PRESSURE AND AUTOCLAVING

One of the essential components in the use of autoclave is pressure. Autoclaves are usually operated at a higher pressure than the environment. High pressure is needed in order to achieve the sterilizing temperature of 121 degrees centigrade. Without pressure water can only boil at 100 degrees centigrade under normal atmospheric pressure. ( Of course at higher elevation such as on mountain tops, where the atmospheric pressure is less water boils at lower temperature!)
Generally pressure of about 15 psi is required for autoclaving. This pressure is achieved by heating the water in the sealed compartment of the autoclave. High pressure is due to the built up of the steam as the water is heated. There is a pressure safety valve in autoclaves that the high pressure is not overshot. ( This explains the regular hissing sound produced during autoclaving as excess pressure is regulated)
While it is very important to build the pressure to the correct value before autoclaving is initiated, it is also important that at the end of a sterilization that the pressure is brought back to normal values before the autoclave is opened to remove the sterilized items.
Heating and cooling processes take time. Most users are impatient for the time it takes to cool and lower the pressure. Impatience often results in users trying to speed up the release of pressure by opening the release valve too quickly. This action would result in the boiling over of the contents of the flasks and test tubes which could result in the wetting of the cotton plugs and increase the possibility of contamination.
Opening the doors to quickly could result in the sudden release of internal pressure by the autoclave. This could result in scalding of the body as the hot steam rushes out. Release of pressure must be done slowly and only when it reaches zero is the door of the autoclave opened

Type rest of the post here. Read more!

THE AUTOCLAVE- APPROACH WITH CAUTION!

The autoclave is one of the standard equipment in any fermentation activity or in the microbiology laboratory. Some of the autoclaves occur as independent units on its own while there are those which are in built into the fermentor for in situ sterilization. Irrespective most of these autoclaves are used for sterilization purposes. This is especially so in pure culture fermentation work where there is the need to remove the occurrence of unwanted microorganisms at the onset of fermentation. The autoclave is also used at the end of the fermentation run for sterilization or disinfection to avoid biohazards.
There are many options available in disinfection or sterilizations besides autoclaving. Yet in most cases in fermentation, autoclaving is the preferred method of sterilizations. Despite its wide usage there are many of us who take the autoclave for granted without understanding its principles of operations and even its limitations. In my years of autoclaving, everybody seems to remember the steps in the operation of the autoclaves without taking time to understand its limitations. The users have more faith in the operation of the autoclaves as 100% ‘fool proof’ and that there would be no problems with its operation or the efficiency of the sterilization process carried out using the autoclaves.
Thus it is often not surprising that often the quality of sterilization is poor and that the autoclave is not working to their expectations. By then it is often too late….. .
One of the biggest issues in having autoclaves is that often the autoclave in the laboratory have to accommodate all kinds of users (from students, post graduates, post docs and even laboratory assistants and attendants) Too many users with too many types of materials to be autoclaved who may vary from having to little knowledge to excessive pseudo knowledge in the proper use of autoclaves.
At some point, these users are exposing themselves to various health hazards from explosions to even being scald alive! REMEMBER! THE AUTOCLAVE IS IN REALITY A BOILER WHICH WRONGLY USED COULD RESULT IN HIGH PRESSURE AND HOT STEAM!
So many years observing autoclaving have seen many common mistakes made mostly attributed to poor understanding of the autoclave operation to the dangerous ‘don’t care attitude’
Common mistakes often observed have seen plastic trays used to hold the stuff to be sterilized becoming lumps of melting plastic, Melting agar flushed down the pipes resulting in blockages, over spilling of media and even projectiles of bolts and nuts!
Yet again and again lessons are not learnt as proven by the mistakes which occur repeatedly.
It is very very important that those using fermentors and autoclaves are properly trained in using the autoclaves to ensure their very own safety! Those that use the autoclaves need proper training and be supervised and to pass examinations on the use of autoclaves!


Type rest of the post here. Read more!

WHAT IS THE RPM?

This is one of the most common and most abused terms used in fermenter when dealing with the speed of rotation of stirrer in fermentation studies. The speed of rotation of the stirrer is commonly expressed as rounds per min (RPM). The power of stirring is often associated directly with the speed of RPM. Higher RPM means more power to stir

There is a simple correlation generally accepted that the higher the RPM, the higher will be the agitation or mixing of the fermentation broth and hopefully a better mass transfer is achieved between the microorganisms and the environment.
One of the common beliefs is that with higher mixing or RPM we should be able to achieve higher mass transfer of oxygen leading to more efficient fermentation process.

This belief has its limitation as there are many factors that affect the mass transfers of oxygen besides RPM other than just obtaining the optimum RPM
What is most surprising is that the use of RPM seems to be carried out with out the proper understanding of the various processes that occur during the fermentation in the bioreactor.

In most textbooks there seems to be a complete trust in one particular set value of RPM without thinking the use of various other options to enhanced the fermentation process and minimizing the negative impact of excessive or under use of RPM
I have seen almost majority of books suggesting the range of RPM around 200 to 250 RPM. Simple visual observations can show how fast or how damaging such high speed of stirring can be on the fermentation process.

We all know that in the case of mass transfer of oxygen to the fermentation broth will be influenced by the volume of air introduced into the fermentor and stirring among other factors. A choice of high RPM may be even more damaging to filamentous microorganisms. Thus great care must be taken in choosing the proper RPM and not to trust blindly by the 200 to 250 RPM often recommended

Mixing of the fermentation broth is not a simple process. Each researcher must find their very own optimum values in terms of both economic and technical success of their fermentation. After all no two fermentors carrying out the fermentation process are the same! This situation will be most critical when the fermentation is carried out on a large scale. In considering stirring and RPM. the impeller or the paddles influence must be considered. Adding an additional impeller will increase the efficiency of the agitation of the fermentation broth but at the additional expense on the load of the stirrer which will increase the strain on the stirrer system


Type rest of the post here. Read more!

OUR FIRST “MADE IN MALAYSIA” PILOT PLANT FERMENTORS

I have mentioned earlier that fermentation can be carried out in any vessel or container. The difference is that if fermentation are carried out in such vessels we might not end up with a proper and efficient fermentation process. Inefficiency could arise out of poor mass transfers, monitoring and lack of stringent aseptic control.
The design and building of good fermentors depends on inputs of engineers and microbiologists. It is just risky to just depend on one set of people to design and build a good fermentor.
Yes, while it is true we can build a vessel or structure that seems to be identical with well known fermentors on the market, however, that is where the similarity just ends. Functionally the fabricated fermentor could just be a failure
A few days ago I was surprised by the news that we have successfully designed and built our pilot plant fermentors. The project is the involvement of a few universities and research institutes. Large amount of money was invested in the project and the opening ceremony was even officiated by the respective Minister of the relevant department.
As I said earlier that I am not surprised we can build fermentors but more worried about the fact as to whether in depth studies have ben carried out to ensure the functionality of the fermentor built. It will be a tragic day to find out later that that there might be serious problems ‘overlooked’ in the design and construction of such fermentor.
Building fermentors require the in depth knowledge and experience of experts and specialists in the field of building fermentors. The only data that I can gleam from the article is more towards the capacity of the pilot plant fermentors. Not much or any other important technical detail were provided.
Building a fermentor is a project in science and technology. Hearsays are just not enough to convince people who wish to rent or even buy the fermentors. Don’t be surprised if such multi million dollar projects will just be underused or just become white elephants! If it happens it will be a waste of the taxpayers money.
As mentioned in this blog earlier there are a number of universities and companies which all ready have existing pilot plant facilities,,,,, almost unused and dying to look for clients to use their pilot plants.
It is most surprising the pilot plant built seems to be equipped with standard components as judged by the type of stirrers used. As we know it has always been the case of the type and rheology of the fermentation of the broth and the type of fermentation that dictates the type of fermentors used in the pilot plants. Having similar geometry in the scale up is idealistic but need not always be obligatory.
I have always wondered if the building of the pilot plants were tested and validated by standard methods? If such preliminary studies were not carried out, it will be a disaster awaiting to happen and reputation at stake.

Type rest of the post here. Read more!

SMOOTH FINISHING OF FERMENTOR SURFACES

Of course in the context of our discussions we are talking mostly of the internal or inside surfaces of fermentors and even of stainless steel pipings to and from the fermentors.
In the fermentation industries involved in the production of biopharmaceuticals and innobiologics such stringent sanitary and sterilized conditions could be the make and break of the fermentation process. It could be a successful and profitable fermentation process or it could be a financial disaster.
The provision of smooth surfaces will not only eliminate microbial contaminants or fermentation residues but also will help improve the cleaning and washing of the surfaces. Not only is the cleaning process becomes more efficient but it is even proven that substantial cost savings made in water and cleansing solutions
Smooth finishing of internal surfaces as provided by stainless steel material and structure have always been regarded as the solution to providing the smooth surfaces of fermentors and the ancillary piping to and from the fermentors
However, most of these statements are often not tested. Different fermentation processes show different fluid properties and thus also different washing and cleaning regimes. Smooth or mirror polishing could itself result in smooth surfaces but also provide hidden niches where microbial contaminants and organic deposits could be hidden in the smoothened crevices. Visually we may see the stainless steel as being very smooth but under the magnification of the microscope, it is not as smooth as we expected.
One of the solutions to producing smooth surfaces is of course by electro polishing, in which passing current help to smoothen the rough surfaces
Whatever the outcome any stringent fermentation industries have to carry out their own cleaning validation process to ensure that they are on the right track.


Type rest of the post here. Read more!

tasmanian holiday

A Tasmanian holiday to remember


'There's nothing like a sunset experience with good friends, each personality as different as the sea, sun and sand but together, a lasting memory to be cherished.'

Fun, friends and sunrise over a white beach – it was all a world away from Raja’s “boring and downright insane” study schedule in Malaysia. Raja and three of her friends had just finished another demanding semester in their architecture degree and were desperate for a holiday. They all agreed that Tasmania, with its pristine nature and tranquil pace, was the best place for a study escape.

“The holiday was memorable because both the company and destination complemented each other. What began as a simple road trip brought us closer as friends, despite our different nationalities and differences in opinions. Together, we were united and awed by the breathtaking sights of Tasmania’s nature,” Raja said.

Raja and her friends spent most of their holiday in and around Hobart, where as photography enthusiasts, they had a special appreciation for the historic architecture. They captured lots of great shots of Salamanca Place, with its cobblestone streets and rows of Georgian warehouses. They also climbed craggy, windswept Mount Wellington, photographing the panoramic vistas over Hobart and the Derwent River. After their descent, the group enjoyed what Raja described as “one of the best fish and chips” of her life, from a little shop near the Hobart waterfront.

Bruny Island wasn’t originally on the itinerary, but Raja and her friends decided to visit after discovering it was only a short drive and ferry ride from Hobart. They also liked the sound of its scenery - emerald countryside, plunging sea cliffs, fern-fringed forests, pristine beaches and coastal heathland. It was here that Raja took the photo which she entered in the Nothing Like Australia competition, and which came to symbolise the essence of her holiday.

“We spent the night there to witness the sunrise and to take more pictures of us frolicking by the beach. It was in three words, a pleasant surprise,” said Raja, who also remembers sharing jokes with locals while waiting for the return ferry.

Later the group ventured along Tasmania’s east coast to Wineglass Bay on the Freycinet Peninsula. Despite missing out on seeing the famous sunset from the lookout, Raja and her friends treasured this time to commune with nature and bond with each other.

It certainly made a welcome change from Raja’s daily student life, which she describes as being “glued to my computer screen and leading a topsy-turvy schedule of eating and sleep.”

For her “next great Australian escapade”, Raja is determined “to set foot in Sydney’s famed Opera House and view the Sydney Harbour Bridge.” After that, she wants to discover Australia “by the chapters….like a great love story.”
Type rest of the post here. Read more!

VENTILATION AND HEATING PROBLEMS IN THE ARCHITECTURAL DESIGN OF MALAY HOUSES

In the first place, I am not an architect and not trained in anyway in architecture. I have never attended any formal courses in architecture be it at colleges or universities. But I am interested in architecture in terms of appreciating its design and function.
There is one strong point that I have in trying to appreciate and understand ( a bit) about architecture. I am trained in the science and the logics and principles of science. Throughout my life I was brought up in a Malay kampong or village environment where most if not all the houses built are the traditional Malay houses with strong input of Minangkabau influence.
Despite of what is being said and heaps of praises thrown out towards the traditional design of the Minangkabau and Malacca houses, I got a very uneasy feeling that the writers of these articles have never really stayed that long in the traditional houses. In terms of architectural design the traditional houses may be rich in culture or beautiful in its presentation but in terms of its functionality and comfort it shows a mediocre performance.
Any one staying in such houses should know how poor the ventilation of the houses and how hot the interior environment of such houses. Most of these houses are often located within the proximity of trees or even forests resulting in such a high humidity content of the air around the area. Not only it is hot but humid which are indeed very uncomfortable to the house dwellers.
The situation was not bad when the original roofs are made of thatched roofs which are cooler compared to the use of zinc layers which makes the house a wonderful oven.
The argument that there is sufficient ventilation to cool the indoor environment is not good enough/ Most of the writers would easily try to explain in terms of “theory” how hot air will rise from the floor to the roof by thermal convection. What they forgot to explain is that the hot air that rises to the ceiling or roofs are not easily dissipated to the external environment. This may be attributed to their poor understanding of the physics of ventilation in their courses or in the universities
Very few or little scientific studies are really carried out to understand the movement of heat or formation of heat sinks in such houses .It doesn’t take much to use tracers or heat sensors to study the heat, humidity and data could easily be analysed by computers
It is time that the local architecture schools carry out proper scientific studies and modellings to understand the ventilation and heat circulations of the traditional houses that can contribute to better designs of such houses. Gone are the days when architecture is likened more to just designing without understanding the physic principles behind it.

Type rest of the post here. Read more!