RESUMO
In this paper, the lytic activity of two variants of Serratia marcescens against promastigotes of Leishmania braziliensis was studied. In vitro assays showed that S. marcescens variant SM365 lyses L. braziliensis promastigotes, while the variant DB11 did not. Scanning electron microscopy (SEM) revealed that S. marcescens SM365 adheres to all cellular body and flagellum of the parasite. Several filamentous structures were formed and identified as biofilms. After 120min incubation, they connect the protozoan to the developing bacterial clusters. SEM also demonstrated that bacteria, adhered onto L. braziliensis promastigote surface, formed small filamentous structures which apparently penetrates into the parasite membrane. d-mannose protects L. braziliensis against the S. marcescens SM365 lytic effect in a dose dependent manner. SM365 variant pre cultivated at 37 degrees C did not synthesize prodigiosin although the adherence and lysis of L. braziliensis were similar to the effect observed with bacteria cultivated at 28 degrees C, which produce high concentrations of prodigiosin. Thus, we suggest that prodigiosin is not involved in the lysis of promastigotes and that adherence promoted by bacterial mannose-sensitive (MS) fimbriae is a determinant factor in the lysis of L. braziliensis by S. marcescens SM365.
Assuntos
Fímbrias Bacterianas/metabolismo , Leishmania braziliensis/metabolismo , Prodigiosina/metabolismo , Serratia marcescens/fisiologia , Animais , Aderência Bacteriana , Carboidratos/farmacologia , Fímbrias Bacterianas/efeitos dos fármacos , Cinética , Leishmania braziliensis/efeitos dos fármacos , Leishmania braziliensis/ultraestrutura , Manose/farmacologia , Microscopia Eletrônica de Varredura , Prodigiosina/isolamento & purificação , Serratia marcescens/química , Serratia marcescens/ultraestruturaRESUMO
Studies on the lysis of L. chagasi caused by the bacteria Serratia marcescens were carried out. In vitro experiments demonstrated that S. marcescens variant SM 365, a prodigiosin pigment producer, lysed this species of Leishmania but variant DB11, a nonpigmented bacteria, was unable to lyse the parasite. High concentrations of d-mannose were found to protect L. chagasi markedly diminishing the lysis by S. marcescens SM 365. Promastigotes of L. chagasi bound the lectin Concanavalin A conjugated with FITC, the fluorescence was intensely found at the base of the flagellum (flagellar pocket). Scanning electron microscopy revealed that the bacteria adherence occurred mainly in the flagellar pocket. S. marcescens SM 365 formed filamentous structures, identified as biofilms, which connect the protozoan to the developing bacterial clusters, in low concentrations of bacteria after 30 min incubation time. We suggest that bacterial mannose-sensitive (MS) fimbriae are relevant to S. marcescens SM 365 in the lysis of L. chagasi.
Assuntos
Leishmania infantum/microbiologia , Serratia marcescens/fisiologia , Animais , Aderência Bacteriana/fisiologia , Biofilmes , Concanavalina A/química , Relação Dose-Resposta a Droga , Fímbrias Bacterianas/fisiologia , Flagelos/microbiologia , Flagelos/ultraestrutura , Fluoresceína-5-Isotiocianato/análogos & derivados , Fluoresceína-5-Isotiocianato/química , Interações Hospedeiro-Patógeno , Cinética , Leishmania infantum/metabolismo , Leishmania infantum/ultraestrutura , Manose/metabolismo , Manose/farmacologia , Microscopia Eletrônica de Varredura , Microscopia de Fluorescência , Microscopia de Interferência , Serratia marcescens/ultraestruturaRESUMO
A few days after blood meal the number of bacteria in the anterior midgut (stomach) of Rhodnius prolixus, a vector of Trypanosoma cruzi, the causative agent of Chagas' disease, increases dramatically. Many of the bloodstream trypomastigotes of the pathogenic protozoan as well as ingested erythrocytes are lysed in the stomach. Incubation of T. cruzi with Serratia marcescens variant SM365, lead to parasite lysis. In the present study, this bacterium rapidly adhered to the protozoan surface through d-mannose recognizing fimbriae and rapidly induced its complete lysis. In contrast, the DB11 variant of the same bacterial species did not adhere and did not induce protozoan lysis. Scanning and transmission electron microscopy revealed that following bacteria-protozoan attachment there is an assembly of long filamentous structures, identified as a biofilm, which connect the protozoan to the bacteria forming bacterial clusters. We conclude that parasite lysis and biofilm formation mechanisms are important for understanding parasite-microbiota interactions in the gut of insect vectors of trypanosomatids.
Assuntos
Aderência Bacteriana/fisiologia , Biofilmes/crescimento & desenvolvimento , Serratia marcescens/fisiologia , Trypanosoma cruzi/microbiologia , Animais , Insetos Vetores/microbiologia , Insetos Vetores/parasitologia , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Microscopia de Vídeo , Rhodnius/microbiologia , Rhodnius/parasitologia , Serratia marcescens/ultraestrutura , Trypanosoma cruzi/ultraestruturaRESUMO
Pollution of aquatic systems by heavy metals has resulted in increasing environmental concern because they cannot be biodegraded. One metal that gives reason for concern due to its toxicity is chromium. Cr(VI) and Cr(III) are the principal forms of chromium found in natural waters. A chromate-resistant strain of the bacterium S. marcescens was isolated from tannery effluent. The strain was able to reduce Cr(VI) to Cr(III), and about 80% of chromate was removed from the medium. The reduction seems to occur on the cell surface. Transmission electron microscopic examination of cells revealed that particles were deposited on the outside of bacterial cells. A stable biofilm was formed in less than 10 h, reaching around 1010 cfu attached per milligram of activated carbon. These findings demonstrate that immobilized S. marcescens might be used in industrial waste treatment processes.