Biomedical subjects

Jiangchun Hu

Publications and source records attributed to Jiangchun Hu.

8 recordsLinked to original sources

PubMed2005

Toxicity and distribution of tetrodotoxin-producing bacteria in puffer fish Fugu rubripes collected from the Bohai Sea of China.

To investigate the relationship between the toxicity of puffer fish and the distribution of tetrodotoxin-producing bacteria in puffer fish Fugu rubripes collected from the Bohai Sea of China, bacteria were isolated from each organ (ovaries, livers, intestines and gallbladders) and screened for tetrodotoxin (TTX) production. 20 out of 36 isolated strains were found to produce TTX in vitro. In the organs of ovaries and livers whose toxicity is more potent than other organs, the number and toxicity of TTX-producing strains was greater than that of others. Most TTX-producing bacterial strains were identified as Bacillus spp. (19 strains) and Actinomycete spp. (1 strain) based on the morphological observation, physiological and biochemical characteristics and G+C content of DNA. The purified toxin was identified to be TTX by high performance liquid chromatography assay, thin-layer chromatography assay and electrospray ionization mass spectrometry analysis. Our results suggested that TTX-producing bacteria are closely related to the toxification of the puffer fish. More research is needed to elucidate the mechanism of TTX synthesis and the role of TTX in bacteria.

Actinomyces↗

PubMed2005

A new tetrodotoxin-producing actinomycete, Nocardiopsis dassonvillei, isolated from the ovaries of puffer fish Fugu rubripes.

Three puffer fishes, Fugu rubripes, collected from the Bohai Sea of China were examined for tetrodotoxin-producing microorganisms. An actinomycete isolated from the ovaries of the puffer fishes was found to produce tetrodotoxin. After being cultured at 28 degrees C for 7 days, cells were harvested by centrifuge and disrupted by ultrasonication. The toxin was purified from the cell lyzate by ultrafiltration, active charcoal column, Bio-gel-p2 and ion exchange column chromatography. Mouse neuroblastoma cell culture, thin-layer chromatography, fluorimetric spectrophotometry, UV-spectrophotometry and electrospray ionization mass spectrometry, together with mouse bioassay demonstrated that the isolated strain produced tetrodotoxin and related toxin during cultivation. Based on morphological, physiological, biochemical characteristics and 16S rDNA alignment, this strain was identified as Nocardiopsis dassonvillei. Our findings suggested that N. dassonvillei in the ovaries was closely related to the toxification of the puffer fish.

Actinobacteria↗

PubMed2005

Exploring novel bioactive compounds from marine microbes.

The historical paradigm of the deep ocean as a biological 'desert' has shifted to one of a 'rainforest' owing to the isolation of many novel microbes and their associated bioactive compounds. Recently, there has been an explosion of information about novel bioactive compounds that have been isolated from marine microbes in an effort to further explore the relatively untapped marine microbes and their secondary metabolites for drug discovery. The microbes are recovered and purified from the ocean by both conventional and innovative isolation methods to obtain those previously thought to be 'uncultivable'. To overcome the difficulties and limitations associated with cultivation techniques, several DNA-based molecular methods have been developed to bypass the culture-dependent bottleneck. Bioactive compounds isolated using the above strategies have not only shown importance in biotechnological and pharmaceutical applications but have also increased our understanding of the diversity of marine microbiota, ecosystem functions and the exploitable biology.

Anti-Infective Agents↗

PubMed2005

[Microbial diversity in continuously planted Chinese fir soil].

The study on the microbial diversity of 1st, 2nd, 3rd and 4th generation Chinese fir soil at Huitong Forest Experimental Station showed that with the increase of generation, the numbers of bacteria and actinomyces decreased markedly, while that of fungi increased evidently. It was found by PCR and DGGE that the bacterial diversity changed slightly and its genetic similarity among different generations reached 87 %, but the fungal diversity reduced and its genetic similarity was only 45%. The numbers of pathogenic and deleterious fungi increased markedly with increasing Chinese fir generations.

Actinomyces↗

PubMed2004

[Function and application of soil microorganisms in forest ecosystem].

Soil microorganism is an important part of forest ecosystem, and plays an important role in sustainable development of forestry. In this paper, we summarized the main functions of soil microorganisms in forest sustainable development from the aspects of 1) the role of soil microorganism and microbiomass; 2) the function of mycorrhizal fungi; 3) the impact of pathogen; and 4) the effect of PGPR. Finally, we also discussed the research trends of forest soil microorganism and its application. Some study areas which should be further studied were also proposed.

Azospirillum↗

PubMed2004

[Research advances in plant growth-promoting rhizobacteria and its application prospects].

The study of plant growth-promoting rhizobacteria will provide possible methods to overcome the difficulties in controlling soil borne plant diseases. PGPR can colonize in rhizosphere at high population density, inhibit plant pathogens and deleterious microorganisms there, and promote crop growth and its yield. More importantly, some PGPR strains applied as biocontrol agents can make treated plant produce induced systemic resistance (ISR), and thus, increases plant overall health. In recent two decades, the researches of PGPR in abroad are very active, and many PGPR products have been applied successfully. In our contry, more attention should be paid to the study of the basic theory and application of GPPR and the industrialization of PGPR products.

Biodiversity↗

PubMed2002

[Bio-active substances derived from marine microorganisms].

Marine microorganisms, which are taxonomically diverse and genetically special, have powerful potential in producing novel bio-active substances. This article summarized research progress in this respect. The results showed that marine bacteria which are main marine microorganism flora can produce rich kinds of bio-active substances and that even though marine actinomycetes and marine fungi are not as many as marine bacteria in species and quantity, they should be paid no less attention about their bio-active substances. Besides, present research are limited to those marine microorganisms which are easily cultured. One of the future research trends will be focused on bio-active substances derived from non-culturable marine microorganisms.

Bacteria↗

PubMed2002

[Obstacles of soybean continuous cropping, III. Mechanism of soybean yield increment by marine actinomyces MB-97].

An isolate of marine actinomyces MB-97 identified as Streptomyces microflavus could successfully colonize in the rhizoshpere of soybean, and inhibit Penicillium purpurogenum, a soybean deleterious rhizospheric microorganisms. After applied MB-97, the ratio of bacteria/fungi in the rhizosphere of soybean was increased, and the soil became to be "Bacterial type" from "Fungal type". The populations of P. purpurogenum were apparently suppressed about 80%, and the harm of toxins in soil was weak. The soybean root rot caused by soilborne fungi such as Fusarium was decreased 50%, and MB-97 could stimulate the growth of soybean seedlings. In field study, the mean yield of soybean raised by 15.2%, implying that Streptomyces microflavus was an effective plant growth-promoting rhizobacteria on soybean.

Actinomyces↗