Dear Student, 1. Methanogens are commonly found in guts of animals, hydrothermal vents, deep layers of marine sediments and wetlands. 2. For maintaining the continuous culture system (CCS) in the bioreactors, they are continuously and regularly fed with the growth culture medium steadily, maintaining the appropriate cobditions (temp, pH) within the bioreactors. From the other end of the bioreactors, finished products re generated as a result of microbial action is continuously or periodically withdrawn in specified amounts. CCS, is maintained in bioreactors because,the cells can be maintained in a constant physiological state which ensures continuous and regular outflow of desired products from the bioreactors. Regards