ABSTRACT
According to current scientific thought, the universe is approximately 15 billion years old and the Earth is approximately 4.5 billion years old. Fossil microorganisms have been found in rocks 3.3 to 3.5 billion years old (1). They were the first forms of life to appear on Earth. They were likely the blue-green algae, which contain a pigment enabling them to use the sun’s radiation to synthesize carbohydrates. They contain deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) similar to all other forms of life today. They also contain the enzymes, proteases, amylases, lipases, and other enzymes required to hydrolyze proteins, starches, and lipids necessary for recycling. This was very fortunate because microorganisms have been required ever since as recyclers of organic matter. Without them, the Earth would be a giant dumping ground containing all forms of organic matter and dead bodies. Initially, microorganisms consumed organic matter, including dead organisms, as food for their own energy requirements. Later, after plants and animals evolved, microorganisms consumed dead plants and animals and became able to invade plants and animals, causing disease-in some ways the first stage in recycling.
