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Flashcards in (2) Microbiology of animals Deck (15):

What factors (±5) influence microorganisms on an individual?

Temp, pH, nutrient supply, immune syst., env.


What are commensals and what are two types of commensals?

Commensals are microorganisms often found in healthy individuals; they colonize w/o an infection.
Can be:
-beneficial: provides nutrients, protection and teaches immune system
-parasitism: under stressful conditions, become pathogenic


What are the two general types of herbivores gastrointestinal tract conformation?

Foregut fermenters: (before stomach)
Hindgut fermenters: uses cecum/large intestine as fermentation chamber


Describe foregut fermentation process (5)

Rumen anaerobic env. w/ cellulase producing microorganisms (ruminococcaceae); cellulose digested; sugars fermented into Volatile Fatty Acids (absorbed as main energy source), H2 & CO2; methanogens use acetate (VFA) to produce CH4; Microbial mass digested (source of amino acids)


What are the main VFAs produced in herbivores?

Acetate, propionate, butyrate


What is added to ruminants to increase VFA production?

Monensin -> inhibits methanogens


Describe hindgut fermentation

Cellulase producing microorganisms (ruminococcaceae) present in caecum; VFAs produced and absorbed; microbial biomass not digested


How can hindgut fermenters eat their microbial biomass?

By eating their fecal pellets = COPROPHAGY


Which between hinggut and foregut fermenters have a higher dietary requirement?

hindgut since do not eat their microbial biomass


Give two characteristics of the skin and its microbiome

Commensals secrete bacteriocin
Sebaceous glands secrete antimicrobial compounds


What can happen in the oral cavity? How, by whom?

Dental plaque (Streptococcus mutans synthesizing extracellular matrix) -> generates anaerobic environment -> lactobacili grow and produce lactic acid -> solubilizes Ca (demineralizes tooth) => CAVITIES


How is the upper respiratory tract different than the lower respiratory tract from the microbiology perspective?

Upper: Nose & nasopharynx orgs. similar to mouth; may harbor potential pathogens
Lower: contains low number of microorgs b/c of mucus & ciliated cells


How does the microbiome changes along the gastrointestinal tract? (3)

Stomach: acidic => most killed
Duodenum: high enzymatic activity => most killed
Colon: harbors anaerobes & facultative anaerobes; complex carbs digested, VFAs produced -> absorbed (by host) or fermented to CO2 & H2; methanogens; production of amino acids & vitamins


Describe the microbiome of the genitourinary tract (2)

Genitourinary tract men + urinary tract women usually free of microorganism (due to flushing)
Vaginal tract has acidic conditions -> lactobacili grows -> protects against intruders


What are considered as sterile zones in the human body? (4)

Spinal fluids
Internal organs
Internal tissues