Morphology of Bacterial Sporulation

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Microorganism Differentiation Sporulation in Bacteria Dormant Structures Produced by Bacteria Morphology of Bacterial Sporulation Spore Strucuture and Chemistry Spore Germination Common Germinating Agents

Morphology of Bacterial Sporulation

	Morphology of Bacterial Sporulation During sporulation in both and the clostridia at least 7-8 distinct stages have been recognized. In the first stage, which follows soon after the cells have reached the stationary phase of growth, the DNA undergoes structural changes and this is called the axial filament stage. In the stage 2, septum formation and the synthesis of prespore occurs and during this period, the spore DNA is separated from the sporangial DNA In stage 3, engulfment and forespore formation occurs and spore attains a separate identity. This stage also marks the stage of commitment and once the cells have reached this stage, they will undergo sporulation event if transferred to distilled water.
Following this sequential set of events occurs such as the cortex formation the deposition of the spore coats, maturation of the spore and finally the lysis of the sporangium and release of the spor r77+Sporulation, as mentioned earlier, is initiated at the end of the growth period when the nutrient limitation sets in.
The total time required for the completion of sporulation varies with the bacterial species and strain. In B.Cereus and B.Subtilis, It normally takes about 7-8 hours to complete sporulation in liquid medium under shake culture conditions. During sporulation a derepretion of functions necessary for sporulation occurs. How ever, it has been difficult to distinguish the functions necessary exclusively for sporulation from those required for vegetative growth Major requirements for sporulation to occur are the derepresition of the TCA cycle" a final round of DNA Synthesis, production of antibiotics such as bacitracin, polymyxin etc., and synthesis of specific endoproteases.
Recently, the production of highly phosphorylated nucleotides (HPN) such as tetra and pentaguanosine phosphates have been found necessary to initiate sporulation. also, the cyclic AMP level during the sporulation has been found to be very low and it is believed that both, a low level of cAMP and a high level of HPN may be essential to trigger sporulation in bacteria.
	Sporulation is a differentiating process; therefore, different proteins are synthesised during different periods of the sporulation cycle. This requires the synthesis of new m-RNAs which are not made during vegetative growth. This in turn would need a change in the enzyme responsible for RNA synthesis namely, the RNA polymerase. In recent years sporulation has been studied in relation to alteration of RNA polymerase using temperature sensitive and antibiotic resistant mutants. The analysis of RNA synthesis in rifamycin resistant mutants has suggested an alteration in the RNA polymerase and the transcription of- DNA regions not normally transcribed during vegetative growth. Roy Doi and his coIleagues using the antibiotic netropsin which binds specifically to A-T rich regions of DNA, have shown that during sporulation new regions of DNA rich in A-T, and not transcribed during vegetative growth are transcribed.

Thus, while vegetative growth is insensitive to this drug, the sporulation process is sensitive. summarizes the sequence of events that occur during sporulation in Bacillus subtilis

The process of sporulation is also under genetic control and various types of asporogenous mutants have been isolated. On the basis of genetic and biochemical analysis these are classified as early (stage O-I) or late (Stage -II-Stage VII) sporulation mutants. The stage O mutants (SPo) do not initiate sporulation and are believed to be mutants in which the initiation process is altered. Genetic analysis of some mutants has shown that these are unlinked although a certain degree of linkage is seen among specific stage mutants.

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Microcycle Sporogenesis Sporulation in Fungi Fungal Spore Germination Microcycle Sporulation in Fungi Bacterial Cell Division

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