CONTENTS INTRODUCTION CHAPTER 1 THE DIVERSE WORLD OF BACTERIA 10 CHAPTER 2 THE IMPORTANCE DANGERS AND USES OF BACTERIA 24 CHAPTER 3 FEATURES AND TYPES OF ALGAE 45 CHAPTER 4 FEATURES AND TYPES OF PROTOZOA 77 79 CONCLUSION GoSSARY For MORE INFORMATION BIBLIOGRAPHY 82 85 INDEX 86
n the 1700s a Dutch draper made a startling discovery Anthony van Leeuwenhoek had a passion for grind ing glass into very precise magnifying lenses He used these lenses to look close up at such things as the scrapings from his teeth He wrote I then most always saw with great wonder that in the said matter there were many very little living animalcules tiny ani mals very prettily a moving Leeuwenhoek became the first person to see and describe bacteria Since that time scientists have identified and classified thou sands of minuscule living creatures Three important categories of microorganisms bacteria algae and protozoa will be explored in this book Bacteria are prokaryotes Prokaryotes don t have a real nucleus the brain of a cell the way a eukaryotic cell such as that of an animal has Bacteria are much more primi tive in design But their simplicity also allows them to survive in many different environ ments For instance some bacteria need Oxygen some would be killed by it Others called facultative anaerobes can live with or without it Salmonella one facultative anaer obe can cause food
INTRODUCTION Some bacteria are vitally important to life Saprophytic bacteria for instance help organic matter rot and turn into rich fertile soil for growing new crops Other bacteria turn milk into cheese and yogurt And yet bacteria can also cause danger ous diseases Some bacteria even create toxins that poison their victims such as Clostridium tetani which produces tetanus Scientists have used bacteria to create bac terial antibodies to develop vaccines both to fight disease causing bacteria and the toxins they produce Algae are eukaryotes complex cells that contain chlorophyll This lets them make their own food through photosynthesis but they are simpler than plants Unlike bacte ria all of which are single celled algae can range in size Many such as dinoflagellates are single celled Others are gigantic such as the Nereocystis luetkeana kelp which can grow to be 115 feet 35 meters tall The word algae comes from a Greek word meaning seaweed and indeed seaweed is an important cate gory of algae But algae can also be found in freshwater on rocks and even on animals Many algae are beneficial for example car rageenan made from red algae is often used
