There are different microbes in different parts of the body such as skin, gut, reproductive tract etc. The most important microbes found in human body are gut microflora. The stomach microflora includes streptococcus, staphylococcus etc. These bacteria are able to survive the acidic conditions of the stomach. The intestinal flora is enterobacteriaceae. These florae are unable the development and the utility of the gut. These microbes help the gut in preventing other microbe’s colonization. They also secrete certain substances that are required for the digestion of the food. Rhizobium bacteria are found in leguminous plants such as pea, bean, etc. This bacterium helps in absorption of nitrogen required by the plants. Viruses are used as a vector for transmission of required gene during recombinant DNA Technology.