Revista latinoamericana de microbiologia最新文献

Living organisms are exposed in nature to heavy metals, commonly present in their ionized species. These ions exert diverse toxic effects on microorganisms. Metal exposure both selects and maintains microbial variants able to tolerate their harmful effects. Varied and efficient metal resistance mechanisms have been identified in diverse species of bacteria, fungi and protists. The study of the interactions between microorganisms and metals may be helpful to understand the relations of toxic metals with higher organisms such as mammals and plants. Some microbial systems of metal tolerance have the potential to be used in biotechnological processes, such as the bioremediation of environmental metal pollution or the recovery of valuable metals. In this work we analyze several examples of the interactions of different types of microbes with heavy metals; these cases are related either with basic research or with possible practical applications.

Sanitary Microbiology is a science based on the detection of risks associated with the production, manufacture and consumption of foods and water. It has been established that environment facts determine the survival, growing and inactivation of the microorganisms. These risks are commonly associated with the presence of microbiological hazards and represent a serious problem from the Public Health viewpoint. The types of microorganisms presents in products will depend of the way they have been elaborated, transportated, stored, taking or prepared before eating. The guarantee of safety foods have impacted both to single and collective level: and also in economics. socials and sanitaries aspects. The sanitary microbiology like a science must be in context to the regional and national needs. with an important vinculation between different sectors of the society such as academy, industry and government, taking care of infrastructure and qualified personal, based on novel technology, actualized normative and making basical and applied research. The application of novel technology for the microbiological analysis of water and foods allows to show the microbial risk and also identify practices that compromise the safety of themself, with the final proposes of diminish or eliminate healthy risk due the food consumption.

This review presents the studies on Salmonella conducted by three research groups in Mexico. Each of these groups belongs to different but complementary disciplines. The need for continuous epidemiological surveillance of Salmonella throughout the food chain, in conjunction with molecular typing of the isolates is discussed. The epidemiological and molecular findings should serve as the basis for a national or regional control program that includes the development of specific vaccines. The information can also be used to develop rapid and specific diagnostic tests.

In the last decade, a significant increase in the antimicrobial resistance of clinical specimens of Propionibacterium acnes to first line antibiotics used for acne treatment, has been informed in Europe and in the USA. No information about strains isolated from Latin-American countries is available. The antimicrobial susceptibility of 53 strains of P. acnes isolated from skin specimens of inflammatory acne patients, at the clinical Hospital University of Chile was tested. All isolates were susceptible to penicillin, minocycline, and nadifloxacin. Erythromycin and clindamycin resistance was found in 3.8 and 1.9% isolates respectively. Resistance to lymecycline was observed in one isolate, which was intermediate to tetracycline and doxycycline.

Infectious acute diarrhea (IAD) is an important health problem affecting a large number of Latin-American children. Several reports show that bacteria, parasites and virus are involved in the burden of this disease. Most reports reveal Rotavirus A as the responsible etiological agent, at the same time, there seems to be some correlation between IAD and seasonal weather changes. To learn about the type of microbial agents associated with IAD in children during mildly changing yearly climatic conditions, as found in a high altitude tropical city, and to identify the viral agents affecting this population, stool samples from 300 children under 5 years of age were studied throughout a one-year period. Bacteria and intestinal parasites were identified by routine methods, while viruses were detected and typed by EIA and PCR. 20.6% of the IAD studied was associated with bacteria; 9% with parasites and 40% with virus. Group C Rotavirus accounted for 20.2%, group A Rotavirus for 13% and Calicivirus 10%. During November-April (p < 0.007) more virus associated IAD was found, while bacteria (p < 0.03) or parasite (p < 0.00014) related IAD was prevalent from May to October. The mild seasonal weather changes don't seem to be associated with any other microbial agent.

Dove's excreta samples from state Bolívar several places in Venezuela, were evaluated to determine the presence of primary pathogen fungi in dove's excreta. Filamentous fungi such as: Aspergillus spp (31.1%), Mucor spp (20.2%), Penicillium spp (9.5%) and Fusarium spp (6.7%) were the most frequently isolated strains. Species such as Candida albicans (4.1%), Cryptococcus albidus and Rhodotorula spp (2.7%), C. neoformans var neoformans (1.4%), Trichosporum asahii (1.4%), Curvularia, Microsporum and Phoma as well as Histoplasma capsulatum (1.3%) were less frecuently isolated. This study shows the presence of C. neoformans and H. capsulatum in dove's excreta from Bolívar state, it remarks infection risk with these pathogens fungi and the necessity to avoid accumulation of dove's excreta.

Approximately 63 strains of Lactobacillus acidophilus were isolated from Egyptian home-made cheese and examined for production of antagonism. Only eight strains demonstrated inhibitory activity against spoilage microorganisms (i.e. Staphylococcus aureus and Bacillus cereus) and pathogens (i.e. E. coli, Salmonella sp. and Shigella sp.). Lactobacillus acidophilus AA11 produced a more antimicrobial activity with a wide range of inhibition. The agent AA11 was sensitive to proteolytic enzymes and retained full activity after 30 min at 100 degrees C. Activity against sensitive cells was bactericidal but not bacteriolytic. The compound was produced during growth phase and can be extracted from the culture supernatant fluids with n-Butanol. 12 % SDS-PAGE analysis of 40% ammonium sulphate precipitated agent showed two peptides with molecular weights of approximately 36 kDa and approximately 29 kDa. No plasmid was identified in Lactobacillus acidophilus AA11 indicating that the genes encoding the inhibitory agent located on the chromosome. These characteristics identify the inhibitory substance as a bacteriocin, designated acidocin AA11 and confer the agent an application potential as a biopreservative.

Polydnaviruses are genetic symbionts of wasp endoparasitoids belonging to the hymenopteran families Ichneumonidae (ichnoviruses) and Braconidae (bracoviruses). They exist as proviruses integrated in the wasp's chromosomal genome, which then excise and undergo replication during the stage of adult development of the wasp. During wasp oviposition into their caterpillar host, the fully formed virus particles are injected along the parasitoid's eggs into the host hemocoel, where the eggs hatch and undergo larval development. The primary function of the polydnavirus is to trigger host immunosuppression so that host hemocytes are prevented from encapsulating the parasitoid's eggs and/or larvae. Polydnavirus transcripts are expressed following parasitization and alter host hemocyte adhesive properties that prevents encapsulation; in some species, viral gene expression triggers host hemocyte apoptosis, thereby rendering the host immunosuppressed. This review summarizes the major features of polydnaviruses and provides a global view of their functions in the lepidopteran hosts of the parasitoid wasps that carry them both as integrated viral sequences in their genome and as free virus to function physiologically in host regulation following parasitization of the host.