The biochemical identification of microorganisms give us an idea of what these microorganisms are able to do, being possible the discrimination of different strains of the same species by specific biochemical profiles. Differences in concrete enzymatic activities tell us about the ecology, the physiology or the natural habitat of the microorganism. I would identify a microorganism by molecular procedures, because they're faster and more specific, but i'd combine these procedures with a biochemical characterization if I was interested in knowing more about the ecology/physiology of the microorganism.

Biochemical tests serve as preliminary characterization, while molecular techniques are confirmatory by characterizing organisms to strains and sub-species level.

The biochemical identification of microorganisms give us an idea of what these microorganisms are able to do, being possible the discrimination of different strains of the same species by specific biochemical profiles. Differences in concrete enzymatic activities tell us about the ecology, the physiology or the natural habitat of the microorganism. I would identify a microorganism by molecular procedures, because they're faster and more specific, but i'd combine these procedures with a biochemical characterization if I was interested in knowing more about the ecology/physiology of the microorganism.

I agree with the previous posts; it is beneficial and cost effective to determine as much information as possible before deduction and confirmation via molecular genetic processes. P.C.R. for microbial identification can be ambiguous and expensive. It will often times yield more than one match at 100%, leaving a mismatched base pair or two somewhere to be later determined as a "subspecies". On that note, microbial genetics are on fast forward in reference to replicant mutations; and who knows... we might be working on our next little antibiotic resistant super-bug!

biochemical test (but more than a single enzymatic activity...) vs genetic test may help you to know if the DNA you have amplified came from a dead or an alive organism!

Biochemical characterization helps in

1. grouping the organisms initially. for example E. coli which is one of the enteric bacteria is differentiated form rest of enteric organisms by its ability to utilize lactose and produce acidic end products

2. for identifying their basic nutritional characteristics,

3. for developing upstream processing and

4. it can strengthen grouping based on molecular level.

I agree with Ricardos answer. In addition, I will give you a simple example which might explain the differences in a different way:

DNA identification (mainly based on sequence information) gives you a name and a position in evolution . Like Kunal Garg is your name, and most probably you are related to other persons called Garg.

On the other hand, biochemical characterization gives you an information on the 'job' of the microbe (what can it do, what enzymes does it use, what nutrients can it use etc.) . Like "researcher' or "microbiologist" is your job ( I suppose). Not every person called Garg will be a researcher, and on the other hand, not every researcher will be called Garg.

best wishes,

Wolfgang

Thanks Dr. Schweigkofler for your nice explanation.

The answer is very simple. No one goes to confirmatory test without performing presumptive test.. Will you put a crude protein mixture to HPGPLC or SDS-PAGE without having some earlier purification or information about your sample?Biochemical test make sure that the results you are getting from molecular techniques are correct.

In chemistry many highly sophisticated tools are there to identify an organic molecule purified as a single entity, but still researcher goes for element analysis C:N;O;H. No methodology could claim 100% correctness. But combination of methods makes your result beyond doubt

Hi Kunal,

All good answers. I think another good example where biochemical tests are very important is the distinction among some Bacillus species. Bacillus anthracis causes anthrax, which sometimes is a fatal disease to humans and animals. B. thuringiensis produces intracellular toxin crystals and it is perhaps the most widely used biological pesticide for insect larva control in agriculture. On the other hand B. cereus is a very common soil bacterium that sometimes can cause food poisoning. These 3 strains have almost identical 16S rRNA gene sequence (a common way for quick identification). This is a big and common problem especially in the “food microbiology cycles” and the only way to distinguish among these strains (and make sure you don’t deal with anthracis!) is several biochemical and other tests.

Cheers

Maria

Very good but basic question. See Kunal, before you start the mol. biol. technique to identify the microbe, it is better to go up to the possible genus level using biochemical reactions/tests or at times morphological characteristics. By this your data mining will reduce to great extent like say from a data bank like GENEBANK.

This is the advantage. Anyway a local alignment tool like BLAST will also not waste its time if you do not give it the possible genus level information.

You might need to know if a fungus is a mycotoxin producer, and so you need chromatography for example.

Thank you Dr, Paterson for your nice and concise example.

Regards

Another possibility for molecular identification of microorganisms is MALDI-TOF MS (like the MALDI Biotyper). Specificity is comparable to 16S but the speed of identification is much faster.

I agree with Thomas about that. We use it for fungal characterisation and wrote a review about it in the Journal of Applied Microbiology.

Dr. Paterson, would you please provide me the link of you article published in JAM?

Thanks.

Did this work? I am never quite sure if these things work in ResearchGate.

Thank you Dr. Paterson for the publication.

As molecular based typing does not give a phenotype, at times identifying something that has a particular phenotype may be important. I would consider molecular-based methods to now be usually more appropriate, but not always.

which ever method of identification to be used is usually being determined by what a particular study is out to achieve. However, carrying out a confirmatory test using biochemical method increases the reliability of a study.