cryophilic (psychrophilic): live in arctic seas below 0
° (make antifreeze)
thermophilic
: live in hot springs above 100° and frequent "black smokers" in the ocean depth
mesophilic
: live on or in man
halophilic
: live in 10 to 12 M NaCl
obligate anaerobes
: killed by O2; ferments in absence of O2
aerotolerant anaerobe (indifferent)
: ferments in presence or absence of O2
facultative
: respires with O2, ferments in absence of O2
obligate aerobes
: requires O2, cannot ferment
heterotrophic
: bacteria which require most nutrients
autotrophs
: photosynthetic bacteria; require only water, light, and some salts
mesotrophs
: requires carbon source (glucose), few other nutrients, and ion or O2 as an e- acceptor
Energy Sources
ATP: from substrate level phosphorylation and from e- transport (oxidative phosphorylation)
If given a choice, bugs prefer to ferment rather than respire
Fermentation
: occurs in absence of O2 (ie glycolysis); use organic compounds as both e- donors and acceptors in a series of partial oxidations
Glu
Þ 2lactic acids via glycolysis
Glu
Þ lactic acid (+1ATP) via pentose pathway
Consequence
: low ATP yield, acid production, toxic end products; grows slow; C-rich; nrg starved
To respire, bugs have to figure out how to deal with the toxic problems of living in presence of O2
Toxic problems due to O2
FADH + O2
Þ H2O2 (hydrogen peroxide)Þ O2 + OH- + OH·
Cyto C + O2
Þ O2- (superoxide anion)Þ HO2· or H2O2 (results in OH· as above)
Heme + O2
Þ O2- (superoxide anion)Þ HO2· or H2O2 (results in OH· as above)
Radicals attack ether linkages between FAs in memb and disrupts cell memb
Þ toxic!
3 critical enzymes:
superoxide dismutase
: 2 O2- + 2 H+
Þ H2O2 + O2
catalase
: H2O2 Þ H2O + ½ O2
peroxidase
: H2O2 + NADH + H Þ 2 H2O
Respiration
: a full range of respiratory capabilities exists:
NAD
Þ FAD Þ bactoquinone (ubiquinone) Þ cyt B Þ cyt C Þ cyt A Þ O2
Some only have FAD, some have the full complement, and some are in between
Consequence
: high ATP yields, no acids, often more biosynthetic
Important Bacteria
lactic acid bacteria (lactobacilli): in vagina (1st to coat us when born); catalase-, no cytochromes, no heme, have a peroxidase; homofermentative rods, survive low pH; big in dairy industry- yogurt, buttermilk, cheese; cocci are streptococci (good type); leuconostoc is heterofermentative in sauerkraut
staphylococcus
: from beards and mustaches, facultative, catalase+, homofermentative but also respires; cause boils, foreign body antigens; can cause food poisoning (exotoxin)
clostridia
: motile, anaerobic spore former, ferments; can cause botulism
bacillus
: motile, aerobic spore former, respires; in hair as well; can cause anthrax
enterobacteriaceae
: some are motile, nonspore forming, facultative; big in medical industry
E. Coli
: aerobic gram(-) rod
Streps
: facultative, hemolysis (a and b (bad)), catalase negative