Essential oils in the management of soft rot of kale in the brazilian semiarid region / Óleos essenciais no manejo da podridão mole em couve no semiárido brasileiro

The aim of this study was to analyze the effect of essential oils on the control of soft rot of kale. Clove essential oil at 0.25%, lemongrass and palmarosa essential oils at 0.5%, melaleuca and orange essential oils at 0.75%, bergamot, rosemary, sage and ginger essential oils at 1% were evaluated for the in vitro inhibition of Pectobacterium carotovorum subsp. brasiliensis (Pcb) and control of soft rot of kale, sprayed 72 hours before or seven hours after inoculation. Clove, citronella, bergamot, rosemary, palmarosa, sage, melaleuca, and lemongrass oils completely inhibited the growth of Pcb. Lemongrass oil (0.5%) caused 0% of disease incidence (INC), providing 100% of disease control in both periods of inoculation. Clove oil (0.25%) showed a lower INC (25%) when applied after inoculation, providing a control percentage of 71.42%. The lemongrass and clove essential oils were analyzed by GC/FID (Gas Chromatography ­ Flame Ionization Detector) and by GC/MS (Gas Chromatography /Mass Spectrometer). The major components were eugenol (91,9%) for clove oil and citral, isometric mixture of neral (34,1%) and geranial (42,9%) for lemongrass oil. The Minimum inhibitory concentration (MIC) of lemongrass, clove oils and their major components (citral and eugenol, respectively) was determined by using a broth macrodilution technique, as well as they were evaluated at different concentrations on the control of soft rot of kale, sprayed according descriptions above. The MIC was 0.03125% for citral, and 0.0625 and 0.125% for lemongrass and clove oils, respectively. Eugenol didn't show MIC. Lemongrass oil at 0.125% (post-inoculation) and citral at 0.125% (pre and post-inoculation) provided the highest percentages of disease control (33.33, 50, and 100%, respectively). Clove oil at 0.125% (post-inoculation) showed better effectiveness than eugenol (0.25%), providing a percentage of disease control of 16.67%. Lemongrass and clove essential oils were the most effective in control of soft rot of kale, suggesting that these oils have a potential to be used as antibacterial agents.

O objetivo do estudo foi avaliar o efeito de óleos essenciais no controle da podridão mole em couve. Os óleos essenciais de cravo a 0,25%, capim-limão e palmarosa a 0,5%, citronela, melaleuca e laranja a 0,75%, bergamota, alecrim, sálvia e gengibre a 1% foram avaliados na inibição in vitro de Pectobacterium carotovorum subsp. brasiliensis (Pcb) e controle da podridão mole em couve, pulverizados 72 horas antes ou sete horas após a inoculação. Os óleos essenciais de cravo, citronela, bergamota, alecrim, palmarosa, sálvia, melaleuca e capim-limão inibiram completamente o crescimento de Pcb. O óleo de capimlimão (0,5%) promoveu 0% de incidência (INC) da doença (percentual de controle de 100%), em ambos os períodos de inoculação. O óleo de cravo (0,25%) proporcionou menor INC (25%) quando aplicado após inoculação (percentual de controle de 71,42%). Os óleos essenciais de capim-limão e cravo foram analisados por GC/FID (cromatografia gasosa/detector por ionização de chama) e por GC/MS (cromatografia gasosa/ espectometria de massas). Os componentes majoritários foram eugenol (91,9%) no óleo de cravo e citral (neral34,1% e geranial- 42,9%) no óleo de capim-limão. A concentração inibitória mínima (CIM) dos óleos essenciais de capim-limão e cravo e de seus componentes majoritários (citral e eugenol, respectivamente) foi determinada por meio da técnica de macrodiluição em caldo, bem como foram avaliados, em diferentes concentrações, no controle da podridão mole em couve, pulverizados conforme descrito acima. A concentração inibitória mínima (CIM) foi de 0,03125% para o citral, e de 0,0625 e 0,125% para os óleos de capim-limão e cravo, respectivamente. O eugenol não apresentou CIM. O óleo de capim-limão a 0,125% (pós-inoculação) e o citral (0,125%), em ambos os períodos de inoculação, proporcionaram os maiores percentuais de controle (33,33; 50 e 100%, respectivamente). O óleo de cravo a 0,125% (pós-inoculação) mostrou maior eficiência que o eugenol (0,25%), promovendo um percentual de controle de 16,67%. Os óleos essenciais de capim-limão e cravo destacaram-se na eficiência de controle da podridão mole em couve, sugerindo que esses óleos têm potencial para serem utilizados como agentes antibacterianos.

Avaliação microbiológica de couve manteiga (Brassica oleracea variedade acephala) comercializada na cidade de Cuiabá-MT / Microbiological evaluation of cabbage butter (Brassica oleracea variedade acephala) commercialized in the city of Cuiabá-MT

A couve manteiga (Brassica oleracea variedade acephala) é uma hortaliça pertencente à família Brassicaceae, rica em nutrientes, susceptível a contaminação e altamente consumida in natura pela população brasileira. O presente trabalho teve como objetivo avaliar a contaminação microbiológica de couve manteiga comercializada na cidade de Cuiabá-MT e analisar a redução da carga microbiana após sanitização desta. Foi realizado a pesquisa de Salmonella sp. e a contagem de bactérias heterotróficas aeróbias mesófilas (BHAM). Todas as amostras apresentaram ausência de Salmonella sp., estando aptas ao consumo e verificou-se que após a sanitização a quantidade de BHAM diminuiu, demonstrando a importância da sanitização para alimentos consumidos in natura.

Bioconversion of waste cooking oil glycerol from cabbage extract to lactic acid by Rhizopus microsporus

Abstract Glycerol from spent oil was processed by transesterification for biodiesel production. Although glycerol contains many types of impurities, it can be used as a C-source for lactic acid production by fungi, such as Rhizopus microsporus. In this study, we found that wild type R. microsporus (LTH23) produced more lactic acid than the mutant strains on cabbage glycerol media (CG media). More lactic acid was produced on CG media than on cabbage extract media (C media) by about two-fold in batch fermentation conditions. In addition, we found that lactic acid production in a fed-batch process was also slightly higher than in a batch process. To study the combined effects of pH, urea, and glycerol waste concentration on lactic acid production, a response surface methodology was used. The optimum pH, urea, and glycerol waste concentrations were pH 6.5, 3.75 g/L, and 17 g/L, respectively. The maximum lactic acid production predicted by this equation model was 4.03 g/L.

Avaliação microbiológica de couve minimamente processada comercializada nos supermercados de Brasília ­ DF / Microbiological evaluation of minimally processed brassica commercialized in the supermarkets of Brasília - DF

No Brasil, a couve minimamente processada é comercializada durante todo o ano e geralmente é considerada segura para o consumo pelos consumidores. Este estudo avaliou a qualidade microbiológica de seis diferentes marcas de couve minimamente processada comercializadas em supermercados de Brasília. As análises realizadas foram: contagem total de bactérias mesófilas e psicrotróficas, determinação de coliformes totais e coliformes termotolerantes e identificação molecular de E. coli, Salmonella spp. e L. monocytogenes por sequenciamento de DNA. Os resultados revelaram que as amostras de couve minimamente processada apresentaram baixa qualidade microbiológica. Coliformes termotolerantes foram encontrados em todas as amostras de couve minimamente processada, com populações superiores a 2 log NMP/g em metade das amostras. Após o sequenciamento de DNA, E. coli O157:H7 foi identificada em 2 das 6 amostras e Salmonella enteritidis foi identificada em 1 das 6 amostras. Listeria monocytogenes foi encontrada em metade das amostras, sendo que a presença desta bactéria é geralmente associada a um período excessivo de armazenamento ou estocagem em temperaturas abusivas. Estes resultados mostraram que a couve minimamente processada exposta ao consumo nos supermercados de Brasília pode ser um veículo para a transmissão de bactérias patogênicas e indicaram a necessidade de melhorar a qualidade na cadeia de produção dos vegetais minimamente processados para garantir a vida útil e a segurança microbiológica desses produtos.(AU)

Characterization of the hrpZ gene from Pseudomonas syringae pv. maculicolaM2

Pseudomonas syringae pv. maculicola is a natural pathogen of members of the Brassicaceae plant family. Using a transposon-based mutagenesis strategy in Pseudomonas syringaepv. maculicola M2 (PsmM2), we conducted a genetic screen to identify mutants that were capable of growing in M9 medium supplemented with a crude extract from the leaves of Arabidopsis thaliana. A mutant containing a transposon insertion in the hrpZ gene (PsmMut8) was unable to infect adult plants from Arabidopsis thaliana or Brassica oleracea, suggesting a loss of pathogenicity. The promotorless cat reporter present in the gene trap was expressed if PsmMut8 was grown in minimal medium (M9) supplemented with the leaf extract but not if grown in normal rich medium (KB). We conducted phylogenetic analysis using hrpAZB genes, showing the classical 5-clade distribution, and nucleotide diversity analysis, showing the putative position for selective pressure in this operon. Our results indicate that the hrpAZB operon from Pseudomonas syringaepv. maculicola M2 is necessary for its pathogenicity and that its diversity would be under host-mediated diversifying selection.

Characterization of the hrpZ gene from Pseudomonas syringae pv. maculicolaM2

Pseudomonas syringae pv. maculicola is a natural pathogen of members of the Brassicaceae plant family. Using a transposon-based mutagenesis strategy in Pseudomonas syringaepv. maculicola M2 (PsmM2), we conducted a genetic screen to identify mutants that were capable of growing in M9 medium supplemented with a crude extract from the leaves of Arabidopsis thaliana. A mutant containing a transposon insertion in the hrpZ gene (PsmMut8) was unable to infect adult plants from Arabidopsis thaliana or Brassica oleracea, suggesting a loss of pathogenicity. The promotorless cat reporter present in the gene trap was expressed if PsmMut8 was grown in minimal medium (M9) supplemented with the leaf extract but not if grown in normal rich medium (KB). We conducted phylogenetic analysis using hrpAZB genes, showing the classical 5-clade distribution, and nucleotide diversity analysis, showing the putative position for selective pressure in this operon. Our results indicate that the hrpAZB operon from Pseudomonas syringaepv. maculicola M2 is necessary for its pathogenicity and that its diversity would be under host-mediated diversifying selection.

Antagonism of Yeasts to Xanthomonas Campestris PV. Campestris on Cabbage Phylloplane in field

Twenty yeast isolates, obtained from cabbage phylloplane, were evaluated for antagonistic activity against Xanthomonas campestris pv. campestris, in field. Plants of cabbage ev. Midori were pulverized simultaneously with suspensions of antagonists and pathogen. After 10 days, plants were evaluated through percentage of foliar area with lesions. Percentage of disease severity reduction (DSR per cent) was also calculated. Yeast isolates LR32, LR42 and LR19 showed, respectively, 72, 75 and 79 (per cent) of DSR. These antagonists were tested in seven different application periods in relation to pathogen inoculation (T1=4 d before; T2=simultaneously; T3=4 d after; T4=4 d before + simultaneously; T5=4 d after + simultaneously; T6=4 d before + 4 d after; T7=4 d before + simultaneously + 4 d after). The highest DSRs were showed by LR42 (71 per cent), LR42 (67 per cent), LR35 (69 per cent) and LR19 (68 per cent) in the treatments T7, T4, T5, and T6, which significantly differed from the others. The same yeast antagonists were also tested for back rot control using different cabbage cultivars (Fuyutoyo, Master-325, Matsukaze, Midori, Sekai I and Red Winner). The DSRs varied from 58 to 61 (per cent), and there was no significant difference among cultivars

Microorganismos solubilizadores de compuestos minerales insolubles de fósforo en rizósfera de colza (Brassica campestris) / Dissolution of insoluble phosphorous mineral compounds in rhizosphere of Brassica campestris

Se estudió la influencia de la raíz de colza, Brassica campestris, desarrollada en un suelo del campo experimental de la Facultad de Agronomía de la UBA, sobre el grupo funcional de microorganismos solubilizadores de compuestos minerales insolubles de fósforo, com fosfatos bi y tricálcio. El análisis microbiológico cuantitativo arrojó los valores siguientes: para el fosfato bicálcio: 5,7 x 10**8, 2,8 x 10**8 y 1,1 x 10**8; para el fosfato tricálcico: 3,2 x 10**8, 1,7 x 10**8 y 2,1 x 10**7, de microorganismos solubilizadores de esos compuestos por grama de suelo, para el rizoplan (Ro) y para las dos regiones del suelo rizosférico (R1 y R2) respectivamente, contra 6,4 x 10**2 y 2 x 10**2 para el fosfato bicálcico y fosfato tricálcico en el suelo testigo, respectivamente. En medio de cultivo artificial se determinó la capacidad solubilizadora de los microorganismos desarrollados. Para el fosfato bicálcico se obtuvieron los porcentajes: 2.32, 17.53, 12.11 y 17.79, tricálcico: 0.88, 13.56, 7.98 y 2.88 de disolución para el suelo testigo, Ro, R1 y R2, en ambos casos, respectivamente. Estos resultados muestran que en la rizosfera de Brassica campestris se desarrolla un proceso microbiológico de disolución de compuestos minerales insolubles de fósforo muy activo, lo que permite suponer que un cultivo de colza elevaría la fertilidad fosfórica del suelo