RESUMEN
Transmission electron microscopy analysis (TEM) of the rickettsiales-like prokaryote, Candidatus Xenohaliotis californiensis (CXc), pathogen of Haliotis spp. from the West Coast of North America, were found to be infected by a bacteriophage hyperparasite previously described in red abalone from California. The hyperparasite has an icosahedrical-like capsid with a narrow long flexible tail, this morphological characteristic tentatively place this virus in the Family Siphoviridae from the order Caudovirales. TEM images also showed the bacteriophage in different stages of assembly in the cytoplasm of CXc, demonstrating its lytic cycle.
Asunto(s)
Alphaproteobacteria/virología , Bacteriófagos/ultraestructura , Alphaproteobacteria/ultraestructura , Animales , Bacteriófagos/aislamiento & purificación , Bacteriófagos/fisiología , Epitelio/microbiología , Epitelio/ultraestructura , Epitelio/virología , Gastrópodos/microbiología , Gastrópodos/virología , Microscopía Electrónica de TransmisiónRESUMEN
A survey of drainage ditches in suburban areas of La Plata, Buenos Aires province, Argentina for pathogens of Culex pipiens larvae was conducted from 2003 to 2006. C. pipiens larvae of opaque, white color were found in several of those field collections. When the white larvae were dissected and observed by phase-contrast microscopy in wet-mount preparations, the presence of bacteria, located in the hemocoel, was recorded. Laboratory experiments were performed to elucidate the pathway for transmission of this pathogen. Although approaches involving traditional culturing had failed to reveal the identity of the new microorganism present, molecular techniques to identify the pathogen in the studies reported here were successful. The partial sequence of the 16S-rRNA gene constitutes a powerful tool for the detection of new isolates from the hemocoele of C. pipiens larvae. These bacteria were characterized as belonging to the genus Novispirillum. In spite of the genus's wide distribution in different aquatic environments, information related to the parasitic relationship of Novispirillum spp. to aquatic insects is scarce, and this association has not been described in other mosquito species. This report constitutes the first documentation of Novispirillum spp. as a pathogen for mosquito larvae.
Asunto(s)
Alphaproteobacteria/aislamiento & purificación , Culex/microbiología , Monitoreo del Ambiente/métodos , Larva/microbiología , Alphaproteobacteria/clasificación , Alphaproteobacteria/genética , Alphaproteobacteria/ultraestructura , Animales , Argentina , Culex/citología , Hemolinfa/microbiología , Larva/citología , ARN Bacteriano/análisis , ARN Ribosómico 16S/análisis , Análisis de Secuencia de ARN , Microbiología del AguaRESUMEN
A Gram-negative, aerobic, mesophilic, non-spore-forming, chemotrophic, chlorophyll-lacking, nitrogen-fixing bacterium, designated strain USBA 355(T), was isolated from the saline spring 'Salado de Consotá' situated in the Colombian Andes. The non-flagellated cells of strain USBA 355(T) were straight to slightly curved rods (0.6-0.7 x 3.0-3.5 microm). Growth occurred optimally at 30 degrees C (growth temperature range between 20 and 40 degrees C), at pH 6.5-6.7 (pH growth range between 5.0 and 8.0) and at 0.5 % NaCl (w/v) (range between 0 and 4 %). The major quinone present was Q-10 and the predominant fatty acids identified were C(19 : 0) cyclo omega8c, C(18 : 1)omega7c and C(18 : 0). The G+C content of the chromosomal DNA was 71+/-1 mol%. 16S rRNA gene sequence analysis indicated that strain USBA 355(T) formed a distant phylogenetic line of descent with members of the genus Thalassobaculum, family Rhodospirillaceae, class Alphaproteobacteria (90 % gene sequence similarity). Comparison of the phylogenetic, chemotaxonomic and physiological features of strain USBA 355(T) with all other members of the family Rhodospirillaceae suggested that it represents a novel genus and species for which the name Tistlia consotensis gen. nov., sp. nov. is proposed. The type strain of the type species is USBA 355(T) (=JCM 15529(T)=KCTC 22406(T)).
Asunto(s)
Alphaproteobacteria/genética , Alphaproteobacteria/metabolismo , Alphaproteobacteria/aislamiento & purificación , Alphaproteobacteria/ultraestructura , Colombia , ADN Bacteriano/genética , Amplificación de Genes , Genes Bacterianos , Manantiales de Aguas Termales/microbiología , Microscopía Electrónica , Datos de Secuencia Molecular , Fijación del Nitrógeno , Reacción en Cadena de la PolimerasaRESUMEN
Chlorella vulgaris, a microalga often used in wastewater treatment, was coimmobilized and coincubated either with the plant growth-promoting bacterium Azospirillum brasilense, or with its natural associative bacterium Phyllobacterium myrsinacearum, in alginate beads designed for advanced wastewater treatment. Interactions between the microalga and each of the bacterial species were followed using transmission electron microscopy for 10 days. Initially, most of the small cavities within the beads were colonized by microcolonies of only one microorganism, regardless of the bacterial species cocultured with the microalga. Subsequently, the bacterial and microalgal microcolonies merged to form large, mixed colonies within the cavities. At this stage, the effect of bacterial association with the microalga differed depending on the bacterium present. Though the microalga entered a senescence phase in the presence of P. myrsinacearum, it remained in a growth phase in the presence of A. brasilense. This study suggests that there are commensal interactions between the microalga and the two plant associative bacteria, and that with time the bacterial species determined whether the outcome for the microalga is senescence or continuous multiplication.