The analytical profile index or API is a classification

Biological classification

Biological classification, or scientific classification in biology, is a method to group and categorize organisms by biological type, such as genus or species. Biological classification is part of scientific taxonomy....

 of bacteria

Bacteria

Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

 based on experiments, allowing fast identification

Identification (biology)

Identification in biology is the process of assigning a pre-existing individual or class name to an individual organism. Identification of organisms to individual names may be based on individualistic natural body features Identification in biology is the process of assigning a pre-existing...

. It was invented in the 1970s in the United States by Pierre Janin of Analytab Products, Inc. http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=3936356.PN.&OS=PN/3936356&RS=PN/3936356 Presently, the API test system is manufactured by bioMérieux.http://www.biomerieux-diagnostics.com/servlet/srt/bio/clinical-diagnostics/dynPage?doc=CNL_PRD_CPL_G_PRD_CLN_11 The API range introduced a standardized, miniaturized version of existing techniques, which up until then were complicated to perform and difficult to read.

The API 20E/NE fast identification system combines some conventional tests and allows the identification of a limited number of Gram-negative

Gram-negative

Gram-negative bacteria are bacteria that do not retain crystal violet dye in the Gram staining protocol. In a Gram stain test, a counterstain is added after the crystal violet, coloring all Gram-negative bacteria with a red or pink color...

 Enterobacteriaceae

Enterobacteriaceae

The Enterobacteriaceae is a large family of bacteria that includes many of the more familiar pathogens, such as Salmonella, Escherichia coli, Yersinia pestis, Klebsiella and Shigella. This family is the only representative in the order Enterobacteriales of the class Gammaproteobacteria in the...

 or non-Enterobacteriaceae. The test systems are stored in 20 small reaction tubes, which include the substrates. An identification is only possible with microbiological culture

Microbiological culture

A microbiological culture, or microbial culture, is a method of multiplying microbial organisms by letting them reproduce in predetermined culture media under controlled laboratory conditions. Microbial cultures are used to determine the type of organism, its abundance in the sample being tested,...

.
To guarantee a comparability of different samples, follow the introductions of the manufacturer.

Before starting a test, it must be sure, the culture is an Enterobacteriaceae or not. To test it, a quick oxidase test for cytochrome c oxidase

Cytochrome c oxidase

The enzyme cytochrome c oxidase or Complex IV is a large transmembrane protein complex found in bacteria and the mitochondrion.It is the last enzyme in the respiratory electron transport chain of mitochondria located in the mitochondrial membrane...

 is mandatory. Here, non-Enterobacteriaceae are cytochrome c oxidase positive and Enterobacteriaceae are negative. Cytochrome c oxidase is the terminal enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 of the electron transport chain

Electron transport chain

An electron transport chain couples electron transfer between an electron donor and an electron acceptor with the transfer of H+ ions across a membrane. The resulting electrochemical proton gradient is used to generate chemical energy in the form of adenosine triphosphate...

, in which the oxidation of cytochrome c

Cytochrome c

The Cytochrome complex, or cyt c is a small heme protein found loosely associated with the inner membrane of the mitochondrion. It belongs to the cytochrome c family of proteins. Cytochrome c is a highly soluble protein, unlike other cytochromes, with a solubility of about 100 g/L and is an...

 and reduction of O₂ is organized. The enzyme is localized in the mitochondria of eukaryotes and in the plasma membrane of several bacteria.

HINT:
This system is developed for quick identification of clinically relevant bacteria. Because of it, only known bacteria can be identified.

REFERENCES:

United States Patent Office, Patent Number 3936356 http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=3936356.PN.&OS=PN/3936356&RS=PN/3936356

API System: a Multitube Micromethod for Identification of Enterobacteriaceae, P. B. Smith, K. M. Tomfohrde, D. L. Rhoden, and A. BalowsCenter for Disease Control, Atlanta, Georgia 30333http://www.ncbi.nlm.nih.gov/pmc/articles/PMC376540/?page=1