For retting of jute, the fermenting microbe used is:

Butyric acid bacteria are used for the retting of jute. Retting is a process that involves the breakdown of the pectic substances that hold the fibers together in the jute plant. Butyric acid bacteria are able to break down these substances, allowing the fibers to be separated and used to make rope, cloth, and other products. So, the correct answer is option D. Notice that the other options are not typically used for retting of jute. Helicobacter pylori is a bacterium that infects the stomach, methanophilic bacteria are able to survive in high-methane environments, and Streptococcus lactis is a bacterium that is commonly found in milk and other dairy products.