oxygen requirements for growth of microorganisms

catalase test

presence of the enzyme catalyst by noting whether bubbles are released when hydrogen peroxide is added to a culture sample

aerobic and anaerobic environments

can be found in diverse niches throughout nature, including different sites within and on the human body

obligate aerobes

depend on aerobic respiration and use oxygen as a terminal electron acceptor

they cannot grow without oxygen

facultative anaerobes

show better growth in the presence of oxygen but will also grow without it

microaerophiles

needs oxygen to grow, albeit at a lower concentration than 21% oxygen in air

peroxidase, superoxide dismutase and catalase

main enzymes involved in the detoxification of the reactive oxygen species

superoxide dismutase

usually present in a cell that can tolerate oxygen

capnophile

an organism that requires a higher than atmospheric concentration of carbon dioxide to grow

artificial fertilizers

provide nitrogen and phosphorus, key limiting nutrients, to crop plants, removing the normal barriers that would otherwise limit the rate of growth