SRB is an interesting group of bacteria which can use sulphate as an electron acceptor for the respiration. Despite the chances of certain other bacteria to use sulphate as the sulphur source for their S-containing cell components, the "real" sulphate reducers transform SO4(2-) to S(-2) in their energy metabolism and oxygen actually inhibits their growth - they are therefore obligate anaerobes. Certain yield of energy may be achieved through fermentation by SRB's but this type of metabolism is regarded as relatively insignificant one for them.
These bacteria have first detected in waste waters of sulphite pulp mills but modern paper machine processes can also induce their growth if certain sulphur-containing compounds are available.
In addition to H2S production (which is a hazardous gas), colour problems can arise because the metal sulphides. FeS is an indicator compound in the analytical detection of SRB's but also a harmful agent of discolorization of paper and paperboard. Last but not least, SRB's have been shown to be conneceted to a certain type of iron corrosion and it is all possible to find those problems still today whenever technical structures with poor steel quality and certain types of organic deposits on their surfaces are combined.
SRB's have also other, peculiar features like the tendency to follow non-exponential growth curve. They have been the subject of firm microbiological research only since the middle of 20th century because their need of anaerobiosis was not understood earlier.
FINNOFLAG Ltd. is currently developing a novel method for the sensitive detection of SRB's with PMEU method - more about this topic in next posts.
Saturday, August 8, 2009
Friday, July 24, 2009
The need of bacterial identification?
IM has discussed about alternative methods for the detection of hazardous or harmful bacteria with Dr. Elias Hakalehto.
It is most important to know the pathogens which will appear in patient samples. Clinical microbiologists shall know who are the enemies of the ill people: their metabolic capabilities, antibiotic resistence patterns etc. Their overall features are easy to find from literature or internet whenever the name of the species is known. This identification can be performed by selective cultivations on agar plates or in PMEU incubator, and further tests like microscopic examinations, API ID systems, immunological tests and/or PCR can be done to confirm the basic identification.
Paper mill is definitely another challenge for microbiologist. In some (relatively rare cases) the names of microorganisms are important to know: if the product shall have high hygiene quality (like LPB and other food-grade cartonboards) or questions about bioterrorism have been arisen (spore-forming Bacillus anthracis as an example). The occurrence of Legionella pneumophila is also a risk in the waste water treatment of paper industry today. Selective cultivations, either on plates or in PMEU, are the solid solutions for continuous microbiological control in those cases. PMEU is preferred because its speed (hours, compared to days with colony count analyses).
Papermakers shall focus more on the metabolic activities than the names of bacteria which they are living with in paper mills, however. Continuous inoculation of the paper production processes by contaminants, delivered with incoming lots of starches, mineral fillers, raw water, dry pulp etc. shall be controlled to avoid spoilage (amylolytic activity as an example), biofilm and slime growth, tastes and odours, spots and colours in the product etc. Because the wide range of bacterial species and their origin from the nature itself, clinical methods do not suit very well for this monitoring. There is no time to start labourous cultivations, pure cultures and identifications when the bacterial input continues day and night, "7/24". PMEU seems to be an excellent tool to check the basic features of process populations, their biocide resistence patterns included.
One important fact must also be taken into account. There are a lot of harmful microbes which actually cannot be cultivated on agar at all. One example are certain filamentous bacteria which may cause biofilm layers into the processes. They can be cultivated in some broths, however, but the usage of the original samples as the growth medium is the best way to detect them all. This can be done with ordinary mb laboratory equipment or with PMEU incubator.
Identification of bacterial species is still needed when the mapping of contamination routes into the processes is the subject of the study. IM will discuss about the microbiological mapping in his next posts.
It is most important to know the pathogens which will appear in patient samples. Clinical microbiologists shall know who are the enemies of the ill people: their metabolic capabilities, antibiotic resistence patterns etc. Their overall features are easy to find from literature or internet whenever the name of the species is known. This identification can be performed by selective cultivations on agar plates or in PMEU incubator, and further tests like microscopic examinations, API ID systems, immunological tests and/or PCR can be done to confirm the basic identification.
Paper mill is definitely another challenge for microbiologist. In some (relatively rare cases) the names of microorganisms are important to know: if the product shall have high hygiene quality (like LPB and other food-grade cartonboards) or questions about bioterrorism have been arisen (spore-forming Bacillus anthracis as an example). The occurrence of Legionella pneumophila is also a risk in the waste water treatment of paper industry today. Selective cultivations, either on plates or in PMEU, are the solid solutions for continuous microbiological control in those cases. PMEU is preferred because its speed (hours, compared to days with colony count analyses).
Papermakers shall focus more on the metabolic activities than the names of bacteria which they are living with in paper mills, however. Continuous inoculation of the paper production processes by contaminants, delivered with incoming lots of starches, mineral fillers, raw water, dry pulp etc. shall be controlled to avoid spoilage (amylolytic activity as an example), biofilm and slime growth, tastes and odours, spots and colours in the product etc. Because the wide range of bacterial species and their origin from the nature itself, clinical methods do not suit very well for this monitoring. There is no time to start labourous cultivations, pure cultures and identifications when the bacterial input continues day and night, "7/24". PMEU seems to be an excellent tool to check the basic features of process populations, their biocide resistence patterns included.
One important fact must also be taken into account. There are a lot of harmful microbes which actually cannot be cultivated on agar at all. One example are certain filamentous bacteria which may cause biofilm layers into the processes. They can be cultivated in some broths, however, but the usage of the original samples as the growth medium is the best way to detect them all. This can be done with ordinary mb laboratory equipment or with PMEU incubator.
Identification of bacterial species is still needed when the mapping of contamination routes into the processes is the subject of the study. IM will discuss about the microbiological mapping in his next posts.
Tuesday, July 21, 2009
Statistical methods in microbiology.
IM has discussed about the evaluation of novel microbiological methods with several professionals. His knowledge of statistical methods in microbiology bases on the lessons by Prof. Seppo Niemelä, who was (and still is) a well-known specialist in this not-so-well-known area of microbiology.
Testing of microbiological data is more complicated than similar analyses in chemistry. The main reason is the model of repeat distribution: chemistry follows the ordinary normal distribution but the colony counts of microbiological analyses are featured by the Poisson distribution. The reason for this difference is easy to understand: the count of molecules is overwhelming when compared to the limited count of colonies in microbiological cultivations. The dependence of variance on the mean of the data is another problem of colony count analyses, preventing the usage of parametric methods.
Luck enough, there are some non-parametric statistical analyses for Poisson-distributed data, helping the comparisons of means and trends of colony count results.
A novel problem seems to have arisen in microbiological evaluations since 70's. Many modern, automatized instruments of microbiology are not based on the measurements of chemical concentrations or counts of colonies but on specified metabolic activities of microbes. Examples of these analytical procedures are eg. measurements of impedance, turbidity, pH or CO2 production. Because these parameters are in a close connection to the growth rates - and to a new parameter, time - , their evaluations are very challenging procedures.
- More in next posts...
Testing of microbiological data is more complicated than similar analyses in chemistry. The main reason is the model of repeat distribution: chemistry follows the ordinary normal distribution but the colony counts of microbiological analyses are featured by the Poisson distribution. The reason for this difference is easy to understand: the count of molecules is overwhelming when compared to the limited count of colonies in microbiological cultivations. The dependence of variance on the mean of the data is another problem of colony count analyses, preventing the usage of parametric methods.
Luck enough, there are some non-parametric statistical analyses for Poisson-distributed data, helping the comparisons of means and trends of colony count results.
A novel problem seems to have arisen in microbiological evaluations since 70's. Many modern, automatized instruments of microbiology are not based on the measurements of chemical concentrations or counts of colonies but on specified metabolic activities of microbes. Examples of these analytical procedures are eg. measurements of impedance, turbidity, pH or CO2 production. Because these parameters are in a close connection to the growth rates - and to a new parameter, time - , their evaluations are very challenging procedures.
- More in next posts...
Wednesday, July 8, 2009
Identification of bacterial species.
Questions about the identification of certain bacterial species are rising time after time. Paper mills - and their customers - are interested to know if the product, paper or board, contains harmful bacteria like food-poisoning bacteria, or even hazardous ones. Could terrorists inoculate a paper machine with Bacillus anthracis? Could Listeria live in wet end processes? Bird-flu?
Another reason for the question is the safety of working environment. Are high densities of bacteria in the wet end air dangerous?
Fortunately all information of the environmental needs, growth factors and capability to survive dry end treatment (="pasteurization") show that there is no need to worry if those real pathogens could be encountered in paper industry products.
There are still some areas inside paper mill where the identifications are needed, like
* food-poisoning, sporeforming bacteria (most important: Bacillus cereus)
* bacteria causing raw material breakdown (amylolytic ones etc.)
* potential primary attachers, causing biofilm formation (several genus)
* bacteria which can cause health symptoms and diseases(Legionella pneumophila, certain coliform bacteria)
Identification of specified bacteria from wet end population isn't easy task. Mixed population, sample matrix, low number of target organisms, their distribution inside the machine all lead to very challenging task.
I will refer the traditional and novel methods for the detection of specified bacteria in next posts. Coming back...
Another reason for the question is the safety of working environment. Are high densities of bacteria in the wet end air dangerous?
Fortunately all information of the environmental needs, growth factors and capability to survive dry end treatment (="pasteurization") show that there is no need to worry if those real pathogens could be encountered in paper industry products.
There are still some areas inside paper mill where the identifications are needed, like
* food-poisoning, sporeforming bacteria (most important: Bacillus cereus)
* bacteria causing raw material breakdown (amylolytic ones etc.)
* potential primary attachers, causing biofilm formation (several genus)
* bacteria which can cause health symptoms and diseases(Legionella pneumophila, certain coliform bacteria)
Identification of specified bacteria from wet end population isn't easy task. Mixed population, sample matrix, low number of target organisms, their distribution inside the machine all lead to very challenging task.
I will refer the traditional and novel methods for the detection of specified bacteria in next posts. Coming back...
Sunday, July 5, 2009
Connections of paper industry microbiology to other sectors of microbiology: what is actually needed?
To make any definitions of paper industry microbiology, it makes sense to compare it with elder sectors of microbiology. Despite the microbiological problems of the paper processes and the paper products have been obvious since the beginning of machine-scale production of paper and board on 19th century, their effects have get worser when the scale, speed and raw material repertoir have increased during last decades. The tradition of the microbiological control, as well as the history of biocide research, intended in the "healthcare" of paper and board machines is therefore much shorter than in related areas like in dairy or food microbiology.
Paper manufacturing processes could be seen as ecosystems where several, complicated microbiological processes are continuing day and night. Microbial communities perform their important role as the actors of chemical transformations which shall modify most living and very many non-living substances into forms which will support the growth of other living creatures. Many species of immigrant bacteria, coming into the processes with the raw water, mechanical fibres and several additives, will feel fine: favourable temperature, pH level and nutrient concentrations, as well as good aeration and a huge supply of contact surfaces to build up biofilms, are available for them. They really do not make any difference between their lives outside and inside of the paper mill walls.
Unfortunately (not for the microbes but for the paper production) there are some features of paper machines which are similar with fermentor and bioreactor processes of biotechnological industry. So many growth factors (some of them were mentioned above) will be kept on so controlled levels that the adaptation of certain microbiological population cannot be avoided. It shall also be kept in mind that the long running periods will increase the microbiological risks by allowing long growing periods of microbes inside the machines.
How to control these problems?
Measures to dose biocidic compounds into the processes cannot be avoided because the conditions of paper and board machines cannot be adjusted on biocidic levels: the rise of the overall temperature over +80 oC is impossible, like the rise of pH value over 12. Before significant technical improvements to prevent the microbial growth in the paper machine processes could be done (if ever), the biocidic treatments and their rapid control methods like ON LINE biofilm measurements and frequent (at least once per 8 hours) AT LINE microbiological control of the main contaminating routes, wet end processes and towers containing white waters, pulps and brokes are the most important tools to secure the runnability of the machines and the quality of the products.
With the price of only 2-3 jumbo rolls can reliable instruments for the AT LINE microbiological control of the wet end processes be bought today. Alternative methods, many of them representing molecular biology methods, are available, but those which can show not only the counts of certain species but also the overall metabolic activities of the waterborne microbes and their potential to produce biofilms should be preferred. A combination of PMEU incubations and ATP Assays, with the addition of PCR if needed, is the most recommended procedure to show the effects of biocides on the microbial activity. PMEU method can be applied to biofilm testing, too.
The most important thing is that not only the counts of microbes (how high they may ever been) but also their overall metabolic activity and certain actions like breakdown of starches by amylase enzymes or production of H2S and H2 in anaerobic conditions shall be controlled all the time when the machines are running. All the laws of microbial ecology are present both in the nature and inside the machines - and they can lead to severe problems if counteracting does not work.
Paper manufacturing processes could be seen as ecosystems where several, complicated microbiological processes are continuing day and night. Microbial communities perform their important role as the actors of chemical transformations which shall modify most living and very many non-living substances into forms which will support the growth of other living creatures. Many species of immigrant bacteria, coming into the processes with the raw water, mechanical fibres and several additives, will feel fine: favourable temperature, pH level and nutrient concentrations, as well as good aeration and a huge supply of contact surfaces to build up biofilms, are available for them. They really do not make any difference between their lives outside and inside of the paper mill walls.
Unfortunately (not for the microbes but for the paper production) there are some features of paper machines which are similar with fermentor and bioreactor processes of biotechnological industry. So many growth factors (some of them were mentioned above) will be kept on so controlled levels that the adaptation of certain microbiological population cannot be avoided. It shall also be kept in mind that the long running periods will increase the microbiological risks by allowing long growing periods of microbes inside the machines.
How to control these problems?
Measures to dose biocidic compounds into the processes cannot be avoided because the conditions of paper and board machines cannot be adjusted on biocidic levels: the rise of the overall temperature over +80 oC is impossible, like the rise of pH value over 12. Before significant technical improvements to prevent the microbial growth in the paper machine processes could be done (if ever), the biocidic treatments and their rapid control methods like ON LINE biofilm measurements and frequent (at least once per 8 hours) AT LINE microbiological control of the main contaminating routes, wet end processes and towers containing white waters, pulps and brokes are the most important tools to secure the runnability of the machines and the quality of the products.
With the price of only 2-3 jumbo rolls can reliable instruments for the AT LINE microbiological control of the wet end processes be bought today. Alternative methods, many of them representing molecular biology methods, are available, but those which can show not only the counts of certain species but also the overall metabolic activities of the waterborne microbes and their potential to produce biofilms should be preferred. A combination of PMEU incubations and ATP Assays, with the addition of PCR if needed, is the most recommended procedure to show the effects of biocides on the microbial activity. PMEU method can be applied to biofilm testing, too.
The most important thing is that not only the counts of microbes (how high they may ever been) but also their overall metabolic activity and certain actions like breakdown of starches by amylase enzymes or production of H2S and H2 in anaerobic conditions shall be controlled all the time when the machines are running. All the laws of microbial ecology are present both in the nature and inside the machines - and they can lead to severe problems if counteracting does not work.
Sunday, June 7, 2009
"Top Three" microbiological problems of paper machines
Certain types of microbiological problems in paper mills seem to be acute all the time. Looking back to last months, this may be "Top Three" among them:
* Microbiological spoilage of raw materials. This is an everlasting hazard for mineral and starch slurries, and the reasons are very easy to understand: both raw materials mentioned may contain high densities of bacteria (mainly aerobic sporeformers and actinobacteria), slurries containing starch are very nutritive growth media for different microbial species and the very challenging biocidic treatments of slurries (especially mineral ones), when inaccurate, can lead to the total spoilage of them.
* Growth of biofilm and production of slime. This problem seems to be connected to poor washing and boil-out programs which leave rests of biofilm inside the machine and give growth time for it because too long running periods. The chose of ineffective biocide and/or its insufficient dosing can also stimulate the activity of these trouble-makers.
* Microbial growth in the broke system. Especially big machines with large broke towers suffer of this problem. If the basic biocide program is insufficient and the retention times inside the towers are too long, aerobic population tend to increase the number of its cells to the level of 10 000 000 cfu/g or even higher. Consumption of oxygen by respirating bacteria leads to anaerobic conditions, redox potential will be dropped and the growth conditions for both fermentative and anaerobic bacteria turns to be excellent. Drop of pH, slime and spore formation, smells and odours - even the production of H2S and H2 - will be found in such situations.
There are some measures to prevent these hazards. Growth period of microbial population shall be kept as short as possible, the control of waterborne and bioflim bacteria shall be as rapid and frequent as possible and the bioside programs, intended in killing of raw material, process water and biofilm bacteria shall be evaluated more frequently.
A realistic and accurate way to control both process water and biofilm growth, as well as to evaluate biocide programs, is now available. The Finnish company SAMPLION Ltd is manufacturing and selling "Portable Microbiological Enrichment Unit", a "mini-fermentor" for 10 simultaneous tests in controlled conditions, to detect the failures of biocide programs in only hours (watesr) or days (biofilms). Some results of PMEU's paper industry applications will be published in next Spring - coming back to refer them later.
Some wrong ideas about the overdosing of biocides will also rise up frequently among publicity. Basically it is not a question of only the cubic meters of biocides consumed, however, The chose of most effective biocides for different areas of processes towards different problems, the dosing of these compounds, their type of action and some other factors play a major role when building an effective biocide program for paper machine. Overdosing of biocides is a problem only in cases, when the program does not work, and leads to the loss of money and the rise of biocide concentration in paper machine effluents.
* Microbiological spoilage of raw materials. This is an everlasting hazard for mineral and starch slurries, and the reasons are very easy to understand: both raw materials mentioned may contain high densities of bacteria (mainly aerobic sporeformers and actinobacteria), slurries containing starch are very nutritive growth media for different microbial species and the very challenging biocidic treatments of slurries (especially mineral ones), when inaccurate, can lead to the total spoilage of them.
* Growth of biofilm and production of slime. This problem seems to be connected to poor washing and boil-out programs which leave rests of biofilm inside the machine and give growth time for it because too long running periods. The chose of ineffective biocide and/or its insufficient dosing can also stimulate the activity of these trouble-makers.
* Microbial growth in the broke system. Especially big machines with large broke towers suffer of this problem. If the basic biocide program is insufficient and the retention times inside the towers are too long, aerobic population tend to increase the number of its cells to the level of 10 000 000 cfu/g or even higher. Consumption of oxygen by respirating bacteria leads to anaerobic conditions, redox potential will be dropped and the growth conditions for both fermentative and anaerobic bacteria turns to be excellent. Drop of pH, slime and spore formation, smells and odours - even the production of H2S and H2 - will be found in such situations.
There are some measures to prevent these hazards. Growth period of microbial population shall be kept as short as possible, the control of waterborne and bioflim bacteria shall be as rapid and frequent as possible and the bioside programs, intended in killing of raw material, process water and biofilm bacteria shall be evaluated more frequently.
A realistic and accurate way to control both process water and biofilm growth, as well as to evaluate biocide programs, is now available. The Finnish company SAMPLION Ltd is manufacturing and selling "Portable Microbiological Enrichment Unit", a "mini-fermentor" for 10 simultaneous tests in controlled conditions, to detect the failures of biocide programs in only hours (watesr) or days (biofilms). Some results of PMEU's paper industry applications will be published in next Spring - coming back to refer them later.
Some wrong ideas about the overdosing of biocides will also rise up frequently among publicity. Basically it is not a question of only the cubic meters of biocides consumed, however, The chose of most effective biocides for different areas of processes towards different problems, the dosing of these compounds, their type of action and some other factors play a major role when building an effective biocide program for paper machine. Overdosing of biocides is a problem only in cases, when the program does not work, and leads to the loss of money and the rise of biocide concentration in paper machine effluents.
Thursday, June 4, 2009
What will the next Spring bring to Finnish paper industry?
After a most busy period in May 2009, IM would like to write something (partly because his insomnia - a common symptom during light & bright Nordic summer nights) to the readers of his blog.
Several seminars for the rise of Nordic forest industry have arranged and will be arranged before Finland "will be closed" for summer holidays. - This is, by the way, a common feature of Finnish lifestyle, and easy to understand: you shall first work in dark and rain for months, the temperature drops well below 0 oC, and you should try to be active all through the winter. But when the summer comes, everybody will wake up again and "see a light at the end of a tunnel" (which was the title in the annual meeting of Finnish Paper Engineer's Association). And then, during the summer months, citizen tend to move to their summer cottages and villas to just rest and collect forces to tolerate the next winter..
Back to the topic:
There was a certain drop in the number of visitors, speakers and companies with exhibition desks in the annual Congress "BioChem" in Helsinki, 27.-29.5.2009. It was a pity to see that a lot of paper industry-associated companies did not arrive to show their products. The depression of global economy was very easy to sense. After all: there were still active participants left, eg. the novel company SAMPLION Ltd. which is now distributing PMEU system for all areas of microbiological control.
Positive attitudes were obvious also in the annual "Summer Summit" by AEL, the major education company for adult professionals, paper industry ones included.
What will happen next? A conference, discussing of future forecasts of forest industry, will be held in the middle of June in Jyväskylä, Finland. After that the annual PIRA congress will be held in Barcelona, Spain, in October.
If only the paper industry research will be activated again..It is, of course, a question of money, but, after all: to leave brilliant Finnish researchers without work is really a vast of excellence. It has be proven several times that the rebuilding of research groups after a depression is a much harder work than to start those activities from zero. It would therefore be better to keep such organisations in work over the bad periods.
IM is looking forward to the next Autumn! A most interesting thing to see what are the forecasts of Nordic P&P industry when the summer is over!
Several seminars for the rise of Nordic forest industry have arranged and will be arranged before Finland "will be closed" for summer holidays. - This is, by the way, a common feature of Finnish lifestyle, and easy to understand: you shall first work in dark and rain for months, the temperature drops well below 0 oC, and you should try to be active all through the winter. But when the summer comes, everybody will wake up again and "see a light at the end of a tunnel" (which was the title in the annual meeting of Finnish Paper Engineer's Association). And then, during the summer months, citizen tend to move to their summer cottages and villas to just rest and collect forces to tolerate the next winter..
Back to the topic:
There was a certain drop in the number of visitors, speakers and companies with exhibition desks in the annual Congress "BioChem" in Helsinki, 27.-29.5.2009. It was a pity to see that a lot of paper industry-associated companies did not arrive to show their products. The depression of global economy was very easy to sense. After all: there were still active participants left, eg. the novel company SAMPLION Ltd. which is now distributing PMEU system for all areas of microbiological control.
Positive attitudes were obvious also in the annual "Summer Summit" by AEL, the major education company for adult professionals, paper industry ones included.
What will happen next? A conference, discussing of future forecasts of forest industry, will be held in the middle of June in Jyväskylä, Finland. After that the annual PIRA congress will be held in Barcelona, Spain, in October.
If only the paper industry research will be activated again..It is, of course, a question of money, but, after all: to leave brilliant Finnish researchers without work is really a vast of excellence. It has be proven several times that the rebuilding of research groups after a depression is a much harder work than to start those activities from zero. It would therefore be better to keep such organisations in work over the bad periods.
IM is looking forward to the next Autumn! A most interesting thing to see what are the forecasts of Nordic P&P industry when the summer is over!
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