What are bacteria?• Single celled organisms• Very small E. Coli O157:H7 can make you very sick• Need a microscope to see.•Can be found on most materialsand surfaces Streptococcus• Billions on and in your can cause strep throat. body right now This E. coli helps you digest food.
What do they look like? Bacilli• Three basic shapes – Rod shaped called bacilli – (buh-sill-eye) – Round shaped called cocci Cocci – (cox-eye) – Spiral shaped• Some exist as single cells, otherscluster together Spiral Cluster of cocci
Bacteria are ALIVE! • What does it mean to be alive? -They reproduce (make more of themselves) - They need to eat
How do bacteria reproduce?• Grow in number not in size – Humans grow in size from child to adult• Make copies of themselves by dividing in half – Human parents create a child
How do bacteria eat?• Some make their own food from Photosynthetic sunlight—like plants bacteria• Some are scavengers – Share the environment around them • Example: The bacteria in your stomach are now eating what you ate for breakfast Harmless bacteria on the stomach lining• Some are warriors (pathogens) – They attack other living things • Example: The bacteria on your face can attack skin E. Coli causing infection and acne O157:H7 is a pathogen
BRIEF HISTORY: In a 1683 letter to the Royal Society Of London, Anton van Leeuwenhoek Described microscopic “STREAKS & THREADS”, among his tiny animals. The streaks and threads remained nameless until 1773,
In 1773, when the DanishscientistOtto Frederick Mullerchristened them bacilli.Bacilli is the plural formof the Latin word Bacillusmeaning but not all“bacilli” were rods. Somewere spiral and somewere circular, & “bacilli”would not do.
Therefore, in the 1850s, TheFrench investigator CasimirDavaine began calling amicroscopic creatures“BACTERIA”, even though thisderivatives of the Greekbacterion also means rod. Inthe next few decades“bacteria” came to refer to allthe micro-organisms in thatgroup, and the word “Bcillus”was reserved for rod formsonly.
Archaebacteria vs EubacteriaArchaebacteria Archaebacteria have prokaryoticcells, which means they dont havea nucleus. While they usually live ingroups, they are consideredunicellular, meaning they have onecell. Archaebacteria can make theirown food, making them autotrophs.They can live in hot springs, deepocean vents with no light and underextreme pressure, and in very saltylakes.. so basically, all extremeenvironments. Some of them caneven live with no oxygen
EubacteriaEubacteria: are a group of unicellular organisms and are similar to archae in not having cell nucleus or organelles.
Comparison chart Archaebacteria EubacteriaCell Membrane: Branched chain ether Straight chain ester linked lipids. linked lipids.tRNA: Lacks thymine in tRNA. Thymine present in tRNA.RNA polymerase: Ten subunit RNA 4 subunit RNA polymerase core. polymerase core.Role in ecology: Role in bio-geochemical Vital in nutrient recycling. cycles is unexplored.
DNA: DNA is closer to DNA differs from eukaryotes (sent on eukaryotes. to daughter cells via mitosis)Definition: Single celled organisms All true bacteria or group without anycell of unicellular prokaryotic organelles or nucleus. microorganisms.Morphology: Occur in various shapes Various shaped bacteria like spheres, rods, plates have been identified like and spirals. rods, cocci, spirals, comma shaped, tightly coiled etc.Cell Wall: Lacks peptidoglycan. Peptidoglycan is present.Extremophilic: Yes. Some.
WAYS OF CLASSIFICATIONBacterial Classification Based on ShapesRod shaped bacterias are also called Bacillie.g. E.coli
Spherical-shaped bacteriaSpherical-shaped bacteria are called cocci e.g. Staphylococcus and Streptococcus
Spiral-shaped bacteria Spiral-shaped bacteria are called spirilla e.g. Treponema
Bacterial Classification Based on Staining MethodsBacteria are grouped as Gram positive and Gram negative bacteria, based on the results of Gram staining method, wherein an agent is used to bind to the cell wall of the bacteria.Gram positive bacteria - take up crystal violet dye and retain their blue or violet color.Gram negative bacteria - do not take up crystal violet dye, and thus appear red or pink.
Bacteria are also classified based on the requirement of oxygen for their survival Anaerobic bacteria Aerobic bacteria Bacteria that do not require oxygen for Bacteria that need oxygen for survival.their survival Anaerobic bacteria cannot bear oxygen and may die if kept in an oxygenated environment. Such types of bacteria are usually found in places like, under the surface of the Earth, deep oceans, and bacteria which live in some medium.
Autotrophic and Heterotrophic BacteriaAutotrophic bacteria (also known as autotrophs) obtain the carbon it requires from carbon dioxideSome autotrophs directly use sunlight in Heterotrophic bacteria obtain sugar from order to produce sugars from the environment they are in (for example, carbondioxide whereas, others depend the living cells or organisms they are in).on various chemical reactions. E.g. bacillus anthraciae.g. cyanobacteria
Bacterial Classification Based on Environment• Mesophiles - which require moderate conditions to survive.• Extremophiles - which can survive in extreme conditions.• Acidophiles - which can tolerate low pH conditions.• Alkaliphiles - which can tolerate high pH conditions.• Thermophiles - which can resist high temperature.• Psychrophilic bacteria - which can survive extremely cold conditions.• Halophiles - which can survive in highly saline conditions.• Osmophiles - which can survive in high sugar osmotic conditions.
Classification of bacteriaBacteria are arranged into 19 groups
5. Spirochetes• Cell shape : slender, helically coiled(spiral).• Most of them are gram negative Example : spirochaeta
6.Spiral and Curved bacteria• Cell shape: helically coiled rods , some with one or more complete turns.• Gram negative• Habitat : aquatic, reproductive organs, intestinal tract and oral cavity of animals (including humans) Example :vibrio species
7.Gram negative aerobic rods and cocci• Cell shape : rod, oval , spherical.• Gram negative• Habitat : soil and aquatic environment , salt brines . Example: brucella species
8.Gram negative facultative anaerobic rods• Cell shape : typically , short rod• Gram negative• Habitat: aquatic environment, soil, urine, faeces Example : E.coli
9.Gram negative anaerobic rods• Cell shape : rod , straight or curved , exhibiting considerably polymorphism• Habitat: natural cavitiesof humans and other Example :bacteroides animals also intestinal tracts of insects.
10.Gram negative cocci and coccobacilli• Cell shape : cocci in pairs (diplococci )some coccobacilli occur single and in pairs• Gram negative• Habitat : on mucous membrane of humans and other animals Example : neisseria gonorrhoaea
11.Gram negative anaerobic cocci• Cell shape: very small to very large spherical cell in pairs , masses, or chains,• Habitat : respiratory and intestinal tracts of human and other animals Example :veillonella
12. Gram negative chemolithotrophic bacteria• Cell shape : spherical, rod , spiral, multilayered membranes in some species• Gram negative• Habitat : soil, sewage , aquatic environments , natural environment with large amount of Example: nitrosomonas sulphur , iron or manganese
13.Methane producing bacteria• Cell shape : spherical , rod spiral• Gram positive or gram negative• Habitat: gastrointestinal tract of animals , aquatic and sewage Example: methanospirillum
14. Gram positive cocci• Cell shape : cocci occurring singly or in pairs , chains or clusters• Gram positive• Habitat: soil , fresh water , skin and mucous membrane of warm blooded animals including human Example : streptococcus
15. Endospore forming rods and cocci• Cell shape; rods• Gram positive• Habitat :soil , air , aquatic, intestinal tracts of animals Example : bacillus
16.Gram positive asporogenous , rod shaped• Cell shape: bacilli occurring singly or in chains• Gram positive• Habitat ; dairy products , grains and meat products , water, sewage , oral cavity and vagina Example : lactobacillus
17.Actinomycetes and related organisms• Cell shape: irregular rod shaped , filaments and branched filaments• Gram positive• Habitat: soil , aquatic , air and animals mycobacterium tuberculosis .
18.The Rickettsias• Cell shape : short rods or ovals , often pleomorphic• Gram negative• Habitat: insect carriers , birds and mammals Example: rickettsia akari
19. The Mycoplasmas• Cell shape: lack true cell wall , highly pleomorphic• Gram negative• Habitat : mucous membrane of respiratory tract , and lower enital tract Example: mycoplasma pneumoniae
Differences between prokaryotes and eukaryotes