ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
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.