Study On Fruiting Body Morphogenesis Of Myxobacteria

The myxobacteria are gram-negative bacilliform bacteria. They can form warious fruiting bodies are various, and belong toδ—Proteobacteria, according to the systematic classification. Even so, but the biological characteristics of them have shown several remarkable similarities to the eukaryote, which are characterized by multicellular aggregation and complicated social behavior. This thesis described cell differentiation; fruit body formation and development of the peculiar types of prokaryotic microorganism by studing on fruiting body morphogenesis of myxobacteria.Seven strains （serial numbers were 91228,92033,90007,91014,94043,92063, BD105） were used as the materials in the experiment. They were isolated, purified, and saved by own laboratory. By improving culture medium, thchniques of culture, and preparation of SEM samples, we found some new experimental methods for the myxobacteria, namely, modified VY/4 solid plate, single fixation by osmium tetroxide. Compared with the traditional methods such as small-hole culture covered with slides, gluteraldehyde-osmiam tetroxide fixation, step alcohol dehydrat-ing, and CO₂ critical point drying for preparation SEM samples. The new methods were more effective, for the results showed many obvious characteristics, such as well-reserved morphology of spore, clear histological structure, nicer electron transport of sample and so on.By the new methods, we observed systemically about basic characteristics of the seven strains. The results included that:（1） The lack of nutritional at the initiation of development led to some nutritive cells of the myxobacteria stopped growing by; （2） The nutritive cells were observed to be arranged in a small spiral. Cells accumulated at the aggregation focus in stacked layers that had a terraced appearance; （3） As aggregation continued, the individual of cells agglutinated together; （4） Some parts of nonadhesive cells lysed, depending on the particular conditions; （5） The viable cells arranged in order after aggregation behavior. Some viable cells can divide into constituent cells which can form some expecial strctures of fruit body, such as caudex, underpan; （6） The fruiting body that had particular shape was constructed from the cells aggregated; （7） The bacilliform cells had changed into myxosopres whose shapes were various.By observeing and analysising the basic characteristics of myxospores and fruiting bodies of these seven strains systemically, we had obtained some patterns of the life cycles which included multicellular growth and development of fruiting body of the seven strains on VY/4. According to the results, although the progress of development of fruiting body were similar to the former results at lower amplificatory times, microsporangium wall were not found in the seven strains.