General characteristics:

• Singled-celled organism (unicellular)
• No nucleus
• Prokaryotic (haven’t membrane nuclei)
• Smallest and simplest kind of living thing
• More monerans than any other kind of organism
• All bacteria reproduce asexually by binary fission

This kingdom is subdivided into:

1.      Archaebacteria

Found in anaerobic and extreme conditions (high salt concentrations, high temperatures and a low pH). The extreme and anaerobic condition is believed to be the conditions on the primitive Earth. Scientists believe that all life kingdoms are descended from this group.

Archabacteria’s phyla are based on their habitats.

• Anaerobic Methanogens – live in the gut of animals, swamps and marshes and produce all of the methane gas found in the Earth’s atmosphere.
• Halophiles – high salt concentrations, found in salt lakes such as the Dead Sea.
• Thermophiles – high temperatures, such as hot springs.

2.     Eubacteria

This group includes the traditional bacteria and is the largest and most successful of the two kingdoms. Eubacteria species have allowed scientists to separate them into six phyla.

3 kinds of bacteria based on the shape

1. Cocci living as separate cells are called monococci, pairs are called diplococci, chains are called streptococci, and grapelike clusters are called staphlococci.
2. Bacilli also exist as single cells, pairs (diplobacilli), or chains (streptobacilli).
3. Spiral bacteria exist only as single cells.

Staphyllococcus bacteria

An example is bacteria that cause strep throat.

E.coli bacteria

Certain bacteria that live in your stomach are bacilli bacteria

Spiral shaped

Best known cause serious disease

Some Characteristics of the Cyanobacteria

• Contain Chlorophyll a and carotenoids, plus the phycobilins (proteinaceous photosynthetic pigments) phycocyanin and phycoerythrin (c f. Rhodophyta), found in thylakoids
• Have cell walls of peptidoglycan, often with a mucilaginous sheath
• The carbohydrate stored is glycogen
• No flagella, but some exhibit gliding movements
• Some fix nitrogen in specialized cells called heterocysts

Filaments of Nostoc commune forming a gelatinous ball

* Spirulina contains 70% its dry weight as protein

* Spirulina grows well in saline and alkaline ponds in arid environments

* Native peoples near Lake Chad (Africa) and Lake Texcoco (Mexico) have traditionally used Spirulina as food

* Spirulina is grown commercially in California, Israel, Japan, Thailand & Mexico

Monera Nutrition (making food)

• Most eubacteria are heterotrophs and obtain energy by breaking down organic molecules from their environment. Some are parasites, absorbing nutrients from living organisms. Others are saprobes, decomposing dead organic matter.

• Some eubacteria are autotrophs and produce their own organic compounds. (example- cyanobacteria (blue-green bacteria) are photoautotrophs using light for energy, but they lack true chloroplasts.

Base on energy and carbon source, organism devided into:

Respiration

• Aerobes, if respiration requires oxygen.

Obligate aerobes, if oxygen is absolutely necessary for survival.

• Anaerobes, if respiration without oxygen.

Obligate anaerobes, if presence of oxygen kills some bacteria. (example- Clostridium botulinum produces

toxins that can cause an extreme form of food poisoning called botulism.)

Facultative anaerobes, can survive with or without oxygen.

Reproduction

Bacteria reproduce asexually and divide by the process of binary fission. In binary fission, the parent cell divides into two offspring cells that are completely identical. There is no exchange of genetic material so the process is asexual. (example- E. coli produces between 10 and 100 million bacteria in 12 hours.)

When conditions begin to fail, either through decrease of food or space, or cooler temperatures, some bacteria take part in a type of sexual reproduction called conjugation. In conjugation the two cells join briefly and one cell donates some DNA (called plasmid) to the other one. Sexual reproduction combines genetic information from two different individuals and increases variation.

When growth conditions become extremely unfavourable, many gram positive bacteria form structures called endospores. Endospores are DNA and a small amount of cytoplasm enclosed in a tough cell wall. They are resistant to extremes in temperature, drying, and harsh chemicals.

Role of Monera

Role in cycling : Monera are chiefly decomposers. Life on earth would have run out were it not for the decomposition of dead matter by bacteria.

Role in symbiosis : Some forms show symbiotic relationship such as

* Rhizobium in the roots of leguminous plants

* Nostoc and Anabaena in coralloid roots of Cycas, which fix free atmospheric nitrogen into nitrates

* Escherichia coli which inhabit the colon of the human intestine and help in synthesizing Vitamin B.

* Anaboena azollae in leaves of the water fern Azolla

* Nostoc in apogeotropic roots of Zamia

* Nostoc and other genera in some lichens

* Nostoc in leaves of some tropical angiosperms

* Richelia in some pennate diatoms

* Nostoc in Anthoceros (Hornworts)

* Gloeocapsa in polar bear hairs

Pathogenic forms : Some Monera are also pathogenic, producing common diseases like:

• Salmonella typhosa, the causes Typhoid
• Mycobacterium tuberculosis, the causes TBC,
• Shigella dysentriae, the cause of dysentery
• Clostridium tetani, the cause of tetanus

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