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Its composition is distinct from that of the cytoplasmic membrane - among other things , the outer leaflet of the outer membrane of many Gram-negative bacteria includes a complex lipopolysaccharide whose lipid portion acts as an endotoxin - and in some bacteria such as E. coli it is linked to the cell 's peptidoglycan by Braun 's lipoprotein .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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