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Learning objectives

  • Describe examples of biosynthesis products within a cell that can be detected to identify bacteria

Accurate identification of bacterial isolates is essential in a clinical microbiology laboratory because the results often inform decisions about treatment that directly affect patient outcomes. For example, cases of food poisoning require accurate identification of the causative agent so that physicians can prescribe appropriate treatment. Likewise, it is important to accurately identify the causative pathogen during an outbreak of disease so that appropriate strategies can be employed to contain the epidemic.

There are many ways to detect, characterize, and identify microorganisms. Some methods rely on phenotypic biochemical characteristics, while others use genotypic identification. The biochemical characteristics of a bacterium provide many traits that are useful for classification and identification. Analyzing the nutritional and metabolic capabilities of the bacterial isolate is a common approach for determining the genus and the species of the bacterium. Some of the most important metabolic pathways that bacteria use to survive will be discussed in Microbial Metabolism . In this section, we will discuss a few methods that use biochemical characteristics to identify microorganisms.

Some microorganisms store certain compounds as granules within their cytoplasm, and the contents of these granules can be used for identification purposes. For example, poly-β-hydroxybutyrate (PHB) is a carbon- and energy-storage compound found in some nonfluorescent bacteria of the genus Pseudomonas . Different species within this genus can be classified by the presence or the absence of PHB and fluorescent pigments. The human pathogen P. aeruginosa and the plant pathogen P. syringae are two examples of fluorescent Pseudomonas species that do not accumulate PHB granules.

Other systems rely on biochemical characteristics to identify microorganisms by their biochemical reactions, such as carbon utilization and other metabolic tests. In small laboratory settings or in teaching laboratories, those assays are carried out using a limited number of test tubes. However, more modern systems, such as the one developed by Biolog, Inc., are based on panels of biochemical reactions performed simultaneously and analyzed by software. Biolog’s system identifies cells based on their ability to metabolize certain biochemicals and on their physiological properties, including pH and chemical sensitivity. It uses all major classes of biochemicals in its analysis. Identifications can be performed manually or with the semi- or fully automated instruments.

Another automated system identifies microorganisms by determining the specimen’s mass spectrum and then comparing it to a database that contains known mass spectra for thousands of microorganisms. This method is based on matrix-assisted laser desorption/ionization time-of-flight mass spectrometry ( MALDI-TOF ) and uses disposable MALDI plates on which the microorganism is mixed with a specialized matrix reagent ( [link] ). The sample/reagent mixture is irradiated with a high-intensity pulsed ultraviolet laser, resulting in the ejection of gaseous ions generated from the various chemical constituents of the microorganism. These gaseous ions are collected and accelerated through the mass spectrometer, with ions traveling at a velocity determined by their mass-to-charge ratio (m/z), thus, reaching the detector at different times. A plot of detector signal versus m/z yields a mass spectrum for the organism that is uniquely related to its biochemical composition. Comparison of the mass spectrum to a library of reference spectra obtained from identical analyses of known microorganisms permits identification of the unknown microbe.

Questions & Answers

What is morphology
Lovely Reply
study of external features
Katta
i think it is about characteristic that we see on the organisms like the shape
Aisyah
morphology is something is it's form and structure.
Rose
yes it's a study deals with the form of living organisms, and with relationship between their structure s.
Rose
what's gram negative and positive bacteria
Dagbanja Reply
is a process that classify bacteria structure
moshtak
how
Dagbanja
1)the crystal voilet dye stains all cells blue 2)the iodine solution two groups are blue 3)alcohol such as acetone or ethanol gram negative colorless while gram positive remains blue 4)the red dye safranin gram positive reamin blue while gram negative red.
moshtak
gram negative and Gram positive bateria aare grouped on the nasis of the thickness of their peptidoglygan gram negative bacteria hava thin layer of petidoglycan while Gram positive bacteria has thick petidoglycane layer
Samina
hence during gram stainig after additon of iodine on crystal voilet it forms crystalvoilet-iodine complex, when we add acetone, due to thin peptidoglyacan layer the Gram negative bateria easily leaves this complex and becomes colourless while the gram positive bateria remains blue...
Samina
after addition of counter stain such as saffranin, the Gram negative gets stained pink
Samina
why are there so many long words and is there simplified versions of these words?
Ethan Reply
What is the different between abiogensis and biogensis
RAPHERA Reply
Abiogenesis is the process by wich living organisms arises from a nonliving matter while Biogenis organisms arises from living matter
Nji
Abiogenesis deals with the law of spountaneous generation which talks about organisms arising from non-living organic matters while biogenesis deals with organisms arising from living organic matters
Ademola
What are the importance of mircobiology
RAPHERA
mechanisms of microbiology
Erneet Reply
What is immunizations
RAPHERA Reply
the action of making a person or animal immune to infection, typically by inoculation.
Pup
pls someone should help with ANTIMICROBIAL MNEMONICS
Shuaib Reply
Aminoglycosides: Charasteristics of Aminoglycosides Nymonics; (AMINO)  Active against Aerobic gram negative Organisms Mechanism Of resistance is by Modifying enzymes Inhibit protein synthesis by binding to 30s ribosomal subunit Nephrotoxic Ototoxic Members  Of Aminoglycosides: Nymonics: (ST
Najeebul
Please can some briefly describe the germ theory?
Michael Reply
hyy all
Shuaib
pls someone should help with ANTIMICROBIAL MNEMONICS
Shuaib
which drug can be used to treat gonococus?
Lambon Reply
Madication - Antibiotic " and Gonorrhoea can be treat with Antibiotic
Maryam
Penicillin -An antibiotic
Michael
Ciprofloxacin tablets also an antibiotic
Michael
Ofloxacin is also antibiotics
Ikenna
yes
Elli
sory no fot gonococus
Elli
oofer gang roblox memes
Ethan
what are eukaryotes
Kakande Reply
eukaryotes simply refers to a cell who does not have a definite nucleus.
Franca
Eukaryotic cell has a true nucleus
arfa
what is right answer ?
krishna
I can remember now truly that eukaryotes have true nucleus.I was referring to procaryotes.
Franca
Eukaryotes have got true nuclues
Ede
they have a nucleus, larger than prokaryotes
Alanna
The eukaryotes cell are found in advance organisms.
Franca
Eukaryotes are multicellular organism which has a membrane bounded structure mostly found in animals and some plant cells
KINGSFORD
bacteria growth curve
sani Reply
No bacteria's don't grow curvey. Curve is a shape for a bacteria not growth
KINGSFORD
What is the difference between eukaryotes and prokaryotes?
KINGSFORD Reply
What's a multicellular organism?
KINGSFORD
multicellular organisms is an organism composed of many cells which are to varying degree integrated and independent.
Ruth
Boiling of milk to kill germs is called?
Kasigwa
pasteurization
Aiyedun
pasteurization
Katta
kadha
Katta
pasteurization
Gomathi
what is microscopic
monish
Pasteurization
Hosy
what are Flora
Hosy
you mean like the normal flora?
Tenucharity
pasteurization has to do with killing of the harmful microbes present for safe consumption. Eg. pasteurized yoghurt beside the bacteria that are supposed to be present, there may be harmful ones that have been killed
Tenucharity
Can someone explain flora
KINGSFORD
what are the normal Flora on the ff anatomical sites? Skin, nose, ear,oral cavity, intestines and the vagina
Hosy
what is cell?
Anita Reply
the cell is the functional and structural unit of the body
Ruth
yes ur right
Kasigwa
who add me
Wali
hy
Katta
hy
Shivangi
basic structural, functional, and biological unit of all known living organisms. A cell is the smallest unit of life.
Haru
hi
Ruth
hi
Haru
coming Oct 2 I have a exam on microbiology
Haru
okay all the best
Ruth
hi
sachin
hi
Ruth
plz bro send question of microbiology
umesh
structural and functional unit of the life
monish
this is not the correct answer
Alanna Reply
why
Hayat
why not
Zaajid
what is the correct answer?
vannessa
where is question
Zaajid
ask you question
Zaajid
What are mitochondria
Hayat
what is mitochondria
Hayat
who is the father of microbiology
T-
not
Hayat
Antonie Van Luweenhoek
Ravikumar
Mitochondria is the powerhouse of the Cell. And is the cell organelle which helps cell in generation of energy by Cellular Respiration
Ravikumar
Mitochondria are threadlike structuresbounded by double membrane,and serves as the power house of the cell
Felicity
can I get notes on introduction to microbiology just started I have no idea please
rita
Mitochondria is a membrane bounded structure, it's sausage in shape and has inner and outer membrane. The inner membrane is folded at the surface called cristae which project to form matrix. They function as the power house for the cell.
KINGSFORD
Rita are you a medilab student?
KINGSFORD
the father of microbiology is Luis pasture
Able
Erythromycin--------(+++) Cefuroxine ------------(++++) Chloramphenicol --(++) Vancomycin ---------(++++) please what does the above result means. under urine culture and sensitivity?
Kwame
francesco redi was the first to challenge spontaneous generation not pasteur
Alanna
Rita are you a medilab student? no please am a public health student
rita
kwame Evans this result ll mean that the bacterial in the urine can be remedy / killed by this antibacterial (cefuroxime and the rest are antibiotics
rita
Rita Appiah thanks.
Kwame
contact backstage
Emmanuel
what is a gram negative bacteria
Dagbanja
what's agram positive bacteria
Dagbanja
what is a vacual
Star Reply
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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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