MALDI-TOF Microbial ID Service:
The MALDI-TOF microbial identification testing process yields a unique protein spectral fingerprint that is then compared to the Accugenix® validated MALDI database for bacterial and yeast identification. The AccuPRO-ID® solution provides higher accuracy rates than phenotypic methods, produces faster results, and is a less expensive option for routine environmental monitoring programs.
Use this guide for interpreting identification results generated by the AccuPRO-ID® MALDI microbial identification service.
Why Outsource MALDI-TOF Microbial Identification Services Using Accugenix®?
- Higher confidence for species-level identifications when applying MALDI-TOF for microbiology lab applications.
- AccuPRO-ID® MALDI-TOF microbial identification process is cGMP-compliant and ISO 17025-accredited.
- Superior performance over existing phenotypic and other MALDI-TOF systems due to relevant microbial databases.
- Demonstrated improvement in accuracy (30 – 40%) over phenotypic identification systems.
- Proven to increase reproducibility and repeatability.
- Accugenix® proprietary MALDI-TOF microbial database provides more extensive coverage for environmental monitoring isolates than any other commercially available MALDI-TOF system for microbiology labs.
- Backed up by our AccuGENX-ID® DNA sequencing method at no additional cost.
AccuPRO-ID® MALDI-TOF microbial identification requires fresh growth, so samples must be alive and healthy. Live cultures should be shipped overnight at ambient temperature. The total time from sample inoculation to arrival should not exceed 48 hours. Live cultures exceeding 48 hours of age may have to be subcultured.
Frequently Asked Questions (FAQ’s) for MALDI-TOF Microbial Identification
What is mass spectrometry?
Mass spectrometry is an analytical technique where chemical substances are identified by sorting gaseous ions in electric and magnetic fields according to mass-to-charge ratios. The exact molecular weight of the sample can often be calculated based on the mass-to charge-ratio. By determining the weight, the sample can be identified. Accugenix® uses MALDI-TOF mass spectrometry for AccuPRO-ID® microbial identification services.
What does the MALDI-TOF acronym stand for?
MALDI-TOF stands for Matrix-Assisted Laser Desorption/Ionization-Time of Flight.
What is a molecular ion peak in mass spectrometry?
Emission of an electron from an electrically neutral compound leads to production of a molecular ion. This ion provides information on molecular weight because the electron mass is so small compared to the mass of a molecule that the mass of a molecular ion is regarded as the mass of the molecule.
What MALDI-TOF system can be used to identify microbial organisms in a microbiology lab?
Our Axcess® MALDI-TOF solution is an ideal combination of precise instrument and relevant microbial libraries for maximizing in-house identification rates.
What is the MALDI-TOF microbial identification process?
The process begins with a small portion of the test colony* being deposited and smeared on a dedicated spot of a plate to form an even layer of cells. Then a solution of an organic acid is referred to ensure good sample integrity.
A second solution of an organic acid referred to as a "matrix" is then deposited on the spot to cover the sample. Upon drying, the matrix co-crystallizes with biomolecules present in the colony material to form a scaffold. The biomolecules include peptides and proteins – the target analytes in the process.
The matrix forms a scaffold and provides a source of protons for ionization and undergoes UV laser irradiation. To preserve the integrity of the sample, the maximum energy absorbance of the matrix matches that of the as the laser (337 nm). The energy of the radiation transfers to the sample, allowing desorption of the main compounds (transition of the solid state to the gas phase).
Next, the sample is ionized by the slightly acidic matrix (proton transfer) and the charged peptides and proteins begin their journey. After initial acceleration as they pass through an electrostatic field, the peptides and proteins drift toward the detector at a speed defined by their mass-to-charge ratio.
As they hit the surface of the detector lined with a semi-conductive layer, the peptides and proteins emit electrical impulses at varying rates, each of which identifies a specific protein.
A major part of information comes from the fraction of ribosomal proteins in addition to DNA-binding proteins as well as heat shock proteins. Along with other data, time-of-flight (ToF) information is then transformed into mass spectra data visually depicted as a sequence of mass peaks forming a characteristic microorganism profile, also called peptide mass fingerprint (PMF).
The final report includes list of closest matching species classified according to protein fingerprint similarity, accompanied by a value which indicates secure species or genus level identification.
* For best results, only freshly grown colonies containing actively dividing cells with intact proteins should be subjected to testing.