RESUMO
The present study was conducted to examine the morphology and antigenicity of Photobacterium damselae subsp. piscicida by culturing the bacterium in vivo in the peritoneal cavity of sea bass (Dicentrarchus labrax) within dialysis bags with either a low molecular weight (LMW) cut-off of 25 kDa or a high molecular weight (HMW) cut-off of 300 kDa. Differences were observed in the growth rate between the bacteria cultured in vivo or in vitro. Bacteria cultured in vivo were smaller and produced a capsular layer, which was more prominent in bacteria cultured in the HMW bag. Antigenicity was examined by Western blot analysis using sera from sea bass injected with live Ph. d. subsp. piscicida. The sera recognised bands at 45 and 20 kDa in bacteria cultured in vivo in the LMW bag. Bacteria cultured in vivo in the HMW bag did not express the 45 kDa band when whole cell extracts were examined, although the antigen was present in their extracellular products. In addition, these bacteria had a band at 18 kDa rather than 20 kDa. Differences in glycoprotein were also evident between bacteria cultured in vitro and in vivo. Bacteria cultured in vitro in LMW and HMW bags displayed a single 26 kDa band. Bacteria cultured in the LMW bag in vivo displayed bands at 26 and 27 kDa, while bacteria cultured in vivo in the HMW bag possessed only the 27 kDa band. These bands may represent sialic acid. The significance of the changes observed in the bacterium's structure and antigenicity when cultured in vivo is discussed.
Assuntos
Animais , Variação Antigênica/genética , Antígenos de Bactérias/genética , Bass/imunologia , Western Blotting , Carboidratos/análise , Eletroforese em Gel de Poliacrilamida , Membranas Artificiais , Microscopia Eletrônica de Transmissão , Ácido N-Acetilneuramínico/genética , Photobacterium/genéticaRESUMO
This study evaluates the effectiveness of three different molecular techniques, repetitive extragenic palindromic PCR (REP-PCR), enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR) and the random amplified polymorphic DNA (RAPD-PCR) for rapid typing of Photobacterium damselae ssp. piscicida strains isolated from different species of marine fish and geographic areas. The results obtained by the three methods showed that RAPD and ERIC-PCR were more discriminative for suitable rapid typing of Ph. damselae ssp. piscicida than REP-PCR. The analysis of DNA banding patterns generated by both molecular methods (RAPD and ERIC-PCR) clearly separated the strains into two main groups that strongly correlated with their geographic origin. Moreover, the REP-PCR analysis was less reproducible than the RAPD and ERIC-PCR methods and does not allow the establishment of genetic groups. RAPD and ERIC-PCR constitute valuable tools for molecular typing of Ph. damselae ssp. piscicida strains, which can be used in epidemiological studies of photobacteriosis infections.
Assuntos
Animais , Técnicas de Tipagem Bacteriana/métodos , Impressões Digitais de DNA/métodos , Variação Genética , Photobacterium/classificação , DNA Bacteriano/genética , Peixes/microbiologia , Photobacterium/genética , Reação em Cadeia da Polimerase/métodos , Técnica de Amplificação ao Acaso de DNA Polimórfico , Sequências Repetitivas de Ácido Nucleico/genéticaRESUMO
A stable dark variant separated from photobacterium phosphoreum (A2) was fixed in agar-gel membrane and immobilized onto an exposed end of a fiber-optic linked with bioluminometer. The variant could emit a luminescent signal in the presence of genotoxic agents, such as Mitomycin C (MC). The performance of this whole-cell optical fiber sensor system was examined as a function of several parameters, including gel probe thickness, bacterial cell density, and diameter of the fiber-optic core and working temperature. An optimal response to a model genotoxicant, Mitomycin C, was achieved with agar-bacterial gel membrane: the thickness of gel membrane was about 5 mm; the cell density of bacteria in gel membrane was about 2.0 x 10(7)/ml; the diameter of fiber-optic core was 5.0 mm; the working temperature was 25 degrees C. Under these optimized conditions, the response time was less than 10 h to Mitomycin C, with a lower detection threshold of 0.1 mg/L.
Assuntos
Técnicas Biossensoriais , Medições Luminescentes , Tecnologia de Fibra Óptica , Proteínas Luminescentes/genética , Mitomicina/farmacologia , Mitomicina/toxicidade , Photobacterium/genética , Transcrição Gênica/efeitos dos fármacos , Variação GenéticaRESUMO
Bioluminescent bacteria are widespread in natural environments. Over the years, many researchers have been studying the physiology, biochemistry and genetic control of bacterial bioluminescence. These discoveries have revolutionized the area of Environmental Microbiology through the use of luminescent genes as biosensors for environmental studies. This paper will review the chronology of scientific discoveries on bacterial bioluminescence and the current applications of bioluminescence in environmental studies, with special emphasis on the Microtox toxicity bioassay. Also, the general ecological significance of bioluminescence will be addressed.
Assuntos
Bactérias/genética , Bactérias/química , Medições Luminescentes , Testes de Toxicidade/métodos , Técnicas Biossensoriais , Microbiologia Ambiental , Luciferases , Photobacterium/genética , Photobacterium/química , Vibrio/genética , Vibrio/químicaRESUMO
The luminous intensity of dark variant (S1) separated from photobacterium phosphoreum (A2) was 1/10,000 less than that of wild-type. Ethidium bromide (EB) (0.6 mg/L), Mytomycin C (MC, 0.05 mg/L), 2-amino fluorene (2-AF, 1.0 mg/L) all could strongly induce reversion mutation for S1 within 24 h and increase reversion ratio significantly. The results of experiments indicated that these revertants had stable genetic characteristic and the mutation may take place at gene levels. The mutagenesis to S1 caused by EB, MC and 2-AF was detected and it may be used as a new rapid, simple and sensitive method for gene toxicant monitoring.