Mlt Microbiology (Week 02)

Front 1

Autotroph's

Back 1

Do not cause human disease! Their carbon source is CO2 and their energy source is from photosynthesis, or oxidation of non-organic compounds.

Front 2

Heterotroph's

Back 2

Heterotroph's are clinically significant. Their carbon and energy source are often the same thing, carbohydrates (-ose,) though many can also use CO2.

Front 3

Oxidation vs Fermentation

Back 3

Oxidation, or aerobic respiration, is the release of electrons as pyruvate is converted to an organic acid and CO2. Drives the synthesis of ATP. Kreb's cycle.

Fermentation uses the Embden-Meyerhof pathway, where homolactic acid bacteria produce lactic acid. Anaerobic fermentation results in stronger, more stable acid end products than aerobic fermentation.

Front 4

Bacterial Nutritional Requirements

Back 4

Bacteria require:

• Water
• Carbohydrates (#1 source of energy, mostly glucose.)
• Nitrogen (Can be atmospheric, mostly from proteins such as amino acids, because they need to make their own proteins.)
• Inorganic Ions (Na+ regulates osmodic pressure or ion pumps. Mg+ and Ca+ are enzyme activators. Ca+ also is critical in spore producing bacteria, and helps with heat and chemical resistance, and prevents drying out. Fe+ is used in aerobic respiration, and is a key component in certain toxins. PO4- aids in DNA & ATP synthesis, lipid membranes, etc.)
• Vitamins

Front 5

Holophytic vs Holozoic

Back 5

Holophytic organisms are bacteria. Nutrients are processed outside of the organism and absorbed inside.

Holozoic organisms are us! Obviously nutrients are processed and absorbed inside the organism.

Front 6

Broth Media

Back 6

A liquid growth media, used less than solid media.

Trypticase Soy Broth (TSB) generally supports the growth of most organisms, looks like flat amber beer, made up of proteins, glucose, salt, and water.

It's growth patterns are: diffuse (uniform throughout,) sedimentary (settles at bottom,)

flocculent (puff balls throughout tube,) and pellicle (scum floating at top.)

Thioglycollate Broth is made up of proteins, glucose, sodium thioglycollate, thioglycollic acid, L-cystine, and an O2 indicator (resazurin, which is pink/red in presence of oxygen, and methylene blue, which is blue in the presence of oxygen.)

This media creates redox potential and effects solubility of oxygen. Autoclaving creates an oxygen gradient, with most O2 at the top, and none at the bottom.

Obligate aerobes will be at the top, obligate anaerobes at the bottom, facultative anaerobes diffused with more towards the top, aerotolerant diffused throughout, and microaerophile in one specific spot in the top/center.

Front 7

Solid Media

Back 7

Agar is used as a solid growth media in dishes or in a tube as a slant.

Minimal media has no proteins, but has glucose and salts, and is not often used clinically.

Enriched media, such as SBA supports the growth of most organisms. SBA differentiates hemolitic patterns. Alpha is incomplete, Beta is complete, and Gamma is none. Enriched media will not grown fastidious organisms.

Highly enriched media, such as chocolate agar, contains hemolyzed blood, and will grow fastidious organisms. It contains Factor X (hemin) and Factor V (NAD. It can donate electrons in redox.)

Selective/Differential media, such as MacConkey Agar and Mannitol Salt Agar, differentiates or selects different organisms.

MacConkey agar will grow GNB and inhibits everything else. Lactose fermenting bacteria will drop the pH and turns the media pink. Nonlactose fermentors use the proteins and turn the media yellow.

MSA has a higher salinity than normal and selects for Staph. Some staph will ferment the mannitol and turn the media yellow.

Front 8

Transport Media

Back 8

Can either be nutritive (actively supports growth) or non-nutritive (only keeps organism from dying until it can get plated.)

A black tube has charcoal, which absorbs toxins or antibodies.

Front 9

Aerobic, Anaerobic, and Facultative Anaerobic

Back 9

Aerobic organisms require oxygen, while anaerobic organisms do not. Facultative anaerobes don't care, and make up the majority of bacteria.

Front 10

Binary Fission & Exponential Growth

Back 10

Binary fission is an asexual reproduction in which bacteria copy DNA and then divide in half. Growth is exponential, doubling the population each generation.

Front 11

Calculating Bacterial Growth Rates

Back 11

Nt = No X 2n (Nt = # of organisms after specific amount of time. No = starting population. _n = # of generation times in a given period.)

Front 12

Bacterial Growth Phases

Back 12

Phases of growth are the lag phase, the log phase, the stationary phase, and the death phase.

Lag: bacteria are maturing and adapting to environment.

Log: growth rate exceeds death rate.

Stationary: growth and death rates are equal.

Death: bacteria die.

Graphed, looks like a curve, starts at bottom, rises up, and ends back at bottom.