AN INTRODUCTION TO MICROBIOLOGY
- Youngest biological sciences
- Started in middle of nineteenth century- Mendelian genetic & natural selection
- Microbiology now stands with older biological science that is zoology and botany
- Microbiology is the study of microscopic forms of life concerned with microorganism structure, function, nutrition, reproduction, heredity, chemical activities, classification, identification.
- Not readily visible with naked eyes
- Every living organism are dependent on microorganism directly or indirectly
- Microorganism are single and multicellular organisms that donot include tissue specialization
- Groups of microorganism includes- bacteria, cyanobacteria, algae, fungi(mould & yeast), protozoa, nematodes, viruses and some viroids and prions.
- Microorganism are present in all environment
- From human beings they are parts of our world.
- Have beneficial influence in our daily life.
- Breads-made of yeast- that ferment sugar and carbonate the dough before baked.
- Cheese,yogurt,sour cream require microorganism.
- As a fertilizer in plants or microorganism reduced nitrogen for plant growth
- Antibiotics for bacteria disease(Strep throat,pneumonias,gonorrhea,syphilis)
- Used as vaccine– tetanus,diphtheria,whooping cough,measles & mumps
- Microbes plays important part in waste disposal.
- Recycling essential nutrient •Microbes produces- organic acid,solvent and enzyme
Produces amino acid, vitamins, growth factors, therapeutic enzymes for curing malnutrition and health problem of human being.
- Roles of extraction of metals from ores
- As a fuel(by using agriculture waste and extreta)- biogas,gasohol
- Genetic engineering technology- produce new form organisms by inserting specific pieces of foreign materials(genes)
- Microorganism is directed to produce protein such as
- Hormones- insulin(treatment of diabetes), •tissue plasminogen activator(TPA- treatment of heart attack victim),
- Antiviral agent-inteferons(treatment of cancers and disease caused by virus),
- Human growth factors(increase bone growth),
- Amino acids
- As a food spoilage agent
- Human disease — Acquired Immune Deficiency Syndrome(AIDS),herpes,legionnaires disease,influenza,Tuberculosis,typhoid,dermatomycoses,dysentery,malaria.
- Animal disease – Burucellosis,tularemia
- Plant disease – Mildews,rusts,smuts,cankers,leaf spoils etc
French scientist Louis Pasteur expressed- The role of infinitely small is infinitely large.He was first scientist to recognize biological function of microbes.
Microbiology: A multifaceted Science
- It is more than just a taxonomic study of microorganism.
- It is also concerned with role of organism in causing disease
- Microbiologist study wide range of microscopic form of life and their activity in natural and artificial environment.
- Field of microbiology includes the study of bacteria, algae, fungi(mould & yeast), protozoa, virus and subviral agents of disease.
- Bacteriology- study of unicellular procaryotic organism known as bacteria.
- It deals with the uses of bacteria in industry
- Role of bacteria in ecology of world
- Bacterial genetics,structure and multiplication
- Mechanism by which bacteria cause disease
- Bacteriologist is a person who studies bacteriology
- Mycology– is a study of fungi,including moulds,mushroom and yeast.
- Fungi have a wide variety of sizes,colours,shapes.
- Non photosynthetic.
- Many live in soil & play important part in decomposition of organic matter.
- Produces several kind of food & antibiotics
- Causes disease in humans,animals & plants.
- Mycologist study about fungi.
- Phycology(Algology)- It can be unicellular & multicellular giant kelp(50m or more)
- Beautiful colours – brown,green,red and yellow
- It increases level of dissolved oxygen in their immediate environment and serve as food sources for humans & livestock.
- Phycologist study algae
- Protozoology – larger than most other organism
- Complex- structure & activities
- Found –sewage,water,intestinal tract of insects and damp soil.
- Feed on other microorganism and dead organic matter.
- But few causes disease such as malaria, amoebiasis, sleeping sickness, leishmaniasis etc.
- Parasitic animals.
- Arthropods of medical importance are subject matter of parasitology.
- Protozoologist study protozoa.
- Virology – study of noncellular(acellular) organism called viruses.
- Structure & reproduction of viruses for studing disease and how to control.
- Different multiplication than other organism.
- Virus depend on host cell for growth & reproduction.
- Obligate intracellular parasites •Microorganism can be infected by cells.
- Virologist study virus
INTEGRATIVE APPROACH FOR SUBDIVISION OF MICROBIOLOGY
- MICROBIAL ECOLOGY – Study the relation between microorganism & environment
- MICROBIAL MORPHOLOGY & CYTOLOGY – Study of shapes and the microscopic & submicroscopic details of microbial cells(ultrastructure).It involve the technique of electron microscopy.
- MICROBIAL PHYSIOLOGY – Study of microorganism function. Metabolic activities, effect of environment on microbial synthetic pathways and nutritional requirement of different groups are studied.
- MICROBIAL GENETICS – Study of genes, inheritance pattern, genetic exchange between microbes, how genes is expressed within organism, control of cellular activities,effect of mutation(genetic change)
- MICROBIAL TAXONOMY – Naming & classification of microorganism on basis of similarities & differences.
- MOLECULAR BIOLOGY – Programming genetic system and creation of macromolecules & important biological chemicals in organism. It deals with DNA and protein synthesis in organism
- BIOCHEMISTRY – Concerned with chemical basis of living matter and varies metabolites reaction associated with them.
- BIOPHYSICS- Principles of physics apply to living organism.
THE POSITION OF MICROORGANISM IN LIVING WORLD
EARLIER LINNAEUS CLASSIFICATION SCHEME( CAROLUS LINNAEUS)
- Animals differ from plants as they lack typical structure of plants, such as leaves, stems & roots.
- They are active motile, non-photosynthetic and quite complex
- Plants are opposite of animals in all these respects.
- Until 1830,taxonomic status of most life forms remained fairly constant.
- Discovery of wide variety of microorganism presented biologist with several problems.
- Some microorganisms presented as either plant or animals, many could not.
- Presence of outer structure called cell wall which could define microbial cell as plants.
- Animal like cell such as protozoa did not have this structure.
- Such cell ingest and capture solid foods but plants cannot.
- Thus algae, bacteria, fungi(moulds and yeast) were grouped into plantae and protozoa as animalia.
- Some microorganism got the properties of both plant & animals.
THE PROTISTA: THE THIRD KINGDOM
- Difficulties were there in applying 2kingdom classification on microorganism.
- Microorganism differ widely in metabolic and structural properties.
- Some are plant like ,some are animal like & some totally different.
- In 1866 Ernst Haekel proposed 3 kingdom to eliminate confusion.
- Kingdom was names Protista (Derived from Greek word-primitive or first)
- The new kingdom consists single celled microbes such as algae,bacteria,fungi and protozoa and multicellular which was not differentiated or organized into tissue or organ such as higher plant or animals.
- It was never universally accepted.
1957- Roger Stanier
- They distinguished two subgroups based on cellular characteristics
- Lower protist – procaryotes – primitive nucleus- All bacteria eubacteria, cyanobacteria, archaeobacteria, rickettsia, chlamydia, mycoplasma )
- Higher protist – Eucaryotes- well defined nucleus- algae, fungi, protozoa
- Virus are left out of this scheme.
WHITTAKER’S 5 KINGDOM CONCEPT
- 2 Kingdom & 3 kingdom is over simplified and many biologist favours dividing organisms among 5 kingdom as first suggested by R.H Whittaker 1969
- Organisms are place in 5 kingdoms on basis of atleast 3 major criteria.
- Cell type- procaryotes or eucaryotes
- Level of organization- solitary and colonial unicellular organization or multicellular
- Mode of nutrition
- In Whittaker’s system,
- Animalia contains- multicellular organism with wall less eucaryotic cell and primarily ingestive nutrition.
- Plantae contain- multicellular plants with called eucaryotes and primariliy photoautotrophic nutrition and pinocytosis.
Other 3 kingdom
- Monera – procaryotes in Bergey’s manual
- Fungi– eucaryotes, multinucleated organism, with nuclei dispersed in a walled and often septate mycelium, nutrition is absorptive
- Protista– least homogeneous and difficult to define – eucaryotic with unicellular organization, either in a form of solitary cell or colonies of cell lacking true tissue.
- They may have ingestive, absorptive or photoautotrophic nutrition
- Includes algae, protozoa and simple fungi
An environmental isolate of Penicillium
WOESE’S THREE KINGDOM SYSTEM
- IN 1977 Carl R. Woese proposed a three kingdom of classification.
- Grouping of all bacteria into procaryotes in 5 kingdom system is based on microscopic observation
- Woese proposal was based on Modern techniques in molecular biology and biochemistry that reveal two types of procaryotics cells
- Ribosomes are not same in all procaryotic cell
- Comparing sequence of nucleotides in ribosomal RNA(rRNA) from different kind of cells there are 3 distinctly different cell groups,the eucaryotic and 2 different procaryotes – Eubacteria (true bacteria) and Archaeobacteria (ancient)
- Woese believed that Archaeobacteria and Eubacteria(Procaryotes in 5 kingdom) having similar appearance should form their own separate branches Evolutionary tree.
- All Eucaryotes- protista, Fungi, plant and Animal in Whittaker’s system)should be grouped into third kingdom.
- Difference in membrane lipid structure,transfer RNA molecules and sensitivity to antibiotics also support classification of 3 kingdom.
Difference between Archeobacteria and Eubacteria
- Archeobacteria- never contain peptidoglycan
- Lives in extreme environment
- Do all unusual metabolic processes
Archeobacteria includes 3 groups
- Methanogens– strict anaerobes- produce methane from carbondioxide
- Extreme Halophiles- require high concentration of salt for survival
- Thermoacidophiles– grow in hot acidic environment
PROCARYOTES AND EUCARYOTES EVOLUTIONARY RELATIONSHIPS
- Mitochondria and chloroplast,two eucaryotic structure are descended from procaryotes.
- It become trapped in large cell and established endosymbiosis relation with it.
- Mitochondria is though to be actively metabolizing bacteria an Chloroplast as photosynthesizing descent occurred in Eucaryotic cells.
- Many portion remain unclear, biochemical and metabolic differences donot support the idea.
- With the discovery of archeobacteria, common ancestor of all form of life & evolution of eucaryotic cell become approachable.
TAXONOMIC STRUCTURE OF VIRUSES
- Virus have definite property that set them apart from all other life form
- Neither procaryotes nor eucaryotes
- Virus are not cell
- Virus consists of DNA or RNA surrounded by protein coat
- After invading living cells,virus use metabolic and genetic machinery of host cell to reproduce.
- Virus infect bacteria,algae,protozoa,fungi .
- Boundry between living and non living.
- They undergo mutation(genetic change)
- Have mean of replicating and increase in number
- Obligatory intracellular parasites
- Virus get incorporated in host cell and resemble host cell.
- Origin of Virus hypothesis
- Arose from independently replicating strands of nucleic acids(Plasmid)
- Developed from degenerative cells through many generation-lost its ability to grow but can grow when associated with living cell