Transcript Slide 1
Anoxygenic Phototrophs What are they? Photosynthetic bacteria which use a reducing agent and light energy to build organic material, but do not produce oxygen Use bacteriochlorophyll to accomplish photosynthesis – specific to each type of bacteria Starch (carbohydrate) is a main product Bacteriochlorophyll 6 types: a,b,c,d,e,g C & D are chlorins (1 reduced pyrrole ring), others are bacteriochlorins (2 reduced rings) Chlorin – heterocyclic aromatic ring with 3 pyrroles at the center Photosynthetic pigment related to chlorophyll Chlorin Bacteriochlorin: 2 reduced pyrroles Chlorin: 1 reduced pyrrole Types Proteobacteria, ie: purple bacteria Green sulfur bacteria Green non-sulfur bacteria Heliobacteria Proteobacteria: Purple Bacteria • Gram negative, non-sporing, non acid fast, varying morphologies Pigmented with bacteriochlorophyll a or b & carotenoids (organic pigments) Anoxygenic type II photosynthesis in rxn centers on cell membranes Reducing agent is sulfur or hydrogen CO2 + 2H2S CH2O + H2O + 2S Purple Sulfur Bacteria Chromatiaceae Electron sources: Example: • • Gamma type Red/purple pigmentation from carotenoids Purple Non-sulfur Bacteria Rhodospirillaceae Alpha type Photoorganoheterotroph Use organic e- donors, simple organic molecules (instead of CO2), and light energy for metabolism Genus Magnetospirillum contain tiny chains of magnetite Allow them to sense the Earth’s magnetic field and orient themselves Rhosospirillum http://www.biol.tsukuba.ac.jp/~inouye/ino/bc/purple%20nonsulfur.html Rhodopseudomonas Green Non-sulfur Bacteria Chloroflexus is major representative Filamentous, gliding, and thermophilic Isolated from neutral to alkaline hot springs Resembles green sulfur bacteria in ultrastructure and photosynthetic pigment Metabolism similar to that of purple nonsulfur Green Sulfur Bacteria Have their own phylum: Chlorobi Non-motile, except for one species Can be baccilus, coccus, or spiralus Environment must be free of oxygen Use bacteriochlorophyll c,d,& e in chlorosome vesicles on cell membrane Sulfide is reducing agent Found in black smokers @ 2500 ft. Heliobacteria Use bacteriochlorophyll g on cell membrane Gram negative, endospore forming, obligate anaerobes Common in dry environments, soil Strong N-fixation possible symbiotic relationship with plants Heliobacterium chlorum Heliobacterium modesticaldum http://et.springer-ny.com:8080/prokPUB/chaprender/jsp/showchap.jsp?chapnum=304 Relatedness Determined from 16s rRNA Shows that they are more closely related to nonphotosynthetic subgroups than each other Works Cited Lindquist, John – Dept. of Bacteriology, U. of Wisconsin - http://www.splammo.net/bact102/102pnsb.html MicroBioNet - http://www.microbionet.com.au/chromatiaceae.htm The Prokaryotes – Ed. Martin Dworkin, Department of Microbiology, of Minnesota http://et.springer-ny.com:8080/prokPUB/chaplist_organism_full.htm