What are examples of two helpful Bacteria and two harmful Bacteria?

Expert Answers

An illustration of the letter 'A' in a speech bubbles

Lactobacillus acidophilus is a helpful bacterium. Lactobacillus acidophilus is a type of probiotic found in yogurt. It resides in the digestive system and aids in digestion. During digestion, L. acidophilus releases hydrogen peroxide and lactic acid. This prevents other, harmful bacterium from living in the digestive system.

Streptococcus pneumoniae is a harmful bacteria strain that can cause pneumonia.  

Escherichia coli (E. coli) is a bacterium that can be helpful or harmful to humans. How E. coli affects humans depends on where the bacteria are located in the human body. 

When E. coli is helpful:

E. coli is helpful to humans when it is located in the large intestine. Here E. coli aids in the production of vitamin K2 and helps humans digest and absorb food. E. coli may even prevent other harmful bacteria from becoming established in the human body. 

When E. coli is harmful:

If ingested (eaten), E. coli can be harmful and cause infection within humans. Infection caused by the ingestion of E. coli may cause severe abdominal cramps, fever, and diarrhea that usually becomes bloody within the first 24 hours.

Approved by eNotes Editorial Team
An illustration of the letter 'A' in a speech bubbles

Examples of helpful bacteria:

Lactobacillus Bacteria: There are several different species of this type of bacteria. These include: Lactobacillus acidophilus, Lactobacillus reuteri, and Lactobacillus planatarum. They are gram-positive, rod shaped bacteria. Lactobacillus bacteria are beneficial in several ways:

  • They make up parts of the normal human oral, intestinal, and vaginal flora. 
  • They are able to ferment lactose to lactic acid. This makes them important as a preservative and in yogurt production.

Streptomyces Bacteria: There are several different species of this type of bacteria. These include: Streptomyces aureofaciens, Streptomyces rimosus, and Streptomyces griseus. They are gram-positive, filamentous bacteria. Streptomyces bacteria are beneficial in the following ways:

  • They are important in the decomposition of organic substances in soil.
  • Some species are used in the production of antibacterial and antifungal substances.

Examples of harmful bacteria: 

Helicobacter pylori: These bacteria colonize the lining of the stomach. They are gram-negative rod shaped bacteria. H. pylori bacteria cause stomach ulcers by producing ammonia and cytotoxins which damage the lining of the stomach.

Clostridium tetani: These bacteria enter the body through wounds. They are gram-negative rod shaped bacteria. These bacteria produce the disease tetanus. Tetanus causes muscle spasms and death from respiratory failure. 

 

Approved by eNotes Editorial Team

We’ll help your grades soar

Start your 48-hour free trial and unlock all the summaries, Q&A, and analyses you need to get better grades now.

  • 30,000+ book summaries
  • 20% study tools discount
  • Ad-free content
  • PDF downloads
  • 300,000+ answers
  • 5-star customer support
Start your 48-Hour Free Trial