Kingdom Bacteria Dr Yogesh Anna Dushing Head Dept

Kingdom Bacteria Dr. Yogesh Anna Dushing Head, Dept. of Botany RFNS, Senior Science College, Akkalkuwa KBCNMU, Jalgaon

What are bacteria? Single celled organisms E. Coli O 157: H 7 can make you very sick. Very small Need a microscope to see Can be found on most materials and surfaces Billions on and in your body right now This E. coli helps you digest food. Streptococcus can cause strep throat.

Bacteria are prokaryotic and unicellular. Bacteria have cell walls. Bacteria have circular DNA called plasmids Bacteria can be anaerobes or aerobes. Bacteria are heterotrophs or autotrophs. Bacteria are awesome!

Bacteria History Bacteria were first observed by Anton Van Leeuwenhoek in 1676. The term ‘bacteria’, Greek for ‘small stuff’ was first used in 1838.

Bacterial History Robert Koch and Louis Pasteur were the first to discover that bacteria caused many diseases (mid 19 th century) The first antibiotic used to treat bacterial disease was made by Paul Ehrlich in 1910. It was used to treat syphilis.

Morphology Bacterial cells are prokaryotic, lacking a nucleus and complex organelles. They have a cell membrane and a cell wall made up of peptidoglycan which is a combo of protein and carbohydrate, making it different from the cell walls of Archaea and Eukaryotes such as plants or fungi.

Two Types of Bacterial Cell Walls Gram Positive Thick Cell Wall (Less Common) Gram Negative Thin Cell Wall with lipoproteins (More Common)

The Gram stain, which divides most clinically significant bacteria into two main groups, is the first step in bacterial identification. Bacteria stained purple are Gram +. Bacteria stained pink are Gram –.

In Gram-positive bacteria, the purple crystal violet stain is trapped by the layer of peptidoglycan which forms the outer layer of the cell. In Gram-negative bacteria, the outer membrane of lipopolysaccharides prevents the stain from reaching the peptidoglycan layer. The outer membrane is then permeabilized by acetone treatment, and the pink safranin counterstain is trapped by the peptidoglycan layer.

The Gram stain has four steps: 1. crystal violet, the primary stain: followed by 2. iodine, which acts as a mordant by forming a crystal violet-iodine complex, then 3. alcohol, which decolorizes, followed by 4. safranin, the counterstain.

Is this gram stain positive or negative? Identify the bacteria.

Morphology Continued Bacteria use flagella or pili for movement and interaction with the environment. Shapes: bacillus – rod coccus – sphere spirillus – spiral vibrio – boomerang spirochaetes – tight coils

Morphology Continued Prefixes are added to the shapes to indicate the living arrangement of the bacteria. Prefixes: Strepto – chain of bacteria Staphylo – grape like cluster

How do bacteria eat? Some make their own food from sunlight—like plants Photosynthetic bacteria Some are scavengers Share the environment around them Example: The bacteria in your stomach are now eating what you ate for breakfast Some are warriors (pathogens) Harmless bacteria on the stomach lining They attack other living things Example: The bacteria on your face can attack skin causing infection and acne USDA NIFSI Food Safety in the Classroom © University of Tennessee, Knoxville 2006 E. Coli O 157: H 7 is a pathogen

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 USDA NIFSI Food Safety in the Classroom © University of Tennessee, Knoxville 2006

Bacteria can reproduce sexually by conjugation or asexually by binary fission.

Bacterial Reproduction Bacteria usually reproduce asexually using the process of binary fission (p. 424 in your textbook).

Endospore Bacteria can survive unfavorable conditions by producing an endospore.

Sexual Reproduction? ? ? Some bacteria reproduce sexually by exchanging some of their DNA through a conjugation tube to another bacterium. Usually plasmid DNA, not genomic DNA.

Bacteria and Technology 1) Food Preparation: Lactobacillus is used in making pickles, soy sauce, cheese, wine, yoghurt, etc… 2) Bioremediation: Cleaning up toxic chemicals in the environment by breaking them down into less toxic products

Bacteria and Technology 3) Biologically Safe Pesticides: they are specific to the pest and do not harm plants, humans, pollinators or similar non-pest species. 4) Bioengineering: Used to reproduce specific genes quickly to mass produce their protein products (i. e. insulin).

V. Economic Importance A. Nitrogen Fixation - convert N 2 gas into Ammonia B. Recycling of Nutrients (decomposition) - breakdown dead organic matter and return nutrients to the soil

The nodules on soybean roots contain Rhizobium bacteria that convert nitrogen gas into ammonia. Symbiosis: plant gains useable source of nitrogen/ bacteria use sugars supplied by the plant

THE NITROGEN CYCLE

C. Food and Medicines 1. vinegar, yogurt, cheese, pickles 2. antibiotics ex. streptomycin

VI. Disease Causing Agents A. It is estimated that half of all human disease is caused by bacteria B. Examples of bacterial disease: 1. tuberculosis 2. strep throat 3. syphilis 4. tetanus

What are some common pathogens? Pathogenic E. coli (like O 157: H 7) E. coli O 157: H 7 Found in ground beef, contaminated fruits and vegetables Salmonella Found in raw meats, poultry, eggs, sprouts, fruit and vegetables Listeria Found in deli foods, lunch meats, smoked fish and vegetables USDA NIFSI Food Safety in the Classroom © University of Tennessee, Knoxville 2006 Listeria

Examples of Pathogens Salmonella Staphylococcus aureus E. coli O 157: H 7 What shape are these bacteria? Cocci, bacilli, or spiral? Campylobacter jejuni USDA NIFSI Food Safety in the Classroom © University of Tennessee, Knoxville 2006

How can I avoid pathogens? Wash your hands often so you won’t transfer bacteria to your mouth or food Warm water with soap for 20 seconds, rub hard between fingers and nails USDA NIFSI Food Safety in the Classroom © University of Tennessee, Knoxville 2006

How can I avoid pathogens? Cook food thoroughly to kill any pathogens that may be in your food Store food properly to limit pathogen growth Cold temperatures (40 F) USDA NIFSI Food Safety in the Classroom © University of Tennessee, Knoxville 2006