RESUMEN
Despite recent studies, relatively few are known about the diversity of fungal communities in the deep Atlantic Ocean. In this study, we investigated the diversity of fungal communities in 15 different deep-sea sediments from the South Atlantic Ocean with a culturedependent approach followed by phylogenetic analysis of ITS sequences. A total of 29fungal strains were isolated from the 15 deep-sea sediments. These strains belong to four fungal genera, including Aspergillus, Cladosporium, Penicillium, and Alternaria. Penicillium, accounting for 44.8% of the total fungal isolates, was a dominant genus. The antiaflatoxigenic activity of these deep-sea fungal isolates was studied. Surprisingly, most of the strains showed moderate to strong antiaflatoxigenic activity. Four isolates, belonging to species of Penicillium polonicum, Penicillium chrysogenum, Aspergillus versicolor, and Cladosporium cladosporioides, could completely inhibit not only the mycelial growth of Aspergillus parasiticus mutant strain NFRI-95, but also the aflatoxin production. To our knowledge, this is the first report to investigate the antiaflatoxigenic activity of culturable deep-sea fungi. Our results provide new insights into the community composition of fungi in the deep South Atlantic Ocean. The high proportion of strains that displayed antiaflatoxigenic activity demonstrates that deep-sea fungi from the Atlantic Ocean are valuable resources for mining bioactive compounds.
RESUMEN
Despite recent studies, relatively few are known about the diversity of fungal communities in the deep Atlantic Ocean. In this study, we investigated the diversity of fungal communities in 15 different deep-sea sediments from the South Atlantic Ocean with a culturedependent approach followed by phylogenetic analysis of ITS sequences. A total of 29fungal strains were isolated from the 15 deep-sea sediments. These strains belong to four fungal genera, including Aspergillus, Cladosporium, Penicillium, and Alternaria. Penicillium, accounting for 44.8% of the total fungal isolates, was a dominant genus. The antiaflatoxigenic activity of these deep-sea fungal isolates was studied. Surprisingly, most of the strains showed moderate to strong antiaflatoxigenic activity. Four isolates, belonging to species of Penicillium polonicum, Penicillium chrysogenum, Aspergillus versicolor, and Cladosporium cladosporioides, could completely inhibit not only the mycelial growth of Aspergillus parasiticus mutant strain NFRI-95, but also the aflatoxin production. To our knowledge, this is the first report to investigate the antiaflatoxigenic activity of culturable deep-sea fungi. Our results provide new insights into the community composition of fungi in the deep South Atlantic Ocean. The high proportion of strains that displayed antiaflatoxigenic activity demonstrates that deep-sea fungi from the Atlantic Ocean are valuable resources for mining bioactive compounds.
RESUMEN
The variability of culturable bacterial diversity and distribution was studied by phylogenetic analysis of 16S rRNA sequences. Seventeen water samples were examined and were collected, from different depths in the range of 5 m to 2700 m at 3 sampling sites (CTD06, CTD10 and CTD11) in the South Atlantic Ocean. Phylogenetic analysis of 16S rRNA gene sequences revealed a significant diversity of culturable bacteria. A total of 247 strains clustered into 8 classes: γ-Proteobacteria, α-Proteobacteria, Actinobacteria, Actinomycetales, Bacilli, Flavobacteria, Opitutae and Sphingobacteria. The 17 water samples were dominated by populations of strains belonging to the genus Erythrobacter (16.60%). Of the 247 strains, 10 were potential new species and might form a minor population in the deep sea. To our knowledge, this is the first report to analyze the diversity of culturable bacteria in the South Atlantic Ocean from different depths across the water column.
Asunto(s)
Bacterias/aislamiento & purificación , Variación Genética/genética , ARN Ribosómico 16S/genética , Agua de Mar/microbiología , Océano Atlántico , Bacterias/clasificación , Filogenia , Especificidad de la EspecieRESUMEN
OBJECTIVE: The aim of this study is to isolate novel and efficient polycyclic aromatic hydrocarbon (PAH) degrading bacteria from deep sea. METHODS: Bacteria in deep-sea water sample from Indian Ocean were enriched in the medium with crude oil as the carbon source. PAH-degrading bacteria were isolated and their degradation potential was tested by Gas Chromatography-Mass Spectrometry. PCR-primers were designed to detect the gene encoding the large subunit of aromatic-ring-hydroxylating dioxygenase. RESULTS: A PAHs-degrading bacterium, named H25 was obtained. Several PAHs including 2-methynaphthalene, 2, 6-dimethynaphthalene, phenanthrene and dibenzothiopheneand dibenzofuran could be used as carbon sources for growth by strain H25. Analysis of 16S rDNA sequence showed that it belonged to genus Novosphingobium with highest similarity (96%) with previously described bacteria. Two fragments of the dioxygenase gene were obtained by PCR with size of about 700bp, which were closest to the counterpart of N. aromaticivorans DSM12444 with 99.6% and 91.0% similarities. Furthermore, two fragments named H25I (2.9 kb) and H25II(4.5kb) containing the upstream and downstream sequences were obtained by another set of primers. CONCLUSION: Strain H25 was a novel PAH-degrading bacterium in deep sea environment, which might play a role in bioattenuation of PAH in oceanic environments and has potential in bioremediation of PAH contaminated environment.
Asunto(s)
Hidrocarburos Policíclicos Aromáticos/metabolismo , Agua de Mar/microbiología , Sphingomonadaceae/aislamiento & purificación , Sphingomonadaceae/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Biodegradación Ambiental , ADN Bacteriano/genética , ADN Ribosómico/genética , Dioxigenasas/genética , Dioxigenasas/metabolismo , Océano Índico , Datos de Secuencia Molecular , Filogenia , ARN Ribosómico 16S/genética , Sphingomonadaceae/clasificación , Sphingomonadaceae/genéticaRESUMEN
This paper reports the optimized electro-transformation parameters of Bacillus thuringiensis plasmid-free mutant strain BMB171 by electroporation, and expressing effect of several cry genes introduced in this recipient. It showed that a highest electro-transformation frequency could be obtained, when SG solution was used as the buffer, and a 10.0V/cm of field strength, one time of pulse as well as a growth phase of recipient cells at the exponential phase (OD650nm value was 0.2~0.3) were selected. The highest of electro-transformation frequency with pHT3101 could reach at 8 ?107 hansformants/?g DNA. The transformation frequencies increased at linear velocity as the concentration increase of pHT3101 from 54.69pg/ml to 3.50?g/mL, then reached saturation afterwards. All plasmids introduced in BMB171 could produce characteristic insecticidal crystal proteins through expression of relevent cry genes carried by them. Meanwhile, these insecticidal crystal proteins could form parasporal crystals, which have characteristic geometric shapes.
RESUMEN
The effect of Ultraviolet (UV) rays on the activity of parasporal crystal of Bacillus thuringiensis, var. Kurstaki HD-1 strain was studied by SEM, SDS-PAGE, bioassay and other methods. It was found that the morphology and surface structure of PC were damaged ,and its solubility in alkaline solution or silkworm gut juice was decreased after being irradiated by UV, the solubility was lost completely after a long time irradiation over 5 hours, so the processed PC could not be degraded into protoxin with insecticidal activity and was denatured.