MMG301 1nd Edition Lecture 27Outline of Last Lecture I. BiotechnologyOutline of Current Lecture II. Hierarchy III. Interactions Current Lecture-hierarchy-Populations of organisms doing similar metabolism constitute groups called guilds-Mixtures of different guilds conducting complementary physiological processes in a habitat interact to form microbial communities-Microbial communities then interact with communities of macroorganisms and the physicochemical environment to define the entire ecosystem-interactions-mutualism-bidirectional; some reciprocal benefit accrues to both partners. Examples: lichen-symbiosis: fungus (mycobiont) and algae or cyanobacteria phycobiont); rumen-microbe symbiosis (cow and anaerobic microbes), nitrogen-fixing Rhizobium-legume root nodule symbiosis-Some interactions of microbes in the human body (e.g. intestinal microbes) may be considered mutualism by some-commensalism-Unidirectional: one partner benefits while the other is neither benefited nor harmedThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.-Examples: many interactions in microbial biofilms and indigenous normal microflora of the healthy human body-predation-Predator engulfs, attacks and kills the prey. Examples: density-dependent predation of bacteria by protozoans in aquatic and soil habitats-parasitism-Parasite infects host, who is harmed. Examples; bacteriophage infecting bacteria, human infectious diseases-amensalism-Unidirectional release of an inhibitory compound by one organisms that harms asusceptible microorganism. Example: production of antibiotics or bacteriocins.; also called antagonism-competition-The demand for a food resource exceeds the supply: a major cause of restricted microbial productivity in soil and marine ecosystems (limitation of energy-yielding organic
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