Bacteria

A. Definition of Bacteria

Bacteria are microscopic living organisms, usually one-celled, that can be found everywhere. They can be dangerous, such as when they cause infection, or beneficial, as in the process of fermentation (such as in wine) and that of decomposition.

Picture of Bacteria

B. Different kinds of bacteria and their gram stain

Gram-positive bacterias : 

• Cocci
• Bacillus

Gram-negative bacterias : 

• Spirillum
• Spirochaete
• Vibrios

C. Diseases that each bacteria cause

Cocci- it causes strep throat, some skin diseases and pneumonia, among many others. They can also cause gonorrhea, meningitis, and skin lesions.

Bacillus-  Escherichia coli do cause disease that's spread typically by eating or drinking contaminated food or water; a typical symptom is diarrhea. Corynebacterium diphtheriae, infects the respiratory tract and causes diphtheria. Diphtheria causes a thick coating on the back of the nose and throat, making it difficult to swallow or breathe, followed by swelling of the neck and potentially death. Bacillus anthracis is the bacteria that cause anthrax.

Spirillum- Rat-Bite fever is one disease caused by spirilla minus

Spirochaete- Treponema pallidum causes the sexually transmitted disease syphilis. Infection typically begins as a single sore at the site of infection. Additional lesions or rashes can develop elsewhere on the body if left untreated. Borrelia burgdorferi is transmitted through the bite of an infected tick and causes Lyme disease. Infection with Borrelia burgdorferi causes a typical "bull's-eye" rash. If left untreated, it can affect your heart and nervous system and cause arthritis.

 
Vibrios-  Vibrio cholera moves in a darting motion by a single flagellum, a whiplike structure, and is the bacteria that causes cholera. Cholera is an intestinal infection that causes severe diarrhea and dehydration.

D. Difference between gram positive and gram negative

Gram-positive bacteria are a class of bacteria that take up the crystal violet stain used in the Gram staining method of bacterial differentiation. The thick peptidoglycan layer in the cell wall that encases their cell membrane retains the stain, making definitive identification possible.

Gram-negative bacteria cannot retain the violet stain after the decolorization step; alcohol used in the decolorization process degrades the outer membrane of gram-negative cells making the cell wall more porous and incapable of retaining the crystal violet stain. Their peptidoglycan layer is much thinner and sandwiched between an inner cell membrane and a bacterial outer membrane, causing them to take up the counterstain (safranin or fuchsine) and appear red or pink.

Gram-positive and -negative cell wall structure
Photo From: Wikipedia