Modes of bacterial reproduction

Modes of Reproduction in Bacteria- Fission, Budding, Fragmentation and Sporulation

1. Modes of Reproduction in Bacteria- Fission, Budding, Fragmentation and Sporulation Dr. Dhanya KC Assistant Professor Department of Microbiology St. Mary’s College Thrissur-680020 Kerala

2. Bacteria are prokaryotic organisms - reproduce asexually Asexual reproduction - offspring arise from a single parent Offspring - Physically and genetically identical to each other and to parent

3. Modes of reproduction in bacteria Binary Fission Budding Fragmentation Sporulation

4. Binary fission or Transverse binary fission Most common mode of bacterial reproduction A single cell divides to form two identical cells Bacterial cell reaches a critical mass in structure and cellular constituents DNA replicates to form two identical copies New DNA molecules move to two poles of the cell Septum formation is triggered Cytoplasmic membrane grows inward at the middle of the cell, associated with mesosome I nward growth of cell wall, transverse septum develops and separates the daughter cells Eg . S treptococcus, Bacillus, E coli, Pseudomonas

5. Fragmentation Also known as Splitting Cell breaks into several fragments – each develop into complete organism The bacterial protoplasm undergoes compartmentalization and subsequent fragmentation Results in minute bacillary or coccoid cells Each bacillary or coccoid cell grow to form a new bacterium Eg . Filamentous Cyanobacteria and Nocardia

6. Budding The bacterial cell develops small swelling or protuberance at one end DNA divides, one remains with the parent and other one with some cytoplasm goes to the bud Bud gradually increases in size - eventually develops into a new cell Gets separated from the parent cell Eg . Rhodopseudomonas acidophila , Planctomycetes , Firmicutes and prosthecate Proteobacteria Some bacteria such as Hyphomicrobium form the bud at the end of prostheca .

7. Formation of transverse septum or cross walls at the hyphal tips/hyphae / division in sporangia at the hyphal tips Results in the formation of spores . Detachment from the parent On contact with suitable substrate, spores germinates to mycelium Formation of Spores Conidiospores In Streptomyces Oval or round spores in chains at the mycelial tips known as conidiophores. In conidiophore spores are enclosed within a sheath. Detached spores germinate to form mycelium (b) Oidiospores In some Actinomyces Septation throughout mycelia to form numerous oidiospores Oidiospore on germination produces a filamentous bacterium. (c) Sporangiospores In some Actinomycetes and Myxobacteria Sporangia-like structures at the end of hyphae Protoplast of the sporangium divides to form sporangiospores . On liberation s pores germinate to form bacterial mycelium

8. G. Formation of conidiospores in Streptomyces Transverse binary fission in Bacillus subtilis B. Transverse binary fission in Streptococcus faecalis C. Transverse binary fission in prosthecate bacterium Prosthecobacter fusiformis D. Budding in Rhodopseudomonas acidophila E. Budding in prosthecate bacterium Hyphomicrobium F. Fragmentation in Nocardia

9. References Text Book of Microbiology By Michael J. Pelczar https ://www.ck12.org/book/cbse_biology_book_class_x/section/3.3/ http://www.biologydiscussion.com/bacteria/how-does-bacteria-reproduce-with-diagram-microbiology/64010 Botany for Degree Students Fungi by A K Sinha

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