Revista de la Asociacion Argentina de Microbiologia最新文献

The influence of culture medium composition and operative conditions on the cellular growth of Rhizobium sp (group Lotus) strain is studied. As much as 1 x 10(9) cell/ml were obtained in 16 hours using sucrose in the medium as carbon source. The best growth rate was obtained (mu = O,22 h-1) when the experiments were performed at 400 r.p.m. and one volume of air/volume of medium x minute (OAR = 793,0 ml of oxygen/1 h).

Using a strain of Ps. aeruginosa (A.T.C.C. 10.145), several preparations were obtained: cytoplasm, cellular wall, extract with veronal buffer and carbohydrates. A morphologic and biochemical study of the bacterium was performed and the soluble fractions were analysed by electrophoresis in poliacrilamide gel with strains for proteins, carbohydrates and lipids. The results led the following conclusions: 1. -Electrophoresis of cytoplasm in poliacrilamide gel made it possible to recognize 17 proteic, 9 carbohydrate and 3 lipid fractions. 2. -Eight of the protein fractions were combined with carbohydrates and 9 were proteins. 3. -The extract obtained with veronal buffer showed 12 protein, 7 carbohydrate and 4 lipid fractions. 4. -The seven carbohydrate fractions were combined with proteins. 5. -Five of the cytoplasm proteins fractions were not extracted with veronal buffer; two protein fractions extracted by veronal buffer were not from cytoplasm. 6. -Heating the extract obtained with veronal buffer determined the loss of most of the fractions extracted probably due to denaturalizations of the proteins. 7. -The heated extract obtained with veronal buffer showed diffuse bands coloured with protein, carbohydrate and lipid strains.

In the course of a study on antibiotic activity of microorganisms isolated from soil samples from Port Stanley, Islas Malvinas, Argentina, four thermophilic Actinomycetes were sudied. The four strains had the same morphological and physiological characteristics. The new species belonged to Seccion Rectiflexibilis genus Streptomyces and had the following characteristics: sporophores straight, round spores of 1,5 or 2 millimicron in diameter. The colonies in agar meat peptone were round, flat, mealy, with fimbriate edges, odorless, friable, easy to emulsify and the aerial mycelium was white to light gray. The sporulation was rapid (less of 24 hours at 50 degrees C), the microorganisms grew in media with organic nitrogen and his ability to utilize carbon was scarce, only a trace of growth was detected with manitol (20 days at 50 degrees C). No growth was observed in gliceril-asparagine agar and the utilization of glucose was scarce or absent. It produced coagulation and peptonization of milk and liquifaction of gelatin. Neither was starch hidrolized nor nitrate reduced. The optimun growth temperature was between 45 - 60 degrees C. Very resistant to high temperatures having a thermal death point of more that 2 hours at 100 degrees C. It produced SH2.

On a commercial poultry farm, a large percentage (9%) of clinically healthy fowls had positive reaction to the plate test, with commercial polyvalent pullorum antigens. We could not isolate Salmonella from the positive birds. An strain, of Escherichia coli Balcarce (E. coli B) was isolated from the feces of one of the birds. The isolate was identified biochemically and the antigenic study showed correlation with E. coli 044 and the somatic fraction 1, 2, 8, 14 and 23 of the Salmonella genus. The common antigens were studied by agglutination, absorption and crossed immunodiffusion tests, comparing the isolated strain and the different Salmonella serotypes. Four pullorum polyvalent commercial antigens reacted with sera containing somatic agglutinins 1, and with the E. coli B antiserum. These observations confirm the high antigenic correlation between the genus of the Enterobacteriaceae family. It is indicated that for the diagnosis of avian salmonelosis rather than using a single serological tests, the isolation and identification of the etiological agent is required.

In the rural area of Las Higueras, Río Cuarto, Córdoba, Argentina, a trypanosoma was isolated from a wild rodent (C. musculinus). The trypanosome was classified as Trypanosoma cruzi because of the following characteristics: morphology as described by Hoare for the Schizotrypanum sub-genus: thin shaped, pointed back end, nucleus placed approximately in the middle of the body, prominent and subterminal kinetoplast and short free flagellum. The size measurements were as follows: total lengh 22.02 +/- 0.40 micron, flagellum lengh 5.93 +/- 0.29 mu, Nuclear mean index (NP/NA) 1,21 +/- 0.07 (Table 1). For some authors, this last value is very important for diagnosis of the parasite. BALB/c albino mice were infected with blood of the captured animal; those mice showed a mild parasitemia and amastigotes nests in cardiac fiber (Fig 2 a y b). The xenodiagnosis performed with nimphs of Triatoma infestans on the laboratory mice was positive. The trypanosome grew very well in blood-agar medium. According with these findings along with the wide geographic distribution and density of C. musculinus in Argentina, one should wonder whether or not this rodent is infested withT. cruzi on its whole distribution range. Passages through T. infestans and laboratory mice produced a virulence enhancement of this strain. With these findings, the question is if this situation should take place in nature, affecting domestic animals in any way. The stated questions and findings should estimulate further research on the role of the wild fauna in the epidemiclogy of Chagas' disease in Argintina.

Supernatants from Vero cells persistently infected with Junin virus interfered with cytolitic and lethal activities of standard virus. Two Vero cell sublines, chronically infected with Junin virus named VRJ1 and VRJ3, were obtained after prolonged cultivation of cells which survived primary infection. VFJ1 was maintained over a period of 48 days, by biweekly serial transfers while VRJ3, similarly treated, was cultivated for 385 days. One of the characteristics of these cell lines was resistance against superinfection with homologous virus that ordinaily produced CPE and plaques in normal Vero cells; the cells were then considered chronically infected. Supernatants taken at different cell passage level were tested for its interference activity after centrifugation to eliminate floating cells and debris. The degree of CPE intensity caused by inoculation of Vero cells with 10(4), 10(5) or 10(6) TCID 50 of standard virus was markdely deppressed (Figure 1) by coinfection with supernatant from passage 3 of VRJ3 (VRJ1p1), VRJ1p1 supernatant also had interference activity as shown by coinfection with standard virus and expressed by plaque forming inhibition(Table 1). The plaque production of standard virus was inhibited by coinfection with VRJ1p1 supernatant which did not originate plaques when inoculated alone. The interference capacity of VRJ1p6 supernatant was reduced (Table 1) coincidentally with the formation of 55 PFU/ml. Interference activity was neutralized by Junin specific antiserum and inhibited by chloroform treatment. When Vero cells infected with VRJ1p6 supernatant were challenged with standard virus 72 hs later, an inhibition of 98% was achieved (Table 2) in contrast with value of 35% showed in Table 1.

The degranulating capacity of guinea pig peritoneal serous membrane mast-cells due to IgG1 and reaginic homocytotropic antibodies and heterocytotropic rabbit IgG antibody was studied, as was the interference which nonspecific immunoglobulins may produce in the fixation of antibodies. Although the capacity to degranulate mast-cells proved identical for all the antibodies studied, reagin appears to possess a greater fixation capacity for a possible cellular membrane site. The greater resistence of reagin to elimination by washing could account for this.