Mimm 465 Lecture 4 Moual

Front 1

Normal microflora

Back 1

1. 10^14 bacteria(10 times more than eukaryotic cells)

2. considered as an additional organ

Front 2

Where do microflora come from

Back 2

1. The fetus is sterile, from birth, humans colonized with bacteria, archea, viruses and fungi.

2. Babies delivered by caesarian have different colonization pattern

3. Succession of species:

Facultative anaerobes: Streptococci and bifidobacteria

Obligate anaerobes appears and predominate

Front 3

Metagenomic sequencing

Back 3

1. the study of genetic material recovered from environmental samples

2. 20% of gut bacteria are culturable

Front 4

16S rRNA Gene Sequencing

Back 4

1. Identify microbial species in a complex community by analyzing universal and conserved target 16S rRNA

2. Sequencing of 2 or 3 variable regions of 16S rRNA amplicons necessary for good result

Front 5

Human microbiome diversity

Back 5

50 different bacterial phyla, 3-5 dominant in human

-Interindividual variation

-Intraindividual variation: depends on time, diet, environment

1. Skin: Actinobacteria

2. Vagina: Lactobacillus

3. Gut: Bacteroidetes, Firmicutes

4. Mouth: Streptococcus

Front 6

Gut microiota

Back 6

1. more and more bacteria the distal is the GI tract (Colon 10^12, stomach 10^1)

2. Increasing number from birth to 1 yar old, then number is maintained, composition evolving

Front 7

Influences on Gut microbiota

Back 7

1. Maternal colonization

2. Diet

3. Environmental exposures

4. Antimicrobial therapies

Front 8

Bacteroidetes phylum

Back 8

1. gram negative, anaerobic, rod-shaped

2. 7000 species, in human: Bacteroides, Prevotella and Xilanibacter

3. Degrade a variety of complex glycans

Front 9

Bacteroides species

Back 9

1. Non-flagellated, non-fimbriated

2. Most abundant Gram Negative bacteria of gut

a. Bacteroides vulgatus (31%)

b. Bacteroides thetaiotaomicron (12%)

c. Bacteroides fragilis (5%)

Front 10

Firmicutes phylum

Back 10

Gram positive species, many are spore-forming and anaerobic.

1.Clostridium

2. Ruminococcus

3. Lactococcus

4. Lactobacillus

5. Eubacterium

6. Roseburia

7. Faecalibacterium

Front 11

Other phyla in gut

Back 11

1. Proteobacteria: Escherichia coli, Desulfovibrio(sulfate-reducing bacteria)

2. Actinobacteria: Collinsella species, Bifidobacterium species(probiotics)

3. Verrucomicrobia: Akkermansia muciniphila(mucus degradation)

Front 12

Archea in gut

Back 12

Similar to bacteria, unicellular, no nucleus but have some features similar to eucaryotes (translational machinery)

Front 13

Methanobrevibacter smithii

Back 13

1. Strict anaerobes, up to 10% of microorganisms in distal colon

2.methanogens (produce methane): Methanogenesis is important for preventing accumulation of acids and reaction end-products

-from CO2, H2/Acetate to CH4, CO2

Front 14

Skin microbiome

Back 14

1. 2m2 of diverse habitats

2. bacteria, fungi, viruses, small arthropods like Demodex mites.

3. Skin bacteria: Actinobacteria (most), Firmicutes, Bacteroidetes and Proteobacteria.

Front 15

Distribution of bacteria at different skin sites

Back 15

1. Propionibacterium spp. are dominant at sebaceous sites(oily)

2. Staphylococcus and Corynebacterium are most abundant at moist areas(sole of foot)

3. Actinobacteria, Proteobacteria, Firmicutes, Bacteroidetes on dry areas

Front 16

Propionibacterium acnes

Back 16

1. Gram positive, anaerobic, part of actinobacteria phylum

2. Opportunistic pathogen, involved in acne vulgaris

3. Acne inflammation: caused by surface immunogenic proteins and secreted porphyrins

4. genome: 2.5 million bp, 2333 genes.

5. many gene can degrade host molecules (causing injuries):

lipases, proteases and hyaluronidases

Front 17

Fungi on skin

Back 17

1. 18S RNA shows that 53-80% of fungi belong to Malassezia genus (can grow as branched filamentous hyphae and individual cells)

2. foot sites showed high diversity of genera:

Malassezia, Aspergillus, Cryptococcus, Rhodotorula, Epicoccum.

3. associated with fungal skin diseases like athletes foot and toenail infections.

Front 18

Vaginal microbiome

Back 18

1. Lactobacillus are dominant vaginal bacterial species

-L. iners

-L. crispatus

-L. gasseri

-L jensenii

2. Lactobacilli produce lactic acid as fermentation product, lowers ph to 4.5. also produce bacteriocins and hydrogen peroxide.

Front 19

Nugent score

Back 19

1. 0 score for 30+ lactobacilli, 0 gardnerella, bacteroides, 0 curved gram-negative bacilli

2. 7 and higher consistent with bacterial vaginosis

Front 20

Bacterial vaginosis

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1. Caused by disruption of vaginal ecosystem

2. lactic acid producing bacteria decreased

3. Diversity and numbers of strict anaerobic bacteria increased

-Gardnerella vaginalis, (Actinobacteria phylum, Bifidobacteriaceae familly).

-Atopobium vaginae, (Actinobacteria phylum, Gram +).

-Mobiluncus species, (Actinobacteria phylum, Gram +).

-Prevotella bivia, (Bacteroidetes phylum, Gram -).

Front 21

Oral microbiome:

Back 21

1. Supragingival: Streptococci. High sugar diet, dysbiosis leads to Streptococcus mutans

2. Subgingival(btw teeth and gingiva): more diverse and anaerobic. Dysbiosis leads to gingivitis and periodontitis(caused by porphyromonas gingivalis)

Front 22

Dental plaque

Back 22

Example of biofilm

1. Primary colonizers: Streptococci.

2. Bridge: Fusobacterium nucleatum

3. Late colonizers: Adhere to bridge

Front 23

Oral streptococci

Back 23

1. S. salivarius, S. gordonii, S. mitis, S.mutans, S. sanguis

2. 80% of bacteria are streptococci in oral cavity

3. primary colonizers: bind to enamel coated with salivary proteins and coaggregate.

4. S. mutans responsible for dental caries. It is acidogenic and acidophilic

5. can cause infective endocarditis if access to blood stream

Front 24

Prophyromonas gingivalis

Back 24

1. gram-negative, strict anaerobe found solely at subgingival sites

2. proteolytic(extracellular proteases --> gingipains)

3. has characteristic black pigment when grown on blood agar. Hemin is essential to growth