Aislamiento de Streptomyces ssp: productores de antibióticos de suelos de Magallanes, XII Región de Chile / Isolation of Streptomyces: producing antibiotics from soils of Magallanes, XII Region of Chile

Muchas cepas de Actinomycetes sintetizan compuestos biodinámicos que se aprovechan como antimicrobianos o sustancias líticas o degradativas de moléculas resistentes, por lo cual se los ha pesquisado en los suelos más diversos del mundo y sobre todo en zonas aún no perturbadas por la acción del humano. Los suelos chilenos y en especial los de la XII (Magallanes) presentan características únicas, por factores climaticos y de aislamiento y tienen una diversidad característica. En esta investigación se estudiaron muestras de suelos de siete estaciones continentales de la XII Región. De 65 muestras de suelos obtenidas, 73.8 por ciento resultaron positivas, aislándose 86 cepas de Streptomyces. Se ensayó la actividad antibiótica mediante la técnica de discos KÅster y Williams y se encontró que el 59.3 por ciento presentaron actividad para algunas de las cepas de referencia, observándose una mayor frecuencia inhibitoria sobre Staphylococcus areus y Bacillus subtilis simultáneamente. Se realizó la extracción de los productos activos mediante solventes de distinta polaridad. Los extractos de n-hexano y cloroformo resultaron ser los más activos.

Efecto antibiótico de cepas silvestres de Streptomyces aisladas de suelos chilenos / Antimicrobial effect of wild Streptomyces strains isolated from chilean soils

Background: the solts of the southern part of Chile, that are isolated, cold, humid, poorly axygenated and with a low acitity, could contain new strains of antimicrobial producing Streptomyces strains with antimicrobial activity towards pathogenic bacteria and fungi. Material and methods: two hundred fifty eight soil and sediment samples were collected from 148 paces in Souther regions of Chile. They were cultured in Kuster-Williams growth media and the presence of Streptomyces was confirmed by microscopic examination and biochemical characterization. The antimicrobial activity against reference microorganisms. Results: Seventy seven percent of soils were positive and 542 wild strains of Streptomyces were isolates; of these, 266 had antimicrobial activity. Fifty three percent of isolates had activity against S aureus 43 percent against B subtilis and 0.7 percent against E coli. Most Streptomyces were active against more than one organism. When there was activity against single organisms, these were mostly eucariotic, such as C albicans and T mentagrophytes. Among clinical microorganisms, 29 percent of S aureus strains were inhibited, while P aeruginosa, Alternaria sp, P vulgaris and Y enterocolitica strains were not inhibited. The most frequent Streptomyces morphotypes were those showing pigmented colonies with flexuous and spiral shaped chains of arthopores. Conclusions: soils of the southern region Chile allow the grouth of abundant native strains of Streptomyces with a promising anticrobial activity

Bacteriocinogenia, un sistema de antagonismo bacteriano / Bacteriocinogenia, a system for bacterial antagonism

Bacterial antagonism depends on many factors. Among others, for example we have competition for an essential nutrient, the production of toxic metabolites or the release of antibiotic substances. The production of bacteriocines by "killer" strains correspons to the latrer, being determined by plasmidial or chromosomal genes. On the other hand, the susceptibility to a given bacteriocine depends on the presence of surface recptors that are codified by the cellular DNA. The bacteriocine particles correspond to protein conglomerates which are sometimes associated with glucolipids. With the death of the productive cell, these particles are livated motivated by synthesis. The similarities which they share with the bacteriophage are many. However, their fundamental differences are that they lack nuclic acid and their incapcity to transmit themselves. Cellular death caused by the action of the bacteriocine is extremely quck, acting on the permeability of the plasmatic membrane, on the macromolecular syntesis (DNA, RNA an proteins) and on cellular oxidation. The wide range of bacteriocine and their respective spectre of action over the more or less related strains are excellent parameters to detect, identify and classify the productive bacteria and the susceptible ones. With only a few exceptions, the bacteriocines not lethal to their own productive cell nor to taxonomically distant species. This has led to intersting ecological and epidemiological outlooks. The amplitude of this phenomenon in Gram+ and Gram- bacteria has led to the study of fine mechanisms which have triggered the genetic expression to elaborate bacteriocines, determining the one responsible for this are the genes and localized signals in transmissible episomes or in chromosomal operons

Espectro bactericida de piocinas sobre cepas colectadas en hospitales de las regiones IX y X de Chile / Bactericidal effects of pyocins upon strains isolated in different hospitals of the IX and X region, Chile

The inhibitory effect of 5 pyocins produced by wildstrains of Ps aeruginosa was tested by qualitative and quantitative techniques. 313 strains of 4 species: E coli, P vulgaris, Ps aeruginosa and St aureus were assayed. It was shown that the most active pyocin was P37, which inhibited 276 out of 313 strains tested. About 80% of E. coli and 90% os St aureus strain were inhibited by the pyocins uner being tested. It was established that sensitivity to pyocin was not restricted to close-related species but extends to unrelated families also