Week 7 Flashcards
Actinobacteria:The High G + C Gram-Positive Bacteria
How are actinomycetes classified
16S rRNA analyses
Characteristics of actinomycetes
Aerobe
What do these bacteria form
Hyphae and asexual spores
Where do the spores form and are they motile
Form on the end of hyphae and can be motile with flagella or immobile
Family and Genus
Order Corynebacteriales
Family Mycobacteriaceae
Genus Mycobacterium
Corynebacteriales filaments
Contain aerobe, catalase positive, straight or slightly curved rods.
Sometimes branched
What happens to the filament when the culture is disturbed
Fragment into single cells
How does the growth of Corynebacteriales look
- Grow slowly on solid media
- may take up to 40 days for visible colony to appear
Corynebacteriales
Cell walls
- High lipid content
- Contain waxes consisting of 60-80 carbons arranged into chains- mycolic acids
Mycolic acid
Fatty acids with hydroxyl group on the 𝛽-carbon and an aliphatic carbon chain on the 𝛼-carbon
What makes Corynebacteriales acid-fast
Presence of mycolic acids and other lipids outside the peptido layer
What are mycobacteria classfied as
Saphrophytes but also known as pathogens
TB
Streptomycetales
- strict aerobe
- form aerial hyphae with chains of conidia
- substrate hyphae dont fragment into single cells
Where are the chains of conidia formed
Within thin membrane-like sheaths
CSSCPMNH
How are streptomyces classified
- colour of aerial and substrate mycelia
- spore arrangement
- spore surface characteristics
- carb utilization
- production of antibiotics
- melanin synthesis
- nitrate reduction
- hydrolysis of urea
Where do Streptomyces occur
Occurs in soil
What causes the smell of wet soil
Geosmin
Role of Streptomycetes
Mineralisation of pectin, lignin, keratin etc
What do Streptomycetes produce
Antibiotics such as amphotericin B, streptomycin etc
Streptomyces
somaliensis
Pathogen in humans. Causes actinomycetoma,
an infection under the skin that causes ulcers and swelling.
Streotomyces gardneri
Aerial hyphae is white and weakly exposed
