Microbial Growth and Culturing



organism that grows in acidic (low pH of usually 2 or below) conditions

aerotolerant anaerobe

organism that thrives in the absence of oxygen but is not harmed by the presence of oxygen


mixture of two sugars that produces a gelatin-like surface and provides a base for a variety of different growth media


organism that grows in basic (high pH of usually 8.5–11) conditions


microbe that lives in conditions of high hydrostatic pressure

binary fission

process by which cells divide asexually


type of cell division in which the daughter cell develops from a bud growing off the mother cell


visible mass of microbes originating from the replication of a single microbe

colony-forming unit (CFU)

each viable microorganism in a sample that is capable of enough replication to form a visible colony

differential media

media containing ingredients that allow for distinguishing bacteria with a visual cue


toughened, condensed form of cell that can withstand harsh environmental conditions and is formed completely within the bacterial cell and is released when the cell dies


spore that begins to form within the bacterial cell and the final encapsulation step occurs by budding


describes an organism that is able to tolerate an environment with or without specific properties

facultative anaerobe

organism capable of aerobic and anaerobic respiration

generation time

amount of time it takes for a population to double in size

hydrostatic pressure

pressure a fluid exerts on points below its surface


substance containing nutrients that support the growth of cells


organism that grows at temperatures between 20°C and 45°C


organism that requires oxygen but can only survive in low-oxygen conditions


organism that grows in neutral pH (between 6.5–7.5) conditions


describes an organism that has a strict requirement for specific factors in order to survive

obligate aerobe

organism that requires oxygen for survival

obligate anaerobe

organism that dies in the presence of oxygen

pour plate

microbe sample that is mixed with the liquid agar before pouring the plate


organism that grows best at temperatures below 20°C

selective media

media designed to support the growth of specific microbes while preventing others from growing

serial dilution

stepwise reduction of a culture population into increasing proportions of a solution


formation of spores

spread plate

microbe sample that is placed in contact with the solid agar surface


organism that grows best between 50°C and 60°C and can grow at hot temperatures of up to 120°C