1. The document discusses various methods for preserving bacteria cultures, including short-term methods like agar slants and stabs as well as long-term methods like ultra-low temperature freezing and freeze-drying.
2. Freeze-drying, or lyophilization, involves freezing samples, then reducing pressure to allow frozen water to sublimate from the sample without passing through the liquid phase.
3. The freeze-drying process helps preserve bacterial viability for decades by preventing damage from ice crystal formation that can occur with other preservation methods.
Capsule is an layer around the bacteria cell which gives bacteria the protection and pathogenicity. Staining such an layer is difficult with the normal stains so it is necessary to stain the background and the cell itself which makes the capsule appear colourless.
Preservation of industrially important microorganisms, methods of preservation, periodic transfer, storage in saline suspension, storage in sterile soil, cryopreservation
Capsule is an layer around the bacteria cell which gives bacteria the protection and pathogenicity. Staining such an layer is difficult with the normal stains so it is necessary to stain the background and the cell itself which makes the capsule appear colourless.
Preservation of industrially important microorganisms, methods of preservation, periodic transfer, storage in saline suspension, storage in sterile soil, cryopreservation
Pure culture preservation of microbes are described in detain. Different short and long term preservation are explained in detail. Methods like Agar slant cultures (Sub culturing) & Refrigeration , Mineral Oil or Liquid Paraffin Method,Saline suspension storage, Drying in Vacuum, Storage at low temperatures (Cryopreservation) and Lyophilization (Freeze drying) are included.
Microbiology of E coli giving basic of Escherichia coli, its morphology, cultural and biochemical characteristics, Antigenic character, pathogenesis, laboratory diagnosis, prevention and control
It has been developed for the detection, enumeration & identification of bacteria & yeasts in clinical specimens.
It is an instrument used for automatic computer-assisted identification of bacteria
It mainly involves staining, motility test, cultural characteristics, a series of biochemical tests.
The automatic bacteria identification system automatically identifies the bacteria in very short time.
Microbiological analysis of food products is the use of biological, biochemical, molecular or chemical methods for the detection, identification or enumeration of microorganisms in a material. Here some of the common methods have been described.
Pure culture preservation of microbes are described in detain. Different short and long term preservation are explained in detail. Methods like Agar slant cultures (Sub culturing) & Refrigeration , Mineral Oil or Liquid Paraffin Method,Saline suspension storage, Drying in Vacuum, Storage at low temperatures (Cryopreservation) and Lyophilization (Freeze drying) are included.
Microbiology of E coli giving basic of Escherichia coli, its morphology, cultural and biochemical characteristics, Antigenic character, pathogenesis, laboratory diagnosis, prevention and control
It has been developed for the detection, enumeration & identification of bacteria & yeasts in clinical specimens.
It is an instrument used for automatic computer-assisted identification of bacteria
It mainly involves staining, motility test, cultural characteristics, a series of biochemical tests.
The automatic bacteria identification system automatically identifies the bacteria in very short time.
Microbiological analysis of food products is the use of biological, biochemical, molecular or chemical methods for the detection, identification or enumeration of microorganisms in a material. Here some of the common methods have been described.
Pure Culture Technique
Culture : Act of cultivating microorganisms or the microorganisms that are cultivated.
Mixed culture : more than one microorganism
Pure culture : containing a single species of organism.
Common isolation techniques:
1. Streak plate method
2. Pour plate method
3. Spread plate method
4. Roll tube method
According to Lokesh, the goal of pure culture preservation is to preserve genetic stability and microbiological viability by use of several methods. Important techniques include the straightforward and inexpensive short-term storage of refrigeration at 4°C on agar slants; the long-term preservation of deep freezing at -70°C to -80°C with cryoprotectants like glycerol or DMSO, which guarantees little genetic changes over years; and the freeze-drying process, or lyophilization, in which cultures are frozen and dehydrated under a vacuum to preserve viability and stability over long periods of time. Research, clinical diagnostics, and industrial applications all depend on these techniques to guarantee the availability of clean microbial cultures when required.
Anti ulcer drugs and their Advance pharmacology ||
Anti-ulcer drugs are medications used to prevent and treat ulcers in the stomach and upper part of the small intestine (duodenal ulcers). These ulcers are often caused by an imbalance between stomach acid and the mucosal lining, which protects the stomach lining.
||Scope: Overview of various classes of anti-ulcer drugs, their mechanisms of action, indications, side effects, and clinical considerations.
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Ve...kevinkariuki227
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
TEST BANK for Operations Management, 14th Edition by William J. Stevenson, Verified Chapters 1 - 19, Complete Newest Version.pdf
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
Report Back from SGO 2024: What’s the Latest in Cervical Cancer?bkling
Are you curious about what’s new in cervical cancer research or unsure what the findings mean? Join Dr. Emily Ko, a gynecologic oncologist at Penn Medicine, to learn about the latest updates from the Society of Gynecologic Oncology (SGO) 2024 Annual Meeting on Women’s Cancer. Dr. Ko will discuss what the research presented at the conference means for you and answer your questions about the new developments.
micro teaching on communication m.sc nursing.pdfAnurag Sharma
Microteaching is a unique model of practice teaching. It is a viable instrument for the. desired change in the teaching behavior or the behavior potential which, in specified types of real. classroom situations, tends to facilitate the achievement of specified types of objectives.
Phone Us ❤85270-49040❤ #ℂall #gIRLS In Surat By Surat @ℂall @Girls Hotel With...
Preservation of bacteria
1. PRESERVATION OF BACTERIA
Dipendra Kumar Mandal (Clinical Microbiologist)
Lecturer
Manmohan Memorial Institute of Health Sciences,
Soalteemode, Kathmandu, Nepal
2. Introduction
• Bacterial species vary greatly in the ability of their cultures to
remain alive after the completion of growth(e.g. after 24 hr at 37°C)
• Problem maintaining them for various periods in a viable condition
• Necessary to eliminate genetic instability, protection against
contaminants and retain their original characters
• Most laboratories maintain a large collection of pure cultures,
frequently referred to as the stock culture collection
• Some species such as Neisseria are poorly viable and their cultures
usually die out within few days in routine conditions, must be
subcultured regularly( 2-4 days)
3. Introduction contd.
• Culture collections of microorganisms are valuable resources for and
scientific research in microbial diversity and evolution, patient
care management, epidemiological investigations, and educational
purposes
• Preserved individual strains of microorganisms serve as permanent
records of microorganisms’ unique phenotypic profiles and provide
the material for further genotypic characterizations
• Effective storage is defined by the ability to maintain an organism in
a viable state free of contamination and without changes in its
genotypic or phenotypic characteristics
• Microbial preservation methods have been evaluated extensively over
the past 50 years, and often, optimal methods for preservation depend
on a microorganism’s taxonomic classification
4. Maintenance Methods
• Pure culture- should be free from contaminants, kept pure
• Frequent way of erroneous results and conclusions if faulty or
contaminated cultures
• Stock cultures- organisms of interest maintained in laboratory as
reference
• Necessary to prevent contamination, retain viability and remain
true to type
• Two methods of maintenance of cultures
1. Agar Slants
2. Agar Stabs
5. Agar Slants
• Agar slants are a form of solid media
generated from the addition of a gelling
agent, such as agar, to a broth culture
• Inoculated and incubated until reasonable
growth – placed in a refrigerator after well
sealing done to prevent drying
• Hardy organisms(Spore formers, GPCs,
Yeasts and Fungi)- remain viable for weeks
to months
• Regular transfer to fresh slants necessary
6. Agar Stabs
• An inoculation technique used when
inoculating semi-solid medium for the
analysis of motility or oxygen usage, or
when inoculating certain types of solid
medium
• Inoculation is done with a straight needle
having a culture – deep all the way to the
bottom
• Culture grows as a thin zone along the
inoculation line
• Acid produced as waste is diluted along the
agar
• Preserve upto 2 weeks
7.
8. Short-Term Preservation Methods
A. Frequency of transfer
B. Immersion in oil
C. Freezing at -20°C
D. Drying
E. Storage in distilled water
Long-Term Preservation Methods
1. Ultra low temperature freezing and
2. freeze-drying (lyophilization) are recommended for
long-term storage
9. Short-Term Preservation Methods
A) Direct Transfer to Subculture
• Simplest method for maintaining the short-term viability of
microorganisms : saved for more than 1 week
• Increases the likelihood of mutation with undesirable changes
• Maintenance Medium- support the survival of the microorganism but
minimize its metabolic processes and slow its rate of growth;
distilled water, tryptic soy broth, and nutrient broths with or without
cryopreservatives
• Transfer organisms into screw-top test tubes and to store them in an
organized location away from light and significant temperature
changes; storage at lower temperatures (5 to 8C)
• No set protocol for the frequency of transfer since storage conditions,
media used and types of microorganisms vary among laboratories
10. B) Immersion in Oil
• An alternative to capping tubes- add a layer of mineral oil to the top of
the specimen
• Many bacteria and fungi can be stored for periods of up to 2 to 3 years
by this method, and transfers are not needed as frequently
• Microorganisms are still metabolically active in this environment and
mutations can still occur
• Mineral oil should be medicinal-grade oil with specific gravity of 0.865
to 0.890 and heated to 170C for 1 to 2 h in an oven : sterilization
• An inoculum of 5 to 10 colonies of the microorganism should be placed
on an agar slant or in tubed broth media
• A layer of mineral oil at least 1 to 2 cm deep is added, and the agar must
not be exposed to air
11. C) Freezing at -20°C
• Refrigeration or freezing in ordinary freezers at -20°C may be
used to preserve microorganisms for periods longer than those
that can be accomplished by repeated transfers
• Viability may be maintained for as long as 1 to 2 years for
specific microorganisms, but overall, damage caused by ice
crystal formation and electrolyte fluctuations results in poor
long-term survival
• Modern self-defrosting freezers with freeze-thaw cycles must
be avoided because cyclic temperature fluctuation will destroy
the microorganism
12. D) Drying
• Molds and some spore-forming bacteria may be dried and stored for prolonged
periods
• Soil should be autoclaved for several hours on two successive days. A 1-ml
suspension of the microorganism is inoculated into the sterile glass tube, and the
tube is left open to air dry before being closed with a sterile stopper and sample
is stored in a refrigerator.
• Instead, commercial silica gel can be used in small cotton-plugged tubes after
being heated in an oven to 175C for 1.5 to 2 h, with moderately successful
recovery of fungi
• Gelatin discs: a thick suspension of bacteria is prepared and added to nutrient
gelatin . Drops of the bacterial suspension in gelatin are placed on sterile waxed
paper or on a plastic petridish and then dried off over P2O5 under vaccum
• Alternatively, a suspension of 10ˆ8 microorganisms can be inoculated onto
sterile filter paper strips or disks’. The paper is dried (over phosphorus
pentoxide in a desiccator under vacuum )in air or under a vacuum and is placed
in sterile vials. These vials can be stored in the refrigerator for up to 4 years,
and then single strips or disks can be removed as needed
• Commonly used for quality control organisms
13. L- drying:
• described by Lapage et al
• bacteria in small ampoules are dried from the liquid
state using a vacuum pump and desiccant and a
water bath to control the temperature
14. E) Storage in Distilled Water
• Most organisms grow poorly in distilled water, but some
survive for prolonged periods
• Many fungi and Pseudomonas sp. survive for several years in
distilled water at room temperature
15. Long-Term Preservation Methods
1. Ultra low temperature freezing and
2. freeze-drying (lyophilization) are recommended for long-
term storage
• Methods are less labor-intensive over time, require less
laboratory space (e.g., a cryovial versus broth or agar media),
and reduce the chances of mutation events
• Of course mutation still occur (e.g. mecA gene lost during long
term preservation at -80°c)
• Prolonged incubation requires-
i. Drying of the culture prevented by hermetic sealing
ii. Stored in a dark, either at RT or 4°C but not at 37°C
iii. Suitable preservation media
16. Ultra low-Temperature Freezing
• Maintained at temperatures of -70°C or lower for prolonged
periods using ultralow-temperature electric freezers and liquid
nitrogen storage units
• Presence of a cryopreservatives such as glycerol may reduce
the risk to microorganisms upon short exposure to higher
temperatures
• Storage Vials
– Plastic (polypropylene) or glass (borosilicate) tubes- able to withstand
very low temperatures and maintain a seal for their contents
• Cryoprotective Agents
– To protect microorganisms from damage during the freezing process,
during storage, and during thawing = are added to the culture
suspension
17. • Two types of cryoprotective agents
1. Those that enter the cell and protect the intracellular
environment and (e.g. Glycerol and dimethyl sulfoxide
(DMSO),
2. Others that protect the external milieu of the organism(e.g.
sucrose, lactose, glucose, mannitol, sorbitol, dextran,
polyvinylpyrrolidone, polyglycol, and skim milk )
• Universal cryoprotectant is DMSO 5% (V/V)
• Glycerol 10% (V/V) is the best preservative for bacteria
• Glycerol- autoclaving
• DMSO- filtering
• Skim milk 20% (Wt/V) in distilled water
18. • Preparation of Microorganisms for Freezing
– Cultures are allowed to mature to the late growth or
stationary phase before being harvested
– Broth specimens are centrifuged (low revolution) to create
a pellet of microorganisms and resuspended in 2 to 5 ml of
broth with the appropriate concentration of cryoprotectant
additive
– Agar – Scraping
– Volume of the aliquots to be frozen is typically 0.2 to 0.5 ml
19. • Freezing Method
– American Type Culture Collection (ATCC) recommends slow,
controlled-rate freezing at a rate of 1°C per min until the vials
cool to a temperature of at least -30°C, followed by more rapid
cooling until the final storage temperature is achieved
– When organisms are stored in liquid nitrogen, however, it is
still recommended that vials be placed initially in a -60°C
freezer for 1 h and then transferred into the liquid nitrogen
(-196°C)
– Small glass beads or plastic beads can also be added to storage
vials before freezing- culture suspension will coat the beads,
and then individual beads can be removed from storage for
reconstitution without thawing the entire sample
20. • Thawing
– Damage to microorganisms occurs as they are warmed from the
frozen state
– critical temperatures appear to be between -40 and -5°C (improves
recovery rates)
– Stored culture vials should be warmed rapidly in a 35°C water bath
until all ice has disappeared
– Once a vial is thawed, it should be opened and the organism should
be transferred to an appropriate growth medium immediately
– Great care must be exercised during the thawing phase since rapid
temperature changes and resulting air pressure changes inside vials
can cause the vials to explode
– So that protective clothing and eye wear must be worn during this
process
26. History
Freeze drying was first actively developed during WORLD
WAR II for transport of serum.
After the war period the technology emerged into its
current popularity for the drying of many different
temperature sensitive materials like pharmaceuticals and
food materials.
27. • The sublimation occurs on the tip of
mount Everest due to:
low temperature
strong wind
low air pressure
sunlight which is suitable for
sublimation to occur.
28. Definition
Freeze drying is a stabilizing process in which a substance is
first frozen and then the quantity of the solvent is reduced, first
by sublimation (primary drying stage) and then desorption
(secondary drying stage) to values that will no longer support
biological activity or chemical reactions.
or
it is a process by which a solvent (usually water) is removed
from a frozen foodstuff or a frozen solution by sublimation of
the solvent and by desorption of the sorbed solvent (nonfrozen
solvent), generally under reduced pressure.
29. Introduction :
• Better preservation occurs with freeze-drying than with other
methods because freeze-drying reduces the risk of
intracellular ice crystallization that compromises viability
• Removal of water from the specimen effectively prevents this
damage
• Lyophilization is greatest with gram-positive bacteria (spore
formers in particular) and decreases with gram-negative
bacteria, but overall, the viability of bacteria can be
maintained for as long as 30 years
30. • Large numbers of vials of dried microorganisms can be stored
with limited space, and organisms can be easily transported
long distances at room temperature
• The process combines freezing and dehydration- Organisms
are initially frozen and then dried by lowering the atmospheric
pressure with a vacuum apparatus
• Specimens can be connected individually to the condenser
(manifold method) or can be placed (in a chamber) where they
are dehydrated in one larger air space
Contd.
31. Objectives of lyophilization process
• To preserve the biological activity of a product.
• To reduce the product weight to lower the transportation cost.
• To extend the shelf life or stability.
• To dry thermolabile materials.
• To eliminate the need for refrigerated storage.
32. Principle
Lyophilization is carried out using a simple principle of physics
, sublimation. Sublimation is the transition of a substance from
the solid to the vapour state, without passing through an
intermediate liquid phase.
Lyophilization is performed at temperature and pressure
conditions below the triple point (4.58 mm Hg, 0 ºC), to enable
sublimation of ice.
The entire process is performed at low temperature and
pressure by applying vacuum, hence is suited for drying of
thermolabile compounds.
The concentration gradient of water vapour between the drying
front and condenser is the driving force for removal of water
during lyophilization.
33. Triple point : triple point of a substance is the temperature and
pressure at which three phases (gas, liquid, and solid) of that substance
may coexist in thermodynamic equilibrium. The triple point of
pure water is at 0.01°C (273.16K, 32.01°F) and 4.58 mm (611.2Pa) of
mercury and is used to calibrate thermometers.
35. Freezing
• Freezing the product solution to a temperature below its
eutectic temperature.
• Decrease the shelf temperature to -50oc.
• Low temperature and low atmospheric pressure are
maintained.
• Formation of ice crystals occurs.
• The rate of ice crystallization defines the freezing process and
efficiency of primary drying.
36. Primary Drying (Sublimation)
• After freezing, the product is placed under vacuum. This
enables the frozen solvent in the product to vaporize without
passing through liquid phase, a process known as
SUBLIMATION.
• Heat is introduced from shelf to the product under graded
control by electrical resistance coils or circulating silicone.
• The temperature and pressure should be below the triple point
of water i.e., 0.0098°C and 4.58mmHg.
• The driving force is vapor pressure difference between the
evaporating surface and the condenser.
• Easily removes moisture up to 98% to 99%.
37. Secondary Drying (Desorption)
• Heat is applied to the frozen product to accelerate
sublimation
• The temperature is raised to 50°C – 60°C and vacuum is
lowered about 50mmHg.
• Bound water is removed.
• Rate of drying is low.
• It takes about 10-20 hrs.
39. Packing
• Ampoules are sealed by either tip
sealing or pull sealing method
• Vials and bottles are sealed with
rubber closures and aluminum caps
40. • Storage Vials
– Glass vials are used for all freeze-dried specimens
– When freeze-drying is performed in a chamber, double glass
vials are used
– (chamber method) : an outer soft glass vial is added for
protection and preservation of the dehydrated specimen
– Silica gel granules are placed in the bottom of the outer vial
before the inner vial is inserted and cushioned with cotton
– Manifold method- a single glass vial is used
– storage vial must be sealed to maintain the vacuum and the
dry atmospheric condition
• Cryoprotective Agents
– Two most commonly used agents are
1. Skim milk for chamber lyophilization, and
2. sucrose for manifold lyophilization
41. • Skim milk is prepared by making a 20% (vol/vol) solution of
skim milk in distilled water.
• divided into 5-ml aliquots and autoclaved at 116°C with care
taken to prevent overheating and caramelizaton(nutty flavor)
of the solution.
• The preparation is then used in smaller volumes
• Sucrose is prepared in an initial mixture of 24% (vol/vol)
sucrose in water and added in equal volumes to the
microorganism suspension in growth medium to make a final
concentration of 12% (vol/vol).
42. Preparation of Microorganisms for Freezing
– As with simple freezing, maximum recovery of organisms is
achieved by using microorganisms in the late growth or
stationary phase from the growth of an inoculum in an
appropriate growth medium
– High concentrations of microorganisms are considered to be
important- ATCC concentration of at least 10ˆ8 CFU/ml but
Heckly suggests a concentration of 1010 CFU/ml or higher
43. Freeze-Drying Methods
chamber method: inner vials with the microorganism suspension are
placed in a single layer inside a stainless steel container
1. Container is placed in a low-temperature Freezer at
-60°C for 1 h and then transferred to a chamber containing dry ice
and ethyl Cellosolve and covered with a sealable vacuum top,
which is connected to a vacuum pump at a minimum of 30µm Hg
for 18 h
2. Outer vials are prepared by being heated in an oven overnight,
filled with silica gel granules and cotton, and placed in a dry
cabinet with <10% relative humidity
3. The freeze-dried inner vials are inserted into the outer vials, and
the outer vials are heat sealed
44. In the manifold method:
1. a rack of individual vials is used rather than a single
container. The rack is placed in a dry ice-ethyl Cellosolve
bath
2. After the freezing process, the vials are connected by
individual rubber tubes in sequence to the condenser
container filled with dry ice and ethyl Cellosolve and to the
vacuum pump
45. Freeze Dry Product Characteristics
• Sufficient strength
• Uniform color
• Sufficiently dry
• Sufficiently porous
• Sterile
• Free of pyrogens and particulates
• Chemically stable both in dry state and reconstitution
46. • Storage
– Storage at room temperature does not maintain viability and is
not recommended
– Storage at 4°C in an ordinary refrigerator is acceptable, but
survival may be improved at temperatures of -30 to -60°C
• Reconstitution
– The surface of the vial should be wiped with 70% alcohol, and
then the top of the glass vial can be scored and broken off or
punctured with a hot needle
– A small amount (0.1 to 0.4 ml) of growth medium is injected
into the vial with a needle and syringe or a Pasteur pipette, the
contents are stirred until the specimen is dissolved, and then the
entire contents are transferred with the same syringe or a pipette
to appropriate broth or agar media
47. Advantages of Lyophilization
• Removal of water at low
temperature
• Thermolabile materials can be
dried.
• Sterility can be maintained.
• Reconstitution is easy
48. Disadvantages of Lyophilization
• Many biological molecules are damaged by the stress
associated with freezing, freeze-drying, or both.
– E.g. the process of drying causes extensive damage to
molds, protozoa, and most viruses
– Hence, these microorganisms can not be stored by this
method
• The product is prone to oxidation, due to high porosity
and large surface area. Therefore the product should be
packed in vacuum or using inert gas
• Cost may be an issue, depending on the product
49. Common Lyophilized Products
• Bacteria
• Viruses
• Vaccines
• Plasma
• Pharmaceuticals – large and small molecules
• Fruit
• Coffee
• Flowers
50. Applications
• Microbiology, pharmaceutical and biotechnology – to
preserve microorganisms, increase the shelf life of products,
such as vaccines and other injectables
• Food industry
to preserve food, very light weight.
to produce essences or flavouring agents.
freeze-dried fruits are produced.
Culinary herbs are preserved.
Instant coffee powder is prepared.
• Technical industries
in chemical synthesis
Formation of stable products.
• Others
Flora & fauna preservation
57. FREEZE DRYING PLANTS AND EQUIPMENT
1. Pilot freeze drying
2. Industrial freeze drying
a. Tray and Pharmaceutical Freeze Dryers
b. Multibatch Freeze Dryers
c. Continuous Freeze Dryers
d. Tunnel Freeze Dryers
e. Vacuum-Spray Freeze Dryers