Tuesday, 16 December

Tuesday, 16 December. We continue our lecture on isolation ,culturing , maintaining and preserving microbes. First, we need know the definition of aseptic technique. Aseptic technique refers to carrying out a procedure under controlled condition in a manner that will minimize the chance of contamination.

Culturing method have 2 basic technique which are liquid and qulture. Liquid can be reared in culture tubes in a liquid medium while qulture use plates where the liquid medium is solidified using agar and poured as a thin layer in the bottom of a culture dish.

Besides, we know how to get pure culture by using streak dilution plate methods.

this is how to obtain pure culture using pour plate method

there are 5 type of culture media which are chemically defined vs. complex media, liquid vs. semisolid media , selective media ,differential media and enrichment media.bacterial growth by budding, spores and fragmentation. Next, we learn on how to calculate number of generation and generation time .

This is the formula for the number of generation time and number of generation.

Generation time=60 min×hours)/ number of generation

Number of generation = Log number of cells (end) – log number of cells (beginning)

                                                                                   0.301

This is bacterial growth curve

Direct measurement of microbial growth , we use plate counts and filtration. Lastly, we can estimating the bacterial numbers by indirect methods using turbidity, periodic transfer of strains to fresh medium, incubate and store in the refrigerator,the short term storage and the long period storage.