Resumo
Citrus variegated chlorosis (CVC) and coffee stem atrophy (CSA) are important diseases in Brazil associated with closely-related strains of Xylella fastidiosa, but little is know about host aoverlappingnd importance of citrus and coffee as inoculum sources of these strains. In this study, reciprocal-inoculation experiments were performed to determine if CVC and CSA isolates are biologically similar within citrus and coffee plants. These two hosts were mechanically inoculated with a CVC and a CSA isolate of X. fastidiosa at four concentrations ranging between10³ and 10(9) colony forming units CFU mL-1. At two, four and eight months after inoculation, the infection efficiency and bacterial populations of the isolates in each host were determined by culturing. The CVC isolate infected both citrus and coffee plants, but developed lower populations in coffee. The CSA isolate did not colonize citrus. Inoculation of coffee plants with the CVC isolate resulted in low rates of infection and required an inoculum concentration ten-fold higher than that necessary to obtain a similar (25%) rate of infection in citrus. The relatively low infection rates and bacterial numbers of the CVC isolate in coffee plants compared with those observed in citrus suggest that coffee is not a suitable host to serve as a source of inoculum of the CVC strain for primary spread to citrus or within coffee plantations.
Clorose variegada dos citros (CVC) e atrofia dos ramos do cafeeiro (ARC) são doenças importantes no Brasil, associadas a estirpes de Xylella fastidiosa que são geneticamente próximas. Entretanto, pouco se sabe a respeito de plantas hospedeiras em comum e da importância de citros e cafeeiro como fontes de inóculo dessas estirpes. Neste estudo, realizaram-se experimentos de inoculação recíproca para determinar se isolados de X. fastidiosa de CVC e de ARC são biologicamente semelhantes em plantas de citros e café. Estes dois hospedeiros foram mecanicamente inoculados com um isolado de CVC e um isolado de ARC, em quatro concentrações que variaram de 10³ a 10(9) unidades formadoras de colônias UFC mL-1. Aos dois, quatro e oito meses após a inoculação, a eficiência de infecção e a população bacteriana dos isolados em cada hospedeiro foram determinadas por cultura. O isolado de CVC infectou tanto plantas de citros quanto de café, mas desenvolveu populações mais baixas em cafeeiro. O isolado de ARC não colonizou citros. A inoculação de plantas de café com o isolado de CVC resultou em baixas taxas de infecção e exigiu uma concentração de inóculo dez vezes mais alta que a necessária para obter uma taxa de infecção semelhante (25%) em citros. A reduzida taxa de infecção e a baixa população bacteriana do isolado de CVC em cafeeiro em relação a citros sugerem que cafeeiro não é um hospedeiro adequado para atuar como fonte de inóculo da estirpe de CVC para disseminação deste patógeno para pomares de laranja ou dentro de cafezais.
Resumo
Citrus variegated chlorosis (CVC) and coffee stem atrophy (CSA) are important diseases in Brazil associated with closely-related strains of Xylella fastidiosa, but little is know about host aoverlappingnd importance of citrus and coffee as inoculum sources of these strains. In this study, reciprocal-inoculation experiments were performed to determine if CVC and CSA isolates are biologically similar within citrus and coffee plants. These two hosts were mechanically inoculated with a CVC and a CSA isolate of X. fastidiosa at four concentrations ranging between10³ and 10(9) colony forming units CFU mL-1. At two, four and eight months after inoculation, the infection efficiency and bacterial populations of the isolates in each host were determined by culturing. The CVC isolate infected both citrus and coffee plants, but developed lower populations in coffee. The CSA isolate did not colonize citrus. Inoculation of coffee plants with the CVC isolate resulted in low rates of infection and required an inoculum concentration ten-fold higher than that necessary to obtain a similar (25%) rate of infection in citrus. The relatively low infection rates and bacterial numbers of the CVC isolate in coffee plants compared with those observed in citrus suggest that coffee is not a suitable host to serve as a source of inoculum of the CVC strain for primary spread to citrus or within coffee plantations.
Clorose variegada dos citros (CVC) e atrofia dos ramos do cafeeiro (ARC) são doenças importantes no Brasil, associadas a estirpes de Xylella fastidiosa que são geneticamente próximas. Entretanto, pouco se sabe a respeito de plantas hospedeiras em comum e da importância de citros e cafeeiro como fontes de inóculo dessas estirpes. Neste estudo, realizaram-se experimentos de inoculação recíproca para determinar se isolados de X. fastidiosa de CVC e de ARC são biologicamente semelhantes em plantas de citros e café. Estes dois hospedeiros foram mecanicamente inoculados com um isolado de CVC e um isolado de ARC, em quatro concentrações que variaram de 10³ a 10(9) unidades formadoras de colônias UFC mL-1. Aos dois, quatro e oito meses após a inoculação, a eficiência de infecção e a população bacteriana dos isolados em cada hospedeiro foram determinadas por cultura. O isolado de CVC infectou tanto plantas de citros quanto de café, mas desenvolveu populações mais baixas em cafeeiro. O isolado de ARC não colonizou citros. A inoculação de plantas de café com o isolado de CVC resultou em baixas taxas de infecção e exigiu uma concentração de inóculo dez vezes mais alta que a necessária para obter uma taxa de infecção semelhante (25%) em citros. A reduzida taxa de infecção e a baixa população bacteriana do isolado de CVC em cafeeiro em relação a citros sugerem que cafeeiro não é um hospedeiro adequado para atuar como fonte de inóculo da estirpe de CVC para disseminação deste patógeno para pomares de laranja ou dentro de cafezais.
Resumo
Composting is a natural biological process that degrades organic matter which is carried out spontaneously by aerobic microorganisms, whose metabolic action leads to the mineralization and partial humification of organic residue. The aim of this study was to investigate survival of potentially pathogenic bacterial species throughout the process and detection of enterotoxigenic Escherichia coli (ETEC) in the compost using PCR. The presence of heterotrophic bacteria, total total and fecal coliforms, and bacteria succession were also de detrermined. Out of the total 222 bacterial colonies isolated, 33 different genera and 56 different species were identified, being Bacillus, Escherichia, Enterobacter, and Pseudomonas, the prevailing genera. Total coliform counts ranged between 9.0 x 104 and 3.0 x 106 cfu/g, and fecal coliform counts between 1.0 x 104 and 2.3 x 106 cfu/g. The composting process was partially efficient, since even though coliform counts were reduced, enterotoxigenic E. coli was detected in mature compost.
Resumo
Composting is a natural biological process that degrades organic matter which is carried out spontaneously by aerobic microorganisms, whose metabolic action leads to the mineralization and partial humification of organic residue. The aim of this study was to investigate survival of potentially pathogenic bacterial species throughout the process and detection of enterotoxigenic Escherichia coli (ETEC) in the compost using PCR. The presence of heterotrophic bacteria, total total and fecal coliforms, and bacteria succession were also de detrermined. Out of the total 222 bacterial colonies isolated, 33 different genera and 56 different species were identified, being Bacillus, Escherichia, Enterobacter, and Pseudomonas, the prevailing genera. Total coliform counts ranged between 9.0 x 104 and 3.0 x 106 cfu/g, and fecal coliform counts between 1.0 x 104 and 2.3 x 106 cfu/g. The composting process was partially efficient, since even though coliform counts were reduced, enterotoxigenic E. coli was detected in mature compost.
Resumo
Composting is a natural biological process that degrades organic matter which is carried out spontaneously by aerobic microorganisms, whose metabolic action leads to the mineralization and partial humification of organic residue. The aim of this study was to investigate survival of potentially pathogenic bacterial species throughout the process and detection of enterotoxigenic Escherichia coli (ETEC) in the compost using PCR. The presence of heterotrophic bacteria, total total and fecal coliforms, and bacteria succession were also de detrermined. Out of the total 222 bacterial colonies isolated, 33 different genera and 56 different species were identified, being Bacillus, Escherichia, Enterobacter, and Pseudomonas, the prevailing genera. Total coliform counts ranged between 9.0 x 104 and 3.0 x 106 cfu/g, and fecal coliform counts between 1.0 x 104 and 2.3 x 106 cfu/g. The composting process was partially efficient, since even though coliform counts were reduced, enterotoxigenic E. coli was detected in mature compost.