welcome to this course is going to be a ten lecture mock spread over about four weeks
this mock will have these lectures and there will be some assignments that come
ones a week or so in addition there will be some numerical problems or thought based
problems that we will discuss in class and probably assign some problems you would
have time to do it and we will check up with solutions in the next class the organization
of this course probably you may not find in text books in a complete way however
two books may be useful two you can consider them as reference books the first one is
shuler and kargi i will give you the details in one of the files that you can download
from the course site thats a nice book in addition there is an older book very
old eighty six it is by bailey and ollis thats also a good book but it is somewhat
dated in um going forward this would be an introduction the first lecture is going
to be an introductiots start with cancer we all know that cancer is an important disease
now a days it is been an important disease for a very long time decades may be and still
it is not been completely conquered there is lot of progress that has been made in treating
cancer in diagnosing cancer but we have still not completely overcome it and it is
still one of the important diseases of today what is cancer very simplistically speaking
it is the uncontrolled growth of cells we all know this the cell has lost its ability
to die when its job is done and when that happens cancer happens and thats one of the
ways cancer happens for example this is a nice example to give you if you look at
a hand and if you look at how this hands started out in a fetus it would have been a complete
completely filled end of a mass then the cells here started dying away and that is what gave
rise to the digits therefore in other words the cells here actually committed suicide
and that is what gave us these digits which are functioning
so cell death is an necessary part of the developmental process the regenevation regeneration
process and so on in the body and of that goes haywire and the cells continues to live
then it is also an cancer why is cancer dangerous its just cell that is there which is lots
cells cells they have lost their ability to die so why should it bother us it bothers
us because a lot of such cells in the body can threaten life itself as they interfere
with the crucial functions of organs and tissues for example let us take the lung if the lung
cells become cancerous they start growing uncontrolled and they interfere with the gas
exchange that happens in the lungs which is whittle to keep up life and so on so for
you can talk of different organs in the body may be liver may be kidney and if there
are cells that continue to grow and refuse to die then it interferes with the normal
function of those organs and that ultimately leads to death in a simplistic sense there
are other complications also there but this is one of the things that leads to death
therefore again straight forward thinking fashion to treat cancer the cancerous cells
need to be killed how do you kill it you use drugs cancer drugs and such a treatment is
called chemotherapy you could use radiation such a treatment it is called radiotherapy
and so on to kill cancer cells our these therapies you know you taken drugs to kill
the cancer cancer cells it could also kill the other normal cells in the body and that
is what leads to the undesirable side effects such as the hair falling out and various other
side effects of chemotherapy and radiotherapy which is not desirable so it becomes helpful
to target the killing agents the drugs that kill the cancer cells directly to the cancerous
cells so that the effect on the normal cells is minimal to target these drugs to the cancer
cells now a days something called monoclonal antibodies or m a bs are used at least for
some cancers some cancers it is been very effective these um ideas started decades probably
at decade and a half ago or more ago and then they have come to flowtion probably a few
years ago now they are effective again some types of cancer
monoclonal antibodies are made by cells called hybridomas hybridoma as the name suggest hybrid
oma it is a fusion or a mixture of a cell that can produce one type of antibody and
therefore you call them monoclonal antibodies and an other type which does not die which
this is a cancerous cell so if you use them together you have a cell that produces one
type of antibodies monoclonal antibodies and can live forever which becomes useful outside
the body when you trying to produce these monoclonal antibodies that are used to target
the drugs to cancerous cells the hybridomas themselves were developed in the mid seventies
by kohler and milstein and its potential was realized quite soon as soon as it was developed
and monoclonal antibodies became a rates even in the early eighties some of my work
doctoral work was related to monoclonal antibody production in a bioreactor these are some
of the monoclonal antibodies that have been used now a days to treat cancer rituximab
trastuzumab bevacizumab cetuximab panitumumab ipilimumab and so on and so forth
if you see here it ends in m a b which stands for monoclonal antibody and each one is effective
against certain kinds of cancers for more information you could look at this website
i am going to list all these websites in a separate file and put it up on your course
page so that is it is easier for you to reach these websites will have some of these websites
throughout the course more so in the introductory modules so that um you can go and read
about them get in death of those aspects because we will cover whatever is necessary for us
in this particular course but they by themselves could be very interesting to some of you so
you could go and read about them and dig further about them based on your interest the file
is going to be something like this the u r l that i gave you just now is the first u
r l cancer treatment here this one says websites videos recommended that could be
some videos also along with this this is a website cancer treatment and this was the
address that was given here you could download this file and click on the appropriate link
i guess you need to use a control or something like that before you click here and then you
would access the website and see through it
this is a nice website for cancer treatment i will highlight as we go through the lecture
the various websites there is an other website that is given there i think which is given
number two on that list we just saw that list and lets now come back from cancer to our
bioreactors course now what is the relevance here the relevant question here is that how
are monoclonal antibodies or m a bs made in large quantities that are needed for therapy
the amounts would be very small if you grow hybridomas in small vessels as they were done
initially but the demand for m a bs is huge now a days
so how do you produce the large quantities of m a b that are needed for therapy the answer
is through something called a bioprocess ok let me live it there for the time being and
we will keep visiting this bioprocess and then i will tell you what that is lets guess
the alternative liquid fuels where in great demand or where kind of hot a few years
ago they are still of great interest they are fuels that would replace the petroleum
or diesel that comes from crude oil the justification was the need was the crude oil sources are
running out and therefore we need alternative liquid fuels it is rather difficult to replace
liquid fuels its rather difficult to imagine um how a plane would fly without a liquid
fuel at least for some time to come or to there are other alternatives available now
on an experimental basis still probably we need a lot of liquid fuels two examples
of liquid fuel are bio ethanol and bio diesel ethanol you know c two h five o h that is
found in a lot of theses intoxicating drinks also but in a puro form if it is mixed with
some amount of petrol and or gas as it is called in some countries and used in
cars then thats a very good fuel but how do you get bio ethanol that is the source of
bio ethanol is con or other plant sources that ultimately give us the ethanol how do
you go from con for example two ethanol that is a because con contains various other things
it does not contain ethanol so how do you contain whatever con has to the ethanol that
is useful has a bio fuel thats a long process its also through a bio process
similarly bio diesel bio diesel is being used in a country from plant sources to run railways
and things like that to a reasonable extent you could also use something called micro
algae to produce bio diesel because micro algae accumulates what is called bio oil and
that bio oil can be convert its somewhat equivalent of the crude oil not exactly somewhat equivalent
of the crude oil and that bio oil can be processed to produce bio diesel so if you are using
micro algae which is a higher generation bio fuel compared to the plant based bio fuel
bio diesel then you need to use a bio process that converts um the raw materials sometimes
it could just be the carbon dioxide in the air and in the presence of sunlight and so
on through photosynthesis to yield bio oil which can then be convert it to bio diesel
so this process also is a bio process so bio processes are required for production of certain
alternative liquid fuels such as bio ethanol and bio diesel i would like you to look at
this animation which gives you details about ethanol making it gives you in a
nice way how ethanol is made from a con or some other source here similarly ya this
is ethanol from con this is ethanol making in general and animation and then this is
algae to fuels
if you are enable to read it here or use it directly from this presentation please
look at i think it is four five ethanol animation is three ethanol from con is four and algae
to fuels is number five on this list you could go through these sites which are commonly
available videos and get some information in a nice way in a non boring way and that
might be useful lets get back to our presentation here so the production of bio ethanol and
bio diesel are also done through bio processes another stretch here you all heard of insulin
what is insulin it is a drug that is used to treat diabetes a widely used drug that
is used to treat diabetes if you look at what kind of a molecule it is it is something called
a protein i i hope you have some background in bio molecules and so on so it is one
kind of a bio molecule um amino acid and a polymer of amino acid is a protein so insulin
is really small protein it was discovered in the nineteen twenties a long time ago and
soon people found that you could use it to treat diabetes and the initial source of
insulin was pig pancreas ok probably a few years after this till about nineteen eighties
they were obtained from the pancreas of pigs the numbers are quite staggering you need
about eight hundred two thousand k g of pancreas to produce hundred grams of insulin which
is a very very small amount compared to the world wide demand for insulin to treat
diabetes its a very very small amount not just that pancreas only one of these organs
of the body so you can imagine what needed to be done to get insulin when no other method
was known
however when a bioprocess for insulin became available because of the ease of getting insulin
this immediately reduced the cost of insulin by twenty four fold and this is also a bioprocess
this is the next video there on insulin that is given in your list you can go and
look at this to get some idea of the relevance of insulin the production of insulin through
a bioprocess and so on ok now lets come closer to home how do you think curd or yoghurt is
made you take milk you heat it to certain warmth in a vessel and then you add some old
curd to this slightly warmish milk and set is set it aside there are also curd makers
that maintain this vessel at thirty seven degree c just by some electrical means and
when this is done in a curd maker curd forms in about two hours or so if you live it over
night at home assuming that the outside temperature is reasonable then curd forms over night very
nicely
what is happening here ok let me introduce some terms that will be using frequently in
this course the milk that you initially take we can call it the medium right the nutrients
a nutrient broth using the nutrients in the nutrient broth the inoculum the small amount
of curd that you add it that contains organisms the organisms utilize the nutrients in the
medium and grow when these organisms grow these particular type of organisms they
are called lactobacillus when they grow they produce something called lactic acid you all
know what an acid does it reduces the p h and because of the controlled production of
acid in an appropriate fashion the p h gets reduced in an appropriate way along with other
things happening in the milk and a protein in the milk called casein curdles and thats
how we get curd appropriately you know even the the taste is made appropriate in
the process because of the way in which it gets done and then you could eat curd
very simplistically speaking curd making is also a bio process ok you have a vessel you
have a medium and you which contains a medium and then you add curd to it so you
have added inoculum to it the cells in the inoculum multiply and make more cells make
a product lactic acid and the lactic acid does something to the milk to give you curd
so this simplistics simplistically speaking is actually a bio process if a curd making
is also a bioprocess so let us look at what actually a bioprocess is this is an overview
of the bioprocess the bioprocess has two major aspects one is the bioreactor aspect this
is called also called the abstream aspect and a huge aspect here called the downstream
processing aspect the bioreactor is represented here by this we will see this in detail later
the raw material for example it could be the milk in the in the case of curd this enters
the bioreactor the bioreactor contains the micro organism of interest along with the
nutrient as we saw in the case of curd making the nutrients that are getting converted to
curd as well as the lactobacillus that converts it into curd or it could even have just an
enzyme which does some enzymatic conversion so after this process is done there are various
ways in which the process is done we will look at the details later
after the process is done what comes out of the bioreactor what is harvested from the
bioreactor contains the product of interest the micro organism and probably other material
we all are interested only in the product therefore we need to separate and purify the
product from these other things that are there and that is what is done through what is called
downstream processing there could be very many steps in downstream processing in fact
the number of steps in downstream processing could constitute about ninety five percent
of the steps in a bioprocess so large number of steps in downstream processing and finally
at the end of it all we have the final purified product so this is a bioprocess this course
will focus on the abstream side or the bioreactor side downstream processing of course is very
important but the focus in this particular course because we need to focus on something
to get something useful out of what ever we are doing and we are going to focus on the
bioreactor aspect or the abstream aspect typically the bioreactor aspect and thats why this mock
is called a bioreactors
as was clear from the previous slide the bioreactor is at the heart of a bioprocess that is necessary
for a bioprocess to exist now let us look at some of the common bioreactor types some
of the kinds of bioreactors that are used commonly the first one that we are going to
look at is called the stirred tank bioreactor in fact this is pretty much the work hours
of the bio industry many industries use this stirred tank bioreactor as the name suggests
it is a tank which is represented by this rectangle here it is actually cylindrical
in reality it could be as small as something that sits on this table may be a one two liter
reactor or may be something that sits on a lab bench may be about fifteen liter reactor
to something that occupies huge spaces in the industry may be one lakh liters few lakh
liters and so on so forth that are required in some in some industries so stirred tank
all these are effectively the same except their sizes are so different all these stirred
tank reactors will have a stirrer with stirs the contents of the bioreactor and thats why
it is called a stirred tank bioreactor
it is any bioreactor for that matter is an instrumented there are various instruments
here and highly controlled kind of an environment here the typical instruments that are used
are those that are needed to measure temperature there is a thermometer or an r t d device
that measures the temperature of the bioreactor contents there are something called d o this
is not do this is d o which stands for dissolved oxygen which happens to be an important parameter
especially when we use certain kinds of micro organisms in the bioreactor p h is an important
parameter that is measured controlled e many bioprocesses or bioreactions take place
in a narrow range of p h the aeration happens here air is used here agitation of course
we talked about and the medium we already talked about what i would like you to wear
in mind is that the stirred tank is a vessel ok that is a bioreactor where as the actual
reactors the bioreactors or the factories that are producing the products are the cells
in the bioreactor that make these products it could be the ethanol that we talked about
the lactic acid that we talked about the m a bs that we talked about the insulin that
we talked about or the bio oil that we talked about all these are made by these microscopic
cells the size of these cells are anywhere between thats a two microns to ten microns
typically there could be larger too and um therefore these cells in so called culture
are the actual factories that produce a product
we need to keep this in mind when ever we look at bioreactors in the initial part of
the course we will look at the bioreactor as this vessel and do things necessary for
this vessel and this will be in the background and later towards the data part of the course
we will focus some attention on how to operate or come up with strategies based on how these
cells actually function thats what makes more sense because these cells are the actual factories
that produce products and therefore we need to have an ideas to how their doing for the
bioreactor to be effective ok this looking at it as sum sort of a black box may not be
very helpful in many situations so that is a stirred tank bioreactor the second type
second common type that is used is what is called an air lift bioreactor
this schematic shows some important features of an air lift bioreactor the main difference
that you would immediately notice between a stirred tank bioreactor and a air lift bioreactor
is that there is no stirrer here ok [hower/however] you need to keep the bioreactor broth in agitation
only then will the bioreactor function properly the agitation the mixed nature is
brought about by air which is pumped in here somewhere the air rises through this it takes
in this is a cylinder inside the reactor the air rises through this and when it rises through
this it carries the cells along with it and then it kind of circulates this is a cylinder
i hope you are able to visualize this this is one cylinder this is the outer cylinder
and therefore air rises through the center comes like this quite vigorously and because
of that it is able to keep the cells in suspension and there by the reactor operates this is
the liquid level that is shown as the dotted line here
so this is an air lift bioreactor this has some advantages over these stirred tank bioreactor
and some disadvantages we had probably look at some of them in the passing after we
know something more about bioreactors the third kind that i would like to present to
you is something called a packed bed bioreactor you have a bed here which is packed there
is an inlet here there is an outlet here it could be continuous typically these bio packed
bed bioreactor are operated in a continuous way and this is where the bioreactions
take place to convert the reactant into the desired product this is a video that you may
want to watch i think it is um let me go back to the packed bed fluidized bed that
is the fluidized bed i will come to that next the packed bed is just a packed bed is a stationary
bed which contains is organisms which convert the reactance to the products the fluidized
bed which is a variant of the packed bed would have this part fluidized fluidized in the
sense fluid like so that it will be the bed would not be stationary it will be jiggling
around jumping around and so on so forth that brings in certain desired aspects in the operation
of bioreactors and fluidized bed bioreactor are used in some situations
a packed bed bioreactor is used commonly in water treatment and so on so forth and
this could just be a sand bed through which the water to be treated flows and what
flows out of here is cleaner water another type of bioreactor is called the solid state
bioreactors as a name indicates there is typically no liquid here ok it is all solid and um this
can be used for producing useful substances say enzymes and so forth from natural substances
which are end of solids they could be cut down chopped on and so on forth and then place
on these trays in probably a large enclosure and appropriate conditions maintained here
and the organisms added to the appropriate sub state as these sub state is a solid
the organisms convert the sub state into the desired product so such a reactor is called
a solid state bioreactors they are used in the industry they were heavily used in the
industry at one point in time to produce very useful products such is enzyme they could
still be used
this is a video that would talk something about these solid state bioreactors you might
want to watch that what is become popular now a days in some industrial applications
and also in some lab applications more so in industrial applications is the use of single
use bioreactors use it throw out this has significant advantages in the process of validation
because a process of validation is rather stringent and people need to establish various
different aspects in reproducible fashion when approvals are given for the production
and approvals are given after inspections and so on so forth such operations become
significantly simplified if you can use and throw the bioreactor and therefore the single
use bioreactors are quite popular the same stirred tank could be made of a disposable
plastic vessel and that becomes a disposable reactor everything else remains the same even
the sizes could be reasonably large in the if you use dis disposable plastic vessels
therefore instead of this stainless steel or appropriate material that is used for
bioreactor construction which is a permanent there you could use disposable plastic vessels
there are advantages as we talked about earlier but there are disadvantages too um there are
some disadvantages that this video this you can go on take a look at that and more
recently or i think about the same time bioreactors called wave bioreactors came into being this
is also given in i think in the same video you can take a look at what wave bioreactors
are they are nothing but plastic bags la they could be large plastic bags with huge capacity
of twenty five liters or so which can be used for the production of low volume high
value products so the disposable aspect helps the validation maintenance and so on so
forth um and they they work they are essentially plastic bags that are kept on rockers as the
video would demonstrate and the production happens in such a condition
the next kind of bioreactor that i would like to talk about is what is called a photobioreactor
a photobioreactor means that it employees light when do we need light whenever an organism
needs light and some thing that requires light is called a photo organism photosynthetic
organism photosynthetic organisms when you use them you need to use something called
a photobioreactor remember we talked about micro algae for the production of biodiesel
micro algae happen to be photosynthetic organisms they convert the carbon dioxide in the air
to bio fuel and that is why it is also considered a carbon neutral kind of a situation that
is it doesnt take any carbon from the earth it just takes the carbon from the air converts
it into biofuel and even if it gets back into air it is still a neutral kind of a situation
there is no addition of carbon carbon dioxide from the earth into the atmosphere
so when an algae is grown micro algae is grown to produce bio oil you use something called
a bioreactor the process is rather straight forward and simple everything is known about
the process this is the vessel here which contains the broth and this vessel has an
outlet which leads to this photo section i think the next picture would show the photo
section a little better you know this is the photo section lighted up this is from this
angle and the second photograph is from this angle i hope you are able to understand that
is the same reactor this is taken from our lab we have we use a photobioreactor we did
some work on micro algae so this vessel there is an outlet which goes into the photo
section this the organisms receive light here when they are in the photo section which are
made up of glass tubes and then they return to the vessel and that happens continuously
so this is a photobioreactor coming back to the process of bio diesel or bio oil production
using micro algae the process is rather simple you grow micro algae the micro algae
convert the carbon dioxide in the air and in that process they accumulate lipids or
bio oil the lipids can be got in on out of the micro algae after production by pre just
pressing them using a press the oil flows out and then you can use the oil for what
ever you need
the process is very simple a lot is known about the process but the economic production
of bio oil from this route is still not happening and that is the reason why this process is
still not available commercially anywhere in the world expect on an experimental basis
may be but its not really commercially viable it has lot of promise lot of challenges some
of which we will talk about in this course those challenges are overcome then it could
be an economic reality and this could be a very good alternative source for bio oil
and biodiesel and many other products even jet fuel can be made from this process ok
this is the schematic of the vessel here and the photo section here this way you might
be able to understand things a little better here this contains the micro algae their let
out here there is a pump that takes it through the glass tubes in the photo section they
are exposed to light as a shown here and they come back and they photo synthesize to accumulate
bio oil this is a video that you could watch on from that list that is taken there i think
it is number eleven here before to bioreactor that would give you an idea is to how it is
possible to produce bio oil from micro algae through a bio process that involves a bio
reactor
and there are very many kinds of bioreactors will not possible to go through all of them
these are the common types that are used for producing useful products through the biological
route and you have seen some of them next let us look at the bioreactor operation modes
many of those reactors stirred tank air lift and the other kinds of reactors that
we saw the packed bed fluidized bed and so on they can be operated in one of three modes
three main modes the first one is a batch operation ok this is the same stirred tank
that we considered earlier and this is a stirrer here which stirs and keeps the cells and suspension
when operated when this stirred tank is operated in a batch mode what is done is we dump everything
in that is the medium the cells the inoculum so on so forth and then the reaction takes
place therefore we wait for the bio products to be made and at the end of the time we dump
everything out and proceed with further processing the downstream processing steps to separate
and purify the product from the other things
so this kind of an operation were you dump everything in wait for the process to complete
and dump everything out that kind of a process is called a batch process or a batch operation
of a bioreactor and many processes in the industry are batch is very simple comparatively
speaking to operate batch bioreactors compared to other types of bioreactors a kinds of operation
the next one is a continuous operation of a bioreactor the same stirred tank here you
could have a continuous input of the sub state as it is called the nutrient broth as it is
called this need not even contain any cells the cells could be here and there is a continuous
output from the bioreactor with the product made the times are adjusted so that the product
is made appropriately and such an operation is called continuous operation
what is important to note here is that during this process there is growth of cells the
product formation and the flow of nutrients all happen simultaneously ok that is important
to internalize in a continuous operation all these happen simultaneously and that internalization
is required to appropriately look at it analyse it and then use it probably design something
of interest to each one of you separately between these two the batch and the continuous
you have something called a fed batch operation ok it is in between the two and you could
guess what that is there could be intermittent input there could be intermittent output and
or both you could have some input and some output what i mean by that you start with
the probably a batch and then for some reason well known reasons you add some sub state
may be in intervals not continuously in intervals that is a fed batch you may not even remove
with anything or you could remove some part of the broth the reacting broth intermittently
that could happen or you could do both you could add intermittently and remove intermittently
and any how these kind of operations is called a fed batch operation and there are
various reasons for example some products that are made by this cells can be toxic to
the cells themselves simple thing is ethanol that is made so much in a so many industries
that produce ethanol and ethanol above some ten some sixteen percent or eighteen
percent is actually toxic to the cells so it cannot cannot be allowed to build up here
there are other products that could be toxic at much lower concentrations and to handle
the toxicity a part of the broth is removed and fresh broth is added so th[at]- the concentration
of the toxic product remains in check
now those were the types of bioreactors that we saw the common types and the modes of operation
of those types of bioreactors some bioreactors lend themselves to all kinds of operation
modes or all the three operation modes batch continuous and fed batch where as may
be a packed bed bioreactor or a fluidized bed bioreactor it may not be very easy
to operate them on may be a batch bases a continuous bases would be easier to operate
typically a continuous operation is a lot more difficult many times more effort are
required to run a continuous operation continuous batch continuous bioreactor compared to the
batch operation
ok now let us look at some other aspect we are using organisms micro oraganisms to produce
the product of our interest therefore only the organisms of interest need to be present
in that space that produces the product however organisms are present everywhere in this room
around us in the space where this bioreactor used um in hospital rooms and so on and so
forth there are organisms present in the air in reasonably large amounts and that is
not good for example you dont want an infectious organism that is present in the air to get
into your body the body has certain defense mechanism that minimize the effects but
still it could lead to complications thats why many of us get this infectious diseases
when the bodys defense mechanism is not able to cope more critically when a person is operated
upon when a surgery is done the persons internals are exposed and there is no skin or the
skin is compromised for a certain purpose for the purpose of the surgery
when the skin is compromised the organisms that are present in the air if they are present
can enter and cause infection and that should not happen and therefore the surroundings
of the surgery must be kept clean of organisms similarly the surroundings of a biorea[ctor]-
or the bioreactor itself must be clean with no organisms and then the organism of interest
alone is added to the bioreactor and that is made to multiply and produce a product
of interest therefore there is a huge need for a clean slate you might be surprised you
have a organisms to the concentration of about um ten power three cells or ten power four
cells per m l in the air around us there could be many types of organisms and you dont want
them to be present either in your body or in the bioreactor which is designed to produce
a particular type of product
what happens is if the other organisms come may be those organisms can grow much faster
than the organism of interest and that will compete with the organism for the food that
is available and the bioreactor will be a failure thats called contamination of the
bioreactor you dont want that so to avoid contamination we need a clean slate how do
we achieve this clean slate is rather interesting let us discuss this and we will close the
introduction lecture we have may be about nine minutes left will close the introductory
lecture with this discussion its very interesting how do you sterilize a hospital room how do
you remove all the organisms from a bioreactor organisms can be present anywhere corner of
the bioreactor there are three major ways in which this is done one is we use very high
temperatures may be a hundred and twenty hundred and twenty one degree c for about fifteen
minutes and a bit conditions typically used a high temperature can be used and that
achieves a clean slate this is been shown repeatedly it works very well
you could use chemicals liquids or vapours and that is what is typically done to sterilize
spaces such as the operation rooms or labs for example labs when we get contaminationed
then we want to remove all the organisms that are contaminating our work related organisms
and therefore what we do is we use formalin solution add potassium permanganate to
it to cause an exothermic reaction in the formality hide actually formality hide
vapours that come out of it kills all the cells in that space it is rather dangerous
and thats why when lab is sterilized there are notices put up everywhere doors are sealed
with ceiling tape the windows are sealed completely and a person of who is places these aluminum
boats with this formalin solution at strategic places in the lab and works out a way by which
a person can get out and seal the glass door the other doors are already sealed other windows
are already sealed and the person keeps dropping these potassium permanganate pallets into
these aluminum boats as the person walks out quickly comes out of the lab seals the door
and the vapours kill all the organisms no vapour is allowed to escape into outside
the lab and the lab is kept sealed for a couple of days and then you enter you can actually
smell the cleanliness or the lack of organisms in the lab along with the chemical balance
so on so forth
so this is a very common procedure for using chemicals in this case it is formalin
you could use seventy percent ethanol to kill the organisms in on your hands on your gloves
and so on so forth while working with um organisms while transferring organisms from one part
to another in a lab also you could use radiation such as u v radiation gamma radiation which
are high energy radiations that can cause changes in the d n a and so on so forth
of the organisms and kill the organisms when you cannot use high temperature for example
when you working with temperature sensitive plastics may be for syringes and so on so
forth you cannot use this high temperature process the high temperature process is
called autoclaving and that is used for substances made of metal such as bioreactors
made of metal if it is a small bioreactor you can place a whole bioreactor inside what
is called an autoclave that helps reach the conditions that we mentioned earlier one twenty
one degree c slightly elevated pressure steam because steam exists a only those conditions
if you remember thermodynamics and if that those conditions are maintained for about
fifteen minutes to half an hour then you could get a sterile space then you take that space
and make sure that the sterility is maintained and then at the right time you add the organisms
of interest that is how the autoclaving is done
if the bioreactors are large we talked of bioreactors that have capacities of may
be lakh few lakh liters then in situ sterilization is done you use similar kind of mechanisms
high temperature caused in place because you cannot move [laughter] those reactors
very easily and a clean slate is achieved radiation such as u v and gamma rises we mentioned
are used to treat or used to kill the organisms in um places where we probably cannot use
high temperature to kill or chemicals to kill so these are some of the common sterilization
methods that are used to achieve the clean slate for a bio process to begin i think we
will stop here for this lecture i think we are almost out of time i briefly introduced
you to this mock its a ten hour mock on bioreactors i mentioned a couple of books that you could
look at but only very loosely this organization is very different um however i will also give
you the corresponding chapters as we go through the various material some of the material
may not be there but whatever is there i will give you the corresponding chapters
in the books so that you can go on read the book
in the end of every week will have some assignment to submit mostly through multiple
choice questions however it will be good for you to develop the skills of problem solving
atleast close closed ended problem solving where you know everything you will have to
analyze apply and get a useful result and for that i will probably pose the problem
in one class give you enough time to solve it at after the lecture and then show you
the solution in the next class lets meet again in the next class