Concept explainers
Bacteria are prokaryotic microorganism. They can grow and live in various environments like soil, ocean, inside rocks and animals. Some bacteria are involved in symbiotic relationships and others may cause serious health problems to humans and animals. Gram-negative bacteria use secretion systems (types I to VI) to insert substances or effector molecules (proteins, toxins, or enzymes) into their outer membranes or secrete substances outside of the gram-negative bacterial cell. Type I to VI secretion systems in gram-negative bacteria facilitate various biological activities such as symbiotic interactions, extracellular enzyme secretion, biofilm formation, release of antibiotics, DNA transfer, and transfer of protein molecules into host cells. Secreted substances by secretion systems help the interaction of bacterial with other organisms or their environment.
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Brock Biology of Microorganisms (15th Edition)
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