Continuous Culture ARUL SELVAM.pptx

PG AND RESEARCH DEPARTMENT OF MICROBIOLOGY - SRI PARAMAKALYANI COLLEGE - ALWARKURICHI

1. SRI PARAMAKALYANI COLLEGE , Reaacredited with B grade with a CGPA of 2.71 in the second cycle of NAAC affiliated to manomanium sundaranar university, tirunelveli . ALWARKURICHI-627412. Post graduate & Research Centre – Department of microbiology (government aided) I sem core: Microbial PHYSIOLOGY AND METABOLISM (zmbm13) UnIT-5 CONTINUOUS CULTURE A.ARUL SELVAM submitted to REGISTER NO ; 20211232516105 guide ; dr . . s. viswanathan I M.sC microbiology ASSISTANTPROFFESSOR&HEAD ASSIgned on : 08/12/2021

2. SYNOPSIS DEFINITION METHODS 1. chemostat 2. turbidostat DISADVANTAGES ADVANTAGES DIFFERENCE BETWEEN BATCH VS CONTINUOUS CONCLUSION

3. Definition : The culture in which organisms can grow continuously for indefinite period of time is called continuous culture .   Generally in batch culture, the organisms cannot grow for long. This is due to the development of unfavorably conditions However if the environment conditions are maintained favorable continuous culture is possible. Based on this principle, continuous culture is obtained. Continuous culture system is also referred to as pen culture system. CONTINUOUS CULTURE

4. In the case of continuous culture, there is no stationary phase and decline phase due to the addition of fresh medium continuously. So, here we can obtain only lag phase and log phase . Growth rate of microbial cells is maintained in the exponential phase ( i.e ) the cells could not reach the stationary phase of growth. The process of maintaining the microbial cells is the log (or) exponential phase refers to steady state of growth

5. Two methods are used for obtaining continuous culture. 1). Turbidostat 2). Chemostat

6. Chemostat : Chemostat was introduced in the  1950s  by three scientists  Monod ,  Novick  and  Szilard. It is an apparatus used for the continuous culture of bacteria where the cell density is kept constant by keeping the  dilution rate  and  flow rate  of nutrient medium constant . The sterile nutrient medium is added into the reservoir along with the microbial cells. The dilution rate controls the concentration of the nutrient medium .

7. The dilution rate is the flow of the nutrient medium into the reservoir by the culture volume within the vessel. The change in dilution rate will change the  growth rate  of bacteria, i.e. both cell growth and cell density. Cell density remains constant in case of constant dilution or the flow rate of the medium. If the dilution rate alters, cell density and cell growth will also change . Dilution factor :

8. The limiting nutrient concentration : In Chemostat , an essential nutrient or amino acid is added in  limited quantity . By limiting the concentration of an essential nutrient, one can determine the  nutrient medium’s flow rate  into the reservoir. Therefore, this essential nutrient will also determine the bacteria’s  growth rate , i.e. whether the cell density is constant or not. If the concentration of the limiting nutrient alters, the cell density will also change.

9. To perform the continuous culture by the chemostat , there are three elements like  substrate reservoir ,  culture vessel  and the  spent culture bottle . The sterile nutrient medium is continuously added into the culture vessel via  flow regulator . The flow regulator allows the constant flow of the fresh substrate into the culture vessel . There is an inoculation port in the culture vessel, from which the inoculum of bacteria is added. Apart from inoculation port, a culture vessel comprises  magnetic stirrer  at the bottom, allowing uniform mixing of the cells within the nutrient medium. The remaining dead cells and the by-products from the culture vessel are released from the  sampling outlet  into the spent culture bottle.

10. Turbidostat Turbidostat is an apparatus introduced by the two scientists  Bryson  and  Szybalski  in the year  1952 .  It is also called “ Biostat ”.  A turbidostat is a device that maintains the constant cell density by controlling the flow rate of the fresh medium . It is a device, which working depends upon the two components like :

11. Photoelectric device : A photoelectric device like photodiode performs a key role in examining the  cell density  in the culture vessel. Therefore, it determines the alternation in the concentration of the medium. Optical sensing device : An optical sensing device plays a pivotal role to measure the  turbidity  or absorbance of the culture in the reservoir. Turbidostat uses a turbidometer , which helps to find out the optical density of the medium. A turbidostat monitors the flow rate or the dilution rate vigorously to make the turbidity constant . Culture of Bacteria by Turbidostat : A turbidostat is an apparatus which includes a  sterile reservoir ,  culture vessel ,  photocell  and a  light source . In turbidostat , the fresh nutrient medium is automatically regulated, which maintains the predetermined turbidity. The fresh nutrient medium is added to the culture vessel through a valve, which controls the flow of the medium . The fresh nutrient medium is added once the optical density increases. The cell density is kept constant is the culture vessel by the help of a  photoelectric device . The photoelectric device measures the turbidity of the medium by absorbing the light source. The turbidity is monitored throughout the process.

12. Disadvantages : There is a high risk of  contamination , as the process continues without cleaning and proper sterilization . To carry out the process of continuous culture, high  technical skills  are required to maintain the bacterial cells’ steady-state. To perform a continuous culture, it requires some additional and  specific equipment . Advantages : The process is  cost-effective . As there is continuous processing, it reduces the number of stages like cleaning, sterilization, preparation of starter cultures etc . In continuous culture, the cell population can be maintained in the exponential phase at constant cell concentration for a long time . By reducing the number of stages, it also  saves time  and  energy . As the product is continuously eluted, the secondary metabolites’ toxicity does not affect the culture medium. Therefore, continuous culture avoids the accumulation of toxic substance. It gives  high productivity  by utilizing the substrate. Conclusion

13. Conclusion : The continuous culture requires two apparatus like chemostat and turbidostat to maintain a cell in a steady phase of growth. Both chemostat and turbidostat follow some similar criteria like: Maintenance of the constant cell density. Growth of microbial cells in steady-state. The flow rate of the medium and the cells are continuously changing Therefore, a continuous culture is preferred over other cells cultivation methods like batch and fed-batch culture. It gives high productivity as the microbial cell exists in their  logarithmic phase.  The log phase is a stage of highest metabolic activity where cells convert  substrates  into a  product .

14. REFERENCE ; https :// biologyreader.com/continuous-culture.html https ://microbiologynote.com/continuous-culture-definition-advantage-application-systems / WWW.PEDIA.COM Prescott , Harley, and Klein's Microbiology (7th Ed.)

15. The Chairman The Secretary Management Committee The Principal of Sri Paramakalyani College The Head - Department of Microbiology The Staff Members - Department of Microbiology THANKS TO