tissue, increased 10,000 times from 10 3 at 30 dpi to approximately 10 8 CN at 240 dpi indicating that CLas multiplication was fastest in young citrus plants. We observed a direct relationship between the concentration of pathogen and the expression of symptoms. Yellowed leaves or shoots, are commonly the first observed symptom of HLB, and were present in trees with a low amount of bacteria (10 5 CN g −1 ). Blotchy mottle symptoms were observed in trees with 10 7 CN g −1 of bacteria after 180 dpi. Buds taken from infected, but nonsymptomatic branches were grafted on Rangpur lime and resulted in transmission rates ranging from 10 to 60%.

No abstract

Oysters are filter feeders able to ingest particles in suspension that may carry pathogenic microorganisms. In this respect, the consumption of raw oysters can cause foodborne diseases in humans. The aim of the present study was to evaluate the microbiological quality of Crassostrea gigas oysters cultivated and commercialized in the coastal region of Florianópolis, SC, Brazil. The study comprised counts of coliforms at 35ºC and at 45ºC, Escherichia coli and coagulase-positive staphylococci, and detection of Salmonella sp, Vibrio cholerae and Vibrio parahaemolyticus. Ninety samples were analyzed, 45 of them collected at seafood commercial establishments and the other 45 were collected in the cultivation area. All analyses were performed according to methods of the American Public Health Association. Vibrio cholerae, V. parahaemolyticus and Salmonella sp. were not detected in any of the samples. Coagulase-positive staphylococci were observed in only one sample (80 CFU/g). The counts of coliforms at 35 and 45ºC indicated that samples obtained from both the cultivation area and place of sale were contaminated. E. coli was detected in 4 (9%) samples collected in the cultivation area and in 16 (35.5%) samples obtained from commercial establishments. These results indicate the need for monitoring the quality of raw oysters, including the implantation of programs for good mollusk manipulation and management practices.

A produção de verotoxinas foi investigada em 1.127 isolamentos de Escherichia coli feitos a partir de 243 bovinos de leite, de água de consumo humano e animal e de amostras de leite de 60 propriedades da bacia leiteira de

Ocurrence of Vibrio spp., positive coagulase staphylococci and enteric bacteria in oysters (Crassostrea gigas) harvested in the south bay of Santa Catarina island, Brazil IntroductionIn Brazil, bivalve mollusks production takes place mainly in Santa Catarina State, south Brazil, due to the excellent geographical conditions of this area for marine organism cultures, such as the presence of a large number of bays facilitating the establishment of mollusk farms (COELHO et al., 2003;CORRÊA et al., 2007;OLIVEIRA NETO, 2005). In 2007, about 11.000 t of mollusks were commercialized in Santa Catarina State, the largest producing region of oysters (Crassostrea gigas). The major production takes place in sea farms located in the South Bay of Santa Catarina Island (OLIVEIRA NETO, 2007).Oysters are filter-feeders that efficiently concentrate microorganisms from polluted habitats, and because they are often consumed raw, they pose a health risk to consumers (CORRÊA et al., 2007;LALOO et al., 2000; PEREIRA et al., 2006;SILVA et al., 2004). The enteric bacteria, originating from the contamination of water with human residues, can readily contaminate the fauna in marine environments, especially molluscan shellfish (CORRÊA et al., 2007, PEREIRA et al., 2006. To guarantee sanitary quality, mollusk cultures should be monitored for contamination by pathogenic microorganisms (CORRÊA et al., 2007).Vibrios are very common in marine and estuarine water environments and some may cause infections in humans that were exposed to seafood or sea water. Several Vibrio species are pathogenic to humans and may be present in raw or partially cooked shellfish (LHAFI; KÜHNE, 2007; PEREIRA et al., 2007a, b , para ambos os microrganismos, sugerindo um monitoramento tanto destas espécies quanto da temperatura das águas marinhas nas regiões de cultivo. Com base nos resultados das análises microbiológicas, as amostras analisadas mostraram qualidade bacteriológica aceitável, ou seja, dentro dos parâmetros estabelecidos na legislação brasileira. Palavras-chave: qualidade microbiológica; moluscos bivalves; filtradores; Escherichia coli; Vibrio parahaemolyticus; Vibrio vulnificus. AbstractThe aim of this study was to assess the contamination of oysters (Crassostrea gigas), harvested in six different regions of the South Bay of Santa Catarina Island, with Coliforms at 45 °C, Escherichia coli, Vibrio spp., positive coagulase staphylococci, and Salmonella sp. over a period of one year. One hundred eighty oyster samples were collected directly from their culture sites and analyzed. Each sample consisted of a pool of 12 oysters. All of the samples analyzed showed absence of Salmonella, 18 (10%) samples showed presence of Escherichia coli, 15 (8.3%) samples were positive for V. alginolyticus, and Vibrio cholerae was detected in 4 samples (2.2%). The counts of positive-coagulase staphylococci varied from <10 to 1.9 × 10 2 CFU.g , for both microorganisms. This suggests the need for monitoring these vibrios contamination in oysters. Based on the results of the ...