Host-Microbe Relationship

Symbiosis

association of organisms of different species

Mutualism

+/+, 2-way obligatory interaction

Commensalism

+/0, 1-way non-obligatory interaction

Predation

+/- antagonistic interaction

Parasitism

+/- antagonistic interaction of coexistence

Coevolution

pressure on each other to evolve

Termites and Intestinal protist and bacteria is what type of relationship

mutualism

What is the relationship of termites and intestinal protist and bacteria

Termites can ingest wood, but can not break them down

Intestinal protists and bacteria can not ingest wood, but can digest wood

Aphids

Pests of plants that feed on plant sap and makes 10 aa that not in the sap and aphids cant make

Buchneara aphidicola

Gram-negative bacterial endosymbionts that live in the bacteriocytes of aphids

contains the genes for aa that aphids can’t synthesize, but lacks the genes for aa that are produced by aphids and lacks genes common in free-living bacteria

Commensals feed on ___

Food not consumed by the host

Example of commensal

microbes on the skin that feeds on metabolic products secreted from the pores

Epibiotic

attachment to the surface of something to release hydrolytic enzymes to release the prey cytoplasm

Endobiotic

Invading cytoplasm

Sequence Bdellovibrio cycle

l. Rotates and bores holes

ll. Attachment to the surface

III. Separates into flagellated progeny

lV. Inhibit DNA, RNA, and protein synthesis

V. Grows into a filament

ll > l > lV > V > lll

Parasite can either ___ or ___ at the expense of the host

harm or live

The host-pathogen relationship depends on

pathogenicity and resistance or susceptibility of host to pathogen

Pathogenicity

the ability of pathogen to damage host

Microbial cells are

normal inhabitants in and on the body, forming a symbiotic relationship with the host

Microbial gene products

are essential to our well-being. Humans rely on the gene products of the microbiota

Early colonization can come from

vaginal birth, cesarean delivery and breast milk

Vaginal Birth

exposure to microbes from the birth canal

Cesarean delivery

exposure from initial caretakers (nurses and doctors)

Breast milk

selects for non-pathogenic bacteria with Bifidobacteria

Bifidobacteria

transports polymeric sugars in breast milk directly across their PM (sugars that the infant can’t metabolize)

The fermentation of these sugars provides infants with calories, lowers gut pH, and limits the growth of pathogens

Antimicrobial characteristics of skin

keratinocytes, lysozymes, tight junctions, dry, low pH, hyperosmotic, slouching

Staphylococcus epidermidis

normal skin bacterium that may prevent the colonization of pathogenic bacteria

Microbiome of the oral cavity

Organisms must be able to adhere properly and resist mechanical removal

The oral cavity is a ___ environment for microbes because ____

optimal; of water, nutrients, pH, and temperature

Colonization of the oral cavity

within hours after birth with mainly aerobes

after teeth appears there are more spaces thus more anaerobes appear

Antimicrobial characteristics of the oral cavity

lysozyme and lactoperoxidase (oxygen radicals)

Streptococcus salivarius

plays a role in preventing oral infections

Streptococcus mutans

Glucosyltransferase converts glucose to dextran to form dental plaque, leading to calculus (mineralized), anaerobic bacterial species colonize these plaques and undergo lactic acid fermentation to decalcify enamel resulting in cavities

Antimicrobial characteristic of stomach

pH of 2-3

Helicobacter pylori

invasion of the gastric mucosa of the stomach wall, which protects the stomach from gastric acid, resulting in gastric ulcers

Duodenum and Jejunum

Gastric juices are still present, along with bile and pancreatic secretion, causing a low pH, thus there are few microorganism present

Ileum

more alkaline thus more organism

Bififobacterium bifidum

microorganism in the ileum

The large intestine has the ____ microbial community

largest with 400 different species

Vitamin B₁₂ and vitamin K production

In the large intestine, essential (not made in humans), absorbed in the gut

Flatus

In the large intestine (intestinal gas), some foods are metabolized by fermentative bacteria or methanogenic bacteria

Antimicrobial characteristics of the Upper resp tract

mucus, ciliated epithelial cells, macrophages, lysozyme

Upper respiratory tract includes the

nasal passages and the throat

Streptococcus pneumoniae

normal inhabitant in many people; those with a weak immune system are more result to pneumonia, which can spread to other parts of the body

Lower respiratory tract includes the ___ and should be

trachea, bronchi, and lungs; be microbe free

Kidney, ureters, and the urinary bladder should be

microbe free

Distal urethra in males and females often have

Gram-negative facultative aerobe

If there is a pH change in the distal urethra in males and females

It can result in overgrowth and UTI

Lactobacillus acidophilus

In the female genital tract, ferment glycogen to lactic acid causing pH of vagina and cervix to be 4.4-4.6, preventing the growth of pathogens

Functional core microbiome

A group of microbes that provides activities and metabolites required for health and homeostasis of host

Your body weight is related more closely to # of calories ___ and not

absorbs; # of calories consumed

Human cells are very good at taking up ___, but they need microbiota to ___

simple sugars and a few polysaccharides; convert food into forms we can use

The breakdown of complex polysaccharides results in

monomer fermentation into short chain fatty acids (SCFAs)

Butyrate

the primary source of calories for intestinal epithelial cells

No weight gain

Propionate

release of intestinal hormones that suppress hunger

no weight gain

Acetate

precursor for lipid synthesis in the liver and fat cells

weight gains