Microorganisms

Microbes

• too small to be seen with the naked eye

• aggregations or colonies can be seen without the aid of a microscope

Microbes

• are found almost anywhere

• are more abundant than any other life form

• they are forms on which all others depend.

Recycle elements required for life

• N - Nitrogen

• O - Oxygen

• P - Phosphorus

• S - Sulfur

• C - Carbon

Microbes produce

• food

• fuel

• air

4 major categories

• bacteria

• fungi

• protists

• viruses

Pathogens

• disease causing agents• AIDS - Acquired Immune

Deficiency Syndrome• Botulism - food poisoning• Tuberculosis• Polio

Pathogens

• Typhoid FeverSyphilis

Disease

• Microbes cause disease by directly damaging tissues and weakening bodily functions or by producing toxins that do.

Pathogenic microbes

• the proportion of pathogenic microbes on earth is very small

Producers

• produce carbohydrates

• break down starch into sugar

• convert sugars into alcohol

Water Dwelling microbes

• algae and bacteria

• largest producers of carbon containing compounds through photosynthesis

Some microbes

• are unable to take in Carbon Dioxide from the air.

• They get Carbon from bicarbonate in the water

Ion

• an atom that carries a positive (+) or a negative (-) charge

• carries the charge because it has gained or lost one or more electrons

Microbes use CHO’s (carbohydrates)

• synthesized during photosynthesis (Ps) to make cell structures and as an energy source

• Provide food for larger organisms

• Replenish Oxygen supply

Single Celled Fungi

• Yeasts

• Producers in wine making, bread baking or beer brewing.

• Convert sugar to alcohol in fermentation process

Cheese Making

• bacteria convert lactose (milk sugar) to lactic acid

Contribute to production

• of food and other substances by their enzymes

Enzymes

• organic molecules that speed up biochemical reactions without being used up or becoming part of the end product.

• A catalyst - causes a reaction to take place

Examples

• foods

• medicines

• vitamins

• leather processing

• textile production

Decomposers and Recyclers

• world’s greatest recyclers

• Keep elements like C and N cycling through the environment

• Used to treat sewage, clean up toxic wastes, processing materials

Recyclers

• more than one type of bacterium is needed to convert atmospheric N into a form useable by plants.

• Requires three different chemical reactions.

Production through decomposition

• Methane - decomposition of organic matter

• Methanogens - swampy areas, land fills, digestive tract of ruminants.

Production through decomposition

• Linen fabric is made from flax stems

• Stems are immersed in water

• Bacterium digests pectin that makes the stalks stiff

Linen Fabric Production

• remainder is washed dried and spun into thread and then woven into fabric

Basic features of MO’s (microorganisms)

• 4 major groups

–bacteria, fungi, protists, viruses

• Viruses are not made up of cells and are not considered organisms by many microbiologists.

Bacteria, fungi and protists

• have a cellular structure, a membrane surrounding cytoplasm

Protists

• have an inner compartment nucleus

• DNA in non circular chromosomes

• unicellular or multicellular

• protozoans, algae, others resemble fungi

Fungi

• have cellular structure

• non circular chromosomes

• in fungi with many cells, walls between cells are sometimes not complete

• cytoplasm and nuclei can stream from one cell to another within slender filaments of cells called hyphae

Fungi

• have cellular structure

• non circular chromosomes

• in fungi with many cells, walls between cells are sometimes not complete

Fungi

• cytoplasm and nuclei can stream from one cell to another within slender filaments of cells called hyphae

Yeasts

• unicellular

Molds

• have many cells

Fungi

• visible to the naked eye

–mushrooms

–bracts

–puffballs

–toadstools

Viruses

• not cellular

• particles made up of nucleic acid and protein

• Include short length of DNA or RNA - never both!

Viruses

• On their own they cannot reproduce at all

• Inject their nucleic acid into a host cell

Viruses

• Injected DNA or RNA tricks host cell into using the viruses chemical instructions to make substances needed for the virus to reproduce

Viruses

• Host cell is damaged when newly reproduced virus particles break out of cell (lyse)

What does it take to keep a microbe alive?

• Lots of variation in environmental and nutritional condition requirements

Nutritional needs

• energy sources

• basic elements to make and replace cell structures

Heterotrophs

• organic compounds to meet energy needs

• Carbon source to make own organic molecules

• get energy from sugars, starches, fats and other organic compounds

Saprobes

• live in soil, get nutrients from dead organic matter

• Clostridium botulinum - botulism, food poisoning

Autotrophs

• build their own organic compounds if they have an available source of inorganic compounds

Phototrophs

• generate their own food using sunlight and inorganics such as carbon dioxide

Chemotrophs

• don’t require sun

• get energy from carbon dioxide, salts, water and others

Nitrosomonas bacteria

• live in soil

• use ammonia (NH4) as energy

hetero, chemo and phototrophs

• use energy from the environment

• light and heat energy from the sun

• energy stored in chemical bonds or organic or inorganic compounds

Six major elements in cells

• C - Carbon• H - Hydrogen• N - Nitrogen• O - Oxygen• P - Phosphorus• S - Sulfur

Also -

• K- potassium

• Ca - Calcium

• Fe - Iron

• Na - Sodium

Trace elements

• Co - Cobalt• Zn - Zinc• Mo - Molybdenum• Cu - Copper• Mn - Manganese• Si - Silicon

hetero, chemo, and phototrophs

• some require organic compounds that they cannot make themselves

• must be added to culture in isolation - called growth factors

• Vitamins

Microbial nutrition in the lab

• hardened gel - called agar

• nutrients are added to the agar

• called growth medium

Pure Cultures

• Grow only one kind of microbe

• Must use aseptic technique to avoid contaminating the culture

Mixed cultures

• may be grown on selective media

• nutritious to some and not to others

• allows researchers to isolate a certain species of microbe

Environmental conditions for microbial growth

• Oxygen - require Oxygen - aerobic

• some microbes live in Oxygen poor environment - anaerobic

Anaerobic processes

• fermentation

• O2 atoms in compounds are rearranged and made available to microbes

Anaerobes

• made up of molecules containing O2 but don’t produce free or gaseous O2

Anaerobes

• free oxygen may be toxic

pH• favorable range - 6-8

• acidophillic - acid loving used in mining operations.

• Oxidize Cu, Fe and other metal sulfides in the process of pulling out the ore

Temperature

• 37 degrees C (98 degrees F)

• some can survive a wide range of temps ranging from 32 degrees F to 212 degrees F

Moisture

• dissolve minerals, ions, gases and organic compounds

Moisture

• in extremely dry conditions microbes form spores that hold the genetic information and some cytoplasm.

Spores

• when moisture is added the spore breaks down and bacteria resume their normal activity

Salt concentrations

• most microbes can’t survive in high salt or sugar concentrations

Microbe sex

• or - how microbes reproduce

• process is known as binary fission

Binary fission

• increase in size, extend cell wall material down center and divide in two.

Speed of reproduction

• in 24 hours some species of bacteria can go from one cell to 16,777,216 cells

Single celled protists

• have a more difficult reproductive process

• DNA in nucleus is fist replicated then divided into 2 identical sets (mitosis)

continued

• cytoplasm of cell then divides to form 2 identical daughter cells.

Fungi• reproduce by a number of

methods

• yeasts - budding - cytoplasm pinches off on one side of cell to form a new cell

• or fuses with another cell

Fungi

• after fusing with a cell, nuclei fuse and divide to form spores when released from the cell

Yeast

• spores become cells on their own

Many celled fungi• hyphae or filaments fuse to form

sporagia

• cases in which nuclei from 2 parent molds excahange pieces of chromosomes

• a type of sexual reproduction

Microbial populations

• can and do change over time

• bacterial populations adapt to changes in the environment

Mutations

• change in DNA

• alteration of base sequence

• occur spontaneously

Genetic recombination

• exchanging or recombining genetic information

• two bacterial cells become connected by a thin strand of cell material called a pilus

Genetic recombination

• DNA can travel from one microbe to another

• gene enters a microbe that did not initially have it