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Online Counseling Resource YCMOU ELearning Drive… School of Architecture, Science and Technology Yashwantrao Chavan Maharashtra Open University, Nashik.

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Presentation on theme: "Online Counseling Resource YCMOU ELearning Drive… School of Architecture, Science and Technology Yashwantrao Chavan Maharashtra Open University, Nashik."— Presentation transcript:

1 Online Counseling Resource YCMOU ELearning Drive… School of Architecture, Science and Technology Yashwantrao Chavan Maharashtra Open University, Nashik – 422222, India

2 OC-SEP041-CP01-05 Introduction Programmes and Courses  SEP – SBT041 – Unit 01  SEP – SBI041 – Unit 01  SEP – SGS041 – Unit 01

3 School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.3 Credits  Academic Inputs by Mrs. Rasika Bhore  M.sc (Microbiology) rasika.bhore@gmail.com

4 School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.4 How to Use This Resource  Counselor at each study center should use this presentation to deliver lecture of 40-60 minutes during Face-To-Face counseling.  Discussion about students difficulties or tutorial with assignments should follow the lecture for about 40-60 minutes.  Handouts (with 6 slides on each A4 size page) of this presentation should be provided to each student.  Each student should discuss on the discussion forum all the terms which could not be understood. This will improve his writing skills and enhance knowledge level about topics, which shall be immensely useful for end exam.  Appear several times, for all the Self-Tests, available for this course.  Student can use handouts for last minutes preparation just before end exam.

5 School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.5 Learning Objectives  After studying this module, you should be able to: Discuss the struggle for existence by the formation of Endospores by bacteria. Describe the germination of endospore back to vegetative form.

6 School of Science and Technology, Online Counseling Resource… Introduction  A bacterial structure sometimes observed as an inclusion is actually a type of dormant cell called an endospore.  Endospores are formed by a few groups of bacteria as intracellular structures, but ultimately they are released as free endospores, a fascinating type of cell.  Endospores exhibit no signs of life, being described as cryptobiotic.  Although cryptobiotic, they retain viability indefinitely such that under appropriate environmental conditions, they germinate back into vegetative cells. © 2007, YCMOU. All Rights Reserved.6

7 School of Science and Technology, Online Counseling Resource… Endospores  Endospores are probably the most durable cell produced in nature.  They are formed by vegetative cells in response to environmental signals that indicate a limiting factor for vegetative growth, such as depletion of an essential nutrient.  They are highly resistant to environmental stresses such as high temperature, irradiation, strong acids, disinfectants, etc.  Endospores are commonly found in soil and water, where they may survive for long periods of time.  Some bacteria produce exospores or cysts instead.  Endospores germinate and become vegetative cells when the environmental stress is relieved.  Hence, endospore formation is a mechanism of survival rather than a mechanism of reproduction. © 2007, YCMOU. All Rights Reserved.7

8 School of Science and Technology, Online Counseling Resource… Endospore Forming Bacterial Genera  Bacillus(B.anthracis, B.cereus, B. subtilis)  Clostridium (Cl.tetani)  Desulfotomaculum  Sporolactobacillus  Sporosarcina  Thermoactinomyces Endospores of different species © 2007, YCMOU. All Rights Reserved.8

9 School of Science and Technology, Online Counseling Resource… Stages of Endospore Formation © 2007, YCMOU. All Rights Reserved.9

10 School of Science and Technology, Online Counseling Resource… Stages of Endospore Formation-2  When the environmental conditions becomes unfavorable bacteria starts sporulation, which takes about eight hours.  The DNA is replicated and a membrane wall known as a spore septum begins to form between it and the rest of the cell.  The plasma membrane of the cell surrounds this wall and pinches off to leave a double membrane around the DNA, and the developing structure is now known as a forespore.  Calcium dipicolinate is incorporated into the forespore during this time.  Next the peptidoglycan cortex forms between the two layers and the bacterium adds a spore coat to the outside of the forespore.  Sporulation is now complete, and the mature endospore will be released when the surrounding vegetative cell is degraded. © 2007, YCMOU. All Rights Reserved.10

11 School of Science and Technology, Online Counseling Resource… Mature Endospore  The spore has a core wall of unique peptidoglycan surrounded by several layers, including the cortex, the spore coat and the exosporium.  The dehydrated core contains the bacterial chromosome and a few ribosomes and enzymes to jump-start protein synthesis and metabolism during germination. © 2007, YCMOU. All Rights Reserved.11

12 School of Science and Technology, Online Counseling Resource… Functions of Structural Components  Spore coat is impermeable to many toxic molecules and contain enzymes that are involved in germination.  The core has normal cell structures, such as DNA and ribosomes, but is metabolically inactive.  The spore cell also contains small acid-soluble spore proteins (SASPs) to protect DNA from UV radiation, desiccation and dry heat, and they also serve as a carbon and energy source during the germination process.  Up to 15% of the dry weight of the endospore consists of calcium dipicolinate within the core, which is thought to stabilize the DNA.  Dipicolinic acid believed to responsible for the heat resistance of the spore, and calcium may aid in resistance to heat and oxidizing agents but mutants resistant to heat but lacking dipicolinic acid have been isolated. © 2007, YCMOU. All Rights Reserved.12

13 School of Science and Technology, Online Counseling Resource… Types of Endospores  Various types of endospores are accounted depending on their positions.  The main types within the cell are: terminal, lateral and centrally placed endospores. Terminal endospores are seen at the poles of cells (1,4) Central endospores are more or less in the middle (2,3,5) Lateral endospores are those between these two extremes, usually seen far enough towards the poles but close enough to the center so as not to be considered either terminal or central (6) © 2007, YCMOU. All Rights Reserved.13

14 School of Science and Technology, Online Counseling Resource… Bacteria Having Different Endospores  Bacteria having terminal endospores include Clostridium tetani, the pathogen which causes the disease tetanus.  Bacteria having a central endospore include Bacillus cereus, and  Those having a subterminal endospore include Bacillus subtilis.  Sometimes the endospore can be so large the cell can be distended around the endospore, this is typical of Clostridium tetani. © 2007, YCMOU. All Rights Reserved.14

15 School of Science and Technology, Online Counseling Resource… Destruction of Endospores 1.Alkylating agents such as ethylene oxide, is effective against endospores. 2.Though resistant to extreme heat and radiation, endospores can be destroyed by burning or autoclaving. 3.Exposure to extreme heat for a long enough period will generally have some effect, though many endospores can survive hours of boiling or cooking. 4.Prolonged exposure to high energy radiation, such as x-rays and gamma rays, will also kill most endospores. © 2007, YCMOU. All Rights Reserved.15

16 School of Science and Technology, Online Counseling Resource… Germination of Endospores  When conditions are favorable reactivation of endospore starts involves activation, germination, and outgrowth.  Even if an endospore is located in plentiful nutrients, it may fail to germinate unless activation has taken place which may be triggered by heating the endospore.  Germination involves the dormant endospore starting metabolic activity and thus breaking hibernation.  It is characterised by rupture or absorption of the spore coat, swelling of the endospore, an increase in metabolic activity, and loss of resistance to environmental stress.  Outgrowth involves the core of the endospore manufacturing new chemical components and exiting the old spore coat to develop into a fully functional vegetative bacterial cell. © 2007, YCMOU. All Rights Reserved.16

17 School of Science and Technology, Online Counseling Resource… Differences Between Endospore & Vegetative Cell © 2007, YCMOU. All Rights Reserved.17 PropertyVegetative cellsEndospores Surface coats Typical Gram-positive murein cell wall polymer Thick spore coat, cortex, and peptidoglycan core wall Microscopic appearanceNonrefractileRefractile Calcium dipicolinic acidAbsentPresent in core Cytoplasmic water activityHighVery low Enzymatic activityPresentAbsent Macromolecular synthesisPresentAbsent Heat resistanceLowHigh Resistance to chemicals and acids LowHigh Radiation resistanceLowHigh Sensitivity to lysozymeSensitiveResistant Sensitivity to dyes and staining SensitiveResistant

18 School of Science and Technology, Online Counseling Resource… What We Learn………….  Endospores are cryptobiotic & highly resistant to heat & radiations.  Commonly found in soil & water.  Early stage of endospore formation involves partition of chromosome & ribosome in mother cell.  Late stage involves formation of several layers i.e. cortex, spore coat, spore wall.  Mature endospore contain calcium dipicolinic acid supposed to role in heat resistance.  Three types of endospores are terminal, subterminal & central.  Endospore germination is carried our by rupture of spore coat & manufacturing of new chemical components.  Differences between endospores & vegetative cell.

19 School of Science and Technology, Online Counseling Resource… Critical Thinking Questions  What is the medical significance of endospore forming bacteria? © 2007, YCMOU. All Rights Reserved.19

20 School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved. Tips For Critical Thinking Questions  Treatment of bacterial infection depend on whether the infecting pathogen is able to form spores.

21 School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.21 Study Tips  Book Title: Microbiology Author: L. M. Prescott  Book Title: Introduction to Microbiology Author: J. L. Ingraham

22 School of Science and Technology, Online Counseling Resource… © 2007, YCMOU. All Rights Reserved.22 Study Tips www.en.wikipedia.org Endospores www.cals.cornell.edu Bacterial endospores

23 End of the Presentation Thank You !


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