Bacteria and other microorganisms play an essential role in food chains and webs as Decomposers, acting at the end of the food chain. Bacteria and other microorganisms break down energy-rich organic molecules. These chemicals are found in dead plant debris such as leaves and animal excrement, and human remains. Microorganisms are of great significance to foods for the following reasons: (1) microorganisms can cause spoilage of foods, (2) microorganisms are used to manufacture a wide variety of food products, and (3) microbial diseases can be transmitted by foods.Microbiology is important to food safety, production, processing, preservation, and storage. Microbes such as bacteria, molds, and yeasts are employed for the foods production and food ingredients such as production of wine, beer, bakery, and dairy products. Within food plant cropping systems, microorganisms provide vital functions and ecosystem services, such as biological pest and disease control, promotion of plant growth and crop quality, and biodegradation of organic matter and pollutants. Microbes are used to synthesize a number of products valuable to human beings in industries also as beverages and antibiotic. Food chains are important because they show the intricate relationships in ecosystems. It is seen that in food chains, each organism fills a specific niche in an ecosystem. Food chains reveal how each organism depends on someone else for survival.

Microorganisms play an important role in the nutrient cycle. Some bacteria (Plant Growth Promoting Bacteria) secrete phytochemicals and organic acids that are helpful in the growth and development of plants. Microorganisms help maintain soil pH but balance nutrients and minerals. Within food plant cropping systems, microorganisms provide vital functions and ecosystem services, such as biological pest and disease control, promotion of plant growth and crop quality, and biodegradation of organic matter and pollutants. Microbes play a vital role in the cycling of elements like carbon, nitrogen, oxygen, sulphur and phosphorus. Microorganisms used for controlling harmful or pathogenic organisms and pests of plants are called as biocontrol agents. Microorganisms or microbes are microscopic organisms that exist as unicellular, multicellular, or cell clusters. Microorganims are widespread in nature and are beneficial to life, but some can cause serious harm. They can be divided into six major types: bacteria, archaea, fungi, protozoa, algae, and viruses. Microbes permeate the entire food and agricultural process. While the most visible role of agriculture is probably that of producing and delivering food, microbiology is critical to other agricultural sectors as well for production of energy and for bioremediation of agricultural wastes. Microbes can make nutrients and minerals in the soil available to plants, produce hormones that spur growth, stimulate the plant immune system and trigger or dampen stress responses. In general a more diverse soil microbiome results in fewer plant diseases and higher yield. Bacteria decompose dead organic matter and releases simple compounds in the soil, which can be taken up by plants. Nitrogen-fixing bacteria fix atmospheric nitrogen and increase the nitrogen content of the soil, which can be readily absorbed by plants.