This document consists of mind maps that covers the practicals of MBY 251: Application of Spectrophotometry to Bacteriology, Pure Culture Techniques and maintenance of bacteria, growth of bacteria on artificial media, microscopy, staining techniques, chemical methods for the control of microbes, su...
Inoculation of a suitable
medium contained in
a Petri dish, tube, or bottle
incubated at an appropriate
temperature and stored
Single colonies are streaked onto the
under suitable conditions.
surface of plates of solid media Subcultures
1 Streak plate method
Drying a cell suspension at a low
Successive dilutions of the inoculum are placed temperature in the presence of a
in the sterile Petri dishes and mixed with the cryoprotective suspending liquid.
The following methods Freeze-drying
cooled but still molten agar medium, which is
may be used for the Methods available for preservation
then allow to solidify. The freezing process
2 Pour plate method isolation of bacteria of cultures can be divided
damages cells.
into pure cultures: into a few categories
The sample is pipetted onto the surface Damaged can be caused by
solidified agar medium in a Petri dish concentration of electrolytes
and the cells are distributed with a spreader. through removal of water as ice
3 Spread plate method by the formation of ice crystals
Prac 1: which damage cell integrity.
Pure culture techniques Freezing
and maintenance
MAINTENANCE & PRESERVATION OF BACTERIA
of bacteria.
Microbes are not usually found as single species
Cultures can be re-isolated Method for successful in nature, but rather as mixed cultures.
or replaced by one of the preservation of all microbes
service culture collections must fulfill the following:
STREAKING OF SINGLE COLONIES
ATCC: Must be minimal loss of viability (streak plate method)
American Type Culture Collection during processing and storage
The microbe's genetic material This method will separate the cells of the colony. What is this technique used for?
must not change Each cell will then give rise to a new colony.
The purity of the culture Used for bacteria, yeasts &
must be maintained sometimes sporulating fungi.
The method must be cost effective
and also easily performed
, Various types of membrane filters are used to sterilise heat liable
compounds. These remove bacteria from the liquid due to the sieving Some compounds are heat sensitive and are degraded or
action of small pores and/ or by absorption of microbes due to differences
destroyed by high temperatures. Such heat liable
in electrical charge.
components must be filter
sterilized separately, and then added to medium under
Other compounds which are stored at 4-8 degrees celsius (blood ASEPTIC CONDITIONS.
serum) must be heated to 37 degrees celsius before it is added The basal medium is cooled to 45-50 degrees celsius before
to the basal medium.
the
heat liable compound is added.
All apparatus, instruments
and culture media
Water
must be sterilized.
Synthetic media are used which
Nitrogen source such as proteins,
amino acids, nitrogen-containing
It's important to destroy include all necessary requirements inorganic salts
any contaminants STERILIZATION OF for growth of microbes, such as:
Prac 2: Growth of
Energy source such as
Most culture media are sterilized by CULTURE MEDIA carbohydrates, proteins
bacteria on artificial media
moist heat using an AUTOCLAVE. and inorganic salts
Grow th factors such as vitamins
What is an autoclave? and trace elements.
A large pressure cooker.
A suitable environment with respects to pH,
osmotic pressure, atmosphere, etc. must
be created in the medium.
Prepared from sea weed
AGAR
Melts at 96 degrees celsius and does
not gel until cooked at 45 degrees celsius
The commonly used empirical medium, Nutrient Agar: capable
of supporting the growth of multiple bacteria.
Solid media is prepared by adding a gelling agent to the liquid
Nutrient agar can be used as basal medium to which blood or
medium, e.g. agar at a concentration of approximately 1.5%
milk is added.
or gelatine at a concentration of approximately 15%.
Grow th media types Defined media Known quantity of all ingredients
Has some complex ingredients such as
Undefined media
yeast extract or casein hydrolysate.
Used for growth of only select microbes. Selective media
Sometimes chosen based on price
Types of growth media
and sometimes by necessity.
Distinguish one microbial species from another growing on the same media Differential media
Contain the nutrients required to support the growth of a wide variety
Undefined media that contains water, a carbon source,
of organisms including some of the fastidious ones. Enriched media Nutrient media
various salts and a source of amino acids and nitrogen.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through EFT, credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying this summary from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller anelgrey. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy this summary for R99,00. You're not tied to anything after your purchase.
