RESUMO
The marine toxic dinoflagellate Ostreopsis lenticularis has been implicated as the major vector in ciguatera seafood poisoning on the southwest coast of Puerto Rico. Studies have demonstrated that associated bacteria play a role in the ciguatoxin production and that different clonal cultures of O. lenticularis harbor different culturable bacteria. In this study, more than 125 associated bacteria from two toxic clonal cultures of O. lenticularis (no. 302 and no. 303) were analyzed utilizing polymerase chain reaction amplification of the partial small subunit ribosomal DNA (rRNA), denaturing gradient gel electrophoresis, and DNA sequencing. Approximately 50% of total bacteria identified in both cultures were a single species belonging to the Cytophaga-Flavobacter-Bacteroides complex. This bacterium was also found in six new O. lenticularis clonal cultures established 10 years after the original cultures used in this study and absent from a clonal culture of a different dinoflagellate species. The data presented here indicate a persistent and apparently specific association of this bacterium with O. lenticularis, which makes it a candidate involved in ciguatoxin production.
Assuntos
Bactérias/classificação , Dinoflagellida/microbiologia , Toxinas Marinhas , Animais , Bactérias/genética , Bactérias/crescimento & desenvolvimento , Bactérias/isolamento & purificação , Células Clonais , Filogenia , RNA Ribossômico 16S/genéticaRESUMO
Flavinogenic yeasts such as Debaryomyces hansenii overproduce riboflavin (RF) in the presence of heavy metals. Growth and RF production were compared between wild-type D. hansenii and a RF production-impaired metal-tolerant ura3 mutant in the presence of sublethal cobalt(II) concentrations. Debaryomyces hansenii (wild type) exhibits an extended lag phase with an increase in RF synthesis. Supplementation of exogenous uracil shortened the lag phase at the highest concentration of cobalt(II) used, suggesting that uracil has a possible role in metal acclimation. The D. hansenii ura3 mutant isolated by chemical mutagenesis exhibited a higher level of metal tolerance, no extended lag phase, and no marked increase in RF synthesis. Transformation of the mutant with the URA3 gene isolated from Saccharyomyces cerevisiae or D. hansenii did not restore wild-type characteristics, suggesting a second mutation that impairs RF oversynthesis. Our results demonstrate that growth, metal sensitivity, and RF biosynthesis are linked.
Assuntos
Cobalto/farmacologia , Riboflavina/biossíntese , Saccharomycetales/efeitos dos fármacos , Regulação Fúngica da Expressão Gênica , Mutação/genética , Saccharomycetales/genética , Saccharomycetales/crescimento & desenvolvimento , Saccharomycetales/metabolismoRESUMO
The toxic benthic dinoflagellate Ostreopsis lenticularis hosts a variety of symbiont bacterial flora. Laboratory cultured Ostreopsis clones require the presence of symbiotic Pseudomonas/Alteromonas bacterial strains for growth and toxicity development. Three culturable bacterial strains associated with Ostreopsis were identified as Pseudomonas/Alteromonas strain 1, Pseudomonas/Alteromonas strain 2 and Acinetobacter. Denaturing gradient gel electrophoresis (DGGE) analyses of extracted Ostreopsis associated bacterial DNAs indicated that there were three culturable and four non-culturable associated bacterial strains. The results presented here are the first report of the presence of unculturable bacterial symbionts in a toxic benthic dinoflagellate. Ostreopsis lost toxicity when exposed to elevated temperatures in the field and laboratory culture and subsequently recovered toxicity at reduced temperatures. Ostreopsis associated culturable Pseudomonas/Alteromonas bacterial strains were significantly reduced in dinoflagellate cultures exposed to elevated temperatures. The decreased toxicity of O. lenticularis exposed to elevated temperatures and their subsequent recovery of toxicity in periods of reduced thermal stress may have resulted from the effects of elevated temperature on the spectrum of culturable and unculturable bacterial species interacting with their Ostreopsis host.
Assuntos
Bactérias/crescimento & desenvolvimento , Dinoflagellida/microbiologia , Simbiose/fisiologia , Acinetobacter/genética , Acinetobacter/crescimento & desenvolvimento , Acinetobacter/isolamento & purificação , Adaptação Fisiológica , Alteromonas/genética , Alteromonas/crescimento & desenvolvimento , Alteromonas/isolamento & purificação , Animais , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Técnicas Bacteriológicas , DNA Bacteriano/genética , DNA Bacteriano/isolamento & purificação , Interações Hospedeiro-Parasita , Toxinas Marinhas/biossíntese , Toxinas Marinhas/toxicidade , Pseudomonas/genética , Pseudomonas/crescimento & desenvolvimento , Pseudomonas/isolamento & purificação , Especificidade da Espécie , Microbiologia da ÁguaRESUMO
Several bacteria from the islands of Puerto Rico, Vieques and Trinidad were isolated for their carbohydrate degrading activities. These terrestrial and marine bacterium were collected from pineapple agricultural lands, tropical rain forests, coastlands and mangrove swamps. Organisms were screened for activity using chromogenic substrates (AZCL Megazyme International Ltd., Ireland). The media composition for the effective culturing of some of the marine organisms has also been standardized. Gram-negative organisms were identified by sequence analysis of the PCR- amplified partial small subunit rRNA gene. Results indicate that the majority of the marine organisms tested belong to the genera Vibrio and Pseudoalteromonas and in the terrestrial environmentsChryseobacterium predominated. These experiments reveal that sub-tropical environments are potentially good sources of microorganisms with novel carbohydrase activities
Assuntos
Carboidratos , Bactérias Gram-Negativas , Compostos Cromogênicos , DNA Bacteriano , Bactérias Gram-Negativas , Reação em Cadeia da Polimerase , RNA Ribossômico 16SRESUMO
Studies were conducted to assess the factors that may influence the rate and extent of biodegradation of biphenyl, naphthalene, phenanthrene, pentachlorophenol (PCP) and p-nitrophenol in water samples collected from the Guayanilla Bay (18 degrees N; 67.45 degrees W), southwest of Puerto Rico. In vitro studies mediated slow degradation of biphenyl, naphthalene and phenanthrene substrates by natural microbial flora present in the Bay. Addition of KNO(3) as a source of inorganic N greatly enhanced the degradation of phenanthrene but not of naphthalene, suggesting that effects on degradation due to nutrient limitation were compound specific. The rate and extent of degradation of naphthalene and PCP were higher in water samples collected closer to the source of contamination, i.e. the petrochemical complex. The identity of a phenanthrene degrading bacterium, previously identified by conventional phenotypic method (Zaidi et al., Utilizing Nature's Advanced Materials, Oxford Unviersity Press, 1999) as Alteromonas sp., was confirmed by partial DNA sequencing of the small subunit rRNA gene.
Assuntos
Hidrocarbonetos/metabolismo , Microbiologia da Água , Poluentes Químicos da Água/metabolismo , Biodegradação Ambiental , Monitoramento Ambiental , Compostos Orgânicos/metabolismo , Porto Rico , Água do Mar/químicaRESUMO
Several bacteria from the islands of Puerto Rico, Vieques and Trinidad were isolated for their carbohydrate degrading activities. These terrestrial and marine bacterium were collected from pineapple agricultural lands, tropical rain forests, coastlands and mangrove swamps. Organisms were screened for activity using chromogenic substrates (AZCL Megazyme International Ltd., Ireland). The media composition for the effective culturing of some of the marine organisms has also been standardized. Gram-negative organisms were identified by sequence analysis of the PCR- amplified partial small subunit rRNA gene. Results indicate that the majority of the marine organisms tested belong to the genera Vibrio and Pseudoalteromonas and in the terrestrial environments Chryseobacterium predominated. These experiments reveal that sub-tropical environments are potentially good sources of microorganisms with novel carbohydrase activities.