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Throughout the body, resident microbiotas are important for human health because they occupy niches that might be otherwise taken by pathogenic microorganisms. For instance, Lactobacillus spp. are the dominant bacterial species of the normal vaginal microbiota for most women. lactobacillus produce lactic acid, contributing to the acidity of the vagina and inhibiting the growth of pathogenic yeasts. However, when the population of the resident microbiota is decreased for some reason (e.g., because of taking antibiotics), the pH of the vagina increases, making it a more favorable environment for the growth of yeasts such as Candida albicans . Antibiotic therapy can also disrupt the microbiota of the intestinal tract and respiratory tract, increasing the risk for secondary infections and/or promoting the long-term carriage and shedding of pathogens.

  • Explain the difference between cooperative and competitive interactions in microbial communities.
  • List the types of symbiosis and explain how each population is affected.

Taxonomy and systematics

Assigning prokaryotes to a certain species is challenging. They do not reproduce sexually, so it is not possible to classify them according to the presence or absence of interbreeding. Also, they do not have many morphological features. Traditionally, the classification of prokaryotes was based on their shape, staining patterns, and biochemical or physiological differences. More recently, as technology has improved, the nucleotide sequences in genes have become an important criterion of microbial classification.

In 1923, American microbiologist David Hendricks Bergey (1860–1937) published A Manual in Determinative Bacteriology. With this manual, he attempted to summarize the information about the kinds of bacteria known at that time, using Latin binomial classification. Bergey also included the morphological, physiological, and biochemical properties of these organisms. His manual has been updated multiple times to include newer bacteria and their properties. It is a great aid in bacterial taxonomy and methods of characterization of bacteria. A more recent sister publication, the five-volume Bergey’s Manual of Systematic Bacteriology , expands on Bergey’s original manual. It includes a large number of additional species, along with up-to-date descriptions of the taxonomy and biological properties of all named prokaryotic taxa. This publication incorporates the approved names of bacteria as determined by the List of Prokaryotic Names with Standing in Nomenclature (LPSN).

Classification by staining patterns

According to their staining patterns , which depend on the properties of their cell walls, bacteria have traditionally been classified into gram-positive, gram-negative, and “atypical,” meaning neither gram-positive nor gram-negative. As explained in Staining Microscopic Specimens , gram-positive bacteria possess a thick peptidoglycan cell wall that retains the primary stain (crystal violet) during the decolorizing step; they remain purple after the gram-stain procedure because the crystal violet dominates the light red/pink color of the secondary counterstain, safranin. In contrast, gram-negative bacteria possess a thin peptidoglycan cell wall that does not prevent the crystal violet from washing away during the decolorizing step; therefore, they appear light red/pink after staining with the safranin. Bacteria that cannot be stained by the standard Gram stain procedure are called atypical bacteria . Included in the atypical category are species of Mycoplasma and Chlamydia , which lack a cell wall and therefore cannot retain the gram-stain reagents. Rickettsia are also considered atypical because they are too small to be evaluated by the Gram stain.

Questions & Answers

what is the hetropolysachharide 's monomeric units?
Hinal Reply
Homopolysaccharides contain only a single type of monomeric unit; heteropolysaccharides contain two or more different kinds of monomeric units.Some homopolysaccharides serve as storage forms of monosaccharides used as fuels; starch and glycogen are homopolysaccharides of this type.
Kaviya
Polysaccharides (glycans) are long chains of monosaccharides. Each monosaccharide is connected together via glycosidic bonds to form the polymeric structure known as polysaccharide. ... units in the chain; whereas, a heteropolysaccharide is composed of two or more types of monosaccharides.
Hetshree
They are polymer of different monosaccharide units...on hydrolysis, it yeilds different monosaccharides example; Mucopolysaccharide and Heparin.
Swetha
what is virulence plasmid
Harsh
Virulence plasmids are usually large (>40 kb) low copy elements and encode genes that promote host–pathogen interactions. Although virulence plasmids provide advantages to bacteria in specific conditions, they often impose fitness costs on their host.
Kaviya
can you suggest a good book for biotechnology
Harsh
In my point of view, u can refer A textbook of biotechnology by R C Dubey
Kaviya
Biotechnology by B. D. Singh
Microbiology
how psychrophiles live at such a low temperature that their proteins dont get denatured
Harsh Reply
anti freeze proteins are synthesized to prevent such denaturations..
Swetha
okay thank u
Harsh
can you suggest me a book for food microbiology
Harsh
and for industrial microbiology
Harsh
food microbiology by M.R Adam and M.O.Moss
Swetha
Industrial microbiology by L.E.casida.
Swetha
maam can you suggest a best book that have applied microbiology concepts
Harsh
mem can you suggest a best book of microscopy
for applied microbiology K.R.Aneja and other book by Allen Laskin
Swetha
for microscopy Kirsteen Roger.
Swetha
Define sterilization
Pramod Reply
Sterilization refers to any process that removes, kills, or deactivates all forms of life and other biological agents like prions present in a specific surface, object or fluid, for example food or biological culture media.
Kaviya
sterilization is the process of making an aseptic condition or microbe free environment to keep the objects from any kind of contamination.
Swetha
Cool. I work for a Sterilisation company in India. We do Gamma Radiation, Steam Sterilisation and Ethylene Oxide Sterilisation
Shanu
Explain the polymerization reaction of DNA polymerase enzyme?
Swetha Reply
I think in my opinion polymerization means monomers connects and produce large molecular chain
LEE
DNA polymerase I catalyzes the polymerization of dNTPs into DNA. This occurs by the addition of a dNTP (as dNMP) to the 3' end of a DNA chain, hence chain growth occurs in a 5' to 3' direction.Thus in this reaction, a phosphoanhydride bond in the dNTP is broken, and a phosphodiester is formed.
Kaviya
Thank you
Swetha
ok..Thank you
Swetha
Nicely explained
Shanu
Welcome 🙏
Kaviya
write a note of microbiology with definition
Lucky Reply
Microbiology is the study of all living organisms that are too small to be visible with the naked eye. This includes bacteria, archaea, viruses, fungi, prions, protozoa and algae, collectively known as 'microbes'.
si
write down the difference branches of microbiology
Lucky
Baccteriolog: the study of bactera. Immunology: the study of the immune system. It looks at the relationships between pathogens such as bacteria and viruses and their hosts. Mycology: the study of fungi, such as yeasts and molds. Nematology:the study of nematodes (roundworms).
Aashi
Bacteriology: the study of bacteria. Immunology: the study of the immune system. It looks at the relationships between pathogens such as bacteria and viruses and their hosts. Mycology: the study of fungi, such as yeasts and molds. Nematology: the study of nematodes (roundworms).
si
Parasitology :the study of parasites. Phycology: the study of algae. Protozoology : the study of protozoa, single-celled organisms like amoebae. Virology:the study of viruses.
Aashi
Parasitology: the study of parasites. Not all parasites are microorganisms, but many are. Protozoa and bacteria can be parasitic; the study of bacterial parasites is usually categorized as part of bacteriology. Phycology: the study of algae. Protozoology: the study of protozoa, single-celled organis
si
Virology: the study of viruses.
si
difference between gram negative and gram positive bacteria.
Hirut
the difference between gram negative and gram positive bacteria is the colour which is obtained after staining techniques.. Gram positive bacteria stain violet due to the presence of a thick layer of peptidoglycan in their cell walls, which retains the crystal violet these cells are stained with.
Kaviya
Father of paleobotany?
LEE
The father of paleobotany is Birbal Sahni...
Kaviya
It is the study and recovery of ancient plants and geological contents
Kaviya
Father of immunology
Kaviya
Louis pasture was really father of immunology,despite Edward jenner poineering by introducing the vaccine against smallpox.
TASAWAR
thank you anna
Kaviya
define a cell?
Swetha
thank you Kaviya
Hirut
Cells have many parts, each with a different function. Some of these parts, called organelles, are specialized structures that perform certain tasks within the cell.
Kaviya
cell is the basic structural and functional unit of life.
TASAWAR
In biology, a cell ([sɛl], ”plural: cells”) is defined as the structural, functional, and biological unit of all organisms. It is an autonomous self-replicating unit that may exist as a functional independent unit of life (as in the case of a unicellular organism), or as a sub-unit in a multicellula
si
thank you
Swetha
all bacterial cells have
Millie Reply
refamycin kills bacterial cell by acting on ...?
Yogesh Reply
monensin kills bacterial cell by acting on
Yogesh
genetic linkage cross over ratio ?
Yogesh
what is microbiology?
onuoha Reply
Hi!!! wants to know the meaning of microbiology
Christian Reply
Microbiology, study of microorganisms, or microbes, a diverse group of generally minute, simple life-forms that include bacteria, archaea, algae, fungi, protozoa, and viruses. The field is concerned with the structure, function, and classification of such organisms .
si
to study the life of microorganisms or microbes by knowing their characteristics types and relative species in lab
ayesha
Microbiology is simply the study of microbial world.
Shyamji
Microbiology is the branch of biology in which we study microorganisms those which cannot be seen with naked eye these are bacteria,fungi,viruses Protozoa etc.
Nisar
thanks for that information
Better
microbiology, is a study of microorganisms adiversegroup of generally, simple life,
Better
Thanks ever so much for the discussion.
Christian
Can anyone help with Organic Chemistry, and types?
Christian
which topic in organic chemistry
si
Introduction to organic chemistry.
Christian
Organic chemistry is the chemistry of carbon, an element that forms strong chemical bonds to other carbon atoms as well as to many other elements like hydrogen, oxygen, nitrogen, and the halogens. ... Many are composed of only carbon and hydrogen, collectively called hydrocarbons.
si
microbiology is the study of microorganisms like (bacteria ,viruses,fungi,protozoa and algae) their relationship to environment and their impact on environment .
TASAWAR
can one tell me what are reservoirs and their types with explanation.
onuoha
structure of protists
Rayyanu Reply
what is enzyme engineering
swati Reply
what is the difference between prokaryotes and eukaryotes?
Guirlaine Reply
Prokaryotes lack nucleus in their cells while eukaryotes have well defined nucleus in their cells
Ayo
Prokaryotes are organisms that consist of a single prokaryotic cell. Eukaryotic cells are found in plants, animals, fungi, and protists. They range from 10–100 μm in diameter, and their DNA is contained within a membrane-bound nucleus. Eukaryotes are organisms containing eukaryotic cells.
Pratibha
The Day Jimmy"s Boa Ate the Wash by TRINKA HAKES NOBLE pictures by STEVEN KELLOGG
Alexia Reply
cytoplasmic membrane system in eukaryotes is called
Myerlyn Reply
I study in French,but I guess it's the same: we call it as the procaryotes "cytoplasme" but it's structure "cytosquelette" hope I helped.
BENNINI
hi bennini , I studied in English but I want to pursue in French .could u plz help me with French .thanks in advance
si
hi Si Yo, yes,of course how can I help you?
BENNINI
here can I download it where I could study it with relax dear
Irfan
hi
Ruth
ok
Francis
meaning of contagium vivum?
Royce Reply
Practice MCQ 3

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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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