MCB 3020C Lecture Notes - Lecture 25: Green Sulfur Bacteria, Root Nodule, Rhizobia
Document Summary
Microbes live with macroorganisms and other microorganisms in long-term relationships called symbioses: mutualisms are interactions where both organisms interact to the benefit of both, most mutualistic organisms evolved together (coevolution) over millions of years, symbioses between microorganisms. In freshwater there are microbial mutualisms called consortia: these consortia are found in stratisfied sulfidic lakes, green sulfur bacteria are obligate anaerobic phototrophs that make up nearly 70 percent of the bacterial biomass in these lakes. The mutualistic relationship between legumes, which are plants with seeds in pods, and nitrogen-fixing bacteria is one of the most important symbiosis known. Examples of legumes include soybeans, clover, alfalfa, beans, and peas. Rhizobia are the best-known nitrogen-fixing bacteria engaging in these symbioses. Rhizobia are a group of species of alphaproteobacteria or betaproteobacteria that can grow freely in soil or infect leguminous plants. Nodulated legumes grow well in areas where other plants would not. After infection, rhizobia rapidly divide in the root nodule.
