11.1 anaerobic chemotrophs, 11. 5 aerobic chemoorganotrophs

Corynebacterium

widespread in nature gram positive pleomorphic rods (often club shaped) coryneforms and diphtheroids generally facultative anaerobes - some are strict aerobes many species reside harmlessly in the throat toxin producing strains of C. diphtheria can cause disease diphtheria

Mycobacterium

widespread in nature include harmless saprophytes - live on dead and decaying matter, as well as pathogens stain poorly - waxy lipid in their unusual cell wall, special procedures can be used to increase penetration of certain dyes once stained, resist destaining - acid fast - important step in identifying them usually pleomorphic rods often occur in chains that sometimes branch or bunch together to form cordlike groups several species important for their effect on human health - M. tuberculosis -> tuberculosis - M. leprae -> Hansens disease (leprosy) more resistant to disinfectants than most other vegetative bacteria resistant to many of the most common antimicrobial meds.

fermentation

anaerobic chemoorganotroph how energy is obtained - producing ATP only by substrate level phosphorylation glucose (energy source) --> pyruvate (terminal electron acceptor) --> lactic acid

Clostridium

genus that are gram positive rods can form endospores common soil inhabitants vegetative cells live in anaerobic microenvironments created when aerobic organisms consume available O2 endospores can tolerate O2 and survive for long time by withstanding levels of heat, drying, chemicals, and irradiation that would kill vegetative bacteria endospores germinate when conditions are favorable --> resulting vegetative bacteria multiply ferment many compounds - sugars and cellulose some species can ferment amino acids by an unusually process that oxidize one amino acid, using another as a terminal electron acceptor --> generates a variety of foul smelling end products associated with rotting flesh

Enterobacteriaceae (enterics or enterobacteria)

gram negative rods name reflects the fact that most reside in intestinal tract of humans and other animals - some thrive in rich soil Enterobacter, Klebsiella, and Proteus species, most strains of E. coli Life threatening systemic disease: typhoid fever caused by Salmonella enterica serotype Typhi and both the bubonic and pneumonic forms of plagues facultative anaerobes that ferment glucose if motile - have peritrichous flagella can be distinguished using biochemical tests - serological tests that detect differences in cell walls, flagella, and capsule coliforms - group of bacteria that ferment lactose - intestinal inhabitants such as E. coli that are easy to detect in food and water E. coli presence shows a possible health risk - fecal borne pathogens might also be present

Psuedomonas

gram negative rods that have polar flagella often produce pigments most are strict aerobes, some can grow anaerobically if nitrate is available as a terminal electron acceptor do not ferment oxidase positive - helps distinguish them from enterbacteriaceae, including E. coli diverse biochemical capabilities - some can metabolize more than 80 different substrate - unusual sugar, amino acids, and compounds with aromatic rings play an important role in degradation of many synthetic and natural compounds that resist breakdown by most other microorganisms - ability to carry out some of these degradations is encoded by plasmids species are widespread - inhabiting soil and water most are harmless but some cause disease in plants and animals P. aeruginosa - common opportunistic pathogen, can grow in nutrient poor environments (water used in respirators) and resistant to many disinfectants and antimicrobial meds - hospitals must be careful to prevent it from infecting patients

Propionibacterium

gram positive pleomorphic (irregular shaped) rods that produce propionic acid as their primary fermentation end product also ferment lactic acid, extracting energy from a waste product of other bacteria valuable to the dairy industry - fermentation end products are important in Swiss cheese production propionic acid gives typical nutty flavor of cheese and CO2 produces the holes found in intestinal tract and in anaerobic microenvironments on the skin

Streptococcus

lactic acid bacteria cocci that grow in chains of varying lengths inhabit the oral cavity, normally as part of normal microbiota some are pathogens - S. pyogenes (group A strep) --> pharyngitis (strep throat) and other diseases S. pyogenes: B-hemolytic - important characteristic used to distinguish it from most members of normal microbiota

Lactobacillus

lactic acid bacteria rod shaped bacteria that grow as single cells or loosely associated chains common members of the microbiota in mouth and healthy vagina during childbearing years. break down glycogen that has been deposited in vaginal lining in response to estrogen --> resulting low pH helps prevent vaginal infections often present in decomposing plant material, milk, and other dairy products important in production of fermented food

Enterococcus

lactic acid bacteria species that typically inhabit the intestinal tract of humans and other animals.

Lactococcus

lactic acid bacteria species used by the dairy industry to produce fermented milk products such as cheese and yogurt

Micrococcus

obligate aerobe gram positive cocci found in soil and on dust particles, inanimate objects, and skin. often airborne - easily contaminate bacteriological media typically form pigmented colonies - helps identify them M. luteus - yellow Like Staph, can tolerate dry conditions and can grow in salty environments such as 7.5% NaCl.

obligate aerobes

obtain energy using respiration exclusively, none can ferment

Chemoorganotrophs

oxidize organic compounds such as glucose to obtain energy those that grow anaerobically often use sulfur or sulfate as a terminal electron acceptor.

facultative anaerobes

preferentially use aerobic respiration if O2 is available can ferment as an alternative

lactic acid bacteria

produced by gram positive bacteria as a major end product of their fermentative metabolism Streptococcus Enterococcus Lactobacillus Leuconostoc most can grow in aerobic environments but they only ferment easily distinguished from other bacteria that grow in O2 - lack the enzyme catalase

sulfur compounds (sulfate and sulfur reducing bacteria)

when used as terminal electron acceptors - become reduced to form hydrogen sulfide - compound responsible for rotten egg smell of many anaerobic environments and a problem to industry - reacts with metals, corroding pipes and other structures reduced by prokaryotes -> essential component of the cycle generally live in mud that has organic material and oxidized compounds The hydrogen sulfide produced --> mud and water turns black when it reacts with iron molecules Desulfovibrio - gram negative curved rods used by some representatives of archaea as terminal electron acceptors - generally do not inhabit the same environments as their bacterial counterparts most bacteria are either mesophiles or thermophiles - most known archaea are hyperthermophiles