Chapter 1 BACTERIA Kingdom Eubacteria True Bacteria Bacteria

Chapter 1 BACTERIA

Kingdom Eubacteria (True Bacteria) Bacteria are located everywhere – air, water, land, and living organisms including people. General Characteristics: 1. All are unicellular (one-celled structural level) 2. All are prokaryotic - cells that lack nucleus (no nuclear envelope) (PRO = NO nucleus) 3. All have cell walls – NO cellulose in cell walls 4. Can live in both aerobic (with O 2) and anaerobic (without O 2) environments

General Characteristics • Bacteria are prokaryotic organisms (Kingdom: Monera), without cell defined organelles like mitochondria, Golgi bodies, Endoplasmic reticulum. , etc • Microscopic, unicellular, they may occur singly or aggregations to form colonies. • They posses rigid cell wall. Cell wall is made up ofpeptidoglycan (Mureins) and Lipo polysaccharides. • Absence of well defined nucleus. i. e. , DNA is not enclosed in a nuclear membrane. • Ribosomes are scattered in the cytoplasmic matrix and are of 70 S type. • The plasma membrane is invaginated to form mesosomes. • Most of the bacteria are heterotrophic. Some bacteria are autotrophic, possesbacteriochlorophyll, which is not in plastids. Instead it is found scattered. • Motile bacteria posses one or more flagella. • The common method of multiplication is binary fission. • True sexual reproduction is lacking, but genetic recombination occurs by conjugation , transformation and transduction

5. Bacteria are much larger in size than viruses.

6. Bacteria usually have one of three different cell shapes: Coccus (Sphere-shaped) Bacilli (rod-shaped) Spirillum (Spiral-shaped) Ex: Streptococcus Ex: Lactobacillus Ex: Spirillium

What shape? bacillus spirillum coccus bacillus spirillum

Cytoplasm Genetic Material Cell Wall Cell Membrane Example: E. coli Flagella

Causes Disease by: 1. Destroying cells of infected organisms by breaking the cells down for food.

2. Releases toxins (poisons) which destroy cells of infected organism. 3. Must have access to new hosts to spread.

Different Hosts

General Characteristics of Prokaryotic Organisms • Prokaryotes – Most diverse group of organisms – Habitats • From Antarctic glaciers to thermal hot springs • From colons of animals to cytoplasm of other prokaryotes • From distilled water to supersaturated brine • From disinfectant solutions to basalt rocks – Only a few capable of colonizing humans and causing disease

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General Characteristics of Prokaryotic Organisms • Reproduction of Prokaryotic Cells – All reproduce asexually – Three main methods • Binary fission (most common) • Snapping division • Budding

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General Characteristics of Prokaryotic Organisms • Arrangement of Prokaryotic Cells – Result from two aspects of division during binary fission • Planes in which cells divide • Separation of daughter cells

General Characteristics of Prokaryotic Organisms

General Characteristics of Prokaryotic Organisms • Endospores – Produced by Gram-positive Bacillus and Clostridium – Each vegetative cell transforms into one endospore – Each endospore germinates to form one vegetative cell – Constitute a defensive strategy against hostile or unfavorable conditions – Serious concern to food processors, health care professionals, and governments

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Modern Prokaryotic Classification • Currently based on genetic relatedness of r. RNA sequences • Three domains – Archaea – Bacteria – Eukarya

• • • Survey of Archaea Common features – Lack peptidoglycan – Cell membrane lipids have branched hydrocarbon chains – AUG codon codes for methionine Classified in three phyla: Crenarchaeota, Euryarchaeota, Korarchaeota Reproduce by binary fission, budding, or fragmentation Most are cocci, bacilli, or spiral forms; pleomorphic forms exist Not known to cause disease

Survey of Archaea • Extremophiles – Require extreme conditions of temperature, p. H, and/or salinity to survive – Prominent members are thermophiles and halophiles

Survey of Archaea • Extremophiles – Thermophiles • DNA, RNA, cytoplasmic membranes, and proteins do not function properly below 45ºC • Hyperthermophiles – require temperatures over 80ºC

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Survey of Archaea • Extremophiles – Halophiles • Inhabit extremely saline habitats • Depend on greater than 9% Na. Cl to maintain integrity of cell walls • Many contain red or orange pigments; require protection from visible and UV light • Most studied – Halobacterium salinarium

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Survey of Archaea • Methanogens – Largest group of archaea – Convert carbon dioxide, hydrogen gas, and organic acids to methane gas – Convert organic wastes in pond, lake, and ocean sediments to methane – Some live in colons of animals; one of primary sources of environmental methane – Have produced ~10 trillion tons of methane that is buried in mud on ocean floor

Survey of Bacteria • Deeply Branching and Phototrophic Bacteria – Deeply branching bacteria • Scientists believe these organisms are similar to earliest bacteria • Autotrophic • Live in habitats similar to those scientists think existed on early Earth • Aquifex – considered to represent earliest branch of bacteria • Deinococcus – has outer membrane similar to Gram-negatives, but stains Gram-positive

Survey of Bacteria • Deeply Branching and Phototrophic Bacteria – Phototrophic bacteria • Phototrophs that contain photosynthetic lamellae; autotrophic • Divided into five groups based on pigments and source of electrons for photosynthesis – – – Blue-green bacteria (cyanobacteria) Green sulfur bacteria Green nonsulfur bacteria Purple nonsulfur bacteria

Survey of Bacteria • Low G+C Gram-Positive Bacteria – Mycoplasmas • Facultative or obligate anaerobes • Lack cell walls • Smallest free-living cells

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Survey of Bacteria • Gram-Negative Proteobacteria – Alphaproteobacteria • Nitrogen fixers – Azospirillum – Rhizobium • Nitrifying bacteria – Nitrobacter • Purple nonsulfur phototrophs

Survey of Bacteria

D. Importance: 1. Beneficial a. breakdown dead matter to recycle nutrients into ecosystem - decomposers

Example: Compost piles need microorganisms (ex. bacteria) to decompose (breakdown) matter.

b. dairy industry - bacteria in yogurt, sour cream and cheese 2: 08 minute video

c. Oil spills - bacteria can digest small oil spills

d. Genetic engineering— Recombinant/synthetic DNA (Ex: Insulin)

e. symbiotic relationship - E. coli and our intestines-both organisms benefit Example: E. coli in intestines helps us digest food and make vitamins (such as Vitamin K and B-complex) In return, human intestines provide food and shelter for bacteria. (This strain of E. coli is different from the E. coli strain that causes food poisoning. )

Harmful : a. human diseases – strep throat, tuberculosis, tooth decay and bad breath, anthrax, plague, tetanus, food poisoning Anthrax Tetanus Strep Throat

b. food spoilage and poisoning – caused by Salmonella and Staphylococcus c. Treated with antibiotics – Some bacteria are able to survive in presence of antibiotics that kill other bacteria – antibiotic resistant bacteria Note: This is why doctors tell you to take the entire amount of medicine given even if you start to feel better because if not, bacteria will have the chance to evolve and become antibiotic resistant.

Salt Lake City Kingdom Archaebacteria a. First known prokaryotes. Archaebacteria (archae=ancient) b. Live in very harsh environments (known as extremophiles)– high salt content, hot temperatures, acidic or alkaline environments Hydrothermal vents Geyser

c. Live in intestines of animals, especially cows and other grazing animals – methanogens Produce methane gas – greatly affects our atmosphere by combining d. Same size and with O 2 to make CO 2 for shape as Eubacteria, photosynthesis but different biochemical makeup methanogenic archaebacteria