Chemical composition and antibacterial activity of Aloysia triphylla (L'Hérit) Britton extracts obtained by pressurized CO2 extraction

This study investigated the chemical composition of five different extracts of Aloysia triphylla and their activity against Aeromonas sp. The extracts were obtained from the dried leaves by pressurized CO2 extraction at 30, 50 and 70ºC, and 100, 150, and 200 bar, and analyzed by GC/FID and GC-MS. The antibacterial activity was assayed by the microdilution method. The tested microorganisms comprised seven Aeromonas isolates obtained from the kidney of infected silver catfish, Rhamdia quelen. The yield, chemical composition and antibacterial activity of the extracts were dependent on the extraction conditions. Mono and sesquiterpenoids were the major constituents of all the extracts and the highest extraction yield was obtained at 70ºC and 200 bar. A. triphylla presented moderate antibacterial activity against Aeromonas sp.

Ocorrência de Aeromonas sp. e microrganismos psicrotróficos e estimativa do prazo de validade comercial de filé de pintado (Pseudoplatystoma coruscans) mantidos sob refrigeração / Occurrence of Aeromonas sp. and psychrotrophic microorganisms and estimate the shelf life of "pintado" (Pseudoplatystoma coruscans) fillets kept under refrigeration

Verificou-se a ocorrência de bactérias do gênero Aeromonas e estimou-se o prazo de validade comercial de filés de pintado (Pseudoplatystoma coruscans) com pele, durante estocagem em refrigeração por meio da quantificação de microrganismos heterotróficos aeróbios psicrotróficos e análises físico-químicas para determinação do pH e detecção de amônia e gás sulfídrico. Foram utilizadas 45 amostras de filé de pintado, com aproximadamente 100 gramas cada, embaladas individualmente em polietileno de alta densidade e armazenadas em câmara frigorífica entre 0ºC e 3ºC. A cada dois a três dias de estocagem, três unidades de filés foram submetidas a análises microbiológicas e físico-químicas, totalizando 15 análises durante o período de estocagem. As contagens de Aeromonas sp. e microrganismos heterotróficos aeróbios psicrotróficos variaram de 1,89 a 9,47logUFC/g e 0 a 6,54logUFC/g, respectivamente. A variação do pH foi de 6,20 a 6,97, e as análises de amônia e gás sulfídrico foram negativas durante todo o período. O pH dos filés de pintado atingiu o limite máximo de 6,4 aos 23 dias de estocagem, e estimou-se o seu prazo de validade comercial.

This word studied the occurrence of bacteria from genus Aeromonas and estimate the shelf life of "pintado" fish fillets (Pseudoplatystoma coruscans), during cold storage, through the quantification of psychrotrophic aerobic microorganisms, physical and chemical analyses for presence of ammonia and gas sulphide (H2S) and pH as used in 45 samples of "pintado" fillets with approximately 100 grams each, individually packed in high density polyethylene and stored in cold storage (0ºC to 3ºC). Every 2-3 days of storage, 3 units of fillets were subjected to microbiological and physicochemical analysis for a total of 15 days during the storage period. The Aeromonas sp. and psychrotrophic microorganisms count varied from 1.89 to 9.47logCFU/g and 0 to 6.54logCFU/g, respectively. The pH variation was from 6.20 to 6.97 and ammonia and H2S analyses were negative during the whole period. According under Brazilian legislation (Brazil, 1981) estimated the commercial shelf life of "pintado" fillets being 23 days when the pH reached a value of 6.4. The pH of the "pintado" fillets reached the maximum limit of 6.4 at 23 days of storage, being its estimated commercial shelf life.

Molecular cloning, characterization and enzymatic properties of a novel βeta-agarase from a marine isolate Psudoalteromonas sp. AG52

An agar-degrading Pseudoalteromonas sp. AG52 bacterial strain was identified from the red seaweed Gelidium amansii collected from Jeju Island, Korea. A β-agarase gene which has 96.8 percent nucleotide identity to Aeromonas β-agarase was cloned from this strain, and was designated as agaA. The coding region is 870 bp, encoding 290 amino acids and possesses characteristic features of the glycoside hydrolase family (GHF)-16. The predicted molecular mass of the mature protein was 32 kDa. The recombinant β-agarase (rAgaA) was overexpressed in Escherichia coli and purified as a fusion protein. The optimal temperature and pH for activity were 55 ºC and 5.5, respectively. The enzyme had a specific activity of 105.1 and 79.5 unit/mg toward agar and agarose, respectively. The pattern of agar hydrolysis demonstrated that the enzyme is an endo-type β-agarase, producing neoagarohexaose and neoagarotetraose as the final main products. Since, Pseudoalteromonas sp. AG52 encodes an agaA gene, which has greater identity to Aeromonas β-agarase, the enzyme could be considered as novel, with its unique bio chemical characteristics. Altogether, the purified rAgaA has potential for use in industrial applications such as development of cosmetics and pharmaceuticals.

Prevalência de Aeromonas spp. em fezes diarréicas de crianças menores de 5 anos de idade na cidade de Goiânia, Goiás, no biênio 1995-1996 / The prevalence of Aeromonas spp. in the diarrheal feces of children under the age of 5 years in the city of Goiânia, Goiás in the 1995-1996 biennium

Foram analisadas 163 amostras de fezes de crianças com idade abaixo de 5 anos no período de 1995 a 1996, sendo 91 de fezes diarréicas e 72 de fezes não diarréicas. O material foi coletado em meio para transporte e submetido ao processo de enriquecimento a 4oC por 7 dias. Para o isolamento primário foi utilizado ágar amido ampicilina e incubado a 35oC por 18 a 24 horas. Foram isoladas 20 (21,9%) das seguintes espécies: Aeromonas A. caviae (7,7%), A. salmonicida salmonicida (6,6%), A. sobria (4,3%), A. hydrophila (2,2%) e Salmonicida achromogenes (1,1%). Nenhuma Aeromonas spp foi isolada dos 72 pacientes-controles. A susceptibilidade das amostras de Aeromonas spp aos antimicrobianos foi maior com a ciprofloxacina, diminuindo gradativamente com cloranfenicol, gentamicina, ampicilina e eritromicina.

From 1995 through 1996, 163 fecal specimens of children aged under 5 years were analysed, 91 being from diarrhea feces and 72 without diarrhea. The material was collected in transport medium and submitted to the enrichment procedure at 4 degrees C for 7 days. For the primary isolation starch ampicillin agar was used and incubated at 35 degrees C for 18 to 24 hours. Twenty (20.9%) from the following specimens were isolated: Aeromonas (A.) caviae (7.7%), A. salmonicida salmonicida (6.6%), A. sobria (4.3%), A. hydrophila (2.2%) and Salmonicida achromogenes (1.1%). No Aeromonas spp. was isolated from the 72 control subjects. The Aeromonas spp. susceptibility to antimicrobial was greater with ciprofloxacin, being this susceptibility gradually diminished with chloranphenicol, gentamicin, ampicillin and erythromycin.