Kingdom Bacteria (Eubacteria)

Bacteria Basic Information

• they are unicellular micro-organisms ranging in length (few micrometers to half a milimeter)

• come in a variety of different shapes

• found in almost all ecosystems on earth

Why is bacteria important

• it’s important to many nutrient cycles and are important decomposers of organic material

• found all over earth and even covering and living in the human body

• some bacteria is pathogenic and cause disease

Bacteria History

• Bacteria first observed by Anton Van Leeuwenhoek

• bacteria is greek for small stuff

• Robert Koch and Louis Pasteur first to discover that bacteria caused diseases

• first antibiotic used to treat bacterial disease was made by Paul Ehrlich (used to treat syphilis)

Evolution of bacteria

• thought by some to be the first forms of life abt 4 billion years ago

• believed that domain Archaea and Eukarya evolved from bacteria

• poor fossil record, scientists unable to determine from what bacteria evolved

Morphology (study of living organisms)

• bacterial cells are prokaryotic

• lack a nucleus and complex organelles

• have a cell membrane and a cell wall made up of peptidoglycan (combo of protein and carbohydrate)

• making it different from cell wall of Archaea and Eukaryotes

Morphology continued

• bacteria use flagella or pili for movement and interaction with the enviorment

• shapes:

• bacillus- rod

• coccus- sphere

• spirillus- spiral

• vibrio- boomerang

• spirochaetes- tight coils

• prefixes are added to the shapes to indicate the living arrangement of the bacteria

• strepto: chain of bacteria

• staphylo: grape like cluster

More about bacteria cell wall

• gram stain: type of stain used to visualize bacteria cell wall structure

• cell wall structure:

• bacteria are classified as gram-positive or gram-negative based on chemical and physical properties of their cell wall

• gram + bacteria: thick layer of peptidoglycan in cell walls, retains crystal violet stain (appears purple)

• gram - bacteria: thinner peptidoglycan layer and lipoproteins and an outer membrane, allowing crystal violet to be washed out during decolorization step (appears pink/red), harder to treat with antibiotics/ more infectious, more common pathogen

bacterial reproduction

• bacteria reproduce asexually through binary fission

conjugation - way to mutate

• some bacteria exchange some of their DNA through a conjugation tube to another bacterium (pilus)

• usually plasmid DNA not genomic DNA

• plasmid DNA: small, extrachromosomal DNA molecule within a cell, physically separated from chromosomal DNA, replicates independently

Bacterial Groth

• lag phase: bacteria adjust to new environment and grow slowly

• log phase: exponential growth

• stationary phase: bacteria reach carrying capacity of the environment

• death phase: logarithmic death of bacteria as nutrients get used up

endospores- sneaky particles

• small spore that develops in some bacterium, includes genetic material and a protective coat

• initiated in response to nutrient deprivation'

• allows bacterium to produce a dormant and highly resistant cell to preserve the cells genetic material in times of extreme stress

Obtaining energy

• Photosynthesizers

• significant fraction of worlds photosynthesis is carried out by bacteria

• cyanobacteria are blue-green bacteria that contain chlorophyll in their cell membrane

• cyanobacteria are thought to have made earths oxygen

• Chemoautotrophs

• breakdown chemicals found in soil; use those chemicals for nutrition

• bacterias waste products act as fertilizer and helps with agriculture

• handful of soil has up to 10 billion bacterial organisms

• Heterotrophs

• most types of eubacteria are heterotrophic

• together with fungi, serve as primary decomposers for the environment by releasing nutrients back to soil after living things have died

Bacterial interactions

mutualism: interaction where all parties benefit

(ex: nitrogen fixing bacteria in the soil as well as the naturally occurring bacteria in our gut)

parasitism: interaction where one party benefits and other is negatively affected

(bacteria cause disease in many organisms, these bacteria are pathogenic

Pathogenic bacteria

• body = wealthy for bacteria

• bacteria have evolved in various ways of entering the body and taking what they need to survive

• competition for resources in body can result in you being ill

bacteria is harmfull in two ways

1. bacteria can metabolize (weaken) their host by using different parts of the body as their food source

• tuberculosis ie less common bacterial infection of lungs

• mycobacterium tuberculosis is bacteria that uses lung tissue as food source

• warm moist environment allows bacteria to reproduce and populate the lungs

2. bacteria cause disease by secreting chemical compounds called toxins into their environment

• humans affected most when food is not properly prepared / cooked (food poisoning)

• most types of toxin bacteria can be killed by boiling water and cooking food at rec temp

• kitchen and antibacterial products help rid our house of these pests

treatment of bacterial diseases

• antibiotics used to treat bacterial diseases

• work by punching holes in the cell walls of bacteria to allow bodies natural defense to be more effective OR prevent bacteria from reproducing

Antibiotic discovery

• Alexander Fleming noticed fungus growing on a petri plate that was growing bacteria

• bacteria did not grow near fungus

• concluded fungus secreted a substance that killed bacteria

• called secretion penicillin

Antibiotic-resistant bacteria

problem 1

• bacteria multiplies quickly (7-10 day course of antibiotics might not kill all the bacteria)

• bacteria that remain become resistant and may mutate their DNA and reproduce more cells

• new cells are resistant to antibiotic and make it harder to treat infection next time

problem 2

• society related, people not taking prescribed course of pills

• stopping too early gives opportunity for bacteria not yet killed by antibiotic to reproduce and create resistant cells

problem 3

• overuse of antibacterial soaps may do more harm than good

• bacteria found our skin can become resistant to antibacterial chemicals in soap

antibiotic resistance main reasons

• overuse for treatment of things not caused by bacteria

• improper use of prescription by patient

• natural selection

created “superbug” term for bacterium that cannot be destroyed by antibiotics

bacteria and technology

1. food preparation: lactobacillus is used in making pickles. soy sauce, etc

2. bioremediation: cleaning up toxic chemicals in environment by breaking them down into less toxic products

3. biologically safe pesticides: specific to the pest and dont harm plants, humans pollinators, or non-pest species

4. bioengineering: used to reproduce specific genes quickly to mass produce their protein products (insulin)

good things about bacteria

• act as decomposers

• live within our digestive tract (probiotics)

• many foods we eat are processed by bacteria (olives, cheese, buttermilk)

• used in mines to breakdown surrounding rock and leave behind the ore/metal

bacteria classification