Green Sulfur and Nonsulfur Bacteria

Green Sulfur Bacteria & Nonsulfur Bacteria

TAXONOMY

Kingdom: Bacteria

Phylum: Chlorobi

Class: Chlorobia

Order: Chlorobiales

Family: Chlorobiaceae

Genus: Chlorobium

Chlorobium

General Morphology

• Gram-negative
• spherical, ovoid, straight or curved rod-shaped
• 0.3-1.1 um wide & 0.4-3 um long or, sometimes, much longer.
• streptococci form filaments; curved rod-shaped strains form long spirals
• Nonmotile
• Color can be either grass-green or chocolate brown.
• Storage materials: polyphosphate and polysaccharides

Photo-synthetic pigments

cytoplasmic membrane & chlorosomes

cytoplasmic membrane

Physiology

• Tropismphototrophic & Photolithoautotrophic growth
• Obligately anaerobic
• 20-35`C
• Ammonia is used as nitrogen source; molecular nitrogen is fixed by many strains
• Major carotenoid: Chlorobactene
• Bacteriochlorophylls c, d or e
• + small amounts of bacteriochloro-phyll a
• Sulfide Oxidation:
• In sulfide-reduced media, thiosulfate = electron donor substrate while sulfur = electron donor.
• In the presence of reduced sulfur compounds and bicarbonate, simple organic substrates can be photoassimilated

Habitat/Ecology:

Hydrogen sulfide-containing mud and water of freshwater, brackish water and marine environments.

What is their

significance?

• Essential for the natural cycling of sulfur.
• Contribute to the biogeochemical cycling of carbon, nitrogen, and sulfur.

Possibility of Biofuel use in the future?

Representative Species

• Chloroflexus aurantiacus
• Oscillochloris

TAXONOMY

• Kingdom: Bacteria
• Phylum: Chloroflexi
• Class: Chloroflexi

General Morphology

• Gram-negative
• Filaments of indefinite length; cells 0.5 to 1.0 um in diameter, 2 to about 6 um in length
• Motile by gliding; no flagella
• 0.01-0.04 um/s
• Cell division by fission
• No internal proliferations of cell membrane, except mesosomes; chlorosomes present when anaerobically grown.
• Thin sheath sometimes present.

Physiology

• Primarily photoheterotrophic -> secondarily photoautotrophic -> chemoheterotrophic
• Carbon sources utilized: eg. acetate, glycerol, glucose, pyruvate and glutamate.
• Anaerobic and facultatively aerobic (some)
• Bacteriochlorophylls a and c present under anaerobic conditions
• Carotenoids include B- and y-carotene and hydroxy- and oxo-derivative and glycosides of both.

Habitat/Ecology:

• Alkaline hot springs
• Forms a symbiotic relationship with various strains of cyanobacteria. In exchange, the cyanobacteria provide various organic byproducts

What is their

significance?

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Representative Species

• http://web2.uwindsor.ca/courses/biology/fackrell/Microbes/10550.htm
• http://www.life.umd.edu/labs/delwiche/PSlife/lectures/GreenSulf.htmlImage: http://www.profimedia.si/picture/green-sulfur-bacteria-chlorobium/0077204304/
• http://www.bio.ku.dk/nuf/research/sulfur.htmhttp://www.genomenewsnetwork.org/articles/07_02/tepidum.shtml
• http://web2.uwindsor.ca/courses/biology/fackrell/Microbes/10675.htm
• http://microbewiki.kenyon.edu/index.php/Chloroflexus_aurantiacus
• http://www.its.caltech.edu/~skopf/ESE_Bi168/files/Xiong_2000_Molecular%20Evidence%20for%20the%20Early.pdf

References

(cc) image by nuonsolarteam on Flickr

What about them?

• Prevents membrane fouling potential in water treatment plants

A possible link between chloroplasts and photosynthetic bacteria?

(cc) image by nuonsolarteam on Flickr